From a2ef9967fe9e3e0d0353c434d7388c13b85c4944 Mon Sep 17 00:00:00 2001
From: penguindark <57967770+penguindark@users.noreply.github.com>
Date: Thu, 25 Mar 2021 16:53:13 +0100
Subject: [PATCH] examples: add .obj viewer as a sokol example (#9456)

---
 .github/workflows/ci.yml                      |   1 +
 cmd/tools/modules/testing/common.v            |   6 +
 examples/sokol/02_cubes_glsl/cube_glsl.v      |  34 +-
 .../sokol/03_march_tracing_glsl/rt_glsl.v     |  34 +-
 examples/sokol/04_multi_shader_glsl/rt_glsl.v |  68 +-
 examples/sokol/05_instancing_glsl/rt_glsl.v   |  36 +-
 .../sokol/06_obj_viewer/assets/models/v.mtl   |  20 +
 .../sokol/06_obj_viewer/assets/models/v.obj_  | 194 ++++++
 examples/sokol/06_obj_viewer/gouraud.glsl     | 108 ++++
 examples/sokol/06_obj_viewer/obj/obj.v        | 587 ++++++++++++++++++
 examples/sokol/06_obj_viewer/obj/rend.v       | 249 ++++++++
 examples/sokol/06_obj_viewer/obj/struct.v     |  98 +++
 examples/sokol/06_obj_viewer/obj/util.v       |  43 ++
 examples/sokol/06_obj_viewer/show_obj.v       | 332 ++++++++++
 examples/sokol/06_obj_viewer/v.mod            |   0
 15 files changed, 1724 insertions(+), 86 deletions(-)
 create mode 100644 examples/sokol/06_obj_viewer/assets/models/v.mtl
 create mode 100644 examples/sokol/06_obj_viewer/assets/models/v.obj_
 create mode 100644 examples/sokol/06_obj_viewer/gouraud.glsl
 create mode 100644 examples/sokol/06_obj_viewer/obj/obj.v
 create mode 100644 examples/sokol/06_obj_viewer/obj/rend.v
 create mode 100644 examples/sokol/06_obj_viewer/obj/struct.v
 create mode 100644 examples/sokol/06_obj_viewer/obj/util.v
 create mode 100644 examples/sokol/06_obj_viewer/show_obj.v
 create mode 100644 examples/sokol/06_obj_viewer/v.mod

diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 8726a1761b..a138d057d0 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -196,6 +196,7 @@ jobs:
               examples/sokol/04_multi_shader_glsl/rt_glsl_puppy \
               examples/sokol/04_multi_shader_glsl/rt_glsl_march \
               examples/sokol/05_instancing_glsl/rt_glsl_instancing \
+              examples/sokol/06_obj_viewer/gouraud \
               ; do \
                  echo "compiling shader $f.glsl ..."; \
                  sokol-tools-bin-pre-feb2021-api-changes/bin/linux/sokol-shdc --input $f.glsl --output $f.h --slang glsl330 ; \
diff --git a/cmd/tools/modules/testing/common.v b/cmd/tools/modules/testing/common.v
index b3802dd712..0d8c0ece79 100644
--- a/cmd/tools/modules/testing/common.v
+++ b/cmd/tools/modules/testing/common.v
@@ -135,6 +135,12 @@ pub fn new_test_session(_vargs string) TestSession {
 		skip_files << 'examples/sokol/03_march_tracing_glsl/rt_glsl.v'
 		skip_files << 'examples/sokol/04_multi_shader_glsl/rt_glsl.v'
 		skip_files << 'examples/sokol/05_instancing_glsl/rt_glsl.v'
+		// Skip obj_viewer code in the CI
+		skip_files << 'examples/sokol/06_obj_viewer/show_obj.v'
+		skip_files << 'examples/sokol/06_obj_viewer/obj/obj.v'
+		skip_files << 'examples/sokol/06_obj_viewer/obj/rend.v'
+		skip_files << 'examples/sokol/06_obj_viewer/obj/struct.v'
+		skip_files << 'examples/sokol/06_obj_viewer/obj/util.v'
 	}
 	if testing.github_job != 'ubuntu-tcc' {
 		skip_files << 'examples/wkhtmltopdf.v' // needs installation of wkhtmltopdf from https://github.com/wkhtmltopdf/packaging/releases
diff --git a/examples/sokol/02_cubes_glsl/cube_glsl.v b/examples/sokol/02_cubes_glsl/cube_glsl.v
index e057f1de27..4c233b872d 100644
--- a/examples/sokol/02_cubes_glsl/cube_glsl.v
+++ b/examples/sokol/02_cubes_glsl/cube_glsl.v
@@ -264,33 +264,33 @@ fn init_cube_glsl(mut app App) {
 		// Face 0
 		Vertex_t{-1.0, -1.0, -1.0, c,  0, 0},
 		Vertex_t{ 1.0, -1.0, -1.0, c,  d, 0},
-    Vertex_t{ 1.0,  1.0, -1.0, c,  d, d},
-    Vertex_t{-1.0,  1.0, -1.0, c,  0, d},
+		Vertex_t{ 1.0,  1.0, -1.0, c,  d, d},
+		Vertex_t{-1.0,  1.0, -1.0, c,  0, d},
 		// Face 1
 		Vertex_t{-1.0, -1.0,  1.0, c,  0, 0},
-    Vertex_t{ 1.0, -1.0,  1.0, c,  d, 0},
-    Vertex_t{ 1.0,  1.0,  1.0, c,  d, d},
-    Vertex_t{-1.0,  1.0,  1.0, c,  0, d},
+		Vertex_t{ 1.0, -1.0,  1.0, c,  d, 0},
+		Vertex_t{ 1.0,  1.0,  1.0, c,  d, d},
+		Vertex_t{-1.0,  1.0,  1.0, c,  0, d},
 		// Face 2
 		Vertex_t{-1.0, -1.0, -1.0, c,  0, 0},
-    Vertex_t{-1.0,  1.0, -1.0, c,  d, 0},
-    Vertex_t{-1.0,  1.0,  1.0, c,  d, d},
-    Vertex_t{-1.0, -1.0,  1.0, c,  0, d},
+		Vertex_t{-1.0,  1.0, -1.0, c,  d, 0},
+		Vertex_t{-1.0,  1.0,  1.0, c,  d, d},
+		Vertex_t{-1.0, -1.0,  1.0, c,  0, d},
 		// Face 3
 		Vertex_t{ 1.0, -1.0, -1.0, c,  0, 0},
-    Vertex_t{ 1.0,  1.0, -1.0, c,  d, 0},
-    Vertex_t{ 1.0,  1.0,  1.0, c,  d, d},
-    Vertex_t{ 1.0, -1.0,  1.0, c,  0, d},
+		Vertex_t{ 1.0,  1.0, -1.0, c,  d, 0},
+		Vertex_t{ 1.0,  1.0,  1.0, c,  d, d},
+		Vertex_t{ 1.0, -1.0,  1.0, c,  0, d},
 		// Face 4
 		Vertex_t{-1.0, -1.0, -1.0, c,  0, 0},
-    Vertex_t{-1.0, -1.0,  1.0, c,  d, 0},
-    Vertex_t{ 1.0, -1.0,  1.0, c,  d, d},
-    Vertex_t{ 1.0, -1.0, -1.0, c,  0, d},
+		Vertex_t{-1.0, -1.0,  1.0, c,  d, 0},
+		Vertex_t{ 1.0, -1.0,  1.0, c,  d, d},
+		Vertex_t{ 1.0, -1.0, -1.0, c,  0, d},
 		// Face 5
 		Vertex_t{-1.0,  1.0, -1.0, c,  0, 0},
-    Vertex_t{-1.0,  1.0,  1.0, c,  d, 0},
-    Vertex_t{ 1.0,  1.0,  1.0, c,  d, d},
-    Vertex_t{ 1.0,  1.0, -1.0, c,  0, d},
+		Vertex_t{-1.0,  1.0,  1.0, c,  d, 0},
+		Vertex_t{ 1.0,  1.0,  1.0, c,  d, d},
+		Vertex_t{ 1.0,  1.0, -1.0, c,  0, d},
 	]
 
 	mut vert_buffer_desc := C.sg_buffer_desc{}
diff --git a/examples/sokol/03_march_tracing_glsl/rt_glsl.v b/examples/sokol/03_march_tracing_glsl/rt_glsl.v
index 1369ad6c36..c747c72061 100644
--- a/examples/sokol/03_march_tracing_glsl/rt_glsl.v
+++ b/examples/sokol/03_march_tracing_glsl/rt_glsl.v
@@ -143,33 +143,33 @@ fn init_cube_glsl(mut app App) {
 		// Face 0
 		Vertex_t{-1.0, -1.0, -1.0, c,  0, 0},
 		Vertex_t{ 1.0, -1.0, -1.0, c,  d, 0},
-    Vertex_t{ 1.0,  1.0, -1.0, c,  d, d},
-    Vertex_t{-1.0,  1.0, -1.0, c,  0, d},
+		Vertex_t{ 1.0,  1.0, -1.0, c,  d, d},
+		Vertex_t{-1.0,  1.0, -1.0, c,  0, d},
 		// Face 1
 		Vertex_t{-1.0, -1.0,  1.0, c,  0, 0},
-    Vertex_t{ 1.0, -1.0,  1.0, c,  d, 0},
-    Vertex_t{ 1.0,  1.0,  1.0, c,  d, d},
-    Vertex_t{-1.0,  1.0,  1.0, c,  0, d},
+		Vertex_t{ 1.0, -1.0,  1.0, c,  d, 0},
+		Vertex_t{ 1.0,  1.0,  1.0, c,  d, d},
+		Vertex_t{-1.0,  1.0,  1.0, c,  0, d},
 		// Face 2
 		Vertex_t{-1.0, -1.0, -1.0, c,  0, 0},
-    Vertex_t{-1.0,  1.0, -1.0, c,  d, 0},
-    Vertex_t{-1.0,  1.0,  1.0, c,  d, d},
-    Vertex_t{-1.0, -1.0,  1.0, c,  0, d},
+		Vertex_t{-1.0,  1.0, -1.0, c,  d, 0},
+		Vertex_t{-1.0,  1.0,  1.0, c,  d, d},
+		Vertex_t{-1.0, -1.0,  1.0, c,  0, d},
 		// Face 3
 		Vertex_t{ 1.0, -1.0, -1.0, c,  0, 0},
-    Vertex_t{ 1.0,  1.0, -1.0, c,  d, 0},
-    Vertex_t{ 1.0,  1.0,  1.0, c,  d, d},
