+++ /dev/null
-/*
- * Demo of (nearly) flicker-free drawing with a single color buffer.
- *
- * Basically, draw the scene into the Z buffer first, then draw the
- * scene into the color buffer. Finally, "clear" the background by
- * setting the fragments we didn't hit earlier.
- *
- * This won't work if you need blending. The technique works best
- * when the scene is relatively simple and can be rendered quickly
- * (i.e. with hardware), and when the objects don't move too much from
- * one frame to the next.
- *
- * Brian Paul
- * 25 August 2005
- *
- * See Mesa license for terms.
- */
-
-
-#include <stdio.h>
-#include <stdlib.h>
-#include <GL/glut.h>
-
-
-#define FLICKER 0
-#define NO_FLICKER 1
-
-static GLint Mode = NO_FLICKER;
-static GLfloat Xrot = 0, Yrot = 0, Zrot = 0;
-static GLboolean Anim = GL_TRUE;
-static GLfloat ClearColor[4] = {0.2, 0.2, 0.9, 0.0};
-static GLfloat NearClip = 5.0, FarClip = 25.0, ViewDist = 7.0;
-static double PrevTime = -1;
-
-struct box {
- float tx, ty, tz;
- float rx, ry, rz, ra;
- float sx, sy, sz;
- float color[4];
-};
-
-#define NUM_BOXES 25
-
-struct box Boxes[NUM_BOXES];
-
-
-/* Return random float in [0,1] */
-static float
-Random(void)
-{
- int i = rand();
- return (float) (i % 1000) / 1000.0;
-}
-
-
-static void
-MakeBoxes(void)
-{
- int i;
- for (i = 0; i < NUM_BOXES; i++) {
- Boxes[i].tx = -1.0 + 2.0 * Random();
- Boxes[i].ty = -1.0 + 2.0 * Random();
- Boxes[i].tz = -1.0 + 2.0 * Random();
- Boxes[i].sx = 0.1 + Random() * 0.4;
- Boxes[i].sy = 0.1 + Random() * 0.4;
- Boxes[i].sz = 0.1 + Random() * 0.4;
- Boxes[i].rx = Random();
- Boxes[i].ry = Random();
- Boxes[i].rz = Random();
- Boxes[i].ra = Random() * 360.0;
- Boxes[i].color[0] = Random();
- Boxes[i].color[1] = Random();
- Boxes[i].color[2] = Random();
- Boxes[i].color[3] = 1.0;
- }
-}
-
-
-static void
-DrawBoxes(void)
-{
- int i;
- for (i = 0; i < NUM_BOXES; i++) {
- glPushMatrix();
- glTranslatef(Boxes[i].tx, Boxes[i].ty, Boxes[i].tz);
- glRotatef(Boxes[i].ra, Boxes[i].rx, Boxes[i].ry, Boxes[i].rz);
- glScalef(Boxes[i].sx, Boxes[i].sy, Boxes[i].sz);
- glMaterialfv(GL_FRONT, GL_AMBIENT_AND_DIFFUSE, Boxes[i].color);
- glutSolidCube(1.0);
- glPopMatrix();
- }
-}
-
-
-static void
-Idle(void)
-{
- double dt, t = glutGet(GLUT_ELAPSED_TIME) * 0.001;
- if (PrevTime < 0.0)
- PrevTime = t;
- dt = t - PrevTime;
- PrevTime = t;
- Xrot += 16.0 * dt;
- Yrot += 12.0 * dt;
- Zrot += 8.0 * dt;
- glutPostRedisplay();
-}
-
-
-static void
-Draw(void)
-{
- if (Mode == FLICKER) {
- glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
- }
- else {
- /* don't clear color buffer */
- glClear(GL_DEPTH_BUFFER_BIT);
- /* update Z buffer only */
- glColorMask(GL_FALSE, GL_FALSE, GL_FALSE, GL_FALSE);
- }
-
- glPushMatrix();
- glRotatef(Xrot, 1, 0, 0);
- glRotatef(Yrot, 0, 1, 0);
- glRotatef(Zrot, 0, 0, 1);
-
- DrawBoxes();
-
- if (Mode == NO_FLICKER) {
- /* update color buffer now */
- glColorMask(GL_TRUE, GL_TRUE, GL_TRUE, GL_TRUE);
- glDepthFunc(GL_EQUAL);
- DrawBoxes();
- glDepthFunc(GL_LESS);
- }
-
- glPopMatrix();
-
- if (Mode == NO_FLICKER) {
- /* "clear" the untouched pixels now.
