func onPaint(sz size.Event) {
	gl.ClearColor(rgb(156), rgb(39), rgb(176), 1)
	gl.Clear(gl.COLOR_BUFFER_BIT)

	var rotationMatrix = []float32{
		f32.Cos(-alpha), -f32.Sin(-alpha), 0.0,
		f32.Sin(-alpha), f32.Cos(-alpha), 0.0,
		0.0, 0.0, 1.0,
	}

	gl.UseProgram(program)
	// setting color
	gl.Uniform4f(color, rgb(255), rgb(255), rgb(255), 1)
	gl.UniformMatrix3fv(matrixId, rotationMatrix)
	gl.Uniform1f(resolutionId, resIndex)

	gl.BindBuffer(gl.ARRAY_BUFFER, swasBuffer)

	gl.EnableVertexAttribArray(position)
	gl.VertexAttribPointer(position, 3, gl.FLOAT, false, 0, 0)
	gl.DrawArrays(gl.LINES, 0, 16)
	gl.DisableVertexAttribArray(position)

	gl.UseProgram(texProgram)
	// setting color
	gl.Uniform4f(color2, rgb(130), rgb(50), rgb(80), 1)
	gl.Uniform1f(resolutionId2, resIndex)
	gl.UniformMatrix3fv(matrixId2, rotationMatrix)

	gl.BindBuffer(gl.ARRAY_BUFFER, quadBuffer)
	gl.EnableVertexAttribArray(position2)
	gl.VertexAttribPointer(position2, 3, gl.FLOAT, false, 0, 0)

	gl.BindBuffer(gl.ARRAY_BUFFER, quadTexBuffer)
	gl.EnableVertexAttribArray(textureCoords)
	gl.VertexAttribPointer(textureCoords, 2, gl.FLOAT, false, 0, 0)

	gl.Uniform1i(gl.GetUniformLocation(texProgram, "myTexture"), 0)
	gl.ActiveTexture(gl.TEXTURE0)
	gl.BindTexture(gl.TEXTURE_2D, textureId)

	gl.DrawArrays(gl.TRIANGLES, 0, 6)
	gl.DisableVertexAttribArray(position2)
	gl.DisableVertexAttribArray(textureCoords)

	if spin == true {
		alpha += 0.1
	}

	if alpha >= 360 {
		alpha = 0.0
	}

}

func onPaint(c size.Event) {
	gl.ClearColor(0, 0.3, 0.3, 1)
	gl.Clear(gl.COLOR_BUFFER_BIT)

	gl.UseProgram(program)

	green += direction
	if green > 1 {
		green = 1
		direction = -direction
	}
	if green < 0.4 {
		green = 0.4
		direction = -direction
	}
	gl.Uniform4f(color, 0, green, 0, 1)

	gl.Uniform2f(offset, touchX/float32(c.WidthPx), touchY/float32(c.HeightPx))

	gl.BindBuffer(gl.ARRAY_BUFFER, buf)

	gl.BufferData(gl.ARRAY_BUFFER, triangleData, gl.STATIC_DRAW) // ?

	gl.EnableVertexAttribArray(position)
	gl.VertexAttribPointer(position, coordsPerVertex, gl.FLOAT, false, 0, 0)
	gl.DrawArrays(gl.TRIANGLES, 0, vertexCount)
	gl.DisableVertexAttribArray(position)

	debug.DrawFPS(c)
}

func onPaint(c size.Event) {
	//清场
	gl.ClearColor(1, 1, 1, 1) //设置背景颜色
	gl.Clear(gl.COLOR_BUFFER_BIT)

	//使用program
	gl.UseProgram(program)