-    Vertex_t{ 1.0, -1.0,  1.0, c,  0, d},
+		Vertex_t{ 1.0,  1.0, -1.0, c,  d, 0},
+		Vertex_t{ 1.0,  1.0,  1.0, c,  d, d},
+		Vertex_t{ 1.0, -1.0,  1.0, c,  0, d},
 		// Face 4
 		Vertex_t{-1.0, -1.0, -1.0, c,  0, 0},
-    Vertex_t{-1.0, -1.0,  1.0, c,  d, 0},
-    Vertex_t{ 1.0, -1.0,  1.0, c,  d, d},
-    Vertex_t{ 1.0, -1.0, -1.0, c,  0, d},
+		Vertex_t{-1.0, -1.0,  1.0, c,  d, 0},
+		Vertex_t{ 1.0, -1.0,  1.0, c,  d, d},
+		Vertex_t{ 1.0, -1.0, -1.0, c,  0, d},
 		// Face 5
 		Vertex_t{-1.0,  1.0, -1.0, c,  0, 0},
-    Vertex_t{-1.0,  1.0,  1.0, c,  d, 0},
-    Vertex_t{ 1.0,  1.0,  1.0, c,  d, d},
-    Vertex_t{ 1.0,  1.0, -1.0, c,  0, d},
+		Vertex_t{-1.0,  1.0,  1.0, c,  d, 0},
+		Vertex_t{ 1.0,  1.0,  1.0, c,  d, d},
+		Vertex_t{ 1.0,  1.0, -1.0, c,  0, d},
 	]
 
 	mut vert_buffer_desc := C.sg_buffer_desc{}
diff --git a/examples/sokol/04_multi_shader_glsl/rt_glsl.v b/examples/sokol/04_multi_shader_glsl/rt_glsl.v
index 6378cef2a7..f109e73d03 100644
--- a/examples/sokol/04_multi_shader_glsl/rt_glsl.v
+++ b/examples/sokol/04_multi_shader_glsl/rt_glsl.v
@@ -147,33 +147,33 @@ fn init_cube_glsl_m(mut app App) {
 		// Face 0
 		Vertex_t{-1.0, -1.0, -1.0, c,  0, 0},
 		Vertex_t{ 1.0, -1.0, -1.0, c,  d, 0},
-    Vertex_t{ 1.0,  1.0, -1.0, c,  d, d},
-    Vertex_t{-1.0,  1.0, -1.0, c,  0, d},
+		Vertex_t{ 1.0,  1.0, -1.0, c,  d, d},
+		Vertex_t{-1.0,  1.0, -1.0, c,  0, d},
 		// Face 1
 		Vertex_t{-1.0, -1.0,  1.0, c,  0, 0},
-    Vertex_t{ 1.0, -1.0,  1.0, c,  d, 0},
-    Vertex_t{ 1.0,  1.0,  1.0, c,  d, d},
-    Vertex_t{-1.0,  1.0,  1.0, c,  0, d},
+		Vertex_t{ 1.0, -1.0,  1.0, c,  d, 0},
+		Vertex_t{ 1.0,  1.0,  1.0, c,  d, d},
+		Vertex_t{-1.0,  1.0,  1.0, c,  0, d},
 		// Face 2
 		Vertex_t{-1.0, -1.0, -1.0, c,  0, 0},
-    Vertex_t{-1.0,  1.0, -1.0, c,  d, 0},
-    Vertex_t{-1.0,  1.0,  1.0, c,  d, d},
-    Vertex_t{-1.0, -1.0,  1.0, c,  0, d},
+		Vertex_t{-1.0,  1.0, -1.0, c,  d, 0},
+		Vertex_t{-1.0,  1.0,  1.0, c,  d, d},
+		Vertex_t{-1.0, -1.0,  1.0, c,  0, d},
 		// Face 3
 		Vertex_t{ 1.0, -1.0, -1.0, c,  0, 0},
-    Vertex_t{ 1.0,  1.0, -1.0, c,  d, 0},
-    Vertex_t{ 1.0,  1.0,  1.0, c,  d, d},
-    Vertex_t{ 1.0, -1.0,  1.0, c,  0, d},
+		Vertex_t{ 1.0,  1.0, -1.0, c,  d, 0},
+		Vertex_t{ 1.0,  1.0,  1.0, c,  d, d},
+		Vertex_t{ 1.0, -1.0,  1.0, c,  0, d},
 		// Face 4
 		Vertex_t{-1.0, -1.0, -1.0, c,  0, 0},
-    Vertex_t{-1.0, -1.0,  1.0, c,  d, 0},
-    Vertex_t{ 1.0, -1.0,  1.0, c,  d, d},
-    Vertex_t{ 1.0, -1.0, -1.0, c,  0, d},
+		Vertex_t{-1.0, -1.0,  1.0, c,  d, 0},
+		Vertex_t{ 1.0, -1.0,  1.0, c,  d, d},
+		Vertex_t{ 1.0, -1.0, -1.0, c,  0, d},
 		// Face 5
 		Vertex_t{-1.0,  1.0, -1.0, c,  0, 0},
-    Vertex_t{-1.0,  1.0,  1.0, c,  d, 0},
-    Vertex_t{ 1.0,  1.0,  1.0, c,  d, d},
-    Vertex_t{ 1.0,  1.0, -1.0, c,  0, d},
+		Vertex_t{-1.0,  1.0,  1.0, c,  d, 0},
+		Vertex_t{ 1.0,  1.0,  1.0, c,  d, d},
+		Vertex_t{ 1.0,  1.0, -1.0, c,  0, d},
 	]
 
 	mut vert_buffer_desc := C.sg_buffer_desc{}
@@ -251,33 +251,33 @@ fn init_cube_glsl_p(mut app App) {
 		// Face 0
 		Vertex_t{-1.0, -1.0, -1.0, c,  0, 0},
 		Vertex_t{ 1.0, -1.0, -1.0, c,  d, 0},
-    Vertex_t{ 1.0,  1.0, -1.0, c,  d, d},
-    Vertex_t{-1.0,  1.0, -1.0, c,  0, d},
+		Vertex_t{ 1.0,  1.0, -1.0, c,  d, d},
+		Vertex_t{-1.0,  1.0, -1.0, c,  0, d},
 		// Face 1
 		Vertex_t{-1.0, -1.0,  1.0, c,  0, 0},
-    Vertex_t{ 1.0, -1.0,  1.0, c,  d, 0},
-    Vertex_t{ 1.0,  1.0,  1.0, c,  d, d},
-    Vertex_t{-1.0,  1.0,  1.0, c,  0, d},
+		Vertex_t{ 1.0, -1.0,  1.0, c,  d, 0},
+		Vertex_t{ 1.0,  1.0,  1.0, c,  d, d},
+		Vertex_t{-1.0,  1.0,  1.0, c,  0, d},
 		// Face 2
 		Vertex_t{-1.0, -1.0, -1.0, c,  0, 0},
-    Vertex_t{-1.0,  1.0, -1.0, c,  d, 0},
-    Vertex_t{-1.0,  1.0,  1.0, c,  d, d},
-    Vertex_t{-1.0, -1.0,  1.0, c,  0, d},
+		Vertex_t{-1.0,  1.0, -1.0, c,  d, 0},
+		Vertex_t{-1.0,  1.0,  1.0, c,  d, d},
+		Vertex_t{-1.0, -1.0,  1.0, c,  0, d},
 		// Face 3
 		Vertex_t{ 1.0, -1.0, -1.0, c,  0, 0},
-    Vertex_t{ 1.0,  1.0, -1.0, c,  d, 0},
-    Vertex_t{ 1.0,  1.0,  1.0, c,  d, d},
-    Vertex_t{ 1.0, -1.0,  1.0, c,  0, d},
+		Vertex_t{ 1.0,  1.0, -1.0, c,  d, 0},
+		Vertex_t{ 1.0,  1.0,  1.0, c,  d, d},
+		Vertex_t{ 1.0, -1.0,  1.0, c,  0, d},
 		// Face 4
 		Vertex_t{-1.0, -1.0, -1.0, c,  0, 0},
-    Vertex_t{-1.0, -1.0,  1.0, c,  d, 0},
-    Vertex_t{ 1.0, -1.0,  1.0, c,  d, d},
-    Vertex_t{ 1.0, -1.0, -1.0, c,  0, d},
+		Vertex_t{-1.0, -1.0,  1.0, c,  d, 0},
+		Vertex_t{ 1.0, -1.0,  1.0, c,  d, d},
+		Vertex_t{ 1.0, -1.0, -1.0, c,  0, d},
 		// Face 5
 		Vertex_t{-1.0,  1.0, -1.0, c,  0, 0},
-    Vertex_t{-1.0,  1.0,  1.0, c,  d, 0},
-    Vertex_t{ 1.0,  1.0,  1.0, c,  d, d},
-    Vertex_t{ 1.0,  1.0, -1.0, c,  0, d},
+		Vertex_t{-1.0,  1.0,  1.0, c,  d, 0},
+		Vertex_t{ 1.0,  1.0,  1.0, c,  d, d},
+		Vertex_t{ 1.0,  1.0, -1.0, c,  0, d},
 	]
 
 	mut vert_buffer_desc := C.sg_buffer_desc{}
diff --git a/examples/sokol/05_instancing_glsl/rt_glsl.v b/examples/sokol/05_instancing_glsl/rt_glsl.v
index f2c6c3fb5e..71dc849b58 100644
--- a/examples/sokol/05_instancing_glsl/rt_glsl.v
+++ b/examples/sokol/05_instancing_glsl/rt_glsl.v
@@ -156,37 +156,37 @@ fn init_cube_glsl_i(mut app App) {
 	//d := u16(32767)     // for compatibility with D3D11, 32767 stand for 1
 	d := f32(1.0)
 	c := u32(0xFFFFFF_FF) // color RGBA8
-  vertices := [
+  	vertices := [
 		// Face 0
 		Vertex_t{-1.0, -1.0, -1.0, c,  0, 0},
 		Vertex_t{ 1.0, -1.0, -1.0, c,  d, 0},
-    Vertex_t{ 1.0,  1.0, -1.0, c,  d, d},
-    Vertex_t{-1.0,  1.0, -1.0, c,  0, d},
+		Vertex_t{ 1.0,  1.0, -1.0, c,  d, d},
+		Vertex_t{-1.0,  1.0, -1.0, c,  0, d},
 		// Face 1
 		Vertex_t{-1.0, -1.0,  1.0, c,  0, 0},
-    Vertex_t{ 1.0, -1.0,  1.0, c,  d, 0},
-    Vertex_t{ 1.0,  1.0,  1.0, c,  d, d},
-    Vertex_t{-1.0,  1.0,  1.0, c,  0, d},
+		Vertex_t{ 1.0, -1.0,  1.0, c,  d, 0},
+		Vertex_t{ 1.0,  1.0,  1.0, c,  d, d},
+		Vertex_t{-1.0,  1.0,  1.0, c,  0, d},
 		// Face 2
 		Vertex_t{-1.0, -1.0, -1.0, c,  0, 0},
-    Vertex_t{-1.0,  1.0, -1.0, c,  d, 0},
-    Vertex_t{-1.0,  1.0,  1.0, c,  d, d},
-    Vertex_t{-1.0, -1.0,  1.0, c,  0, d},
+		Vertex_t{-1.0,  1.0, -1.0, c,  d, 0},
+		Vertex_t{-1.0,  1.0,  1.0, c,  d, d},
+		Vertex_t{-1.0, -1.0,  1.0, c,  0, d},
 		// Face 3
 		Vertex_t{ 1.0, -1.0, -1.0, c,  0, 0},
-    Vertex_t{ 1.0,  1.0, -1.0, c,  d, 0},
-    Vertex_t{ 1.0,  1.0,  1.0, c,  d, d},
-    Vertex_t{ 1.0, -1.0,  1.0, c,  0, d},
+		Vertex_t{ 1.0,  1.0, -1.0, c,  d, 0},
+		Vertex_t{ 1.0,  1.0,  1.0, c,  d, d},
+		Vertex_t{ 1.0, -1.0,  1.0, c,  0, d},
 		// Face 4
 		Vertex_t{-1.0, -1.0, -1.0, c,  0, 0},
-    Vertex_t{-1.0, -1.0,  1.0, c,  d, 0},
-    Vertex_t{ 1.0, -1.0,  1.0, c,  d, d},
-    Vertex_t{ 1.0, -1.0, -1.0, c,  0, d},
+		Vertex_t{-1.0, -1.0,  1.0, c,  d, 0},
+		Vertex_t{ 1.0, -1.0,  1.0, c,  d, d},
+		Vertex_t{ 1.0, -1.0, -1.0, c,  0, d},
