Implemented proper transformation of rectangle into triangles.

src/cmd/test/main.go

@@ -53,6 +53,7 @@ func NewRect() *Rect {
 }
 
 func (r *Rect) Update(e *gx.Engine) error {
+	r.R += 0.3 * e.DT()
 	return nil
 }
 
@@ -90,7 +91,7 @@ func (p *Player) Draw(e *gx.Engine, i *gx.Image) {
 		Rectangle: gx.Rectangle{
 			Transform: gx.Transform{
 				P: player.P,
-				S: gx.Vector{10, 10},
+				S: gx.Vector{100, 100},
 			},
 		},
 		Color: gx.Color{0, 0, gx.MaxColorV, gx.MaxColorV},

src/gx/rect.go

@@ -41,8 +41,8 @@ func (r Rectangle) Triangles() Triangles {
 	
 	p1 := V(0, 0).Apply(&m)
 	p2 := V(1, 0).Apply(&m)
-	p3 := V(1, -1).Apply(&m)
+	p3 := V(1, 1).Apply(&m)
-	p4 := V(0, -1).Apply(&m)
+	p4 := V(0, 1).Apply(&m)
 	
 	//fmt.Println("in:", p1, p2, p3, p4)
 	
@@ -66,17 +66,14 @@ func (r *DrawableRectangle) Draw(
 	e *Engine,
 	i *Image,
 ) {
-	t := r.Transform
+	m := r.Matrix()
-	
+	rm := e.Camera().RealMatrix(e)
+	m.Concat(rm)
 	// Draw solid color if no shader.
 	if r.Shader == nil {
 		img := NewImage(1, 1)
 		img.Set(0, 0, r.Color)
 		
-		m := t.Matrix()
-		rm := e.Camera().RealMatrix(e)
-		
-		m.Concat(rm)
 		
 		opts := &ebiten.DrawImageOptions{
 			GeoM: m,
@@ -103,11 +100,6 @@ func (r *DrawableRectangle) Draw(
 		t.S.Y *= r.H
 	}*/
 	
-	
-	rm := e.Camera().RealMatrix(e)
-	m := t.Matrix()
-	m.Concat(rm)
-	
 	// Drawing with shader.
 	opts := &ebiten.DrawRectShaderOptions{
 		GeoM: m,