	gl.Uniform4f(color, 0, 0.5, 0.8, 1) //设置color对象值,设置4个浮点数.
	//offset有两个值X,Y,窗口左上角为(0,0),右下角为(1,1)
	//gl.Uniform4f(offset,5.0,1.0,1.0,1.0 )
	//gl.Uniform2f(offset,offsetx,offsety )//为2参数的uniform变量赋值
	//log.Println("offset:",offsetx,offsety, 0, 0)
	gl.UniformMatrix4fv(scan, []float32{
		float32(touchLoc.X/c.WidthPt*4 - 2), 0, 0, 0,
		0, float32(touchLoc.Y/c.HeightPt*4 - 2), 0, 0,
		0, 0, 0, 0,
		0, 0, 0, 1,
	})
	gl.BindBuffer(gl.ARRAY_BUFFER, buf)
	gl.EnableVertexAttribArray(position)
	/*glVertexAttribPointer 指定了渲染时索引值为 index 的顶点属性数组的数据格式和位置。调用gl.vertexAttribPointer()方法，把顶点着色器中某个属性相对应的通用属性索引连接到绑定的webGLBUffer对象上。
	  index 指定要修改的顶点属性的索引值
	  size    指定每个顶点属性的组件数量。必须为1、2、3或者4。初始值为4。（如position是由3个（x,y,z）组成，而颜色是4个（r,g,b,a））
	  type    指定数组中每个组件的数据类型。可用的符号常量有GL_BYTE, GL_UNSIGNED_BYTE, GL_SHORT,GL_UNSIGNED_SHORT, GL_FIXED, 和 GL_FLOAT，初始值为GL_FLOAT。
	  normalized  指定当被访问时，固定点数据值是否应该被归一化（GL_TRUE）或者直接转换为固定点值（GL_FALSE）。
	  stride  指定连续顶点属性之间的偏移量。如果为0，那么顶点属性会被理解为：它们是紧密排列在一起的。初始值为0。
	  pointer 指定第一个组件在数组的第一个顶点属性中的偏移量。该数组与GL_ARRAY_BUFFER绑定，储存于缓冲区中。初始值为0；
	*/
	gl.VertexAttribPointer(position, coordsPerVertex, gl.FLOAT, false, 0, 0) //更新position值
	gl.DrawArrays(gl.TRIANGLES, 0, vertexCount)
	gl.DisableVertexAttribArray(position)

	debug.DrawFPS(c)
}

func draw() {
	if program.Value == 0 {
		initGL()
		initCL()
	}
	if numPlatforms == 0 {
		gl.ClearColor(1, 0, 0, 1)
	} else {
		gl.ClearColor(0, 1, 0, 1)
	}
	gl.Clear(gl.COLOR_BUFFER_BIT)

	gl.UseProgram(program)

	blue += 0.01
	if blue > 1 {
		blue = 0
	}
	gl.Uniform4f(color, 0, 0, blue, 1)

	gl.Uniform2f(offset, float32(touchLoc.X/geom.Width), float32(touchLoc.Y/geom.Height))

	gl.BindBuffer(gl.ARRAY_BUFFER, buf)
	gl.EnableVertexAttribArray(position)
	gl.VertexAttribPointer(position, coordsPerVertex, gl.FLOAT, false, 0, 0)
	gl.DrawArrays(gl.TRIANGLES, 0, vertexCount)
	gl.DisableVertexAttribArray(position)

	debug.DrawFPS()
}

func (e *Engine) Start() {
	var err error

	e.shader.program, err = LoadProgram("shader.v.glsl", "shader.f.glsl")
	if err != nil {
		panic(fmt.Sprintln("LoadProgram failed:", err))
	}

	e.shape.buf = gl.CreateBuffer()
	gl.BindBuffer(gl.ARRAY_BUFFER, e.shape.buf)
	gl.BufferData(gl.ARRAY_BUFFER, cubeData, gl.STATIC_DRAW)
	fmt.Println(len(cubeData))
	e.shader.vertCoord = gl.GetAttribLocation(e.shader.program, "vertCoord")
	e.shader.projection = gl.GetUniformLocation(e.shader.program, "projection")
	e.shader.view = gl.GetUniformLocation(e.shader.program, "view")
	e.shader.modelx = gl.GetUniformLocation(e.shader.program, "modelx")
	e.shader.modely = gl.GetUniformLocation(e.shader.program, "modely")

	e.shader.color = gl.GetAttribLocation(e.shader.program, "color")
	e.shape.colorbuf = gl.CreateBuffer()
	gl.BindBuffer(gl.ARRAY_BUFFER, e.shape.colorbuf)
	gl.BufferData(gl.ARRAY_BUFFER, colorData, gl.STATIC_DRAW)
	gl.VertexAttribPointer(e.shader.color, colorsPerVertex, gl.FLOAT, false, 4, 0) //更新color值
	gl.DrawArrays(gl.TRIANGLES, 0, vertexCount)

	e.started = time.Now()
}

func (video *Video) drawFrame() {
	gl.Clear(gl.COLOR_BUFFER_BIT | gl.DEPTH_BUFFER_BIT)
	gl.UseProgram(video.prog)
	gl.ActiveTexture(gl.TEXTURE0)
	gl.BindTexture(gl.TEXTURE_2D, video.texture)

	log.Print("Reading")
	frame := <-video.pixelBuffer
	buf := make([]float32, len(frame))
	log.Print("Read frame")

