OpenGL代码学习（23）--绘制通道中的更多处理
注意：需要在配置好OpenGL的编程环境中运行下列代码，环境配置文章可参考：
OpenGL在Mac项目上的配置
下面的代码，直接放置在main.cpp文件中即可：
#include "GLTools.h" #include "GLShaderManager.h" #include "GLFrustum.h" #include "GLBatch.h" #include "GLFrame.h" #include "GLMatrixStack.h" #include "GLGeometryTransform.h" #ifdef __APPLE__ #include <glut/glut.h> #else #define FREEGLUT_STATIC #include <GL/glut.h> #endif // 着色器管理器 GLShaderManager shaderManager; // 视景体 GLFrustum viewFrustum; // 变换管线，以及它管理的2个矩阵堆栈 GLGeometryTransform transformPipeline; GLMatrixStack modelViewMatrix; GLMatrixStack projectionMatrix; // 4个数据批次 GLBatch floorBatch; GLBatch ceilingBatch; GLBatch leftWallBatch; GLBatch rightWallBatch; // 用于控制观察者向前和向后 GLfloat viewZ = -65.0f; // 宏定义，地板、天花板、墙分别对应的纹理标识数组索引 #define TEXTURE_BRICK 0 #define TEXTURE_FLOOR 1 #define TEXTURE_CEILING 2 #define TEXTURE_COUNT 3 // 纹理标识数组 GLuint textures[TEXTURE_COUNT]; // 纹理文件名数组 const char *szTextureFiles[TEXTURE_COUNT] = { "brick.tga", "floor.tga", "ceiling.tga" }; // 点击右键菜单选项回调 void ProcessMenu(int value) { // 循环遍历所有纹理数据 for(GLint iLoop = 0; iLoop < TEXTURE_COUNT; iLoop++) { // 绑定当前纹理为该索引对应的纹理数据 glBindTexture(GL_TEXTURE_2D, textures[iLoop]); // 设置该纹理数据的缩小过滤器 switch(value) { case 0: glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST); break; case 1: glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR); break; case 2: glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST_MIPMAP_NEAREST); break; case 3: glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST_MIPMAP_LINEAR); break; case 4: glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR_MIPMAP_NEAREST); break; case 5: glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR_MIPMAP_LINEAR); break; case 6: // 设置各向异性 GLfloat fLargest; glGetFloatv(GL_MAX_TEXTURE_MAX_ANISOTROPY_EXT, &fLargest); glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MAX_ANISOTROPY_EXT, fLargest); break; case 7: // 设置各向同性 glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MAX_ANISOTROPY_EXT, 1.0f); break; } } // 触发渲染 glutPostRedisplay(); } // 加载所有的纹理数据 void LoadAllTextureData() { GLbyte *pBytes; GLint iWidth, iHeight, iComponents; GLenum eFormat; GLint iLoop; // 申请要加载的纹理数据数量 glGenTextures(TEXTURE_COUNT, textures); // 循环遍历所有纹理文件 for(iLoop = 0; iLoop < TEXTURE_COUNT; iLoop++) { // 绑定当前纹理为该索引对应的纹理数据 glBindTexture(GL_TEXTURE_2D, textures[iLoop]); // 从 TGA 文件中读取纹理数据 pBytes = gltReadTGABits(szTextureFiles[iLoop], &iWidth, &iHeight, &iComponents, &eFormat); // 设置纹理数据缩小、放大过滤器 glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST); // 