diff --git a/imageparts.go b/imageparts.go
index a7533aa6f..5e8d8f26d 100644
--- a/imageparts.go
+++ b/imageparts.go
@@ -84,7 +84,7 @@ type textureQuads struct {
 }
 
 func (t *textureQuads) vertices() []uint8 {
-	const size = graphics.QuadVertexNum
+	size := graphics.QuadVertexSizeInBytes()
 	l := t.parts.Len()
 	vertices := make([]uint8, l*size)
 	p := t.parts
diff --git a/internal/graphics/command.go b/internal/graphics/command.go
index b69093415..f71cba871 100644
--- a/internal/graphics/command.go
+++ b/internal/graphics/command.go
@@ -108,7 +108,7 @@ func (q *commandQueue) Flush(context *opengl.Context) error {
 		}
 		// NOTE: WebGL doesn't seem to have Check gl.MAX_ELEMENTS_VERTICES or gl.MAX_ELEMENTS_INDICES so far.
 		// Let's use them to compare to len(quads) in the future.
-		if maxQuads < len(vertices)/QuadVertexNum {
+		if maxQuads < len(vertices)/QuadVertexSizeInBytes() {
 			return fmt.Errorf("len(quads) must be equal to or less than %d", maxQuads)
 		}
 		numc := len(g)
@@ -118,7 +118,7 @@ func (q *commandQueue) Flush(context *opengl.Context) error {
 				return err
 			}
 			if c, ok := c.(*drawImageCommand); ok {
-				indexOffsetInBytes += 6 * len(c.vertices) / QuadVertexNum * 2
+				indexOffsetInBytes += 6 * len(c.vertices) / QuadVertexSizeInBytes() * 2
 			}
 		}
 		if 0 < numc {
@@ -161,9 +161,9 @@ type drawImageCommand struct {
 	mode     opengl.CompositeMode
 }
 
-const (
-	QuadVertexNum = 32 // 4 * 2 [vertices] * 2 [tex_coords] * 2[bytes]
-)
+func QuadVertexSizeInBytes() int {
+	return 4 * theArrayBufferLayout.total()
+}
 
 func (c *drawImageCommand) Exec(context *opengl.Context, indexOffsetInBytes int) error {
 	if err := c.dst.framebuffer.setAsViewport(context); err != nil {
@@ -199,13 +199,13 @@ func (c *drawImageCommand) Exec(context *opengl.Context, indexOffsetInBytes int)
 func (c *drawImageCommand) split(quadsNum int) [2]*drawImageCommand {
 	c1 := *c
 	c2 := *c
-	c1.vertices = c.vertices[:quadsNum*QuadVertexNum]
-	c2.vertices = c.vertices[quadsNum*QuadVertexNum:]
+	c1.vertices = c.vertices[:quadsNum*QuadVertexSizeInBytes()]
+	c2.vertices = c.vertices[quadsNum*QuadVertexSizeInBytes():]
 	return [2]*drawImageCommand{&c1, &c2}
 }
 
 func (c *drawImageCommand) quadsNum() int {
-	return len(c.vertices) / QuadVertexNum
+	return len(c.vertices) / QuadVertexSizeInBytes()
 }
 
 type replacePixelsCommand struct {
diff --git a/internal/graphics/program.go b/internal/graphics/program.go
index f83015d3e..e7788c994 100644
--- a/internal/graphics/program.go
+++ b/internal/graphics/program.go
@@ -32,22 +32,23 @@ type arrayBufferLayout struct {
 	parts []arrayBufferLayoutPart
 }
 
-func (a *arrayBufferLayout) newArrayBuffer(c *opengl.Context) opengl.Buffer {
-	total := 0
+func (a *arrayBufferLayout) total() int {
+	t := 0
 	for _, p := range a.parts {
-		total += p.dataType.SizeInBytes() * p.num
+		t += p.dataType.SizeInBytes() * p.num
 	}
-	return c.NewBuffer(opengl.ArrayBuffer, total*4*maxQuads, opengl.DynamicDraw)
+	return t
+}
+
+func (a *arrayBufferLayout) newArrayBuffer(c *opengl.Context) opengl.Buffer {
+	return c.NewBuffer(opengl.ArrayBuffer, a.total()*4*maxQuads, opengl.DynamicDraw)
 }
 
 func (a *arrayBufferLayout) enable(c *opengl.Context, program opengl.Program) {
 	for _, p := range a.parts {
 		c.EnableVertexAttribArray(program, p.name)
 	}
-	total := 0
-	for _, p := range a.parts {
-		total += p.dataType.SizeInBytes() * p.num
-	}
+	total := a.total()
 	offset := 0
 	for _, p := range a.parts {
 		c.VertexAttribPointer(program, p.name, p.num, p.dataType, p.normalize, total, offset)