	for k, v := range frame {
		buf[k] = float32(v)
	}

	log.Print("Writing")
	if video.pixelBuffer != nil {
		gl.TexImage2D(gl.TEXTURE_2D, 0, 256, 256, gl.RGBA,
			gl.UNSIGNED_SHORT_4_4_4_4, f32.Bytes(binary.LittleEndian, buf...))
	}
	log.Print("Wrote")

	gl.DrawArrays(gl.TRIANGLES, 0, 6)
	video.fpsmanager.FramerateDelay()
}

func (shape *StaticShape) Draw(shader Shader, camera Camera) {
	gl.BindBuffer(gl.ARRAY_BUFFER, shape.VBO)
	stride := shape.Stride()

	gl.EnableVertexAttribArray(shader.Attrib("vertCoord"))
	gl.VertexAttribPointer(shader.Attrib("vertCoord"), vertexDim, gl.FLOAT, false, stride, 0)

	if len(shape.normals) > 0 {
		gl.EnableVertexAttribArray(shader.Attrib("vertNormal"))
		gl.VertexAttribPointer(shader.Attrib("vertNormal"), normalDim, gl.FLOAT, false, stride, vertexDim*vecSize)
	}
	// TODO: texture

	if len(shape.indices) > 0 {
		gl.BindBuffer(gl.ELEMENT_ARRAY_BUFFER, shape.IBO)
		gl.DrawElements(gl.TRIANGLES, len(shape.indices), gl.UNSIGNED_BYTE, 0)
	} else {
		gl.DrawArrays(gl.TRIANGLES, 0, shape.Len())
	}

	gl.DisableVertexAttribArray(shader.Attrib("vertCoord"))
	if len(shape.normals) > 0 {
		gl.DisableVertexAttribArray(shader.Attrib("vertNormal"))
	}
	// TODO: texture
}

func (w *windowImpl) Draw(src2dst f64.Aff3, src screen.Texture, sr image.Rectangle, op draw.Op, opts *screen.DrawOptions) {
	t := src.(*textureImpl)
	a := w.vertexAff3(sr)

	gl.UseProgram(w.s.texture.program)
	writeAff3(w.s.texture.mvp, mul(a, src2dst))

	// OpenGL's fragment shaders' UV coordinates run from (0,0)-(1,1),
	// unlike vertex shaders' XY coordinates running from (-1,+1)-(+1,-1).
	//
	// We are drawing a rectangle PQRS, defined by two of its
	// corners, onto the entire texture. The two quads may actually
	// be equal, but in the general case, PQRS can be smaller.
	//
	//	(0,0) +---------------+ (1,0)
	//	      |  P +-----+ Q  |
	//	      |    |     |    |
	//	      |  S +-----+ R  |
	//	(0,1) +---------------+ (1,1)
	//
	// The PQRS quad is always axis-aligned. First of all, convert
	// from pixel space to texture space.
	tw := float64(t.size.X)
	th := float64(t.size.Y)
	px := float64(sr.Min.X-0) / tw
	py := float64(sr.Min.Y-0) / th
	qx := float64(sr.Max.X-0) / tw
	sy := float64(sr.Max.Y-0) / th
	// Due to axis alignment, qy = py and sx = px.
	//
	// The simultaneous equations are:
	//	  0 +   0 + a02 = px
	//	  0 +   0 + a12 = py
	//	a00 +   0 + a02 = qx
	//	a10 +   0 + a12 = qy = py
	//	  0 + a01 + a02 = sx = px
	//	  0 + a11 + a12 = sy
	writeAff3(w.s.texture.uvp, f64.Aff3{
		qx - px, 0, px,
		0, sy - py, py,
	})

	gl.ActiveTexture(gl.TEXTURE0)
	gl.BindTexture(gl.TEXTURE_2D, t.id)
	gl.Uniform1i(w.s.texture.sample, 0)

	gl.BindBuffer(gl.ARRAY_BUFFER, w.s.texture.quadXY)
	gl.EnableVertexAttribArray(w.s.texture.pos)
	gl.VertexAttribPointer(w.s.texture.pos, 2, gl.FLOAT, false, 0, 0)

	gl.BindBuffer(gl.ARRAY_BUFFER, w.s.texture.quadUV)
	gl.EnableVertexAttribArray(w.s.texture.inUV)
	gl.VertexAttribPointer(w.s.texture.inUV, 2, gl.FLOAT, false, 0, 0)

	gl.DrawArrays(gl.TRIANGLE_STRIP, 0, 4)

	gl.DisableVertexAttribArray(w.s.texture.pos)
	gl.DisableVertexAttribArray(w.s.texture.inUV)
}

func (emitter *particleEmitter) Draw(shader Shader, camera Camera) {
	gl.BindBuffer(gl.ARRAY_BUFFER, emitter.VBO)