设置纹理数据（s, t）环绕模式 glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE); // 加载纹理数据到2维纹理缓冲区 glTexImage2D(GL_TEXTURE_2D, 0, iComponents, iWidth, iHeight, 0, eFormat, GL_UNSIGNED_BYTE, pBytes); // 2维纹理缓冲区开启 Mip 贴图 glGenerateMipmap(GL_TEXTURE_2D); // 释放纹理数据 free(pBytes); } } // 初始化地板数据 void SetupFloorBatch() { GLfloat z; floorBatch.Begin(GL_TRIANGLE_STRIP, 28, 1); for(z = 60.0f; z >= 0.0f; z -=10.0f) { floorBatch.MultiTexCoord2f(0, 0.0f, 0.0f); floorBatch.Vertex3f(-10.0f, -10.0f, z); floorBatch.MultiTexCoord2f(0, 1.0f, 0.0f); floorBatch.Vertex3f(10.0f, -10.0f, z); floorBatch.MultiTexCoord2f(0, 0.0f, 1.0f); floorBatch.Vertex3f(-10.0f, -10.0f, z - 10.0f); floorBatch.MultiTexCoord2f(0, 1.0f, 1.0f); floorBatch.Vertex3f(10.0f, -10.0f, z - 10.0f); } floorBatch.End(); } // 初始化天花板数据 void SetupCeilingBatch() { GLfloat z; ceilingBatch.Begin(GL_TRIANGLE_STRIP, 28, 1); for(z = 60.0f; z >= 0.0f; z -=10.0f) { ceilingBatch.MultiTexCoord2f(0, 0.0f, 1.0f); ceilingBatch.Vertex3f(-10.0f, 10.0f, z - 10.0f); ceilingBatch.MultiTexCoord2f(0, 1.0f, 1.0f); ceilingBatch.Vertex3f(10.0f, 10.0f, z - 10.0f); ceilingBatch.MultiTexCoord2f(0, 0.0f, 0.0f); ceilingBatch.Vertex3f(-10.0f, 10.0f, z); ceilingBatch.MultiTexCoord2f(0, 1.0f, 0.0f); ceilingBatch.Vertex3f(10.0f, 10.0f, z); } ceilingBatch.End(); } // 初始化左右墙数据 void SetupWallBatch() { // 左墙 GLfloat z; leftWallBatch.Begin(GL_TRIANGLE_STRIP, 28, 1); for(z = 60.0f; z >= 0.0f; z -=10.0f) { leftWallBatch.MultiTexCoord2f(0, 0.0f, 0.0f); leftWallBatch.Vertex3f(-10.0f, -10.0f, z); leftWallBatch.MultiTexCoord2f(0, 0.0f, 1.0f); leftWallBatch.Vertex3f(-10.0f, 10.0f, z); leftWallBatch.MultiTexCoord2f(0, 1.0f, 0.0f); leftWallBatch.Vertex3f(-10.0f, -10.0f, z - 10.0f); leftWallBatch.MultiTexCoord2f(0, 1.0f, 1.0f); leftWallBatch.Vertex3f(-10.0f, 10.0f, z - 10.0f); } leftWallBatch.End(); // 右墙 rightWallBatch.Begin(GL_TRIANGLE_STRIP, 28, 1); for(z = 60.0f; z >= 0.0f; z -=10.0f) { rightWallBatch.MultiTexCoord2f(0, 0.0f, 0.0f); rightWallBatch.Vertex3f(10.0f, -10.0f, z); rightWallBatch.MultiTexCoord2f(0, 0.0f, 1.0f); rightWallBatch.Vertex3f(10.0f, 10.0f, z); rightWallBatch.MultiTexCoord2f(0, 1.0f, 0.0f); rightWallBatch.Vertex3f(10.0f, -10.0f, z - 10.0f); rightWallBatch.MultiTexCoord2f(0, 1.0f, 1.0f); rightWallBatch.Vertex3f(10.0f, 10.0f, z - 10.0f); } rightWallBatch.End(); } // 程序初始化渲染环境 void SetupRC() { // 设置窗口背景为黑色 glClearColor(0.0f, 0.0f, 0.0f,1.0f); // 初始化着色器 shaderManager.InitializeStockShaders(); // 加载所有纹理数据 LoadAllTextureData(); // 初始化地板 SetupFloorBatch(); // 初始化天花板 