《虚拟现实与系统仿真》实验指导书- 修订(7)

if(x > windowWidth-rsize || x < -windowWidth) xstep = -xstep; // Reverse direction when you reach top or bottom edge if(y > windowHeight || y < -windowHeight + rsize) ystep = -ystep; // Actually move the square x += xstep; y += ystep; // Check bounds. This is in case the window is made // smaller while the rectangle is bouncing and the // rectangle suddenly finds itself outside the new // clipping volume if(x > (windowWidth-rsize + xstep)) x = windowWidth-rsize-1; else if(x < -(windowWidth + xstep)) x = -windowWidth -1; if(y > (windowHeight + ystep)) y = windowHeight-1; else if(y < -(windowHeight - rsize + ystep)) y = -windowHeight + rsize - 1; // Redraw the scene with new coordinates glutPostRedisplay(); glutTimerFunc(33,TimerFunction, 1); }

/////////////////////////////////////////////////////////// // Setup the rendering state void SetupRC(void) { // Set clear color to blue glClearColor(0.0f, 0.0f, 1.0f, 1.0f); }

/////////////////////////////////////////////////////////// // Called by GLUT library when the window has chanaged size void ChangeSize(int w, int h) { GLfloat aspectRatio; // Prevent a divide by zero if(h == 0) h = 1; // Set Viewport to window dimensions glViewport(0, 0, w, h); // Reset coordinate system glMatrixMode(GL_PROJECTION); glLoadIdentity();

// Establish clipping volume (left, right, bottom, top, near, far) aspectRatio = (GLfloat)w / (GLfloat)h; if (w <= h) { windowWidth = 100; windowHeight = 100 / aspectRatio; glOrtho (-100.0, 100.0, -windowHeight, windowHeight, 1.0, -1.0); } else { windowWidth = 100 * aspectRatio; windowHeight = 100; glOrtho (-windowWidth, windowWidth, -100.0, 100.0, 1.0, -1.0); } glMatrixMode(GL_MODELVIEW); glLoadIdentity(); }

/////////////////////////////////////////////////////////// // Main program entry point

int main(int argc, char* argv[]) { glutInit(&argc, argv); glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGB); glutInitWindowSize(800,600); glutCreateWindow(\ glutDisplayFunc(RenderScene); glutReshapeFunc(ChangeSize); glutTimerFunc(33, TimerFunction, 1); SetupRC(); glutMainLoop();

return 0; }