Golang gl.Clear函数代码示例

func render() {
	modelMatrix = trig.MatrixMult(trig.RotateY(math.Pi/360), modelMatrix)

	gl.Viewport(0, 0, 768, 768)
	gl.ClearColor(0.0, 0.0, 0, 0)
	gl.Enable(gl.DEPTH_TEST)

	raytraceProgram.Use()
	mInput.UniformMatrix4f(false, (*[16]float32)(modelMatrix))
	vInput.UniformMatrix4f(false, (*[16]float32)(viewMatrix))
	pInput.UniformMatrix4f(false, (*[16]float32)(projMatrix))
	glh.With(framebuffer, func() {
		framebuffer.UpdateTextures()

		gl.DrawBuffer(gl.COLOR_ATTACHMENT0)

		gl.Clear(gl.COLOR_BUFFER_BIT)
		gl.DepthFunc(gl.GREATER)
		gl.CullFace(gl.BACK)
		cube.Render(gl.TRIANGLES, raytraceProgram)

		gl.DrawBuffer(gl.COLOR_ATTACHMENT1)
		gl.Clear(gl.COLOR_BUFFER_BIT)
		gl.DepthFunc(gl.LESS)
		gl.CullFace(gl.FRONT)
		cube.Render(gl.TRIANGLES, raytraceProgram)
	})
}

// OpenGL draw function & timing
func draw() {
	gl.Clear(gl.COLOR_BUFFER_BIT | gl.DEPTH_BUFFER_BIT)

	gl.PushMatrix()
	gl.Rotated(view_rotx, 1.0, 0.0, 0.0)
	gl.Rotated(view_roty, 0.0, 1.0, 0.0)
	gl.Rotated(view_rotz, 0.0, 0.0, 1.0)

	gl.PushMatrix()
	gl.Translated(-3.0, -2.0, 0.0)
	gl.Rotated(angle, 0.0, 0.0, 1.0)
	gl.CallList(gear1)
	gl.PopMatrix()

	gl.PushMatrix()
	gl.Translated(3.1, -2.0, 0.0)
	gl.Rotated(-2.0*angle-9.0, 0.0, 0.0, 1.0)
	gl.CallList(gear2)
	gl.PopMatrix()

	gl.PushMatrix()
	gl.Translated(-3.1, 4.2, 0.0)
	gl.Rotated(-2.0*angle-25.0, 0.0, 0.0, 1.0)
	gl.CallList(gear3)
	gl.PopMatrix()

	gl.PopMatrix()
}

func gameOverScreen(
	screen *sdl.Surface,
	score string,
	bg *glh.Texture,
	font *gltext.Font) bool {

	for {
		gl.Clear(gl.COLOR_BUFFER_BIT | gl.DEPTH_BUFFER_BIT)
		for e := sdl.PollEvent(); e != nil; e = sdl.PollEvent() {
			switch e.(type) {
			case *sdl.ResizeEvent:
				resize(screen, e.(*sdl.ResizeEvent))
			case *sdl.QuitEvent:
				return true
			case *sdl.MouseButtonEvent:
				return false
			}
		}
		renderBackground(screen, bg)
		font.Printf(110, 50, "Game Over")
		font.Printf(110, 100, "Your score: "+score)
		font.Printf(110, 150, "Click to play again")
		sdl.GL_SwapBuffers()
		time.Sleep((1 / 30) * time.Second)
	}
	return false
}

func drawScene(mvp *glm.Matrix4, dt float64) {
	gl.Clear(gl.COLOR_BUFFER_BIT | gl.DEPTH_BUFFER_BIT)
	program, err := compileProgram(shaderDir, "sample")
	if err != nil {
		log.Printf("Error reading program. Cause: %v", err)
	} else {
		defer program.Delete()
	}