 		// Face 5
 		Vertex_t{-1.0,  1.0, -1.0, c,  0, 0},
-    Vertex_t{-1.0,  1.0,  1.0, c,  d, 0},
-    Vertex_t{ 1.0,  1.0,  1.0, c,  d, d},
-    Vertex_t{ 1.0,  1.0, -1.0, c,  0, d},
+		Vertex_t{-1.0,  1.0,  1.0, c,  d, 0},
+		Vertex_t{ 1.0,  1.0,  1.0, c,  d, d},
+		Vertex_t{ 1.0,  1.0, -1.0, c,  0, d},
 	]
 
 	mut vert_buffer_desc := C.sg_buffer_desc{}
diff --git a/examples/sokol/06_obj_viewer/assets/models/v.mtl b/examples/sokol/06_obj_viewer/assets/models/v.mtl
new file mode 100644
index 0000000000..47d03811de
--- /dev/null
+++ b/examples/sokol/06_obj_viewer/assets/models/v.mtl
@@ -0,0 +1,20 @@
+# Blender MTL File: 'v-logo.blend'
+# Material Count: 2
+newmtl Material.001
+Ns 96.078431
+Ka 0.2 0.2 0.2
+Kd 0.365 0.529 0.749
+Ks 0.85 0.85 0.85
+Ke 0 0 0
+Ni 1
+d 1
+illum 1
+newmtl Material.002
+Ns 96.078431
+Ka 0.1 0.1 0.1
+Kd 0.325 0.42 0.541
+Ks 0.85 0.85 0.85
+Ke 0 0 0
+Ni 1
+d 1
+illum 1
\ No newline at end of file
diff --git a/examples/sokol/06_obj_viewer/assets/models/v.obj_ b/examples/sokol/06_obj_viewer/assets/models/v.obj_
new file mode 100644
index 0000000000..d25cc0aafd
--- /dev/null
+++ b/examples/sokol/06_obj_viewer/assets/models/v.obj_
@@ -0,0 +1,194 @@
+# Blender v2.92.0 V Logo
+mtllib v.mtl
+o Vleft.020_Plane.030
+v -1.379 6.295 0.625
+v -1.389 6.019 -3.177
+v -1.442 6.063 -3.177
+v -1.433 6.339 0.625
+v -4.038 6.499 0.662
+v -4.037 6.537 0.661
+v -4.047 6.261 -3.141
+v -4.048 6.222 -3.140
+v -3.900 6.637 0.658
+v -3.910 6.360 -3.144
+v -3.974 6.342 -3.142
+v -3.964 6.618 0.660
+v -4.012 6.582 0.661
+v -4.022 6.306 -3.142
+v -1.273 6.135 0.624
+v -1.283 5.859 -3.178
+v -1.321 5.933 -3.178
+v -1.311 6.209 0.624
+v 1.288 -1.652 0.018
+v 1.282 -1.628 -3.759
+v -1.510 6.387 0.625
+v -1.520 6.111 -3.177
+v -1.559 6.128 -3.176
+v -1.550 6.404 0.626
+v -1.103 -1.603 0.043
+v -1.113 -1.579 -3.759
+v -1.082 -1.597 -3.759
+v -1.072 -1.620 0.043
+v -1.127 -1.583 0.043
+v -1.137 -1.560 -3.759
+v -1.042 -1.631 0.043
+v -1.052 -1.608 -3.759
+v -1.490 6.095 -3.177
+v -1.480 6.372 0.625
+v -1.148 -1.563 0.043
+v -1.158 -1.540 -3.759
+v -1.164 -1.541 0.043
+v -1.174 -1.518 -3.759
+v -1.171 -1.528 0.043
+v -1.181 -1.504 -3.759
+v -1.347 5.974 -3.178
+v -1.337 6.250 0.624
+v -4.034 6.459 0.662
+v -4.044 6.183 -3.140
+vn 0.634 0.771 -0.057
+vn -0.999 0.034 0.000
+vn -0.278 0.958 -0.068
+vn -0.868 0.494 -0.033
+vn 0.889 0.455 -0.035
+vn 0.947 0.319 -0.012
+vn 0.399 0.914 -0.067
+vn -0.502 -0.864 -0.004
+vn 0.097 0.992 -0.072
+vn -0.630 -0.776 -0.003
+vn -0.009 -0.999 -0.006
+vn 0.564 0.822 -0.061
+vn -0.693 -0.720 -0.002
+vn -0.805 -0.592 -0.001
+vn -0.888 -0.458 -0.000
+vn 0.843 0.535 -0.041
+vn -0.993 -0.116 0.011
+vn 0.731 0.680 -0.051
+vn -0.938 -0.344 0.013
+vn 0.450 0.890 -0.065
+vn -0.604 0.794 -0.056
+vn 0.005 -0.072 0.997
+vn -0.000 0.075 -0.997
+vn -0.329 -0.944 -0.005
+usemtl Material.001
+s 1
+f 1//1 2//1 3//1 4//1
+f 5//2 6//2 7//2 8//2
+f 9//3 10//3 11//3 12//3
+f 6//4 13//4 14//4 7//4
+f 15//5 16//5 17//5 18//5
+f 19//6 20//6 16//6 15//6
+f 21//7 22//7 23//7 24//7
+f 25//8 26//8 27//8 28//8
+f 24//9 23//9 10//9 9//9
+f 29//10 30//10 26//10 25//10
+f 19//11 31//11 32//11 20//11
+f 4//12 3//12 33//12 34//12
+f 35//13 36//13 30//13 29//13
+f 37//14 38//14 36//14 35//14
+f 39//15 40//15 38//15 37//15
+f 18//16 17//16 41//16 42//16
+f 43//17 5//17 8//17 44//17
+f 42//18 41//18 2//18 1//18
+f 39//19 43//19 44//19 40//19
+f 34//20 33//20 22//20 21//20
+f 13//21 12//21 11//21 14//21
+f 15//22 18//22 42//22 1//22 4//22 34//22 21//22 24//22 9//22 12//22 13//22 6//22 5//22 43//22 39//22 37//22 35//22 29//22 25//22 28//22 31//22 19//22
+f 22//23 33//23 3//23 2//23 41//23 17//23 16//23 20//23 32//23 27//23 26//23 30//23 36//23 38//23 40//23 44//23 8//23 7//23 14//23 11//23 10//23 23//23
+f 28//24 27//24 32//24 31//24
+o Vleft.019_Plane.029
+v 1.617 6.547 -4.385
+v 1.627 6.270 -0.582
+v 1.681 6.314 -0.582
+v 1.671 6.591 -4.385
+v 4.277 6.750 -4.422
+v 4.276 6.789 -4.421
+v 4.286 6.513 -0.618
+v 4.287 6.474 -0.618
+v 1.280 -1.685 -3.803
+v 1.290 -1.656 -0.000
+v -1.044 -1.625 -0.000
+v -1.059 -1.615 -3.788
+v 4.250 6.834 -4.420
+v 4.260 6.557 -0.617
+v 1.512 6.387 -4.384
+v 1.522 6.110 -0.581
+v 1.559 6.184 -0.581
+v 1.550 6.461 -4.384
+v 1.410 -1.581 -3.803
+v 4.273 6.711 -4.422
+v 4.282 6.434 -0.619
+v 1.419 -1.552 -0.000
+v 1.749 6.639 -4.385
+v 1.758 6.362 -0.582
+v 1.798 6.380 -0.582
+v 1.788 6.656 -4.386
+v 1.342 -1.657 -3.803
+v 1.351 -1.628 -0.000
+v 1.321 -1.645 -0.000
+v 1.311 -1.674 -3.803
+v 4.148 6.612 -0.615
+v 4.139 6.888 -4.418
+v 4.213 6.593 -0.617
+v 4.203 6.870 -4.420
+v 1.366 -1.637 -3.803
+v 1.375 -1.608 -0.000
+v 1.728 6.347 -0.582
+v 1.719 6.623 -4.385
+v 1.386 -1.617 -3.803
+v 1.396 -1.588 -0.000
+v 1.402 -1.595 -3.803
+v 1.412 -1.566 -0.000
+v 1.585 6.225 -0.581
+v 1.575 6.501 -4.384
+vn -0.634 0.771 0.057
+vn 0.999 0.034 -0.000
+vn -0.021 -0.999 0.002
+vn 0.868 0.494 0.033
+vn -0.889 0.455 0.035
+vn 0.943 -0.332 -0.013
+vn -0.399 0.914 0.067
+vn 0.502 -0.864 0.005
+vn -0.097 0.992 0.072
+vn 0.278 0.958 0.068
+vn 0.630 -0.776 0.004
+vn -0.564 0.822 0.061
+vn 0.693 -0.720 0.003
+vn -0.950 0.311 0.014
+vn 0.805 -0.592 0.002
+vn 0.888 -0.458 0.001
+vn -0.843 0.535 0.041
+vn 0.993 -0.116 -0.011
+vn -0.731 0.680 0.051
+vn -0.450 0.890 0.065
+vn 0.604 0.794 0.056
+vn -0.005 -0.070 -0.997
+vn 0.000 -0.000 1.000
+vn 0.001 0.072 0.997
+vn 0.329 -0.944 0.006
+usemtl Material.002
+s 1
+f 45//25 46//25 47//25 48//25
+f 49//26 50//26 51//26 52//26
+f 53//27 54//27 55//27 56//27
+f 50//28 57//28 58//28 51//28
+f 59//29 60//29 61//29 62//29
+f 63//30 64//30 65//30 66//30
+f 67//31 68//31 69//31 70//31
+f 71//32 72//32 73//32 74//32
+f 70//33 69//33 75//33 76//33
+f 76//34 75//34 77//34 78//34
+f 79//35 80//35 72//35 71//35
+f 48//36 47//36 81//36 82//36
+f 83//37 84//37 80//37 79//37
+f 56//38 55//38 60//38 59//38
+f 85//39 86//39 84//39 83//39
+f 63//40 66//40 86//40 85//40
+f 62//41 61//41 87//41 88//41
+f 64//42 49//42 52//42 65//42
+f 88//43 87//43 46//43 45//43
+f 82//44 81//44 68//44 67//44
+f 57//45 78//45 77//45 58//45
+f 63//46 85//46 83//46 79//46 71//46 74//46 53//46 56//46 59//46 62//46 88//46 45//46 48//46 82//46 67//46 70//46 76//46 78//46 57//46 50//46 49//46 64//46
+f 66//47 84//47 86//47
+f 66//48 65//48 52//48 51//48 58//48 77//48 75//48 69//48 68//48 81//48 47//48 46//48 87//48 61//48 60//48 55//48 54//48 73//48 72//48 80//48 84//48
+f 74//49 73//49 54//49 53//49
diff --git a/examples/sokol/06_obj_viewer/gouraud.glsl b/examples/sokol/06_obj_viewer/gouraud.glsl
new file mode 100644
index 0000000000..7f36499be7
--- /dev/null
+++ b/examples/sokol/06_obj_viewer/gouraud.glsl
@@ -0,0 +1,108 @@
+//#pragma sokol @ctype mat4 hmm_mat4
+
+#pragma sokol @vs vs
+
+uniform vs_params {
+	mat4 u_MVMatrix;       // A constant representing the combined model/view matrix.