	gl.EnableVertexAttribArray(shader.Attrib("vertCoord"))
	gl.VertexAttribPointer(shader.Attrib("vertCoord"), vertexDim, gl.FLOAT, false, emitter.Stride(), 0)

	gl.DrawArrays(gl.TRIANGLES, 0, emitter.Len()*particleLen/vertexDim)

	gl.DisableVertexAttribArray(shader.Attrib("vertCoord"))
}

func (e *Engine) Draw(c size.Event) {

	gl.Enable(gl.DEPTH_TEST)
	gl.DepthFunc(gl.LESS)

	gl.ClearColor(0.5, 0.8, 0.8, 1)
	gl.Clear(gl.COLOR_BUFFER_BIT)
	gl.Clear(gl.DEPTH_BUFFER_BIT)

	gl.UseProgram(e.shader.program)

	gl.Uniform3fv(e.shader.lightdir, []float32{0.5, 0.6, 0.7})

	m := mgl32.Perspective(1.3, float32(c.WidthPt/c.HeightPt), 0.1, 10.0)
	gl.UniformMatrix4fv(e.shader.projectionmatrix, m[:])

	eye := mgl32.Vec3{0, 0, 0.2}
	center := mgl32.Vec3{0, 0, 0}
	up := mgl32.Vec3{0, 1, 0}

	m = mgl32.LookAtV(eye, center, up)
	gl.UniformMatrix4fv(e.shader.viewmatrix, m[:])

	m = mgl32.HomogRotate3D((e.touchx/float32(c.WidthPt)-0.5)*6.28, mgl32.Vec3{0, 1, 0})
	gl.UniformMatrix4fv(e.shader.modelmatrix, m[:])

	m = mgl32.HomogRotate3D((e.touchx/float32(c.WidthPt)-0.5)*6.28, mgl32.Vec3{0, -1, 0})
	gl.UniformMatrix4fv(e.shader.lightmatrix, m[:])

	coordsPerVertex := 3
	for _, obj := range e.shape.Objs {
		gl.BindBuffer(gl.ARRAY_BUFFER, obj.coord)
		gl.EnableVertexAttribArray(e.shader.vertCoord)
		gl.VertexAttribPointer(e.shader.vertCoord, coordsPerVertex, gl.FLOAT, false, 12, 0)

		texCoordsPerVertex := 2
		gl.BindBuffer(gl.ARRAY_BUFFER, obj.uvcoord)
		gl.EnableVertexAttribArray(e.shader.texcoord)
		gl.VertexAttribPointer(e.shader.texcoord, texCoordsPerVertex, gl.FLOAT, false, 8, 0)

		gl.BindBuffer(gl.ARRAY_BUFFER, obj.normal)
		gl.EnableVertexAttribArray(e.shader.normal)
		gl.VertexAttribPointer(e.shader.normal, 3, gl.FLOAT, false, 12, 0)

		gl.BindTexture(gl.TEXTURE_2D, obj.tex)

		gl.DrawArrays(gl.TRIANGLES, 0, obj.vcount)

		gl.DisableVertexAttribArray(e.shader.texcoord)
		gl.DisableVertexAttribArray(e.shader.normal)
		gl.DisableVertexAttribArray(e.shader.vertCoord)
	}

	debug.DrawFPS(c)
}

func (e *Engine) Draw(c size.Event) {

	gl.Enable(gl.DEPTH_TEST)
	gl.DepthFunc(gl.LESS)

	gl.ClearColor(0.2, 0.2, 0.2, 1)
	gl.Clear(gl.COLOR_BUFFER_BIT)
	gl.Clear(gl.DEPTH_BUFFER_BIT)

	gl.UseProgram(e.shader.program)

	m := mgl32.Perspective(0.785, float32(c.WidthPt/c.HeightPt), 0.1, 10.0)
	gl.UniformMatrix4fv(e.shader.projection, m[:])

	eye := mgl32.Vec3{0, 0, 8}
	center := mgl32.Vec3{0, 0, 0}
	up := mgl32.Vec3{0, 1, 0}

	m = mgl32.LookAtV(eye, center, up)
	gl.UniformMatrix4fv(e.shader.view, m[:])

	m = mgl32.HomogRotate3D(float32(e.touchLoc.X/c.WidthPt-0.5)*3.14*2, mgl32.Vec3{0, 1, 0})
	gl.UniformMatrix4fv(e.shader.modelx, m[:])

	m = mgl32.HomogRotate3D(float32(e.touchLoc.Y/c.HeightPt-0.5)*3.14, mgl32.Vec3{1, 0, 0})
	gl.UniformMatrix4fv(e.shader.modely, m[:])

