glm: improve matrix mult function and add tests

vlib/glm/glm.v

@@ -219,56 +219,16 @@ pub fn scale(m Mat4, v Vec3) Mat4 {
 
 // multiplicates two matrices
 pub fn mult(a, b Mat4) Mat4 {
-	db := b.data
 	mut out := f32_calloc(16)
-	mut row0 := f32_calloc(4)
-	mut row1 := f32_calloc(4)
-	mut row2 := f32_calloc(4)
-	mut row3 := f32_calloc(4)
-
-	row0[0] = db[0]row0[1] = db[1]row0[2] = db[2]row0[3] = db[3]
-	row1[0] = db[4]row1[1] = db[5]row1[2] = db[6]row1[3] = db[7]
-	row2[0] = db[8]row2[1] = db[9]row2[2] = db[10]row2[3] = db[11]
-	row3[0] = db[12]row3[1] = db[13]row3[2] = db[14]row3[3] = db[15]
-
-	a_ := mult_mat_point(a, mat4(row0))
-	b_ := mult_mat_point(a, mat4(row1))
-	c_ := mult_mat_point(a, mat4(row2))
-	d_ := mult_mat_point(a, mat4(row3))
-
-	res0 := a_.data res1 := b_.data res2 := c_.data res3 := d_.data
-
-	out[0] = res0[0] out[1] = res0[1] out[2] = res0[2] out[3] = res0[3]
-	out[4] = res1[0] out[5] = res1[1] out[6] = res1[2] out[7] = res1[3]
-	out[8] = res2[0] out[9] = res2[1] out[10] = res2[2] out[11] = res2[3]
-	out[12] = res3[0] out[13] = res3[1] out[14] = res3[2] out[15] = res3[3]
-
-	return mat4(out)
-}
-
-// helper function for mult
-fn mult_mat_point(a Mat4, point Mat4) Mat4 {
-	data := a.data
-	c0r0 := data[0]c1r0 := data[1]c2r0 := data[2]c3r0 := data[3]
-	c0r1 := data[4]c1r1 := data[5]c2r1 := data[6]c3r1 := data[7]
-	c0r2 := data[8]c1r2 := data[9]c2r2 := data[10]c3r2 := data[11]
-	c0r3 := data[12]c1r3 := data[13]c2r3 := data[14]c3r3 := data[15]
-
-	pdata := point.data
-	x := pdata[0]
-	y := pdata[1]
-	z := pdata[2]
-	w := pdata[3]
-
-	mut out := f32_calloc(4)
-
-	rx := (x * c0r0) + (y * c0r1) + (z * c0r2) + (w * c0r3)
-	ry := (x * c1r0) + (y * c1r1) + (z * c1r2) + (w * c1r3)
-	rz := (x * c2r0) + (y * c2r1) + (z * c2r2) + (w * c2r3)
-	rw := (x * c3r0) + (y * c3r1) + (z * c3r2) + (w * c3r3)
-
-	out[0] = rx out[1] = ry	out[2] = rz out[3] = rw
-
+	for i in 0..4 {
+		for r in 0..4 {
+			mut prod := f32(0)
+			for c in 0..4 {
+				prod += a.data[c*4+r] * b.data[i*4+c]
+			}
+			out[i*4+r] = prod
+		}
+	}
 	return mat4(out)
 }
 

vlib/glm/glm_test.v

@@ -110,13 +110,48 @@ fn test_translate() {
     assert m.data[15] == 1.0
 }
 
-fn test_mult() {
-	//TODO improve test
-	mut a := glm.identity()
-	mut b := glm.identity()
-	mut c := glm.identity()
+fn f32_calloc(n int) &f32 {
+	return voidptr(vcalloc(n * int(sizeof(f32))))
+}
+
+fn test_mult1() {
+	mut adata := f32_calloc(16)
+	adata[1*4+1] = 6
+	adata[2*4+3] = 2
+	adata[0*4+2] = 3
+	adata[2*4+1] = 1
+
+	mut bdata := f32_calloc(16)
+	bdata[1*4+1] = -2
+	bdata[2*4+3] = 1
+	bdata[0*4+2] = 6
+	bdata[2*4+1] = -3
+
+	mut expected := f32_calloc(16)
+	expected[0*4+0] = 0  	/* 0*0+0*0+0*6+0*0 */
+	expected[0*4+1] = 6  	/* 0*0+0*6+1*6+0*0 */
+	expected[0*4+2] = 0  	/* 3*0+0*0+0*6+0*0 */
+	expected[0*4+3] = 12 	/* 0*0+0*0+2*6+0*0 */
+
+	expected[1*4+0] = 0		/* 0*0+0*-2+0*0+0*0 */
+	expected[1*4+1] = -12	/* 0*0­+6*-2+1*0­+0*0 */
+	expected[1*4+2] = 0		/* 3*0­+0*-2­+0*0­+0*0 */
+	expected[1*4+3] = 0		/* 0*0­+0*-2­+2*0­+0*0 */
+
+	expected[2*4+0] = 0		/* 0*0­+0*-3­+0*0­+0*1 */
+	expected[2*4+1] = -18	/* 0*0­+6*-3­+1*0­+0*1 */
+	expected[2*4+2] = 0		/* 3*0­+0*-3+0*0­+0*1 */
+	expected[2*4+3] = 0		/* 0*0­+0*-3­+2*0­+0*1 */
+
+	expected[3*4+0] = 0		/* 0*0­+0*0­+0*0­+0*0 */
+	expected[3*4+1] = 0		/* 0*0­+6*0­+1*0­+0*0 */
+	expected[3*4+2] = 0		/* 3*0­+0*0­+0*0­+0*0 */
+	expected[3*4+3] = 0		/* 0*0­+0*0­+2*0­+0*0 */
+
+	mut a := glm.Mat4{adata}
+	b := glm.Mat4{bdata}
 	a = glm.mult(a, b)
 	for i in 0..15 {
-		assert a.data[i] == c.data[i]
+		assert a.data[i] == expected[i]
 	}
-}
+}