	// lets scale our model by 100, otherwise
	// the triangle will be 1 pixel width
	// let's make our triangle pulsate
	triangleScale += triangleScaleChangeFactor * float32(dt)
	if triangleScale >= 200 {
		triangleScale = 200
		triangleScaleChangeFactor *= -1
	} else if triangleScale < 10 {
		triangleScale = 10
		triangleScaleChangeFactor *= -1
	}
	scaled := mvp.Scale(glm.Vector3{triangleScale, triangleScale, triangleScale})

	loc := program.GetUniformLocation("MVP")
	loc.UniformMatrix4f(false, ptrForMatrix(scaled))
	theTriangleBuf.Render(gl.TRIANGLES)
}

func draw() {                  // 从这里开始进行所有的绘制

	gl.Clear(gl.COLOR_BUFFER_BIT | gl.DEPTH_BUFFER_BIT) // 清除屏幕和深度缓存
	gl.LoadIdentity()                                   // 重置当前的模型观察矩阵
	gl.Translatef(-1.5, 0.0, -6.0)                      // 左移 1.5 单位，并移入屏幕 6.0

	gl.Rotatef(rtri, 0.0, 1.0, 0.0) // 绕Y轴旋转三角形
	gl.Begin(gl.TRIANGLES)          // 绘制三角形
	gl.Color3f(1.0, 0.0, 0.0)       // 设置当前色为红色
	gl.Vertex3f(0.0, 1.0, 0.0)      // 上顶点
	gl.Color3f(0.0, 1.0, 0.0)       // 设置当前色为绿色
	gl.Vertex3f(-1.0, -1.0, 0.0)    // 左下
	gl.Color3f(0.0, 0.0, 1.0)       // 设置当前色为蓝色
	gl.Vertex3f(1.0, -1.0, 0.0)     // 右下
	gl.End()                        // 三角形绘制结束

	gl.LoadIdentity()                // 重置当前的模型观察矩阵
	gl.Translatef(1.5, 0.0, -6.0)    // 右移1.5单位,并移入屏幕 6.0
	gl.Rotatef(rquad, 1.0, 0.0, 0.0) //  绕X轴旋转四边形
	gl.Color3f(0.5, 0.5, 1.0)        // 一次性将当前色设置为蓝色
	gl.Begin(gl.QUADS)               //  绘制正方形
	gl.Vertex3f(-1.0, 1.0, 0.0)      // 左上
	gl.Vertex3f(1.0, 1.0, 0.0)       // 右上
	gl.Vertex3f(1.0, -1.0, 0.0)      // 左下
	gl.Vertex3f(-1.0, -1.0, 0.0)     // 右下
	gl.End()

	rtri += 0.2 // 增加三角形的旋转变量

	rquad -= 0.15 // 减少四边形的旋转变量
}

func drawScene() {
	gl.Clear(gl.COLOR_BUFFER_BIT | gl.DEPTH_BUFFER_BIT) /// 清除屏幕及深度缓存
	gl.LoadIdentity()                                   /// 重置模型观察矩阵

	gl.Translatef(-1.5, 0, -6) /// 左移 1.5 单位，并移入屏幕 6.0

	gl.Begin(gl.TRIANGLES) /// 绘制三角形
	gl.Color3f(1, 0, 0)    ///  设置当前色为红色
	gl.Vertex3f(0, 1, 0)   ///上顶点
	gl.Color3f(0, 1, 0)    /// 设置当前色为绿色
	gl.Vertex3f(-1, -1, 0) /// 左下
	gl.Color3f(0, 0, 1)    ///设置当前色为蓝色
	gl.Vertex3f(1, -1, 0)  ///右下
	gl.End()               ///三角形绘制结束,三角形将被填充。
	//但是因为每个顶点有不同的颜色，因此看起来颜色从每个角喷出，并刚好在三角形的中心汇合，三种颜色相互混合。这就是平滑着色。

	gl.Translatef(3, 0, 0)    ///右移3单位
	gl.Color3f(0.5, 0.5, 1.0) ///一次性将当前色设置为蓝色

	/// @note 顺时针绘制的正方形意味着我们所看见的是四边形的背面
	gl.Begin(gl.QUADS)     ///绘制正方形
	gl.Vertex3f(-1, 1, 0)  /// 左上
	gl.Vertex3f(1, 1, 0)   /// 右上
	gl.Vertex3f(1, -1, 0)  /// 右下
	gl.Vertex3f(-1, -1, 0) /// 左下
	gl.End()               ///正方形绘制结束

	glfw.SwapBuffers() ///必须交换显示区才能展现
}

func draw() { // 从这里开始进行所有的绘制

	gl.Clear(gl.COLOR_BUFFER_BIT | gl.DEPTH_BUFFER_BIT) // 清除屏幕和深度缓存

	gl.LoadIdentity() // 重置当前的模型观察矩阵

}

func main() {

	if !glfw.Init() {
		log.Fatal("glfw failed to initialize")
	}
	defer glfw.Terminate()