	coordsPerVertex := 3
	for _, obj := range e.shape.Objs {
		gl.BindBuffer(gl.ARRAY_BUFFER, obj.coord)
		gl.EnableVertexAttribArray(e.shader.vertCoord)

		gl.VertexAttribPointer(e.shader.vertCoord, coordsPerVertex, gl.FLOAT, false, 12, 0)

		if obj.useuv == true {
			gl.Uniform1i(e.shader.useuv, 1)
			texCoordsPerVertex := 2
			gl.BindBuffer(gl.ARRAY_BUFFER, obj.uvcoord)
			gl.EnableVertexAttribArray(e.shader.vertTexCoord)
			gl.VertexAttribPointer(e.shader.vertTexCoord, texCoordsPerVertex, gl.FLOAT, false, 8, 0)

			gl.BindTexture(gl.TEXTURE_2D, obj.tex)
		} else {
			gl.Uniform1i(e.shader.useuv, 0)
			gl.Uniform4f(e.shader.color, obj.color[0], obj.color[1], obj.color[2], obj.color[3])
		}
		gl.DrawArrays(gl.TRIANGLES, 0, obj.vcount)
		if obj.useuv {
			gl.DisableVertexAttribArray(e.shader.vertTexCoord)
		}
		gl.DisableVertexAttribArray(e.shader.vertCoord)
	}

	debug.DrawFPS(c)
}

func (e *Engine) Draw(c event.Config) {
	since := time.Now().Sub(e.started)

	gl.Enable(gl.DEPTH_TEST)
	gl.DepthFunc(gl.LESS)

	gl.ClearColor(0, 0, 0, 1)
	gl.Clear(gl.COLOR_BUFFER_BIT)
	gl.Clear(gl.DEPTH_BUFFER_BIT)

	gl.UseProgram(e.shader.program)

	// Setup MVP
	var m mgl.Mat4
	m = mgl.Perspective(0.785, float32(c.Width/c.Height), 0.1, 10.0)
	gl.UniformMatrix4fv(e.shader.projection, m[:])

	m = mgl.LookAtV(
		mgl.Vec3{3, 3, 3}, // eye
		mgl.Vec3{0, 0, 0}, // center
		mgl.Vec3{0, 1, 0}, // up
	)
	gl.UniformMatrix4fv(e.shader.view, m[:])

	m = mgl.HomogRotate3D(float32(since.Seconds()), mgl.Vec3{0, 1, 0})
	gl.UniformMatrix4fv(e.shader.model, m[:])

	// Draw our shape
	gl.BindBuffer(gl.ARRAY_BUFFER, e.shape.buf)

	gl.EnableVertexAttribArray(e.shader.vertCoord)
	gl.VertexAttribPointer(e.shader.vertCoord, e.shape.coordsPerVertex, gl.FLOAT, false, 20, 0) // 4 bytes in float, 5 values per vertex

	gl.EnableVertexAttribArray(e.shader.vertTexCoord)
	gl.VertexAttribPointer(e.shader.vertTexCoord, e.shape.texCoordsPerVertex, gl.FLOAT, false, 20, 12)

	gl.ActiveTexture(gl.TEXTURE0)
	gl.BindTexture(gl.TEXTURE_2D, e.shape.texture)

	gl.DrawArrays(gl.TRIANGLES, 0, e.shape.vertexCount)

	gl.DisableVertexAttribArray(e.shader.vertCoord)

	//debug.DrawFPS(c)
}

func onPaint(c config.Event) {
	gl.ClearColor(1, 1, 1, 1)
	gl.Clear(gl.COLOR_BUFFER_BIT)

	gl.UseProgram(program)

	gl.Uniform4f(color, 0.3, 0.3, 0.3, 1) // color
	// position
	x := float32(touchLoc.X / c.Width)
	y := float32(touchLoc.Y / c.Height)
	gl.Uniform2f(offset, x, y)

	gl.BindBuffer(gl.ARRAY_BUFFER, buf)
	gl.EnableVertexAttribArray(position)
	gl.VertexAttribPointer(position, 2, gl.FLOAT, false, 0, 0)
	gl.DrawArrays(gl.TRIANGLE_STRIP, 0, 4)
	gl.DisableVertexAttribArray(position)
}

func onPaint(sz size.Event) {
	gl.ClearColor(1, 0, 0, 1)
	gl.Clear(gl.COLOR_BUFFER_BIT)

	gl.UseProgram(program)

	green += 0.01
	if green > 1 {
		green = 0
	}
	gl.Uniform4f(color, 0, green, 0, 1)