+	mat4 u_MVPMatrix;      // A constant representing the combined model/view/projection matrix.
+	mat4 u_NMatrix;        // A constant representing the Normal Matrix
+};
+ 
+in vec4 a_Position;     // Per-vertex position information we will pass in.
+in vec3 a_Normal;       // Per-vertex normal information we will pass in.
+in vec4 a_Color;        // Per-vertex color information we will pass in.
+in vec2 a_Texcoord0;
+
+out vec3 v_Position;   // This will be passed into the fragment shader.
+out vec4 v_Color;      // This will be passed into the fragment shader.
+out vec3 v_Normal;     // This will be passed into the fragment shader.
+out vec3 v_Normal1;
+out vec2 uv;           // This will be passed into the fragment shader.
+
+// The entry point for our vertex shader.
+void main()
+{
+	// Transform the vertex into eye space.
+	v_Position = vec3(u_MVMatrix * a_Position);
+	// Pass through the color.
+	v_Color = a_Color;
+	// calc eye space normal
+	v_Normal = vec3(u_NMatrix * vec4(a_Normal, 1.0));
+	// texture coord
+	uv = a_Texcoord0;
+	
+	v_Normal1 = normalize(vec3(u_MVMatrix * vec4(a_Normal, 1.0)));
+	
+	// gl_Position is a special variable used to store the final position.
+	// Multiply the vertex by the matrix to get the final point in normalized screen coordinates.
+	gl_Position = u_MVPMatrix * a_Position;
+}
+
+#pragma sokol @end
+
+#pragma sokol @fs fs
+//precision mediump float;       // Set the default precision to medium. We don't need as high of a precision in the fragment shader
+uniform sampler2D tex;
+uniform fs_params {
+	vec4 u_LightPos;       // The position of the light in eye space.
+	vec4 ambientColor;
+	vec4 diffuseColor;
+	vec4 specularColor;
+	
+};
+in vec3 v_Position;       // Interpolated position for this fragment.
+in vec4 v_Color;          // This is the color from the vertex shader interpolated across the triangle per fragment.
+in vec3 v_Normal;         // Interpolated normal for this fragment.
+in vec3 v_Normal1;
+in vec2 uv;
+out vec4 frag_color;
+
+vec3 lightDirection = -u_LightPos.xyz;// vec3(0.0, -0.5, 0.5);
+//const vec4 ambientColor = vec4(0.094, 0.0, 0.0, 1.0);
+//const vec4 diffuseColor = vec4(0.5, 0.0, 0.0, 1.0);
+//const vec4 specularColor = vec4(1.0, 1.0, 1.0, 1.0);
+//const float shininess = 10.0;
+const vec4 lightColor = vec4(1.0, 1.0, 1.0, 1.0);
+
+vec3 phongBRDF(vec3 lightDir, vec3 viewDir, vec3 normal, vec3 phongDiffuseCol, vec3 phongSpecularCol, float phongShininess) {
+  vec3 color = phongDiffuseCol;
+  vec3 reflectDir = reflect(-lightDir, normal);
+  float specDot = max(dot(reflectDir, viewDir), 0.0);
+  color += pow(specDot, phongShininess) * phongSpecularCol;
+  return color;
+}
+
+vec4 getPhong(in vec4 diffuseColor) {
+  vec3 lightDir = normalize(-lightDirection);
+  vec3 viewDir = normalize(-v_Position);
+  vec3 n = normalize(v_Normal);
+
+  vec3 luminance = ambientColor.rgb * 0.5;
+  
+  float illuminance = dot(lightDir, n);
+  if(illuminance > 0.0) {
+		// we save specular shiness in specularColor.a
+    vec3 brdf = phongBRDF(lightDir, viewDir, n, diffuseColor.rgb, specularColor.rgb, specularColor.a * 1000);
+    luminance += brdf * illuminance * lightColor.rgb;
+  }
+
+  vec4 outColor = vec4(luminance,1.0);
+  return outColor;
+}
+          
+// The entry point for our fragment shader.
+void main()
+{
+	vec4 txt = texture(tex, uv);
+ 
+	// Directional light
+	float directional = dot(normalize(v_Normal1), normalize(vec3(0,0.5,1))) ;
+	directional = directional * 0.15;
+	 
+  // Multiply the color by the diffuse illumination level to get final output color.	
+	frag_color = vec4(clamp(directional + txt.rgb * getPhong(diffuseColor).rgb,0,1), txt.a * diffuseColor.a);
+	
+}
+#pragma sokol @end
+
+#pragma sokol @program gouraud vs fs
\ No newline at end of file
diff --git a/examples/sokol/06_obj_viewer/obj/obj.v b/examples/sokol/06_obj_viewer/obj/obj.v
new file mode 100644
index 0000000000..18ed278d9c
--- /dev/null
+++ b/examples/sokol/06_obj_viewer/obj/obj.v
@@ -0,0 +1,587 @@
+/**********************************************************************
+*
+* .obj loader
+*
+* Copyright (c) 2021 Dario Deledda. All rights reserved.
+* Use of this source code is governed by an MIT license
+* that can be found in the LICENSE file.
+*
+* TODO:
+**********************************************************************/
+module obj
+import gg.m4
+import strconv
+
+enum F_state{
+	start
+	first
+	ints
+	decimals
+	exp_start
+	exp_sign
+	exp_int
+}
+
+// read a int from a string
+fn get_int(s string, start_index int) (int, int) {
+	mut i     := start_index
+	mut res   := 0
+	mut sgn   := 1
+	
+	mut state := F_state.start
+	for true {
+		if i >= s.len {
+			break
+		}
+		c := s[i]
+		if state == .start {
+			match c {
+				`+` {
+					i++
+					state = .ints
+					continue
+				}
+				`-` {
+					sgn = -1
+					i++
+					state = .ints
+					continue
+				}
+				`0`...`9` {
+					state = .ints
+				}
+				` `,`\t` {
+					i++
+					continue
+				}
+				else{ // no number found
+					break
+				}
+			}
+		}
+				
+		if state == .ints {
+			match c {
+				`0`...`9` {
+					//println("$res => ${(int(c) - 48)}")
+					res = res * 10 + (int(c) - 48)
+					i++
+					continue
+				}
+				else {
+					break
+				}
+			}
+		}
+		
+	}
+	//println("---")
+	return res * sgn, i
+}
+
+// reas a float number from a string
+fn get_float(s string, start_index int) (f64, int) {
+	mut i1 := start_index //+ 1
+	for i1 < s.len && s[i1] in [` `,`\t`] {
+		i1++
+	}
+	mut i := i1
+	for i < s.len {
+		if s[i] in [` `,`\t`] {
+			break
+		}
+		i++
+	}	
+	//println(" get_float: ($start_index,$i) [${s[start_index..i]}]")
+  //f_res := strconv.atof_quick(s[start_index..i])
+	f_res := strconv.atof_quick(s[i1..i])
+	return f_res, i
+}
+
+// read 3 f32 in sequence from a string
+fn parse_3f(row string, start_index int) m4.Vec4 {
+	//println(row)
+	mut i := start_index //+ 1
+	mut f1 := f64(0)
+	mut f2 := f64(0)
+	f0,mut p := get_float(row,i)
+	//print("Here f0: $f0 $p ")
+	f1, p = get_float(row,p+1)
+	//print("Here f1: $f1 $p ")
+	f2, p = get_float(row,p+1)
+	//print("Here f2: $f2 $p ")
+	return m4.Vec4{e:[f32(f0), f32(f1), f32(f2), 1]!}
+}
+
+// reas a sequence of f32 from a string
+fn (mut m ObjPart) parse_floats(row string, start_index int) m4.Vec4 {
+	mut i       := start_index //+ 1
+	mut res_f   := f64(0)
+	mut res     := m4.Vec4{e:[f32(0), 0, 0, 1]!}
+	mut c       := 0
+	for true {
+		res_f, i = get_float(row, i)
+		unsafe { res.e[c] = f32(res_f) }
+		c++
+		i++
+		if i >= row.len {
+			break
+		}
+	}
+	return res
+}
+
+// read and manage all the faes from an .obj file data
+fn (mut p Part) parse_faces(row string, start_index int, obj ObjPart) {
+	mut i       := start_index + 1
+	mut res     := [][3]int{}
+	mut v       := 0
+	mut t       := 0
+	mut n       := 0
+	//println("row: ${row[i..]}")
+	for true {
+		t = 0
+		n = 0
+		if i >= row.len {
+			break
+		}
+		mut c := row[i]
+		if (c > `9` || c < `0`) && c != `-`{
+			i++
+			continue
+		}
+		v, i = get_int(row, i)
+		if i < row.len && row[i] == `/` {
+			if row[i+1] != `/` {
+				t,i = get_int(row, i+1)
+				if i < row.len && row[i] == `/` {
+					n,i = get_int(row, i+1)
+				}
+			} else {
+				i++
+				n,i = get_int(row, i+1)
+			}
+			
+		}
+		// manage negative indexes
+		// NOTE: not well suporeted now
+		if v < 0 {
+			//println("${obj.v.len} ${obj.v.len-c}")
+			v = obj.v.len - v + 1
+			//exit(0)
+		}
+		if n < 0 {
+			n = obj.vn.len - n + 1
+		}
+		if t < 0 {
+			t = obj.vt.len - t + 1
+		}
+		res << [v-1,n-1,t-1]!