SetupCeilingBatch(); // 初始化墙 SetupWallBatch(); } // 程序释放资源 void ShutdownRC(void) { // 删除所有的纹理数据 glDeleteTextures(TEXTURE_COUNT, textures); } // 特殊按键点击回调 void SpecialKeys(int key, int x, int y) { // 上按键前进 if(key == GLUT_KEY_UP) viewZ += 0.5f; // 下按键后退 if(key == GLUT_KEY_DOWN) viewZ -= 0.5f; // 触发渲染 glutPostRedisplay(); } // 窗口渲染回调方法 void RenderScene(void) { // 清除缓冲区内容 glClear(GL_COLOR_BUFFER_BIT); // 压入单位矩阵 modelViewMatrix.PushMatrix(); // 模型视图向Z轴平移 modelViewMatrix.Translate(0.0f, 0.0f, viewZ); // 采用纹理替换着色器进行绘制 shaderManager.UseStockShader(GLT_SHADER_TEXTURE_REPLACE, transformPipeline.GetModelViewProjectionMatrix(), 0); // 绑定当前纹理为地板纹理，进行地板绘制 glBindTexture(GL_TEXTURE_2D, textures[TEXTURE_FLOOR]); floorBatch.Draw(); // 绑定当前纹理为天花板，进行天花板绘制 glBindTexture(GL_TEXTURE_2D, textures[TEXTURE_CEILING]); ceilingBatch.Draw(); // 绑定当前纹理为左右墙纹理，进行左右墙绘制 glBindTexture(GL_TEXTURE_2D, textures[TEXTURE_BRICK]); leftWallBatch.Draw(); rightWallBatch.Draw(); // 出栈，恢复原来环境 modelViewMatrix.PopMatrix(); // 因为是双缓冲区模式，后台缓冲区替换到前台缓存区进行显示 glutSwapBuffers(); } // 窗口大小变化回调方法 void ChangeSize(int width, int height) { // 防止除数为0 if(height == 0) height = 1; // 设置视口 glViewport(0, 0, width, height); // 计算窗口宽高比 GLfloat fAspect = (GLfloat)width / (GLfloat)height; // 设置投影矩阵 viewFrustum.SetPerspective(80.0f, fAspect, 1.0, 120.0); // 投影矩阵堆栈保持投影矩阵 projectionMatrix.LoadMatrix(viewFrustum.GetProjectionMatrix()); // 设置变换管线的投影矩阵堆栈和模型视图矩阵堆栈 transformPipeline.SetMatrixStacks(modelViewMatrix, projectionMatrix); } // 程序入口 int main(int argc, char *argv[]) { // 设置 Mac OS 工作目录路径 gltSetWorkingDirectory(argv[0]); // GLUT 初始化 glutInit(&argc, argv); // 设置 GLUT 渲染模式 glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGB); // 创建窗口 glutInitWindowSize(800, 720); glutCreateWindow("Tunnel"); // 绑定事件回调 glutReshapeFunc(ChangeSize); glutSpecialFunc(SpecialKeys); glutDisplayFunc(RenderScene); // 创建右键菜单 glutCreateMenu(ProcessMenu); // 添加右键菜单选项 glutAddMenuEntry("GL_NEAREST",0); glutAddMenuEntry("GL_LINEAR",1); glutAddMenuEntry("GL_NEAREST_MIPMAP_NEAREST",2); glutAddMenuEntry("GL_NEAREST_MIPMAP_LINEAR", 3); glutAddMenuEntry("GL_LINEAR_MIPMAP_NEAREST", 4); glutAddMenuEntry("GL_LINEAR_MIPMAP_LINEAR", 5); glutAddMenuEntry("Anisotropic Filter", 6); glutAddMenuEntry("Anisotropic Off", 7); // 设置右键菜单弹出 glutAttachMenu(GLUT_RIGHT_BUTTON); // GLEW 驱动程序初始化 GLenum err = glewInit(); if (GLEW_OK != err) { fprintf(stderr, "GLEW Error: %s\n", glewGetErrorString(err)); return 1; } // 程序初始化渲染环境 SetupRC(); // 运行循环 glutMainLoop(); // 程序释放资源 ShutdownRC(); return 0; }
两个比较明显的对比图：