	gl.Uniform2f(offset, touchX/float32(sz.WidthPx), touchY/float32(sz.HeightPx))

	gl.BindBuffer(gl.ARRAY_BUFFER, buf)
	gl.EnableVertexAttribArray(position)
	gl.VertexAttribPointer(position, coordsPerVertex, gl.FLOAT, false, 0, 0)
	gl.DrawArrays(gl.TRIANGLES, 0, vertexCount)
	gl.DisableVertexAttribArray(position)

	debug.DrawFPS(sz)
}

func onDraw(c config.Event) {
	gl.ClearColor(1, 0, 0, 1)
	gl.Clear(gl.COLOR_BUFFER_BIT)

	gl.UseProgram(program)

	green += 0.01
	if green > 1 {
		green = 0
	}
	gl.Uniform4f(color, 0, green, 0, 1)

	gl.Uniform2f(offset, float32(touchLoc.X/c.Width), float32(touchLoc.Y/c.Height))

	gl.BindBuffer(gl.ARRAY_BUFFER, buf)
	gl.EnableVertexAttribArray(position)
	gl.VertexAttribPointer(position, coordsPerVertex, gl.FLOAT, false, 0, 0)
	gl.DrawArrays(gl.TRIANGLES, 0, vertexCount)
	gl.DisableVertexAttribArray(position)

	debug.DrawFPS(c)
}

func (shape *Line) Draw(camera Camera) {
	shader := shape.shader

	// Set uniforms
	gl.Uniform1f(shader.Uniform("lights[0].intensity"), 2.0)
	gl.Uniform3fv(shader.Uniform("lights[0].position"), shape.position[:])
	gl.Uniform3fv(shader.Uniform("lights[0].color"), []float32{0.4, 0.2, 0.1})

	gl.Uniform3fv(shader.Uniform("material.ambient"), []float32{0.1, 0.15, 0.4})
	//gl.Uniform3fv(shader.Uniform("material.diffuse"), []float32{0.8, 0.6, 0.6})
	//gl.Uniform3fv(shader.Uniform("material.specular"), []float32{1.0, 1.0, 1.0})
	//gl.Uniform1f(shader.Uniform("material.shininess"), 16.0)
	//gl.Uniform1f(shader.Uniform("material.refraction"), 1.0/1.52)

	gl.BindBuffer(gl.ARRAY_BUFFER, shape.VBO)
	stride := shape.Stride()

	gl.EnableVertexAttribArray(shader.Attrib("vertCoord"))
	gl.VertexAttribPointer(shader.Attrib("vertCoord"), vertexDim, gl.FLOAT, false, stride, 0)

	gl.DrawArrays(gl.TRIANGLE_STRIP, 0, shape.Len())
}

func onStart() {
	var err error
	program, err = glutil.CreateProgram(vertexShader, fragmentShader)
	if err != nil {
		log.Printf("error creating GL program: %v", err)
		return
	}

	/*opengl中三种变量
	  uniform变量是外部application程序传递给（vertex和fragment）shader的变量。因此它是application通过函数glUniform**（）函数赋值的。
	  在（vertex和fragment）shader程序内部，uniform变量就像是C语言里面的常量（const ），它不能被shader程序修改。（shader只能用，不能改）

	  attribute变量是只能在vertex shader中使用的变量。（它不能在fragment shader中声明attribute变量，也不能被fragment shader中使用）
	  一般用attribute变量来表示一些顶点的数据，如：顶点坐标，法线，纹理坐标，顶点颜色等。
	  在application中，一般用函数glBindAttribLocation（）来绑定每个attribute变量的位置，然后用函数glVertexAttribPointer（）为每个attribute变量赋值。

	  varying变量是vertex和fragment shader之间做数据传递用的。一般vertex shader修改varying变量的值，然后fragment shader使用该varying变量的值。
	  因此varying变量在vertex和fragment shader二者之间的声明必须是一致的。application不能使用此变量。
	*/

	position = gl.GetAttribLocation(program, "position") //获取位置对象(索引)
	color = gl.GetAttribLocation(program, "color")       // 获取颜色对象(索引)
	scan = gl.GetUniformLocation(program, "scan")        // 获取偏移对象(索引)

	positionbuf = gl.CreateBuffer()
	gl.BindBuffer(gl.ARRAY_BUFFER, positionbuf)
	gl.BufferData(gl.ARRAY_BUFFER, triangleData, gl.STATIC_DRAW)

	colorbuf = gl.CreateBuffer()
	gl.BindBuffer(gl.ARRAY_BUFFER, colorbuf)
	gl.BufferData(gl.ARRAY_BUFFER, colorData, gl.STATIC_DRAW)
	gl.VertexAttribPointer(color, colorsPerVertex, gl.FLOAT, false, 0, 0) //更新color值
	gl.DrawArrays(gl.TRIANGLES, 0, vertexCount)

