Bug fix: the default framebuffer can't bind a texture

example/alphablending/main.go

@@ -72,7 +72,7 @@ func main() {
 	if err != nil {
 		log.Fatal(err)
 	}
-	if err := ebiten.Run(g.Update, screenWidth, screenHeight, 2, "Perspective (Ebiten Demo)"); err != nil {
+	if err := ebiten.Run(g.Update, screenWidth, screenHeight, 2, "Alpha Blending (Ebiten Demo)"); err != nil {
 		log.Fatal(err)
 	}
 }

graphicscontext.go

@@ -23,7 +23,7 @@ import (
 )
 
 func newGraphicsContext(screenWidth, screenHeight, screenScale int) (*graphicsContext, error) {
-	r, t, err := opengl.NewZeroRenderTarget(screenWidth*screenScale, screenHeight*screenScale, true)
+	r, err := opengl.NewZeroRenderTarget(screenWidth*screenScale, screenHeight*screenScale)
 	if err != nil {
 		return nil, err
 	}
@@ -32,18 +32,14 @@ func newGraphicsContext(screenWidth, screenHeight, screenScale int) (*graphicsCo
 	if err != nil {
 		return nil, err
 	}
-
 	c := &graphicsContext{
 		currents:     make([]*RenderTarget, 1),
-		defaultR:     &RenderTarget{r, &Texture{t}},
+		defaultR:     &RenderTarget{r, nil},
 		screen:       screen,
 		screenWidth:  screenWidth,
 		screenHeight: screenHeight,
 		screenScale:  screenScale,
 	}
-
-	idsInstance.fillRenderTarget(c.screen, color.RGBA{0, 0, 0, 0})
-
 	return c, nil
 }
 
@@ -92,17 +88,18 @@ func (c *graphicsContext) PopRenderTarget() {
 func (c *graphicsContext) preUpdate() {
 	c.currents = c.currents[0:1]
 	c.currents[0] = c.defaultR
+
 	c.PushRenderTarget(c.screen)
-	c.Fill(color.RGBA{0, 0, 0, 0xff})
+	c.Clear()
 }
 
 func (c *graphicsContext) postUpdate() {
 	c.PopRenderTarget()
-	c.Clear()
 
 	scale := float64(c.screenScale)
 	geo := ScaleGeometry(scale, scale)
-	DrawWholeTexture(c, c.screen.texture, geo, ColorMatrixI())
+	clr := ColorMatrixI()
+	DrawWholeTexture(c, c.screen.texture, geo, clr)
 
 	gl.Flush()
 }

ids.go

@@ -49,6 +49,7 @@ func (i *ids) createRenderTarget(width, height int, filter int) (*RenderTarget,
 	texture := &Texture{glTexture}
 	// TODO: Is |texture| necessary?
 	renderTarget := &RenderTarget{glRenderTarget, texture}
+	i.fillRenderTarget(renderTarget, color.RGBA{0, 0, 0, 0})
 
 	return renderTarget, nil
 }
@@ -72,7 +73,11 @@ func (i *ids) drawTexture(target *RenderTarget, texture *Texture, parts []Textur
 	projectionMatrix := target.glRenderTarget.ProjectionMatrix()
 	quads := textureQuads(parts, glTexture.Width(), glTexture.Height())
 	w, h := target.Size()
-	shader.DrawTexture(glTexture.Native(), target.texture.glTexture.Native(), w, h, projectionMatrix, quads, &geo, &color)
+	targetNativeTexture := gl.Texture(0)
+	if target.texture != nil {
+		targetNativeTexture = target.texture.glTexture.Native()
+	}
+	shader.DrawTexture(glTexture.Native(), targetNativeTexture, w, h, projectionMatrix, quads, &geo, &color)
 	return nil
 }
 

internal/opengl/internal/shader/drawtexture.go

@@ -48,30 +48,39 @@ func DrawTexture(native gl.Texture, target gl.Texture, width, height int, projec
 		return
 	}
 	// TODO: Check performance
-	shaderProgram := use(glMatrix(projectionMatrix), width, height, geo, color)
+	program := gl.Program(0)
+	if 0 < target {
+		program = useProgramColorMatrix(glMatrix(projectionMatrix), width, height, geo, color)
+	} else {
+		program = useProgramColorFinal(glMatrix(projectionMatrix), geo)
+	}
 
 	gl.ActiveTexture(gl.TEXTURE0)
 	native.Bind(gl.TEXTURE_2D)
 
+	if 0 < target {
 		gl.ActiveTexture(gl.TEXTURE1)
 		target.Bind(gl.TEXTURE_2D)
+	}
 
