/* * Test glRead/DrawPixels for GL_DEPTH_COMPONENT, with pixelzoom. * * Brian Paul * 23 August 2003 */ #include <stdio.h> #include <stdlib.h> #include <math.h> #define GL_GLEXT_PROTOTYPES #include <GL/glut.h> static GLint WinWidth = 500, WinHeight = 500; static void Display(void) { GLfloat depth[100 * 100]; GLfloat depth2[400 * 400]; GLfloat min, max; int i; glClearColor(0.5, 0.5, 0.5, 0); glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); /* draw a sphere */ glViewport(0, 0, 100, 100); glMatrixMode(GL_PROJECTION); glLoadIdentity(); glOrtho(-1, 1, -1, 1, -1, 0); /* clip away back half of sphere */ glMatrixMode(GL_MODELVIEW); glLoadIdentity(); glutSolidSphere(1.0, 20, 10); /* read the depth image */ glReadPixels(0, 0, 100, 100, GL_DEPTH_COMPONENT, GL_FLOAT, depth); min = max = depth[0]; for (i = 1; i < 100 * 100; i++) { if (depth[i] < min) min = depth[i]; if (depth[i] > max) max = depth[i]; } printf("Depth value range: [%f, %f]\n", min, max); /* draw depth image with scaling (into z buffer) */ glPixelZoom(4.0, 4.0); glWindowPos2i(100, 0); glDrawPixels(100, 100, GL_DEPTH_COMPONENT, GL_FLOAT, depth); /* read back scaled depth image */ glReadPixels(100, 0, 400, 400, GL_DEPTH_COMPONENT, GL_FLOAT, depth2); /* draw as luminance */ glPixelZoom(1.0, 1.0); glDrawPixels(400, 400, GL_LUMINANCE, GL_FLOAT, depth2); glutSwapBuffers(); } static void Reshape(int width, int height) { WinWidth = width; WinHeight = height; glViewport(0, 0, width, height); } static void Key(unsigned char key, int x, int y) { (void) x; (void) y; switch (key) { case 27: exit(0); break; } glutPostRedisplay(); } static void Init(void) { const GLfloat blue[4] = {.1, .1, 1.0, 0.0}; const GLfloat gray[4] = {0.2, 0.2, 0.2, 1.0}; const GLfloat white[4] = {1.0, 1.0, 1.0, 1.0}; const GLfloat pos[4] = {0, 0, 10, 0}; printf("GL_VERSION = %s\n", (char *) glGetString(GL_VERSION)); printf("GL_RENDERER = %s\n", (char *) glGetString(GL_RENDERER)); glMaterialfv(GL_FRONT_AND_BACK, GL_DIFFUSE, blue); glLightfv(GL_LIGHT0, GL_AMBIENT, gray); glLightfv(GL_LIGHT0, GL_DIFFUSE, white); glLightfv(GL_LIGHT0, GL_POSITION, pos); glEnable(GL_LIGHTING); glEnable(GL_LIGHT0); glEnable(GL_DEPTH_TEST); } int main(int argc, char *argv[]) { glutInit(&argc, argv); glutInitWindowPosition(0, 0); glutInitWindowSize(WinWidth, WinHeight); glutInitDisplayMode(GLUT_RGB | GLUT_DEPTH | GLUT_DOUBLE); glutCreateWindow(argv[0]); glutReshapeFunc(Reshape); glutKeyboardFunc(Key); glutDisplayFunc(Display); Init(); glutMainLoop(); return 0; }