	// fmt.Println(position.String(),color.String(),offset.String())//Attrib(0) Uniform(1) Uniform(0)
	// TODO(crawshaw): the debug package needs to put GL state init here
	// Can this be an event.Register call now??
}

func (w *windowImpl) Fill(dr image.Rectangle, src color.Color, op draw.Op) {
	if !gl.IsProgram(w.s.fill.program) {
		p, err := compileProgram(fillVertexSrc, fillFragmentSrc)
		if err != nil {
			// TODO: initialize this somewhere else we can better handle the error.
			panic(err.Error())
		}
		w.s.fill.program = p
		w.s.fill.pos = gl.GetAttribLocation(p, "pos")
		w.s.fill.mvp = gl.GetUniformLocation(p, "mvp")
		w.s.fill.color = gl.GetUniformLocation(p, "color")
		w.s.fill.quadXY = gl.CreateBuffer()

		gl.BindBuffer(gl.ARRAY_BUFFER, w.s.fill.quadXY)
		gl.BufferData(gl.ARRAY_BUFFER, quadXYCoords, gl.STATIC_DRAW)
	}

	gl.UseProgram(w.s.fill.program)
	writeAff3(w.s.fill.mvp, w.vertexAff3(dr))

	r, g, b, a := src.RGBA()
	gl.Uniform4f(
		w.s.fill.color,
		float32(r)/65535,
		float32(g)/65535,
		float32(b)/65535,
		float32(a)/65535,
	)

	gl.BindBuffer(gl.ARRAY_BUFFER, w.s.fill.quadXY)
	gl.EnableVertexAttribArray(w.s.fill.pos)
	gl.VertexAttribPointer(w.s.fill.pos, 2, gl.FLOAT, false, 0, 0)

	gl.DrawArrays(gl.TRIANGLE_STRIP, 0, 4)

	gl.DisableVertexAttribArray(w.s.fill.pos)
}

//.........这里部分代码省略.........
		// and the PQRS quad is:
		//
		//	(topLeft.X,    topLeft.Y)    (topRight.X, topRight.Y)
		//	(bottomLeft.X, bottomLeft.Y) (implicit,   implicit)
		//
		// In framebuffer space, the ABCD rectangle is:
		//
		//	(-1, +1) (+1, +1)
		//	(-1, -1) (+1, -1)
		//
		// First of all, convert from geom space to framebuffer space. For
		// later convenience, we divide everything by 2 here: px2 is half of
		// the P.X co-ordinate (in framebuffer space).
		px2 := -0.5 + float32(topLeft.X/geom.Width)
		py2 := +0.5 - float32(topLeft.Y/geom.Height)
		qx2 := -0.5 + float32(topRight.X/geom.Width)
		qy2 := +0.5 - float32(topRight.Y/geom.Height)
		sx2 := -0.5 + float32(bottomLeft.X/geom.Width)
		sy2 := +0.5 - float32(bottomLeft.Y/geom.Height)
		// Next, solve for the affine transformation matrix
		//	    [ a00 a01 a02 ]
		//	a = [ a10 a11 a12 ]
		//	    [   0   0   1 ]
		// that maps A to P:
		//	a × [ -1 +1 1 ]' = [ 2*px2 2*py2 1 ]'
		// and likewise maps B to Q and D to S. Solving those three constraints
		// implies that C maps to R, since affine transformations keep parallel
		// lines parallel. This gives 6 equations in 6 unknowns:
		//	-a00 + a01 + a02 = 2*px2
		//	-a10 + a11 + a12 = 2*py2
		//	+a00 + a01 + a02 = 2*qx2
		//	+a10 + a11 + a12 = 2*qy2
		//	-a00 - a01 + a02 = 2*sx2
		//	-a10 - a11 + a12 = 2*sy2
		// which gives:
		//	a00 = (2*qx2 - 2*px2) / 2 = qx2 - px2
		// and similarly for the other elements of a.
		glimage.mvp.WriteAffine(&f32.Affine{{
			qx2 - px2,
			px2 - sx2,
			qx2 + sx2,
		}, {
			qy2 - py2,
			py2 - sy2,
			qy2 + sy2,
		}})
	}