+	}
+	//println("ok res: ${res}")
+	//println(p.faces.len)
+	p.faces << res
+	
+}
+
+// parse the obj file, if single_material is true it use only one default material
+pub fn (mut obj_part ObjPart) parse_obj_buffer(rows []string, single_material bool){
+	mut mat_count := 0
+	mut row_count := 0
+	default_part := Part{name:"default part"}
+	obj_part.part << default_part
+	//println("OBJ file has ${rows.len} rows")
+	for c, row in rows {
+		//println("$c $row")
+		mut i := 0
+		row_count++
+		for true {
+			if i >= row.len {
+				break
+			}
+			match row[i] {
+				`s` {
+					break
+				}
+				`m` {
+					if row[i..i+6] == "mtllib" {
+						obj_part.material_file = row[i+7..].trim_space()
+						obj_part.load_materials()
+					}
+					break
+				}
+				`o`, `g` {
+					mut part := Part{}
+					part.name = row[i+1..].trim_space()
+					obj_part.part << part
+					mat_count = 0
+					break
+				}
+				`u` {
+					if single_material == false && row[i..i+6] == "usemtl" {
+						material := row[i+7..].trim_space()
+						//println("material: $material")
+						// manage multiple materials in an part
+						if obj_part.part[obj_part.part.len - 1].material.len > 0 {
+							mat_count++
+							mut part := Part{}
+							if mat_count > 1 {
+								li := obj_part.part[obj_part.part.len - 1].name.last_index("_m") or {obj_part.part[obj_part.part.len - 1].name.len - 1}
+								part.name = obj_part.part[obj_part.part.len - 1].name[..li] + "_m${mat_count:02}"
+							} else {
+								part.name = obj_part.part[obj_part.part.len - 1].name + "_m01"
+							}
+							obj_part.part << part
+						}
+						obj_part.part[obj_part.part.len - 1].material = material
+					}
+					break
+				}
+				`v` {
+					i++
+					match row[i]{
+						// normals
+						`n` {
+							obj_part.vn << parse_3f(row, i+2)
+							//println("Vertex line: $c")
+							break
+						}
+						// parameteres uvw
+						`p` {
+							obj_part.vp << parse_3f(row, i+2)
+							//println("Vertex line: ${obj_part.vp.len}")
+							break
+						}
+						// texture uvw
+						`t` {
+							obj_part.vt << obj_part.parse_floats(row, i+2)
+							//println("Vertex line: $c")
+							break
+						}
+						
+						else {
+							obj_part.v << parse_3f(row, i+1)
+							//println("$row => ${obj_part.v[obj_part.v.len-1]}")
+							break
+						}
+					}
+				}
+				`f` {
+					//println("$c $row")
+					obj_part.part[obj_part.part.len - 1].parse_faces(row, i, obj_part)
+					//println(obj_part.part[obj_part.part.len - 1].faces.len)
+					//println("Faces line: $c")
+					break
+				}
+				// end of the line, comments
+				`\n`,`#` {
+					break
+				}
+				else{}
+			}
+			i++
+		}
+		//if c == 2 { break }
+		if c % 100000 == 0 && c > 0{
+			println("$c rows parsed")
+		}
+	}
+	println("$row_count .obj Rows parsed")
+	// remove default part if empty
+	if obj_part.part.len > 1 && obj_part.part[0].faces.len == 0 {
+		obj_part.part = obj_part.part[1..]
+	}
+}
+
+// load the materials if found the .mtl file
+fn (mut obj_part ObjPart) load_materials() {
+	rows := obj.read_lines_from_file(obj_part.material_file)
+	println("Material file [${obj_part.material_file}] ${rows.len} Rows.")
+	for row in rows {
+		//println("$row")
+		mut i := 0
+		for true {
+			if i >= row.len {
+				break
+			}
+			match row[i] {
+				`n` {
+					if row[i..i+6] == "newmtl" {
+						name := row[i+6..].trim_space()
+						mut mat := Material{name: name} 
+						obj_part.mat << mat
+						break
+					}
+				}
+				`K` {
+					if row[i+1] !in [`a`, `d`, `e`, `s`] {
+						break
+					}
+					k_name := row[i..i+2]
+					i += 3
+					value := parse_3f(row, i)
+					obj_part.mat[obj_part.mat.len - 1].ks[k_name] = value
+					break
+				}
+				`N` {
+					n_name := row[i..i+2]
+					i += 3
+					value, _ := get_float(row, i)
+					obj_part.mat[obj_part.mat.len - 1].ns[n_name] = f32(value)
+					break
+				}
+				`m` {
+					if row[i..i+4] == "map_" {
+						name := row[i..i+6]
+						if (i + 7) < row.len {
+							file_name := row[i+7..].trim_space()
+							obj_part.mat[obj_part.mat.len - 1].maps[name] = file_name
+						}
+						break
+					}
+				}
+				// trasparency
+				`d` {
+					if row[i+1] == ` ` {
+						value, _ := get_float(row, i+2)
+						obj_part.mat[obj_part.mat.len - 1].ns['Tr'] = f32(value)
+					}
+				}
+				`T` {
+					if row[i+1] == `r` {
+						value, _ := get_float(row, i+3)
+						obj_part.mat[obj_part.mat.len - 1].ns['Tr'] = f32(1.0 - value)
+					}
+				}
+				// end of the line, comments
+				`\n`,`#` {
+					break
+				}
+				` `,`\t` {
+					i++
+					continue
+				}
+				else{
+					break
+				}
+			}
+			i++
+		}
+	}
+	
+	// create map material name => material index
+	for i, m in obj_part.mat {
+		if m.name !in obj_part.mat_map {
+			obj_part.mat_map[m.name] = i
+		}
+	}
+
+	println("Material Loading Done!")
+}
+
+//==============================================================================
+// Sokol data
+//==============================================================================
+
+// vertex data struct
+pub struct Vertex_pnct {
+pub mut:
+	x     f32 // poistion
+	y     f32
+	z     f32
+	nx    f32 // normal
+	ny    f32
+	nz    f32
+	color u32  = 0xFFFFFFFF // color
+	u     f32 // uv
+	v     f32
+	// u u16   // for compatibility with D3D11
+	// v u16   // for compatibility with D3D11
+}
+
+// struct used to pass the data to the sokol calls
+pub struct Skl_buffer {
+pub mut:
+	vbuf []Vertex_pnct
+	ibuf []u32
+	n_vertex u32
+}
+
+// transforms data from .obj format to buffer ready to be used in the render
+pub fn (mut obj_part ObjPart) get_buffer(in_part_list []int) Skl_buffer {
+	//in_part           := 0
+	mut v_count_index := 0
+	mut out_buf       := Skl_buffer{}
+	
+	mut cache := map[string]int
+	mut cache_hit := 0
+	
+	//has_normals := obj_part.vn.len > 0
+	//has_uvs     := obj_part.vt.len > 0
+	
+	for in_part in in_part_list {
+		part := obj_part.part[in_part]
+		for fc, face in part.faces {
+			//println("$fc $face")
+			// default 3 faces
+			mut v_seq := [0, 1, 2]
+			if face.len == 4 {
+				v_seq = [0, 1, 2, 0, 2, 3]
+			}
+			
+			// if big faces => use the fan of triangles as solution
+			// Note: this trick doesn't work with concave faces
+			if face.len > 4 {
+				v_seq = []
+				mut i := 1
+				for i < (face.len - 1) {
+					v_seq << 0
+					v_seq << i
+					v_seq << (i + 1)					
+					i++
+				}
+				//println("BIG FACES! ${fc} ${face.len} v_seq:${v_seq.len}")
+			}
+			
+			// no vertex index, generate normals
+			if face[0][1] == -1 && face.len >= 3 {
+				mut v_count := 0
+				v0 := face[v_count + 0][0]
+				v1 := face[v_count + 1][0]
+				v2 := face[v_count + 2][0]
+				
+				vec0 := obj_part.v[v2] - obj_part.v[v1]
+				vec1 := obj_part.v[v0] - obj_part.v[v1]
+				tmp_normal := vec0 % vec1
+					
+				for v_count < face.len {
+					obj_part.vn << tmp_normal
+					obj_part.part[in_part].faces[fc][v_count][1] = obj_part.vn.len - 1
+					v_count ++
+				}
+			}
+			
+			for vertex_index in v_seq {
+				// position
+				if vertex_index >= face.len {
+					continue
+				}				
+				v_index := face[vertex_index][0] // vertex index
+				n_index := face[vertex_index][1] // normal index
+				t_index := face[vertex_index][2] // uv texture index
+				key := "${v_index}_${n_index}_${t_index}"
+				if key !in cache {
+					cache[key] = v_count_index
+					mut pnct := Vertex_pnct {
+						x: obj_part.v[v_index].e[0]
+						y: obj_part.v[v_index].e[1]
+						z: obj_part.v[v_index].e[2]
+					}
+					// normal
+					if n_index >= 0 {
+						pnct.nx = obj_part.vn[n_index].e[0]
+						pnct.ny = obj_part.vn[n_index].e[1]
+						pnct.nz = obj_part.vn[n_index].e[2]
+					}
+					// texture uv
+					if t_index >= 0 {
+						pnct.u = obj_part.vt[t_index].e[0]
+						pnct.v = obj_part.vt[t_index].e[1]					
+					}
+					
+					out_buf.vbuf << pnct
+					out_buf.ibuf << u32(v_count_index)
+					v_count_index++
+				} else {
+					//println("Cache used! $key")
+					out_buf.ibuf << u32(cache[key])
+					cache_hit++
+				}
+				
+			}
+			
+		}
+	}
+	
+	/*
+	println("------------")
+	for c1, x1 in out_buf.vbuf[..10] {
+		println("$c1 $x1")
+	}
+	println(out_buf.ibuf[..10])
+	*/
+	//println("vbuf size: ${out_buf.vbuf.len} ibuf size: ${out_buf.ibuf.len} Cache hit: $cache_hit")
+	out_buf.n_vertex = u32(out_buf.ibuf.len)
+	return out_buf
+}
+
+//==============================================================================
+// Utility
+//==============================================================================
+// print on the console the summary of the .obj model loaded
+pub fn (obj_part ObjPart) summary() {
+	println("---- Stats     ----")
+	println("vertices: ${obj_part.v.len}")
+	println("normals : ${obj_part.vn.len}")
+	println("uv      : ${obj_part.vt.len}")
+	println("parts   : ${obj_part.part.len}")
+	// Parts
+	println("---- Parts     ----")
+	for c, x in obj_part.part {
+		println("${c:3} [${x.name:-16}] mat:[${x.material:-10}] ${x.faces.len:7} faces")
+	}
+	// Materials
+	println("---- Materials ----")
+	println("Material dict: ${obj_part.mat_map.keys()}")
+	for c, mat in obj_part.mat {
+		println("${c:3} [${mat.name:-16}]")
+		for k,v in mat.ks {
+			print("$k = $v")
+		}
+		for k,v in mat.ns {
+			println("$k = $v")
+		}
+		for k,v in mat.maps {
+			println("$k = $v")
+		}
+	}
+}
+
+// debug test function, do not remove.
