Xcode+Opengl學習（5）使一個花托以一定速度旋轉

本篇繼承上篇的矩陣變換知識，加上了利用CStopWatch類來定義速度的思路

• static CStopWatch rotTimer;
• float yRot=rotTimer.GetElapsedSeconds()*30;
• m3dRotationMatrix44(mRottion,m3dDegToRad(yRot),0.0f,1.0f,0.0f);

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• 利用GLFrustum類的SetPerspective函數來設置透視投影
• 利用GLFrustum類的GetProjectionMatrix()函數來得到投影矩陣與旋轉操作相乘進行矩陣變換

#include<GLTools.h>
#include<GLMatrixStack.h>
#include<GLFrame.h>
#include<GLFrustum.h>
#include<GLGeometryTransform.h>
#include<GLBatch.h>
#include<StopWatch.h>

#include<GLUT/GLUT.h>

GLFrustum viewFrustum;

GLShaderManager shaderManager;

GLTriangleBatch torusBatch;

void ChangeSize(int w,int h)
{
   if(h==0)
       h=1;
   glViewport(0,0,w,h);
   
   viewFrustum.SetPerspective(35.0f,float(w)/float(h),1.0f,1000.0f);
        //GlFrustum::SetPerspective(float fFov,float fAspect,float fNear,float fFar);
       //四個參數分別爲從頂點方向看過去的視場角度，寬高比，視角到近剪切面的距離，視角到遠剪切面的距離
}

void RenderScene(void)
{
   static CStopWatch rotTimer;
   float yRot=rotTimer.GetElapsedSeconds()*30.0f;
   
   glClear(GL_COLOR_BUFFER_BIT|GL_DEPTH_BUFFER_BIT);
   
   M3DMatrix44f mTranslate, mRotate, mModelView,mModelViewProjection;
   
   m3dTranslationMatrix44(mTranslate,0.0f,0.0f,-2.5f);
   
   m3dRotationMatrix44(mRotate,m3dDegToRad(yRot),0.0f,1.0f,0.0f);
   
   m3dMatrixMultiply44(mModelView,mTranslate,mRotate);
   
   m3dMatrixMultiply44(mModelViewProjection,viewFrustum.GetProjectionMatrix(),mModelView);
   
   GLfloat vBlack[]={0.0f,0.0f,0.0f,1.0f};
   shaderManager.UseStockShader(GLT_SHADER_FLAT,mModelViewProjection,vBlack);
   torusBatch.Draw();
   
   glutSwapBuffers();
   glutPostRedisplay();
   
}

void SetupRC()
{
   glClearColor(0.8f,0.8f,0.8f,1.0f);
   glEnable(GL_DEPTH_TEST);
   shaderManager.InitializeStockShaders();
   gltMakeTorus(torusBatch,0.4f,0.15f,30,30);
   //花托創建函數，gltMakeTorus(GLTriangleBatch& torusBatch,GLfloat majorRaidus,GLfloat minorRadius,GLint numMajor,Glint numMinor);後四個參數分別爲中心到外邊緣的半徑，中心到內邊緣的半徑，沿主半徑和內部較小半徑的細分單元的數量。
   glPolygonMode(GL_FRONT_AND_BACK,GL_LINE);
}

int main(int argc, char* argv[])
{
   gltSetWorkingDirectory(argv[0]);
   
   glutInit(&argc, argv);
   glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGBA | GLUT_DEPTH | GLUT_STENCIL);
   glutInitWindowSize(800, 600);
   glutCreateWindow("ModelViewProjection Example");
   glutReshapeFunc(ChangeSize);
   glutDisplayFunc(RenderScene);
   
   
   GLenum err = glewInit();
   if (GLEW_OK != err) {
       fprintf(stderr, "GLEW Error: %s\n", glewGetErrorString(err));
       return 1;
   }
   
   SetupRC();
   
   glutMainLoop();
   return 0;
}