需求：绘制一个简单的地月太阳的旋转模型：地球绕太阳（绕y轴）旋转，月球绕地球（绕x轴）旋转。 实现的步骤： //openGL 坐标系：z朝向屏幕外， y朝上，x朝右 push 向里移动300 画了一颗太阳 绕y轴旋转坐标系，旋转角度为fEarthRot //（此时太阳的坐标系已经在绕太阳中心点（绕x轴）旋转呢，不管后面有没有下一步。理解这点很重要。） 向上移动105 画一个颗地球 //（这时地球自然而然在绕y轴旋转，半径为上面移动的105。） 绕x轴旋转坐标系，旋转角度为fMoonRot //（此时地球的坐标系在绕地球中心点（绕x轴）旋转。） 向上移动30 画一颗月亮 //（这时地球自然而然在绕x轴旋转，半径为上面移动的30。） pop //（物体坐标系又回到世界坐标系原点） //注意它两是静态变量 fEarthRot++ fMoonRot++ 循环上面这动作，实现了动画。
效果：
实现：
#include<gl/glut.h> #include <math.h> // Lighting values GLfloat whiteLight[] = { 0.2f, 0.2f, 0.2f, 1.0f }; GLfloat sourceLight[] = { 0.8f, 0.8f, 0.8f, 1.0f }; GLfloat lightPos[] = { 0.0f, 0.0f, 0.0f, 1.0f }; void createCoordinate(); //执行顺序： main --> SetupRC --> TimerFunc --> ChangeSize -->RenderScene // Called to draw scene void RenderScene(void) { //openGL 坐标系：z朝向屏幕外， y朝上，x朝右 // Earth and Moon angle of revolution static float fMoonRot = 0.0f; static float fEarthRot = 0.0f; // Clear the window with current clearing color glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); // Save the matrix state and do the rotations glMatrixMode(GL_MODELVIEW); glPushMatrix(); // Translate the whole scene out and into view //向里移动300 glTranslatef(0.0f, 0.0f, -300.0f); createCoordinate(); // Set material color, Red // Sun 画了一颗太阳 glDisable(GL_LIGHTING); glColor3ub(255, 255, 0); glutSolidSphere(15.0f, 30, 17); glEnable(GL_LIGHTING); // Move the light after we draw the sun! glLightfv(GL_LIGHT0,GL_POSITION,lightPos); // 绕y轴旋转坐标系 glRotatef(fEarthRot, 0.0f, 1.0f, 0.0f); //向上移动105 glTranslatef(105.0f,0.0f,0.0f); //画一个颗地球 glColor3ub(0,0,255); glutSolidSphere(15.0f, 30, 17); //绘制一个坐标系， createCoordinate(); // Rotate from Earth based coordinates and draw Moon glColor3ub(200,200,200); //绕x轴旋转 glRotatef(fMoonRot,1.0f, 0.0f, 0.0f); //向上移动30 glTranslatef(0.0f, 30.0f, 0.0f); //画一颗月亮 glutSolidSphere(6.0f, 30, 17); createCoordinate(); // Restore the matrix state glPopMatrix(); // Modelview matrix //月亮在转 fMoonRot+= 5.0f; if(fMoonRot > 360.0f) fMoonRot = 0.0f; // Step earth orbit 5 degrees //地球在转 fEarthRot += 5.0f; if(fEarthRot > 360.0f) fEarthRot = 0.0f; // Show the image glutSwapBuffers(); } void createCoordinate(){ //绘制一个坐标系， GLint factor = 2; GLushort pattern = 0x5555; //启用点画 glEnable(GL_LINE_STIPPLE); //点画模式 glLineStipple(factor,pattern); glLineWidth(1.0f); glBegin(GL_LINES); //x轴 glColor3ub((GLubyte)255,(GLubyte)0,(GLubyte)0); glVertex3f(-100.0f,0.0f,0.0f); glVertex3f(100.0f,0.0f,0.0f); glColor3ub((GLubyte)0,(GLubyte)255,(GLubyte)0); //y轴 glVertex3f(0.0f,-100.0f,0.0f); glVertex3f(0.0f,100.0f,0.0f); //z轴 glColor3ub((GLubyte)0,(GLubyte)0,(GLubyte)255); glVertex3f(0.0f,0.0f,-100.0f); glVertex3f(0.0f,0.0f,100.0f); glEnd(); //关闭点画 glDisable(GL_LINE_STIPPLE); } // This function does any needed initialization on the rendering // context. void SetupRC() { // Light values and coordinates glEnable(GL_DEPTH_TEST); // Hidden surface removal glFrontFace(GL_CCW); // Counter clock-wise polygons face out glEnable(GL_CULL_FACE); // Do not calculate inside of jet // Enable lighting glEnable(GL_LIGHTING); // Setup and enable light 0 glLightModelfv(GL_LIGHT_MODEL_AMBIENT,whiteLight); glLightfv(GL_LIGHT0,GL_DIFFUSE,sourceLight); glLightfv(GL_LIGHT0,GL_POSITION,lightPos); glEnable(GL_LIGHT0); // Enable color tracking glEnable(GL_COLOR_MATERIAL); glColorMaterial(GL_FRONT, GL_AMBIENT_AND_DIFFUSE); glClearColor(0.0f, 0.0f, 0.0f, 1.0f ); } void TimerFunc(int value) { glutPostRedisplay(); glutTimerFunc(100, TimerFunc, 1); } void ChangeSize(int w, int h) { GLfloat fAspect; if(h == 0)h = 1; glViewport(0, 0, w, h); fAspect = (GLfloat)w/(GLfloat)h; //使用并初始化投影矩阵 glMatrixMode(GL_PROJECTION); glLoadIdentity(); gluPerspective(45.0f, fAspect, 1.0, 425.0); glMatrixMode(GL_MODELVIEW); glLoadIdentity(); } int main(int argc, char* argv[]) { glutInit(&argc, argv); glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGB | GLUT_DEPTH); glutInitWindowSize(800, 600); glutCreateWindow("Earth/Moon/Sun System"); glutReshapeFunc(ChangeSize); glutDisplayFunc(RenderScene); glutTimerFunc(250, TimerFunc, 1); SetupRC(); glutMainLoop(); return 0; }