194 lines
3.6 KiB
C
194 lines
3.6 KiB
C
/**
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* Test glDrawPixels(GL_DEPTH_COMPONENT)
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*
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* We load a window-sized buffer of Z values so that Z=1 at the top and
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* Z=0 at the bottom (and interpolate between).
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* We draw that image into the Z buffer, then draw an ordinary cube.
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* The bottom part of the cube should be "clipped" where the cube fails
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* the Z test.
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*
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* Press 'd' to view the Z buffer as a grayscale image.
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*/
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#include <stdio.h>
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#include <stdlib.h>
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#include <math.h>
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#include <GL/glew.h>
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#include <GL/glut.h>
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#include "../util/showbuffer.c"
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static int Win;
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static GLfloat Xrot = 50, Yrot = 40, Zpos = 6;
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static GLboolean Anim = GL_FALSE;
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static int Width = 200, Height = 200;
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static GLfloat *z;
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static GLboolean showZ = 0;
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static void
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Idle(void)
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{
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Xrot += 3.0;
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Yrot += 4.0;
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glutPostRedisplay();
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}
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static void
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Draw(void)
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{
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glClearColor(0, 0, 0.5, 0);
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glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
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#if 1
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glColor3f(1, 0, 0);
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glWindowPos2i(0,0);
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glColorMask(0,0,0,0);
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glDrawPixels(Width, Height, GL_DEPTH_COMPONENT, GL_FLOAT, z);
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#elif 0
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glPushMatrix();
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glTranslatef(-0.75, 0, Zpos);
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glutSolidSphere(1.0, 20, 10);
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glPopMatrix();
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#endif
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glColorMask(1,1,1,1);
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/* draw cube */
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glPushMatrix();
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glTranslatef(0, 0, Zpos);
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glRotatef(Xrot, 1, 0, 0);
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glRotatef(Yrot, 0, 1, 0);
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glutSolidCube(2.0);
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glPopMatrix();
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#if 0
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/* drawpixels after cube */
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glColor3f(1, 0, 0);
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glWindowPos2i(0,0);
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//glColorMask(0,0,0,0);
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glDrawPixels(Width, Height, GL_DEPTH_COMPONENT, GL_FLOAT, z);
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#endif
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if (showZ) {
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ShowDepthBuffer(Width, Height, 0.0, 1.0);
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}
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glutSwapBuffers();
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}
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static void
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Reshape(int width, int height)
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{
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glViewport(0, 0, width, height);
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glMatrixMode(GL_PROJECTION);
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glLoadIdentity();
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glFrustum(-1.0, 1.0, -1.0, 1.0, 5.0, 30.0);
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glMatrixMode(GL_MODELVIEW);
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glLoadIdentity();
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glTranslatef(0.0, 0.0, -15.0);
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Width = width;
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Height = height;
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z = (float *) malloc(width * height * 4);
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{
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int i, j, k = 0;
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for (i = 0; i < height; i++) {
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float zval = (float) i / (height - 1);
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for (j = 0; j < width; j++) {
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z[k++] = zval;
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}
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}
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}
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}
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static void
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Key(unsigned char key, int x, int y)
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{
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const GLfloat step = 1.0;
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(void) x;
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(void) y;
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switch (key) {
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case 'a':
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Anim = !Anim;
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if (Anim)
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glutIdleFunc(Idle);
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else
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glutIdleFunc(NULL);
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break;
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case 'd':
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showZ = !showZ;
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break;
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case 'z':
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Zpos -= step;
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break;
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case 'Z':
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Zpos += step;
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break;
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case 27:
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glutDestroyWindow(Win);
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exit(0);
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break;
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}
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glutPostRedisplay();
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}
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static void
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SpecialKey(int key, int x, int y)
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{
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const GLfloat step = 3.0;
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(void) x;
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(void) y;
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switch (key) {
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case GLUT_KEY_UP:
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Xrot -= step;
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break;
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case GLUT_KEY_DOWN:
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Xrot += step;
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break;
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case GLUT_KEY_LEFT:
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Yrot -= step;
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break;
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case GLUT_KEY_RIGHT:
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Yrot += step;
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break;
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}
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glutPostRedisplay();
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}
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static void
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Init(void)
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{
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/* setup lighting, etc */
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glEnable(GL_DEPTH_TEST);
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glEnable(GL_LIGHTING);
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glEnable(GL_LIGHT0);
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}
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int
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main(int argc, char *argv[])
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{
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glutInit(&argc, argv);
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glutInitWindowPosition(0, 0);
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glutInitWindowSize(400, 400);
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glutInitDisplayMode(GLUT_RGB | GLUT_DOUBLE | GLUT_DEPTH);
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Win = glutCreateWindow(argv[0]);
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glewInit();
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glutReshapeFunc(Reshape);
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glutKeyboardFunc(Key);
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glutSpecialFunc(SpecialKey);
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glutDisplayFunc(Draw);
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if (Anim)
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glutIdleFunc(Idle);
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Init();
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glutMainLoop();
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return 0;
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}
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