	window, err := glfw.CreateWindow(640, 480, "Deformable", nil, nil)
	if err != nil {
		log.Fatal(err.Error())
	}

	window.MakeContextCurrent()
	glfw.SwapInterval(1)
	window.SetMouseButtonCallback(handleMouseButton)
	window.SetKeyCallback(handleKeyDown)
	window.SetInputMode(glfw.Cursor, glfw.CursorHidden)

	gl.Init()
	initGL()

	i := 16
	m = GenerateMap(1600/i, 1200/i, i)
	for running && !window.ShouldClose() {

		x, y := window.GetCursorPosition()

		if drawing != 0 {
			m.Add(int(x)+int(camera[0]), int(y)+int(camera[1]), drawing, brushSizes[currentBrushSize])
		}

		gl.Clear(gl.COLOR_BUFFER_BIT)
		gl.LoadIdentity()

		gl.PushMatrix()
		gl.PushAttrib(gl.CURRENT_BIT | gl.ENABLE_BIT | gl.LIGHTING_BIT | gl.POLYGON_BIT | gl.LINE_BIT)
		gl.Translatef(-camera[0], -camera[1], 0)
		m.Draw()
		gl.PopAttrib()
		gl.PopMatrix()

		gl.PushAttrib(gl.COLOR_BUFFER_BIT)
		gl.LineWidth(2)
		gl.Enable(gl.BLEND)
		gl.BlendFunc(gl.ONE_MINUS_DST_COLOR, gl.ZERO)
		// gl.Enable(gl.LINE_SMOOTH)
		// gl.Hint(gl.LINE_SMOOTH_HINT, gl.NICEST)

		gl.Translatef(float32(x), float32(y), 0)

		gl.EnableClientState(gl.VERTEX_ARRAY)
		gl.VertexPointer(2, gl.DOUBLE, 0, cursorVerts)
		gl.DrawArrays(gl.LINE_LOOP, 0, 24)
		gl.PopAttrib()

		window.SwapBuffers()
		glfw.PollEvents()
	}

}

// OpenGL draw function
func draw() {
	gl.Clear(gl.COLOR_BUFFER_BIT)
	gl.Enable(gl.BLEND)
	gl.Enable(gl.POINT_SMOOTH)
	gl.Enable(gl.LINE_SMOOTH)
	gl.BlendFunc(gl.SRC_ALPHA, gl.ONE_MINUS_SRC_ALPHA)
	gl.LoadIdentity()

	gl.Begin(gl.LINES)
	gl.Color3f(.2, .2, .2)
	for i := range staticLines {
		x := staticLines[i].GetAsSegment().A.X
		y := staticLines[i].GetAsSegment().A.Y
		gl.Vertex3f(float32(x), float32(y), 0)
		x = staticLines[i].GetAsSegment().B.X
		y = staticLines[i].GetAsSegment().B.Y
		gl.Vertex3f(float32(x), float32(y), 0)
	}
	gl.End()

	gl.Color4f(.3, .3, 1, .8)
	// draw balls
	for _, ball := range balls {
		gl.PushMatrix()
		pos := ball.Body.Position()
		rot := ball.Body.Angle() * chipmunk.DegreeConst
		gl.Translatef(float32(pos.X), float32(pos.Y), 0.0)
		gl.Rotatef(float32(rot), 0, 0, 1)
		drawCircle(float64(ballRadius), 60)
		gl.PopMatrix()
	}
}

// Clear the alpha channel in the color buffer
func ClearAlpha(alpha_value gl.GLclampf) {
	With(Attrib{gl.COLOR_BUFFER_BIT}, func() {
		gl.ColorMask(false, false, false, true)
		gl.ClearColor(0, 0, 0, alpha_value)
		gl.Clear(gl.COLOR_BUFFER_BIT)
	})
}

func display() {
	gl.Clear(gl.COLOR_BUFFER_BIT)
	bitmap_output(40, 35, "This is written in a GLUT bitmap font.", glut.BITMAP_TIMES_ROMAN_24)
	bitmap_output(30, 210, "More bitmap text is a fixed 9 by 15 font.", glut.BITMAP_9_BY_15)
	bitmap_output(70, 240, "                Helvetica is yet another bitmap font.", glut.BITMAP_HELVETICA_18)

