Better interfacing for shaders.

src/cmd/test/main.go

@@ -132,8 +132,8 @@ func main() {
 	e.Add(1, &Debug{})
 	e.Add(-1, gx.DrawableRectangle{
 		Rectangle: gx.Rectangle{
-			W: 100,
-			H: 100,
+			W: 4,
+			H: 4,
 			T: gx.T(),
 		},
 		Color: gx.Color{
@@ -144,6 +144,14 @@ func main() {
 		},
 		Visible: true,
 		Shader: gx.SolidWhiteColorShader,
+		Options: gx.ShaderOptions{
+			Images: [4]*gx.Image{
+				playerImg,
+				nil,
+				nil,
+				nil,
+			},
+		},
 	})
 	e.Run()
 }

src/gx/rect.go

@@ -14,9 +14,6 @@ type Rectangle struct {
 	// rotate around(relatively of position, not absolute).
 	T Transform
 	// Width and height.
-	// In fact are needed only to specify
-	// relation of width and height.
-	// Change transform to actually change things.
 	W, H Float
 	
 }
@@ -24,8 +21,15 @@ type Rectangle struct {
 // The type describes rectangle that can be drawn.
 type DrawableRectangle struct {
 	Rectangle
+	
 	Shader *Shader
+	// Solid color of the rectangle.
+	// Will be ignored if the Shader
+	// field is not nil.
 	Color Color
+	
+	Options ShaderOptions
+	
 	Visible bool
 }
 
@@ -67,11 +71,11 @@ func (r DrawableRectangle) Draw(
 	rm := e.Camera().RealMatrix(e, true)
 	m := t.Matrix(e)
 	m.Concat(rm)
+	
 	// Draw solid color if no shader.
 	if r.Shader == nil {
 		img := NewImage(1, 1)
 		img.Set(0, 0, r.Color)
-		
 		opts := &ebiten.DrawImageOptions{
 			GeoM: m,
 		}
@@ -79,20 +83,20 @@ func (r DrawableRectangle) Draw(
 		return
 	}
 	
-	v := 1
-	opts := &ebiten.DrawRectShaderOptions{
-		GeoM: m,
-		Images: [4]*Image{
-			NewImage(v, v),
-			nil,
-			nil,
-			nil,
-		},
+	// Use the Color as base image if no is provided.
+	if r.Options.Images[0] == nil {
+		r.Options.Images[0] = NewImage(1, 1)
+		r.Options.Images[0].Set(0, 0, r.Color)
 	} 
 	
-	//w := int(r.W * r.T.S.X)
-	//h := int(r.H * r.T.S.Y)
+	// Drawing with shader.
+	opts := &ebiten.DrawRectShaderOptions{
+		GeoM: m,
+		Images: r.Options.Images,
+		Uniforms: r.Options.Uniforms,
+	}
 	
-	i.DrawRectShader(v, v, r.Shader, opts)
+	w, h := r.Options.Images[0].Size()
+	i.DrawRectShader(w, h, r.Shader, opts)
 }
 

src/gx/shader.go

@@ -6,6 +6,10 @@ import (
 )
 
 type Shader = ebiten.Shader
+type ShaderOptions struct {
+	Uniforms map[string] any
+	Images [4]*Image
+}
 
 var (
 	// The shader is for example only.
@@ -15,14 +19,14 @@ var (
 		func Fragment(position vec4, texCoord vec2, color vec4) vec4 {
 			//ts := imageSrcTextureSize()
 			
-			_, size := imageSrcRegionOnTexture()
+			//_, size := imageSrcRegionOnTexture()
 			/*return vec4(
 				position.y/size.y,
 				position.y/size.y,
 				position.y/size.y,
 				position.y/size.y,
 			)*/
-			py := int(position.y / size.y) % 5
+			/*py := int(position.y / size.y) % 5
 			px := int(position.x / size.x) % 5
 			if py >= 1 && px >= 1 {
 				return vec4(
@@ -31,14 +35,16 @@ var (
 					0,
 					1,
 				)
-			}
+			}*/
 			
-			return vec4(
-				0,
-				1,
+			ret := vec4(
 				0,
+				sin(position.x),
+				sin(position.y),
 				1,
 			)
+			
+			return imageSrc0UnsafeAt(texCoord) * (ret)
 		}
 	`))
 )