- * Note: if you comment-out this code you'll see something interesting.
- */
- GLfloat x = FarClip / NearClip;
- GLfloat z = -(FarClip - ViewDist - 1.0);
- glDisable(GL_LIGHTING);
- glColor4fv(ClearColor);
- glBegin(GL_POLYGON);
- glVertex3f(-x, -x, z);
- glVertex3f( x, -x, z);
- glVertex3f( x, x, z);
- glVertex3f(-x, x, z);
- glEnd();
- glEnable(GL_LIGHTING);
- }
-
- /* This is where you'd normally do SwapBuffers */
- glFinish();
-}
-
-
-static void
-Reshape(int width, int height)
-{
- glViewport(0, 0, width, height);
- glMatrixMode(GL_PROJECTION);
- glLoadIdentity();
- glFrustum(-1.0, 1.0, -1.0, 1.0, NearClip, FarClip);
- glMatrixMode(GL_MODELVIEW);
- glLoadIdentity();
- glTranslatef(0.0, 0.0, -ViewDist);
-}
-
-
-static void
-Key(unsigned char key, int x, int y)
-{
- (void) x;
- (void) y;
- switch (key) {
- case 'a':
- Anim = !Anim;
- if (Anim)
- glutIdleFunc(Idle);
- else
- glutIdleFunc(NULL);
- PrevTime = -1;
- break;
- case 'm':
- Mode = !Mode;
- break;
- case 'b':
- MakeBoxes();
- break;
- case 27:
- exit(0);
- break;
- }
- glutPostRedisplay();
-}
-
-
-static void
-SpecialKey(int key, int x, int y)
-{
- const GLfloat step = 3.0;
- (void) x;
- (void) y;
- switch (key) {
- case GLUT_KEY_UP:
- Xrot -= step;
- break;
- case GLUT_KEY_DOWN:
- Xrot += step;
- break;
- case GLUT_KEY_LEFT:
- Yrot -= step;
- break;
- case GLUT_KEY_RIGHT:
- Yrot += step;
- break;
- }
- glutPostRedisplay();
-}
-
-
-static void
-Init(void)
-{
- glClearColor(ClearColor[0], ClearColor[1], ClearColor[2], ClearColor[3]);
- glEnable(GL_DEPTH_TEST);
- glEnable(GL_LIGHTING);
- glEnable(GL_LIGHT0);
- glEnable(GL_CULL_FACE);
- glEnable(GL_NORMALIZE);
- MakeBoxes();
-}
-
-
-static void
-Usage(void)
-{
- printf("Keys:\n");
- printf(" m - toggle drawing mode (flicker vs. no flicker)\n");
- printf(" a - toggle animation\n");
- printf(" b - generate new boxes\n");
- printf(" ARROWS - rotate scene\n");
- printf(" ESC - exit\n");
-}
-
-
-int
-main(int argc, char *argv[])
-{
- glutInit(&argc, argv);
- glutInitWindowSize(800, 800);
- glutInitDisplayMode(GLUT_RGB | GLUT_SINGLE | GLUT_DEPTH);
- glutCreateWindow(argv[0]);
- glutReshapeFunc(Reshape);
- glutKeyboardFunc(Key);
- glutSpecialFunc(SpecialKey);
- glutDisplayFunc(Draw);
- if (Anim)
- glutIdleFunc(Idle);
- Init();
- Usage();
- glutMainLoop();
- return 0;
-}
projects / mesa.git / blobdiff