examples: tetris: better mobile device support (#8519)

examples/tetris/tetris.v

@@ -11,7 +11,7 @@ import gg
 import sokol.sapp
 
 const (
-	block_size      = 20 // pixels
+	block_size      = 20 // virtual pixels
 	field_height    = 20 // # of blocks
 	field_width     = 10
 	tetro_size      = 4
@@ -88,6 +88,10 @@ mut:
 	lines int
 	// State of the current game
 	state GameState
+	// Block size in screen dimensions
+	block_size int = block_size
+	// Field margin
+	margin int
 	// Position of the current tetro
 	pos_x int
 	pos_y int
@@ -119,6 +123,10 @@ mut:
 	second_sw time.StopWatch = time.new_stopwatch({})
 }
 
+fn remap(v f32, min f32, max f32, new_min f32, new_max f32) f32 {
+	return (((v - min) * (new_max - new_min)) / (max - min)) + new_min
+}
+
 [if showfps]
 fn (mut game Game) showfps() {
 	game.frame++
@@ -135,6 +143,11 @@ fn (mut game Game) showfps() {
 }
 
 fn frame(mut game Game) {
+	ws := gg.window_size()
+	bs := remap(block_size, 0, win_height, 0, ws.height)
+	m := (f32(ws.width) - bs * field_width) * 0.5
+	game.block_size = int(bs)
+	game.margin = int(m)
 	game.frame_sw.restart()
 	game.gg.begin()
 	game.draw_scene()
@@ -343,8 +356,8 @@ fn (g &Game) draw_next_tetro() {
 }
 
 fn (g &Game) draw_block_color(i int, j int, color gx.Color) {
-	g.gg.draw_rect(f32((j - 1) * block_size), f32((i - 1) * block_size), f32(block_size - 1),
+	g.gg.draw_rect(f32((j - 1) * g.block_size) + g.margin, f32((i - 1) * g.block_size),
-		f32(block_size - 1), color)
+		f32(g.block_size - 1), f32(g.block_size - 1), color)
 }
 
 fn (g &Game) draw_block(i int, j int, color_idx int) {
@@ -363,17 +376,19 @@ fn (g &Game) draw_field() {
 }
 
 fn (mut g Game) draw_ui() {
+	ws := gg.window_size()
+	textsize := int(remap(text_size, 0, win_width, 0, ws.width))
 	g.gg.draw_text(1, 3, g.score.str(), text_cfg)
 	lines := g.lines.str()
-	g.gg.draw_text(win_width - lines.len * text_size, 3, lines, text_cfg)
+	g.gg.draw_text(ws.width - lines.len * textsize, 3, lines, text_cfg)
 	if g.state == .gameover {
-		g.gg.draw_rect(0, win_height / 2 - text_size, win_width, 5 * text_size, ui_color)
+		g.gg.draw_rect(0, ws.height / 2 - textsize, ws.width, 5 * textsize, ui_color)
-		g.gg.draw_text(1, win_height / 2 + 0 * text_size, 'Game Over', over_cfg)
+		g.gg.draw_text(1, ws.height / 2 + 0 * textsize, 'Game Over', over_cfg)
-		g.gg.draw_text(1, win_height / 2 + 2 * text_size, 'Space to restart', over_cfg)
+		g.gg.draw_text(1, ws.height / 2 + 2 * textsize, 'Space to restart', over_cfg)
 	} else if g.state == .paused {
-		g.gg.draw_rect(0, win_height / 2 - text_size, win_width, 5 * text_size, ui_color)
+		g.gg.draw_rect(0, ws.height / 2 - textsize, ws.width, 5 * textsize, ui_color)
-		g.gg.draw_text(1, win_height / 2 + 0 * text_size, 'Game Paused', text_cfg)
+		g.gg.draw_text(1, ws.height / 2 + 0 * textsize, 'Game Paused', text_cfg)
-		g.gg.draw_text(1, win_height / 2 + 2 * text_size, 'SPACE to resume', text_cfg)
+		g.gg.draw_text(1, ws.height / 2 + 2 * textsize, 'SPACE to resume', text_cfg)
 	}
 	// g.gg.draw_rect(0, block_size, win_width, limit_thickness, ui_color)
 }
@@ -416,6 +431,28 @@ fn on_event(e &sapp.Event, mut game Game) {
 	if e.typ == .key_down {
 		game.key_down(e.key_code)
 	}
+	if e.typ == .touches_began || e.typ == .touches_moved {
+		if e.num_touches > 0 {
+			touch_point := e.touches[0]
+			game.touch_event(touch_point)
+		}
+	}
+}
+
+fn (mut game Game) rotate_tetro() {
+	old_rotation_idx := game.rotation_idx
+	game.rotation_idx++
+	if game.rotation_idx == tetro_size {
+		game.rotation_idx = 0
+	}
+	game.get_tetro()
+	if !game.move_right(0) {
+		game.rotation_idx = old_rotation_idx
+		game.get_tetro()
+	}
+	if game.pos_x < 0 {
+		// game.pos_x = 1
+	}
 }
 
 fn (mut game Game) key_down(key sapp.KeyCode) {
@@ -443,19 +480,7 @@ fn (mut game Game) key_down(key sapp.KeyCode) {
 	match key {
 		.up {
 			// Rotate the tetro
-			old_rotation_idx := game.rotation_idx
+			game.rotate_tetro()
-			game.rotation_idx++
-			if game.rotation_idx == tetro_size {
-				game.rotation_idx = 0
-			}
-			game.get_tetro()
-			if !game.move_right(0) {
-				game.rotation_idx = old_rotation_idx
-				game.get_tetro()
-			}
-			if game.pos_x < 0 {
-				// game.pos_x = 1
-			}
 		}
 		.left {
 			game.move_right(-1)
@@ -476,3 +501,18 @@ fn (mut game Game) key_down(key sapp.KeyCode) {
 		else {}
 	}
 }
+
+fn (mut game Game) touch_event(touch_point C.sapp_touchpoint) {
+	ws := gg.window_size()
+	tx := touch_point.pos_x
+	ty := touch_point.pos_y
+	if ty < f32(ws.height) * 0.5 {
+		game.rotate_tetro()
+	} else {
+		if tx <= f32(ws.width) * 0.5 {
+			game.move_right(-1)
+		} else {
+			game.move_right(1)
+		}
+	}
+}