+pub fn tst(){
+/*
+	//fname := "capsule.obj"
+	//fname := "Forklift.obj"
+	fname := "cube.obj"
+	//fname := "Orange Robot 3D ObjPart.obj"
+	
+	mut obj := ObjPart{}
+	buf := os.read_lines(fname) or { panic(err.msg) }
+	obj.parse_obj_buffer(buf)
+	obj.summary()
+*/
+/*
+	a :="f 7048 7070 7071 7072 7073 7074 7075 7076 7077 7078 7079 7080 7003"
+	mut f1 := 0
+	mut f2 := 0
+	f0,mut p := get_int(a,1)
+	f1, p = get_int(a,p)
+	f2, p = get_int(a,p)
+	println("res: ${f0} ${f1} ${f2}")
+*/
+/*
+	a :="v -0 0.107769 -0.755914"
+	println("${parse_3f(a,1)}")
+*/
+/*
+	ort := m4.ortho(0,300,0,200,0,0)
+	println(ort)
+	a := m4.vec3(0,0,0)
+	println("a: $a")
+	res := m4.mul_vec(ort, a)
+	println("res:\n${res}")
+*/
+	s := "K 1 1 1"
+	r := strconv.atof_quick(s[1..s.len-1])
+	println(r)
+}
\ No newline at end of file
diff --git a/examples/sokol/06_obj_viewer/obj/rend.v b/examples/sokol/06_obj_viewer/obj/rend.v
new file mode 100644
index 0000000000..695200ba7d
--- /dev/null
+++ b/examples/sokol/06_obj_viewer/obj/rend.v
@@ -0,0 +1,249 @@
+/**********************************************************************
+*
+* .obj loader
+*
+* Copyright (c) 2021 Dario Deledda. All rights reserved.
+* Use of this source code is governed by an MIT license
+* that can be found in the LICENSE file.
+*
+* TODO:
+**********************************************************************/
+module obj
+import sokol.gfx
+import gg.m4
+import math
+import stbi
+
+/******************************************************************************
+* Texture functions
+******************************************************************************/
+pub fn create_texture(w int, h int, buf byteptr) C.sg_image {
+	sz := w * h * 4
+	mut img_desc := C.sg_image_desc{
+		width: w
+		height: h
+		num_mipmaps: 0
+		min_filter: .linear
+		mag_filter: .linear
+		// usage: .dynamic
+		wrap_u: .clamp_to_edge
+		wrap_v: .clamp_to_edge
+		label: &byte(0)
+		d3d11_texture: 0
+	}
+	// comment if .dynamic is enabled
+	img_desc.content.subimage[0][0] = C.sg_subimage_content{
+		ptr: buf
+		size: sz
+	}
+
+	sg_img := C.sg_make_image(&img_desc)
+	return sg_img
+}
+
+pub fn destroy_texture(sg_img C.sg_image) {
+	C.sg_destroy_image(sg_img)
+}
+
+pub fn load_texture(file_name string) C.sg_image {
+	buffer := obj.read_bytes_from_file(file_name)
+	stbi.set_flip_vertically_on_load(true)
+	img := stbi.load_from_memory(buffer.data, buffer.len) or {
+		eprintln("Texure file: [$file_name] ERROR!")
+		exit(0)
+	}
+	res := create_texture(int(img.width), int(img.height), img.data)
+	img.free()
+	return res
+}
+
+/******************************************************************************
+* Pipeline
+******************************************************************************/
+pub fn (mut obj_part ObjPart) create_pipeline(in_part []int, shader C.sg_shader, texture C.sg_image) Render_data {
+	mut res := Render_data{}
+	obj_buf := obj_part.get_buffer(in_part)
+	res.n_vert = obj_buf.n_vertex
+	res.material = obj_part.part[in_part[0]].material
+	
+	// vertex buffer
+	mut vert_buffer_desc := C.sg_buffer_desc{}
+	unsafe { C.memset(&vert_buffer_desc, 0, sizeof(vert_buffer_desc)) }
+	vert_buffer_desc.size = obj_buf.vbuf.len * int(sizeof(Vertex_pnct))
+	vert_buffer_desc.content = byteptr(obj_buf.vbuf.data)
+	vert_buffer_desc.@type = .vertexbuffer
+	vert_buffer_desc.label = 'vertbuf_part_${in_part:03}'.str
+	vbuf := gfx.make_buffer(&vert_buffer_desc)
+	
+	// index buffer
+	mut index_buffer_desc := C.sg_buffer_desc{}
+	unsafe {C.memset(&index_buffer_desc, 0, sizeof(index_buffer_desc))}
+	index_buffer_desc.size    = obj_buf.ibuf.len * int(sizeof(u32))
+	index_buffer_desc.content = byteptr(obj_buf.ibuf.data)
+	index_buffer_desc.@type   = .indexbuffer
+	index_buffer_desc.label   = "indbuf_part_${in_part:03}".str
+	ibuf := gfx.make_buffer(&index_buffer_desc)
+	
+	mut pipdesc := C.sg_pipeline_desc{}
+	unsafe { C.memset(&pipdesc, 0, sizeof(pipdesc)) }
+	pipdesc.layout.buffers[0].stride = int(sizeof(Vertex_pnct))
+
+	// the constants [C.ATTR_vs_a_Position, C.ATTR_vs_a_Color, C.ATTR_vs_a_Texcoord0] are generated by sokol-shdc
+	pipdesc.layout.attrs[C.ATTR_vs_a_Position].format = .float3  // x,y,z as f32
+	pipdesc.layout.attrs[C.ATTR_vs_a_Normal  ].format = .float3  // x,y,z as f32
+	pipdesc.layout.attrs[C.ATTR_vs_a_Color   ].format = .ubyte4n // color as u32
+	pipdesc.layout.attrs[C.ATTR_vs_a_Texcoord0 ].format = .float2  // u,v as f32
+	// pipdesc.layout.attrs[C.ATTR_vs_a_Texcoord0].format  = .short2n  // u,v as u16
+	pipdesc.index_type = .uint32
+
+	pipdesc.blend.enabled = true
+	pipdesc.blend.src_factor_rgb = gfx.BlendFactor(C.SG_BLENDFACTOR_SRC_ALPHA)
+	pipdesc.blend.dst_factor_rgb = gfx.BlendFactor(C.SG_BLENDFACTOR_ONE_MINUS_SRC_ALPHA)
+	
+	pipdesc.depth_stencil = C.sg_depth_stencil_state{
+		depth_write_enabled: true
+		depth_compare_func: gfx.CompareFunc(C.SG_COMPAREFUNC_LESS_EQUAL)
+	}
+	pipdesc.rasterizer = C.sg_rasterizer_state{
+		cull_mode: .front //.back
+	}
+	pipdesc.label = 'pip_part_${in_part:03}'.str
+	
+	// shader
+	pipdesc.shader = shader
+
+	res.bind.vertex_buffers[0] = vbuf
+	res.bind.index_buffer = ibuf
+	res.bind.fs_images[C.SLOT_tex] = texture
+	res.pipeline = gfx.make_pipeline(&pipdesc)
+	//println('Buffers part [$in_part] init done!')
+
+	return res
+}
+
+/******************************************************************************
+* Render functions
+******************************************************************************/
+// agregate all the part by materials
+pub fn (mut obj_part ObjPart) init_render_data(texture C.sg_image) {
+	// create shader
+	// One shader for all the model
+	shader := gfx.make_shader(C.gouraud_shader_desc())
+	//shader := gfx.make_shader(C.gouraud_shader_desc(gfx.query_backend()))
+	
+	mut part_dict := map[string][]int{}
+	for i, p in obj_part.part {
+		if p.faces.len > 0 {
+			part_dict[p.material] << i
+		}
+	}
+	obj_part.rend_data.clear()
+	//println("Material dict: ${obj_part.mat_map.keys()}")
+		
+	for k, v in part_dict {
+		//println("$k => Parts $v")
+
+		mut txt := texture
+
+		if k in obj_part.mat_map {
+			mat_map := obj_part.mat[obj_part.mat_map[k]]
+			if 'map_Kd' in mat_map.maps {
+				file_name := mat_map.maps['map_Kd']
+				if file_name in obj_part.texture {
+					txt = obj_part.texture[file_name]
+					//println("Texture [${file_name}] => from CACHE")
+				} else {
+					txt = obj.load_texture(file_name)
+					obj_part.texture[file_name] = txt
+					//println("Texture [${file_name}] => LOADED")
+				}
+			}
+		}
+		//key := obj_part.texture.keys()[0]
+		//obj_part.rend_data << obj_part.create_pipeline(v, shader, obj_part.texture[key])
+		obj_part.rend_data << obj_part.create_pipeline(v, shader, txt)
+	}
+	//println("Texture array len: ${obj_part.texture.len}")
+	//println("Calc bounding box.")
