opengl-Planets.rar_opengl 选_拣选

// Planets.c // OpenGL SuperBible, Chapter 14 // Demonstrates OpenGL Selection/Picking // Program by Richard S. Wright Jr. #include <windows.h> #include <gl/gl.h> #include <gl/glu.h> #include <gl/glut.h> #include <math.h> #define glRGB(x, y, z) glColor3ub((GLubyte)x, (GLubyte)y, (GLubyte)z) #define SUN 1 #define MERCURY 2 #define VENUS 3 #define EARTH 4 #define MARS 5 GLfloat fAspect; // Lighting values GLfloat whiteLight[] = { 0.35f, 0.35f, 0.35f, 1.0f }; GLfloat sourceLight[] = { 0.65f, 0.65f, 0.65f, 1.0f }; GLfloat lightPos[] = { 0.0f, 0.0f, 0.0f, 1.0f }; // Called to draw scene void RenderScene(void) { // 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 glTranslatef(0.0f, 0.0f, -300.0f); // Initialize the names stack glInitNames(); glPushName(0); // Set material color, Yellow // Sun glRGB(255, 255, 0); glLoadName(SUN); glutSolidSphere(15.0f, 15, 15); // Draw Mercury glRGB(128,0,0); glPushMatrix(); glTranslatef(24.0f, 0.0f, 0.0f); glLoadName(MERCURY); glutSolidSphere(2.0f,15,15); glPopMatrix(); // Draw Venus glPushMatrix(); glRGB(128,128,255); glTranslatef(60.0f, 0.0f, 0.0f); glLoadName(VENUS); glutSolidSphere(4.0f,15,15); glPopMatrix(); // Draw the Earth glPushMatrix(); glRGB(0,0,255); glTranslatef(100.0f,0.0f,0.0f); glLoadName(EARTH); glutSolidSphere(8.0f,15,15); glPopMatrix(); // Draw Mars glRGB(255,0,0); glPushMatrix(); glTranslatef(150.0f, 0.0f, 0.0f); glLoadName(MARS); glutSolidSphere(4.0f,15,15); glPopMatrix(); // Restore the matrix state glPopMatrix(); // Modelview matrix glutSwapBuffers(); } // Present the information on which planet/sun was selected and displayed void ProcessPlanet(GLuint id) { switch(id) { case SUN: MessageBox(NULL,"You clicked on the Sun!","Info",MB_OK | MB_ICONEXCLAMATION); break; case MERCURY: MessageBox(NULL,"You clicked on Mercury!","Info",MB_OK | MB_ICONEXCLAMATION); break; case VENUS: MessageBox(NULL,"You clicked on Venus!","Info",MB_OK | MB_ICONEXCLAMATION); break; case EARTH: MessageBox(NULL,"You clicked on Earth!","Info",MB_OK | MB_ICONEXCLAMATION); break; case MARS: MessageBox(NULL,"You clicked on Mars!","Info",MB_OK | MB_ICONEXCLAMATION); break; default: MessageBox(NULL,"Nothing was clicked on!","Error",MB_OK | MB_ICONEXCLAMATION); break; } } // Process the selection, which is triggered by a right mouse // click at (xPos, yPos). #define BUFFER_LENGTH 64 void ProcessSelection(int xPos, int yPos) { // Space for selection buffer GLuint selectBuff[BUFFER_LENGTH]; // Hit counter and viewport storeage GLint hits, viewport[4]; // Setup selection buffer glSelectBuffer(BUFFER_LENGTH, selectBuff); // Get the viewport glGetIntegerv(GL_VIEWPORT, viewport); // Switch to projection and save the matrix glMatrixMode(GL_PROJECTION); glPushMatrix(); // Change render mode glRenderMode(GL_SELECT); // Establish new clipping volume to be unit cube around // mouse cursor point (xPos, yPos) and extending two pixels // in the vertical and horzontal direction glLoadIdentity(); gluPickMatrix(xPos, viewport[3] - yPos, 2,2, viewport); // Apply perspective matrix gluPerspective(45.0f, fAspect, 1.0, 425.0); // Draw the scene RenderScene(); // Collect the hits hits = glRenderMode(GL_RENDER); // If a single hit occured, display the info. if(hits == 1) ProcessPlanet(selectBuff[3]); // Restore the projection matrix glMatrixMode(GL_PROJECTION); glPopMatrix(); // Go back to modelview for normal rendering glMatrixMode(GL_MODELVIEW); } // Process the mouse click void MouseCallback(int button, int state, int x, int y) { if(button == GLUT_LEFT_BUTTON && state == GLUT_DOWN) ProcessSelection(x, y); } // 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 insides // 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); // Set Material properties to follow glColor values glColorMaterial(GL_FRONT, GL_AMBIENT_AND_DIFFUSE); // Black blue background glClearColor(0.60f, 0.60f, 0.60f, 1.0f ); } void ChangeSize(int w, int h) { // Prevent a divide by zero if(h == 0) h = 1; // Set Viewport to window dimensions glViewport(0, 0, w, h); // Calculate aspect ratio of the window fAspect = (GLfloat)w/(GLfloat)h; // Set the perspective coordinate system glMatrixMode(GL_PROJECTION); glLoadIdentity(); // Field of view of 45 degrees, near and far planes 1.0 and 425 gluPerspective(45.0f, fAspect, 1.0, 425.0); // Modelview matrix reset glMatrixMode(GL_MODELVIEW); glLoadIdentity(); } int main(int argc, char* argv[]) { glutInit(&argc, argv); glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGB | GLUT_DEPTH); glutInitWindowSize(600,300); glutCreateWindow("Pick a Planet"); glutReshapeFunc(ChangeSize); glutMouseFunc(MouseCallback); glutDisplayFunc(RenderScene); SetupRC(); glutMainLoop(); return 0; }