-	texture0UniformLocation := getUniformLocation(shaderProgram, "texture0")
+	vertexAttrLocation := getAttributeLocation(program, "vertex")
-	texture1UniformLocation := getUniformLocation(shaderProgram, "texture1")
+	texCoord0AttrLocation := getAttributeLocation(program, "tex_coord0")
-	texture0UniformLocation.Uniform1i(0)
+	texCoord1AttrLocation := gl.AttribLocation(0)
-	texture1UniformLocation.Uniform1i(1)
+	if program == programColorMatrix.native {
-
+		texCoord1AttrLocation = getAttributeLocation(program, "tex_coord1")
-	vertexAttrLocation := getAttributeLocation(shaderProgram, "vertex")
+	}
-	texCoord0AttrLocation := getAttributeLocation(shaderProgram, "tex_coord0")
-	texCoord1AttrLocation := getAttributeLocation(shaderProgram, "tex_coord1")
 
 	gl.EnableClientState(gl.VERTEX_ARRAY)
 	gl.EnableClientState(gl.TEXTURE_COORD_ARRAY)
 	vertexAttrLocation.EnableArray()
 	texCoord0AttrLocation.EnableArray()
+	if program == programColorMatrix.native {
 		texCoord1AttrLocation.EnableArray()
+	}
 	defer func() {
+		if program == programColorMatrix.native {
 			texCoord1AttrLocation.DisableArray()
+		}
 		texCoord0AttrLocation.DisableArray()
 		vertexAttrLocation.DisableArray()
 		gl.DisableClientState(gl.TEXTURE_COORD_ARRAY)
@@ -104,6 +113,7 @@ func DrawTexture(native gl.Texture, target gl.Texture, width, height int, projec
 			u1, v2,
 			u2, v2,
 		)
+		if program == programColorMatrix.native {
 			w := float32(internal.AdjustSizeForTexture(width))
 			h := float32(internal.AdjustSizeForTexture(height))
 			xx1 := x1 / w
@@ -116,6 +126,7 @@ func DrawTexture(native gl.Texture, target gl.Texture, width, height int, projec
 				xx1, yy2,
 				xx2, yy2,
 			)
+		}
 		base := uint32(i * 4)
 		indicies = append(indicies,
 			base, base+1, base+2,
@@ -124,7 +135,9 @@ func DrawTexture(native gl.Texture, target gl.Texture, width, height int, projec
 	}
 	vertexAttrLocation.AttribPointer(2, gl.FLOAT, false, 0, vertices)
 	texCoord0AttrLocation.AttribPointer(2, gl.FLOAT, false, 0, texCoords0)
+	if program == programColorMatrix.native {
 		texCoord1AttrLocation.AttribPointer(2, gl.FLOAT, false, 0, texCoords1)
+	}
 	gl.DrawElements(gl.TRIANGLES, len(indicies), gl.UNSIGNED_INT, indicies)
 
 	gl.Flush()

internal/opengl/internal/shader/program.go

@@ -30,6 +30,10 @@ var programColorMatrix = program{
 	shaderIds: []shaderId{shaderVertex, shaderColorMatrix},
 }
 
+var programColorFinal = program{
+	shaderIds: []shaderId{shaderVertexFinal, shaderColorFinal},
+}
+
 func (p *program) create() {
 	p.native = gl.CreateProgram()
 	if p.native == 0 {
@@ -56,32 +60,24 @@ func initialize() {
 	}()
 
 	programColorMatrix.create()
-	programColorMatrix.native.Use()
+	programColorFinal.create()
 }
 
-// NOTE: This caches are now used only for programColorMatrix
-var attribLocationCache = map[string]gl.AttribLocation{}
-var uniformLocationCache = map[string]gl.UniformLocation{}
-
 func getAttributeLocation(program gl.Program, name string) gl.AttribLocation {
-	if location, ok := attribLocationCache[name]; ok {
+	return program.GetAttribLocation(name)
-		return location
-	}
-	location := program.GetAttribLocation(name)
-	attribLocationCache[name] = location
-	return location
 }
 
 func getUniformLocation(program gl.Program, name string) gl.UniformLocation {
-	if location, ok := uniformLocationCache[name]; ok {
+	return program.GetUniformLocation(name)
-		return location
-	}
-	location := program.GetUniformLocation(name)
-	uniformLocationCache[name] = location
-	return location
 }
 
-func use(projectionMatrix [16]float32, width, height int, geo Matrix, color Matrix) gl.Program {
+var lastProgram gl.Program = 0
+
+func useProgramColorMatrix(projectionMatrix [16]float32, width, height int, geo Matrix, color Matrix) gl.Program {
+	if lastProgram != programColorMatrix.native {
+		programColorMatrix.native.Use()
+		lastProgram = programColorMatrix.native
+	}
 	// TODO: Check the performance.
 	program := programColorMatrix
 
@@ -100,6 +96,7 @@ func use(projectionMatrix [16]float32, width, height int, geo Matrix, color Matr
 		tx, ty, 0, 1,
 	}
 	getUniformLocation(program.native, "modelview_matrix").UniformMatrix4fv(false, glModelviewMatrix)
+
 	txn := tx / float32(internal.AdjustSizeForTexture(width))
 	tyn := ty / float32(internal.AdjustSizeForTexture(height))
 	glModelviewMatrixN := [...]float32{
@@ -110,7 +107,8 @@ func use(projectionMatrix [16]float32, width, height int, geo Matrix, color Matr
 	}
 	getUniformLocation(program.native, "modelview_matrix_n").UniformMatrix4fv(false, glModelviewMatrixN)
 