+	obj_part.calc_bbox()
+	println("init_render_data DONE!")
+}
+
+pub fn (obj_part ObjPart) bind_and_draw(rend_data_index int, in_data Shader_data) u32 {
+	// apply the pipline and bindings
+	mut part_render_data := obj_part.rend_data[rend_data_index]
+	
+	// pass light position
+	mut tmp_fs_params := obj.Tmp_fs_param{}
+	tmp_fs_params.ligth = in_data.fs_data.ligth
+	
+	if part_render_data.material in obj_part.mat_map {
+		mat_index := obj_part.mat_map[part_render_data.material]
+		mat := obj_part.mat[mat_index]
+		
+		// ambient
+		tmp_fs_params.ka = in_data.fs_data.ka
+		if 'Ka' in mat.ks {
+			tmp_fs_params.ka = mat.ks['Ka']
+		}
+		
+		// specular
+		tmp_fs_params.ks = in_data.fs_data.ks
+		if 'Ks' in mat.ks {
+			tmp_fs_params.ks = mat.ks['Ks']
+		}
+		
+		//  specular exponent Ns
+		if 'Ns' in mat.ns {
+			tmp_fs_params.ks.e[3] = mat.ns['Ns'] / 1000.0
+		} else {
+			// defautl value is 10
+			tmp_fs_params.ks.e[3] = f32(10) / 1000.0
+		}
+		
+		// diffuse
+		tmp_fs_params.kd = in_data.fs_data.kd
+		if 'Kd' in mat.ks {
+			tmp_fs_params.kd = mat.ks['Kd']
+		}
+
+		// alpha/transparency
+		if 'Tr' in mat.ns {
+			tmp_fs_params.kd.e[3] = mat.ns['Tr']
+		}
+	}
+	
+	gfx.apply_pipeline(part_render_data.pipeline)
+	gfx.apply_bindings(part_render_data.bind)
+	gfx.apply_uniforms(C.SG_SHADERSTAGE_VS, C.SLOT_vs_params, in_data.vs_data, in_data.vs_len)
+	gfx.apply_uniforms(C.SG_SHADERSTAGE_FS, C.SLOT_fs_params, &tmp_fs_params, in_data.fs_len)
+	gfx.draw(0, int(part_render_data.n_vert), 1)
+	return part_render_data.n_vert
+}
+
+pub fn (obj_part ObjPart) bind_and_draw_all(in_data Shader_data) u32 {
+	mut n_vert := u32(0)
+	//println("Parts: ${obj_part.rend_data.len}")
+	for i, _ in obj_part.rend_data {
+		n_vert += obj_part.bind_and_draw(i,in_data)
+	}
+	return n_vert
+}
+
+pub fn (mut obj_part ObjPart) calc_bbox() {
+	obj_part.max = m4.Vec4{e:[f32(-math.max_f32), -math.max_f32, -math.max_f32, 0]!}
+	obj_part.min = m4.Vec4{e:[f32( math.max_f32),  math.max_f32,  math.max_f32, 0]!}
+	for v in obj_part.v {
+		if v.e[0] > obj_part.max.e[0] { obj_part.max.e[0] = v.e[0] }
+		if v.e[1] > obj_part.max.e[1] { obj_part.max.e[1] = v.e[1] }
+		if v.e[2] > obj_part.max.e[2] { obj_part.max.e[2] = v.e[2] }
+		
+		if v.e[0] < obj_part.min.e[0] { obj_part.min.e[0] = v.e[0] }
+		if v.e[1] < obj_part.min.e[1] { obj_part.min.e[1] = v.e[1] }
+		if v.e[2] < obj_part.min.e[2] { obj_part.min.e[2] = v.e[2] }
+	}
+	val1 := obj_part.max.mod3()
+	val2 := obj_part.min.mod3()
+	if val1 > val2 { obj_part.radius = f32(val1) } else { obj_part.radius = f32(val2) }
+	//println("BBox: ${obj_part.min} <=> ${obj_part.max}\nRadius: ${obj_part.radius}")
+}
diff --git a/examples/sokol/06_obj_viewer/obj/struct.v b/examples/sokol/06_obj_viewer/obj/struct.v
new file mode 100644
index 0000000000..bfd335eada
--- /dev/null
+++ b/examples/sokol/06_obj_viewer/obj/struct.v
@@ -0,0 +1,98 @@
+/**********************************************************************
+*
+* .obj loader
+*
+* Copyright (c) 2021 Dario Deledda. All rights reserved.
+* Use of this source code is governed by an MIT license
+* that can be found in the LICENSE file.
+*
+* TODO:
+**********************************************************************/
+module obj
+import gg.m4
+
+// part struct mantain the fae indexes list
+pub struct Part {
+pub mut:
+	faces     [][][3]int // v n t index order, if -1 not available
+	name      string
+	material  string
+}
+
+// materias struct, all Ks and Ns are stored as maps of string
+pub struct Material {
+pub mut:
+	name     string
+	ks       map[string]m4.Vec4
+	ns       map[string]f32
+	maps     map[string]string
+}
+
+// render data used for the rendering
+pub struct Render_data{
+pub mut:
+	pipeline C.sg_pipeline
+	bind     C.sg_bindings
+	n_vert   u32
+	material string
+}
+
+// base object parts struct
+pub struct ObjPart {
+pub mut:
+	v    []m4.Vec4  // position
+	vn   []m4.Vec4  // normals
+	vp   []m4.Vec4  // vertex params
+	vt   []m4.Vec4  // textures
+	
+	name    string
+	part    []Part                // parts of the ObjPart
+	mat     []Material            // list of the materials of the ObjPart
+	mat_map map[string]int        // maping material name to its material index
+	texture map[string]C.sg_image // GPU loaded texture map
+	material_file string          // .mtl file name for the .obj
+		
+	rend_data []Render_data       // render data used for the rendering
+	
+	t_m  m4.Mat4 = m4.unit_m4() // transform matrix for this ObjPart
+	//child []ObjPart           // childs
+	
+	// stats
+	min    m4.Vec4   // min 3d position in the ObjPart
+	max    m4.Vec4   // max 3d position in the ObjPart
+	radius f32       // bounding circle radius of the ObjPart
+}
+
+// used in to pass the matrices to the shader
+pub struct Mats {
+pub mut:
+	mv   m4.Mat4
+	mvp  m4.Mat4
+	nm   m4.Mat4
+}
+
+// data passed to the vertex shader
+pub struct Tmp_vs_param {
+pub mut:
+	mv m4.Mat4
+	mvp m4.Mat4
+	nm  m4.Mat4
+}
+
+// data passed to the pixel shader
+pub struct Tmp_fs_param {
+pub mut:
+	ligth m4.Vec4
+	ka    m4.Vec4 = m4.Vec4{e:[f32(0.1), 0.0, 0.0, 1.0]!}
+	kd    m4.Vec4 = m4.Vec4{e:[f32(0.5), 0.5, 0.5, 1.0]!}
+	ks    m4.Vec4 = m4.Vec4{e:[f32(1.0), 1.0, 1.0, 1.0]!}
+}
+
+// shader data for the rendering
+pub struct Shader_data {
+pub mut:
+	vs_data &Tmp_vs_param
+	vs_len  int
+	fs_data &Tmp_fs_param
+	fs_len  int
+}
\ No newline at end of file
diff --git a/examples/sokol/06_obj_viewer/obj/util.v b/examples/sokol/06_obj_viewer/obj/util.v
new file mode 100644
index 0000000000..e46524a007
--- /dev/null
+++ b/examples/sokol/06_obj_viewer/obj/util.v
@@ -0,0 +1,43 @@
+module obj
+import os
+
+// read a file as single lines
+pub fn read_lines_from_file(file_path string) []string {
+	mut path := ""
+	mut rows := []string{}
+	$if android {
+		path = "models/"+file_path
+		bts := os.read_apk_asset(path) or {
+			eprintln("File [$path] NOT FOUND!")
+			return rows
+		}
+		rows = bts.bytestr().split_into_lines()
+	} $else {
+		path = "assets/models/"+file_path
+		rows = os.read_lines(path) or {
+			eprintln("File [$path] NOT FOUND!")
+			return rows
+		}
+	}
+	return rows
+}
+
+// read a file as []byte
+pub fn read_bytes_from_file(file_path string) []byte {
+	mut path := ""
+	mut buffer := []byte{}
+	$if android {
+		path = "models/"+file_path
+		buffer = os.read_apk_asset(path) or {
+			eprintln("Texure file: [$path] NOT FOUND!")
+			exit(0)
+		}
+	} $else {
+		path = "assets/models/"+file_path
+		buffer = os.read_bytes(path) or {
+			eprintln("Texure file: [$path] NOT FOUND!")
+			exit(0)
+		}
+	}
+	return buffer
+}
\ No newline at end of file
diff --git a/examples/sokol/06_obj_viewer/show_obj.v b/examples/sokol/06_obj_viewer/show_obj.v
new file mode 100644
index 0000000000..0f80b9d7c7
--- /dev/null
+++ b/examples/sokol/06_obj_viewer/show_obj.v
@@ -0,0 +1,332 @@
+/**********************************************************************
+*
+* .obj viewer
+*
+* Copyright (c) 2021 Dario Deledda. All rights reserved.
+* Use of this source code is governed by an MIT license
+* that can be found in the LICENSE file.
+*
+* Example .obj model of V from SurmanPP
+*
+* HOW TO COMPILE SHADERS:
+* - download the sokol shader convertor tool from https://github.com/floooh/sokol-tools-bin/archive/pre-feb2021-api-changes.tar.gz
+* ( also look at https://github.com/floooh/sokol-tools/blob/master/docs/sokol-shdc.md )
+* - compile the .glsl shader with:
+* linux  :  sokol-shdc --input gouraud.glsl --output gouraud.h --slang glsl330
+* windows:  sokol-shdc.exe --input gouraud.glsl --output gouraud.h --slang glsl330
+*
+* --slang parameter can be:
+* - glsl330: desktop GL
+* - glsl100: GLES2 / WebGL
+* - glsl300es: GLES3 / WebGL2
+* - hlsl4: D3D11
+* - hlsl5: D3D11
+* - metal_macos: Metal on macOS
+* - metal_ios: Metal on iOS device
+* - metal_sim: Metal on iOS simulator
+* - wgpu: WebGPU
+*
+* you can have multiple platforms at the same time passing parameters like this: --slang glsl330:hlsl5:metal_macos
+* for further infos have a look at the sokol shader tool docs.