	gl.MatrixMode(gl.PROJECTION)
	gl.PushMatrix()
	gl.LoadIdentity()
	glu.Perspective(40.0, 1.0, 0.1, 20.0)
	gl.MatrixMode(gl.MODELVIEW)
	gl.PushMatrix()
	glu.LookAt(0.0, 0.0, 4.0, /* eye is at (0,0,30) */
		0.0, 0.0, 0.0, /* center is at (0,0,0) */
		0.0, 1.0, 0.0) /* up is in postivie Y direction */
	gl.PushMatrix()
	gl.Translatef(0, 0, -4)
	gl.Rotatef(50, 0, 1, 0)
	stroke_output(-2.5, 1.1, "  This is written in a", glut.STROKE_ROMAN)
	stroke_output(-2.5, 0, " GLUT stroke font.", glut.STROKE_ROMAN)
	stroke_output(-2.5, -1.1, "using 3D perspective.", glut.STROKE_ROMAN)
	gl.PopMatrix()
	gl.MatrixMode(gl.MODELVIEW)
	gl.PopMatrix()
	gl.MatrixMode(gl.PROJECTION)
	gl.PopMatrix()
	gl.MatrixMode(gl.MODELVIEW)
	gl.Flush()
}

func drawScene() {
	gl.Clear(gl.COLOR_BUFFER_BIT | gl.DEPTH_BUFFER_BIT)

	gl.LoadIdentity()
	gl.Translatef(-1.5, 0, -6)
	gl.Rotatef(trisAngle, 0, 1, 0)

	gl.Begin(gl.TRIANGLES)
	gl.Color3f(1, 0, 0)
	gl.Vertex3f(0, 1, 0)
	gl.Color3f(0, 1, 0)
	gl.Vertex3f(-1, -1, 0)
	gl.Color3f(0, 0, 1)
	gl.Vertex3f(1, -1, 0)
	gl.End()

	gl.LoadIdentity()
	gl.Translatef(1.5, 0, -6)
	gl.Rotatef(quadAngle, 1, 0, 0)
	gl.Color3f(0.5, 0.5, 1.0)

	gl.Begin(gl.QUADS)
	gl.Vertex3f(-1, 1, 0)
	gl.Vertex3f(1, 1, 0)
	gl.Vertex3f(1, -1, 0)
	gl.Vertex3f(-1, -1, 0)
	gl.End()

	trisAngle += 0.2
	quadAngle -= 0.15

	glfw.SwapBuffers()
}

func onKey(key, state int) {
	switch key {
	case glfw.KeyEsc:
		running = state == 0
	case 67: // 'c'
		gl.Clear(gl.COLOR_BUFFER_BIT)
	}
}

func (rw *RenderWindow) onKey(key, state int) {
	switch key {
	case glfw.KeyEsc:
		close(rw.quit)
	case 67: // 'c'
		gl.Clear(gl.COLOR_BUFFER_BIT)
	}
}

func runGameLoop(window *glfw.Window) {
	for !window.ShouldClose() {
		// update objects
		updateObjects()

		// hit detection
		hitDetection()

		// ---------------------------------------------------------------
		// draw calls
		gl.Clear(gl.COLOR_BUFFER_BIT)

		drawCurrentScore()
		drawHighScore()

		if isGameWon() {
			drawWinningScreen()
		} else if isGameLost() {
			drawGameOverScreen()
		}

		// draw everything 9 times in a 3x3 grid stitched together for seamless clipping
		for x := -1.0; x < 2.0; x++ {
			for y := -1.0; y < 2.0; y++ {
				gl.MatrixMode(gl.MODELVIEW)
				gl.PushMatrix()
				gl.Translated(gameWidth*x, gameHeight*y, 0)

				drawObjects()

				gl.PopMatrix()
			}
		}

		gl.Flush()
		window.SwapBuffers()
		glfw.PollEvents()

		// switch resolution
		if altEnter {
			window.Destroy()

			fullscreen = !fullscreen
			var err error
			window, err = initWindow()
			if err != nil {
				panic(err)
			}

			altEnter = false

			gl.LineWidth(1)
			if fullscreen {
				gl.LineWidth(2)
			}
		}
	}
}