OpenGL 使用矩阵变换改变视图

前言

在上一篇OpenGL 深度测试基础上修改main.cpp文件，完成此demo。

代码

本篇主要是使用矩阵相关操作，来完成视图的变换。与之前demo的区别在与，之前通过改变观察点位置来获取不同位置物体的视图。次demo则是直接通过矩阵变换修改物体的位置，来让观察者看到不同位置的物体。代码如下：

 #include "GLMatrixStack.h" #include "GLFrame.h" #include "GLFrustum.h" #include "GLBatch.h" #include "GLGeometryTransform.h" #include <math.h> #include <GLUT/GLUT.h> #include "GLTools.h" #include "StopWatch.h" GLShaderManager shaderManager; GLMatrixStack modelViewMatrix; //投影矩阵 GLFrustum viewFrustum; GLTriangleBatch cylinderBatch; void changeSize(int w, int h) { glViewport(0, 0, w, h); //设置透视投影 viewFrustum.SetPerspective(30.0f, float(w) / float(h), 2.0f, 400.0f); } void renderScene() { //清理缓冲区 glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT | GL_STENCIL_BUFFER_BIT); static CStopWatch rotTimer; float yRot = rotTimer.GetElapsedSeconds() * 30; M3DMatrix44f mTranslate, mRotate, mModelView, mModelViewProjection; //创建平移矩阵 m3dTranslationMatrix44(mTranslate,0.0f,0.0f,-8.0f); //创建旋转矩阵 m3dRotationMatrix44(mRotate, m3dDegToRad(yRot), 0.0f,1.0f,0.0f); //模型矩阵 = 旋转矩阵 * 平移矩阵 m3dMatrixMultiply44(mModelView, mTranslate, mRotate); //模型视图矩阵 = 视图矩阵 * 模型矩阵 m3dMatrixMultiply44(mModelViewProjection, viewFrustum.GetProjectionMatrix(), mModelView); GLfloat vOrange[] = {1.0f,0.6f,0.0f,1.0f}; shaderManager.UseStockShader(GLT_SHADER_FLAT,mModelViewProjection,vOrange); cylinderBatch.Draw(); glutSwapBuffers(); glutPostRedisplay(); } void setupRC() { glClearColor(0.5f, 0.5f, 0.5f, 1.0f); shaderManager.InitializeStockShaders(); glEnable(GL_DEPTH_TEST); gltMakeCylinder(cylinderBatch, 0.3f, 0.8f, 0.8f, 100, 1); } int main(int argc, char* argv[]) { gltSetWorkingDirectory(argv[0]); glutInit(&argc, argv); glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGBA | GLUT_DEPTH | GLUT_STENCIL); glutInitWindowSize(600, 600); glutCreateWindow("dowZhang"); glutReshapeFunc(changeSize); glutDisplayFunc(renderScene); GLenum err = glewInit(); if (GLEW_OK != err) { return 1; } setupRC(); glutMainLoop(); return 0; } 复制代码 

效果如下：