+*
+* ALTERNATIVE .OBJ MODELS:
+* you can load alternative models putting them in the "assets/model" folder with or without their .mtl file.
+* use the program help for further instructions.
+*
+* TODO:
+* - frame counter
+**********************************************************************/
+import gg
+import gg.m4
+import gx
+import math
+import sokol.sapp
+import sokol.gfx
+import sokol.sgl
+import time
+
+import os
+import obj
+
+// GLSL Include and functions
+
+#flag -I @VROOT/.
+#include "gouraud.h" #Please use sokol-shdc to generate the necessary rt_glsl.h file from rt_glsl.glsl (see the instructions at the top of this file)
+//fn C.gouraud_shader_desc(gfx.Backend) &C.sg_shader_desc
+fn C.gouraud_shader_desc() &C.sg_shader_desc
+
+const (
+	win_width  = 600
+	win_height = 600
+	bg_color   = gx.white
+)
+
+struct App {
+mut:
+	gg          &gg.Context
+	texture     C.sg_image
+	init_flag   bool
+	frame_count int
+
+	mouse_x     int = -1
+	mouse_y     int = -1
+	scroll_y    int      //mouse wheel value
+
+	// time
+	ticks       i64
+	
+	// model
+	obj_part    &obj.ObjPart
+	n_vertex    u32
+	
+	// init parameters
+	file_name   string
+	single_material_flag bool
+}
+
+/******************************************************************************
+* Draw functions
+******************************************************************************/
+[inline] 
+fn vec4(x f32, y f32, z f32, w f32) m4.Vec4 {
+	return m4.Vec4{e:[x, y, z, w]!}
+}
+
+fn calc_matrices(w f32, h f32, rx f32, ry f32, in_scale f32, pos m4.Vec4) obj.Mats {
+	proj := m4.perspective(60, w/h, 0.01, 100.0)  // set far plane to 100 fro the zoom function
+	view := m4.look_at(vec4(f32(0.0) ,0 , 6, 0), vec4(f32(0), 0, 0, 0), vec4(f32(0), 1, 0, 0))
+	view_proj := view * proj
+
+	rxm := m4.rotate(m4.rad(rx), vec4(f32(1), 0, 0, 0))
+	rym := m4.rotate(m4.rad(ry), vec4(f32(0), 1, 0, 0))
+	
+	model_pos := m4.unit_m4().translate(pos)
+
+	model_m :=  (rym * rxm) * model_pos
+	scale_m := m4.scale(vec4(in_scale, in_scale, in_scale, 1))
+
+	mv := scale_m * model_m        // model view
+	nm := mv.inverse().transpose() // normal matrix
+	mvp :=  mv * view_proj         // model view projection
+	
+	return obj.Mats{mv:mv, mvp:mvp, nm:nm}
+}
+
+fn draw_model(app App, model_pos m4.Vec4) u32 {
+	if app.init_flag == false {
+		return 0
+	}
+
+	ws := gg.window_size_real_pixels()
+	dw := ws.width/2
+	dh := ws.height/2
+
+	mut scale := f32(1)
+	if app.obj_part.radius > 1 {
+		scale = 1/(app.obj_part.radius) 
+	} else {
+		scale = app.obj_part.radius
+	}
+	scale *= 3
+	
+	// *** vertex shader uniforms ***
+	rot := [f32(app.mouse_y), f32(app.mouse_x)]
+	mut zoom_scale := scale + f32(app.scroll_y) / (app.obj_part.radius*4)
+	mats := calc_matrices(dw, dh, rot[0], rot[1] , zoom_scale, model_pos)
+	
+	mut tmp_vs_param := obj.Tmp_vs_param{
+		mv:  mats.mv,
+		mvp: mats.mvp,
+		nm:  mats.nm
+	}
+	
+	// *** fragment shader uniforms ***
+	time_ticks := f32(time.ticks() - app.ticks) / 1000
+	radius_light  := f32(app.obj_part.radius)
+	x_light       := f32(math.cos(time_ticks) * radius_light)
+	z_light       := f32(math.sin(time_ticks) * radius_light)
+
+	mut tmp_fs_params := obj.Tmp_fs_param{}
+	tmp_fs_params.ligth = m4.vec3(x_light, radius_light, z_light)
+	
+	sd := obj.Shader_data{
+		vs_data: &tmp_vs_param
+		vs_len:  int(sizeof(tmp_vs_param))
+		fs_data: &tmp_fs_params
+		fs_len:  int(sizeof(tmp_fs_params))
+	}
+
+	return app.obj_part.bind_and_draw_all(sd)	
+}
+
+fn frame(mut app App) {
+	ws := gg.window_size_real_pixels()
+
+	// clear
+	mut color_action := C.sg_color_attachment_action{
+		action: gfx.Action(C.SG_ACTION_CLEAR)
+	}
+	color_action.val[0] = 0
+	color_action.val[1] = 0
+	color_action.val[2] = 0
+	color_action.val[3] = 1.0
+	mut pass_action := C.sg_pass_action{}
+	pass_action.colors[0] = color_action
+	gfx.begin_default_pass(&pass_action, ws.width, ws.height)
+
+	// render the data
+	draw_start_glsl(app)
+	draw_model(app, m4.Vec4{})
+// uncoment if you want a raw benchmark mode
+/*	
+	mut n_vertex_drawn := u32(0)
+	n_x_obj := 20
+
+	for x in 0..n_x_obj {
+		for z in 0..30 {
+			for y in 0..4 {
+				n_vertex_drawn += draw_model(app, m4.Vec4{e:[f32((x-(n_x_obj>>1))*3),-3 + y*3,f32(-6*z),1]!})
+			}
+		}
+	}
+*/	
+	draw_end_glsl(app)
+		
+	//println("v:$n_vertex_drawn")
+	app.frame_count++
+}
+
+fn draw_start_glsl(app App){
+	if app.init_flag == false {
+		return
+	}
+	ws := gg.window_size_real_pixels()
+	gfx.apply_viewport(0, 0, ws.width, ws.height, true)
+}
+
+fn draw_end_glsl(app App){
+	gfx.end_pass()
+	gfx.commit()
+}
+
+/******************************************************************************
+* Init / Cleanup
+******************************************************************************/
+fn my_init(mut app App) {
+	mut object := &obj.ObjPart{}
+	obj_file_lines := obj.read_lines_from_file(app.file_name)
+	object.parse_obj_buffer(obj_file_lines, app.single_material_flag)
+	object.summary()
+	app.obj_part = object
+
+	// set max vertices,
+	// for a large number of the same type of object it is better use the instances!!
+	desc := sapp.create_desc()
+	gfx.setup(&desc)
+	sgl_desc := C.sgl_desc_t{
+		max_vertices: 128 * 65536
+	}
+	sgl.setup(&sgl_desc)
+	
+	// 1x1 pixel white, default texture
+	unsafe {
+		tmp_txt := malloc(4)
+		tmp_txt[0] = byte(0xFF)
+		tmp_txt[1] = byte(0xFF)
+		tmp_txt[2] = byte(0xFF)
+		tmp_txt[3] = byte(0xFF)
+		app.texture = obj.create_texture(1, 1, tmp_txt)
+		free(tmp_txt)
+	}
+	
+	// glsl
+	app.obj_part.init_render_data(app.texture)
+	app.init_flag = true
+}
+
+fn cleanup(mut app App) {
+	gfx.shutdown()
+/*
+	for _, mat in app.obj_part.texture {
+		obj.destroy_texture(mat)
+	}
+*/	
+}
+
+/******************************************************************************
+* events handling
+******************************************************************************/
+fn my_event_manager(mut ev gg.Event, mut app App) {
+	if ev.typ == .mouse_move {
+		app.mouse_x = int(ev.mouse_x)
+		app.mouse_y = int(ev.mouse_y)
+	}
+	
+	if ev.scroll_y != 0 {
+		app.scroll_y += int(ev.scroll_y)
+	}
+	
+	if ev.typ == .touches_began || ev.typ == .touches_moved {
+		if ev.num_touches > 0 {
+			touch_point := ev.touches[0]
+			app.mouse_x = int(touch_point.pos_x)
+			app.mouse_y = int(touch_point.pos_y)
+		}
+	}
+}
+
+/******************************************************************************
+* Main
+******************************************************************************/
+[console] // is needed for easier diagnostics on windows
+fn main() {
+/*
+	obj.tst()
+	exit(0)
+*/
+
+	// App init
+	mut app := &App{
+		gg:       0
+		obj_part: 0
+	}
+	
+	app.file_name            = "v.obj" // default object is the v logo
+	app.single_material_flag = false
+	$if !android {
+		if os.args.len > 3 || (os.args.len >= 2 && os.args[1] in ['-h', '--help', '\\?', '-?']) {
+			eprintln('Usage:\nshow_obj [file_name:string] [single_material_flag:(true|false)]\n')
+			eprintln('file_name           : name of the .obj file, it must be in the folder "assets/models"')
+			eprintln('                      if no file name is passed the default V logo will be showed.')
+			eprintln('                      if you want custom models you can put them in the folder "assets/models".')
+			eprintln('single_material_flag: if true the viewer use for all the model\'s parts the default material\n')
+			exit(0)
+		}
+		
+		if os.args.len >= 2 { 
+			app.file_name = os.args[1]
+		}
+		if os.args.len >= 3 {
+			app.single_material_flag = os.args[2].bool()
+		}
+		println("Loading model: $app.file_name")
+		println("Using single material: $app.single_material_flag")
+	}
+	
+	app.gg = gg.new_context(
+		width: win_width
+		height: win_height
+		use_ortho: true // This is needed for 2D drawing
+		create_window: true
+		window_title: 'V Wavefront OBJ viewer - Use the mouse wheel to zoom'
+		user_data: app
+		bg_color: bg_color
+		frame_fn: frame
+		init_fn: my_init
+		cleanup_fn: cleanup
+		event_fn: my_event_manager
+	)
+
+	app.ticks = time.ticks()
+	app.gg.run()
+}
diff --git a/examples/sokol/06_obj_viewer/v.mod b/examples/sokol/06_obj_viewer/v.mod
new file mode 100644
index 0000000000..e69de29bb2