	{
		// Mapping texture co-ordinates is similar, except that in texture
		// space, the ABCD rectangle is:
		//
		//	(0,0) (1,0)
		//	(0,1) (1,1)
		//
		// and the PQRS quad is always axis-aligned. First of all, convert
		// from pixel space to texture space.
		w := float32(img.texWidth)
		h := float32(img.texHeight)
		px := float32(srcBounds.Min.X-img.Rect.Min.X) / w
		py := float32(srcBounds.Min.Y-img.Rect.Min.Y) / h
		qx := float32(srcBounds.Max.X-img.Rect.Min.X) / w
		sy := float32(srcBounds.Max.Y-img.Rect.Min.Y) / h
		// Due to axis alignment, qy = py and sx = px.
		//
		// The simultaneous equations are:
		//	  0 +   0 + a02 = px
		//	  0 +   0 + a12 = py
		//	a00 +   0 + a02 = qx
		//	a10 +   0 + a12 = qy = py
		//	  0 + a01 + a02 = sx = px
		//	  0 + a11 + a12 = sy
		glimage.uvp.WriteAffine(&f32.Affine{{
			qx - px,
			0,
			px,
		}, {
			0,
			sy - py,
			py,
		}})
	}

	gl.ActiveTexture(gl.TEXTURE0)
	gl.BindTexture(gl.TEXTURE_2D, img.Texture)
	gl.Uniform1i(glimage.textureSample, 0)

	gl.BindBuffer(gl.ARRAY_BUFFER, glimage.quadXY)
	gl.EnableVertexAttribArray(glimage.pos)
	gl.VertexAttribPointer(glimage.pos, 2, gl.FLOAT, false, 0, 0)

	gl.BindBuffer(gl.ARRAY_BUFFER, glimage.quadUV)
	gl.EnableVertexAttribArray(glimage.inUV)
	gl.VertexAttribPointer(glimage.inUV, 2, gl.FLOAT, false, 0, 0)

	gl.DrawArrays(gl.TRIANGLE_STRIP, 0, 4)

	gl.DisableVertexAttribArray(glimage.pos)
	gl.DisableVertexAttribArray(glimage.inUV)
}

func drawKeys() {
	gl.UseProgram(program)
	projection.WriteMat4(&projmat)

	iPlaying := []int{}
	playing := []ratio{}
	amps := []float64{}
	for i, k := range keys {
		k := k.base()
		if k.voice != nil && !k.voice.Done() {
			iPlaying = append(iPlaying, i)
			playing = append(playing, k.ratio)
			amps = append(amps, k.voice.amp())
		}
	}
	complexities := make([]float64, len(keys))
	minComplexity := math.MaxFloat64
	for i, k := range keys {
		k := k.base()
		c := -1.0
		for j, iPlaying := range iPlaying {
			if i == iPlaying {
				a := amps[j]
				amps[j] = 1
				c = complexity(playing, amps)
				amps[j] = a
				break
			}
		}
		if c == -1 {
			c = complexity(append(playing, k.ratio), append(amps, 1))
		}
		complexities[i] = c
		if c < minComplexity {
			minComplexity = c
		}
	}
	data := []float32{}
	pointsizedata := []float32{}
	for i, k := range keys {
		k := k.base()
		k.y = 1 - math.Exp2(-float64(complexities[i]-minComplexity)/4)
		k.size = math.Exp2(-float64(complexities[i])/4) * float64(geom.Width) * float64(geom.PixelsPerPt) / 4
		data = append(data, float32(k.pitch), float32(k.y))
		pointsizedata = append(pointsizedata, float32(k.size))
	}
	gl.BindBuffer(gl.ARRAY_BUFFER, positionbuf)
	gl.BufferData(gl.ARRAY_BUFFER, f32.Bytes(binary.LittleEndian, data...), gl.DYNAMIC_DRAW)
	gl.BindBuffer(gl.ARRAY_BUFFER, pointsizebuf)
	gl.BufferData(gl.ARRAY_BUFFER, f32.Bytes(binary.LittleEndian, pointsizedata...), gl.DYNAMIC_DRAW)

	gl.EnableVertexAttribArray(position)
	gl.EnableVertexAttribArray(pointsize)
	gl.Uniform4f(color, 1, 1, 1, 1)
	gl.BindBuffer(gl.ARRAY_BUFFER, positionbuf)
	gl.VertexAttribPointer(position, 2, gl.FLOAT, false, 0, 0)
	gl.BindBuffer(gl.ARRAY_BUFFER, pointsizebuf)
	gl.VertexAttribPointer(pointsize, 1, gl.FLOAT, false, 0, 0)
	gl.DrawArrays(gl.POINTS, 0, len(keys))
	gl.DisableVertexAttribArray(position)
	gl.DisableVertexAttribArray(pointsize)
}