-	getUniformLocation(program.native, "texture").Uniform1i(0)
+	getUniformLocation(program.native, "texture0").Uniform1i(0)
+	getUniformLocation(program.native, "texture1").Uniform1i(1)
 
 	e := [4][5]float32{}
 	for i := 0; i < 4; i++ {
@@ -133,3 +131,32 @@ func use(projectionMatrix [16]float32, width, height int, geo Matrix, color Matr
 
 	return program.native
 }
+
+func useProgramColorFinal(projectionMatrix [16]float32, geo Matrix) gl.Program {
+	if lastProgram != programColorFinal.native {
+		programColorFinal.native.Use()
+		lastProgram = programColorFinal.native
+	}
+
+	program := programColorFinal
+
+	getUniformLocation(program.native, "projection_matrix").UniformMatrix4fv(false, projectionMatrix)
+
+	a := float32(geo.Element(0, 0))
+	b := float32(geo.Element(0, 1))
+	c := float32(geo.Element(1, 0))
+	d := float32(geo.Element(1, 1))
+	tx := float32(geo.Element(0, 2))
+	ty := float32(geo.Element(1, 2))
+	glModelviewMatrix := [...]float32{
+		a, c, 0, 0,
+		b, d, 0, 0,
+		0, 0, 1, 0,
+		tx, ty, 0, 1,
+	}
+	getUniformLocation(program.native, "modelview_matrix").UniformMatrix4fv(false, glModelviewMatrix)
+
+	getUniformLocation(program.native, "texture0").Uniform1i(0)
+
+	return program.native
+}

internal/opengl/internal/shader/shader.go

@@ -31,9 +31,9 @@ type shaderId int
 
 const (
 	shaderVertex shaderId = iota
-	shaderFragment
+	shaderVertexFinal
 	shaderColorMatrix
-	shaderSolidColor
+	shaderColorFinal
 )
 
 var shaders = map[shaderId]*shader{
@@ -54,6 +54,21 @@ void main(void) {
   vertex_out_tex_coord1 = (modelview_matrix_n * vec4(tex_coord1, 0, 1)).xy;
   gl_Position = projection_matrix * modelview_matrix * vec4(vertex, 0, 1);
 }
+`,
+	},
+	shaderVertexFinal: {
+		shaderType: gl.VERTEX_SHADER,
+		source: `
+uniform mat4 projection_matrix;
+uniform mat4 modelview_matrix;
+attribute vec2 vertex;
+attribute vec2 tex_coord0;
+varying vec2 vertex_out_tex_coord0;
+
+void main(void) {
+  vertex_out_tex_coord0 = tex_coord0;
+  gl_Position = projection_matrix * modelview_matrix * vec4(vertex, 0, 1);
+}
 `,
 	},
 	shaderColorMatrix: {
@@ -74,6 +89,19 @@ void main(void) {
   gl_FragColor.a = color0.a + color1.a - color0.a * color1.a;
   gl_FragColor.rgb = (color0.a * color0.rgb + (1.0 - color0.a) * color1.a * color1.rgb) / gl_FragColor.a;
 }
+`,
+	},
+	shaderColorFinal: {
+		shaderType: gl.FRAGMENT_SHADER,
+		source: `
+uniform sampler2D texture0;
+varying vec2 vertex_out_tex_coord0;
+
+void main(void) {
+  vec4 color0 = texture2D(texture0, vertex_out_tex_coord0);
+  gl_FragColor.rgb = color0.a * color0.rgb;
+  gl_FragColor.a = 1.0;
+}
 `,
 	},
 }

internal/opengl/rendertarget.go

@@ -44,23 +44,13 @@ type RenderTarget struct {
 	flipY       bool
 }
 
-func NewZeroRenderTarget(width, height int, flipY bool) (*RenderTarget, *Texture, error) {
+func NewZeroRenderTarget(width, height int) (*RenderTarget, error) {
 	r := &RenderTarget{
 		width:  width,
 		height: height,
-		flipY:  flipY,
+		flipY:  true,
 	}
-	// The framebuffer 0 can't be enlarged, so any filter is acceptable.
+	return r, nil
-	t, err := NewTexture(width, height, gl.NEAREST)
-	if err != nil {
-		return nil, nil, err
-	}
-	// TODO: Does this affect the current rendering target?
-	gl.Framebuffer(0).Bind()
-	if err := framebufferTexture(t.native); err != nil {
-		return nil, nil, err
-	}
-	return r, t, err
 }
 
 func NewRenderTargetFromTexture(texture *Texture) (*RenderTarget, error) {