--- /dev/null
+/**
+ * Draw colored quads.
+ */
+
+
+#define GL_GLEXT_PROTOTYPES
+#include <stdio.h>
+#include <stdlib.h>
+#include <math.h>
+#include <GL/glut.h>
+
+#define NUM_QUADS 20
+
+
+static int Win;
+static GLfloat Xrot = 40, Yrot = 0, Zrot = 0;
+static GLboolean Anim = GL_TRUE;
+static GLuint Vbuffer = 0;
+
+static GLfloat buf[NUM_QUADS * 6 * 4];
+
+static GLboolean SwapBuffers = GL_TRUE;
+
+static GLint Frames = 0, T0 = 0;
+
+
+static void
+Idle(void)
+{
+ Xrot += 3.0;
+ Yrot += 4.0;
+ Zrot += 2.0;
+ glutPostRedisplay();
+}
+
+
+static void
+Draw(void)
+{
+ glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
+
+ glPushMatrix();
+ glRotatef(Xrot, 1, 0, 0);
+ glRotatef(Yrot, 0, 1, 0);
+ glRotatef(Zrot, 0, 0, 1);
+
+ glDrawArrays(GL_QUADS, 0, NUM_QUADS*4);
+
+ glPopMatrix();
+
+ if (SwapBuffers)
+ glutSwapBuffers();
+ /*
+ else
+ glFinish();
+ */
+
+ {
+ GLint t = glutGet(GLUT_ELAPSED_TIME);
+ Frames++;
+ if (t - T0 >= 5000) {
+ GLfloat seconds = (t - T0) / 1000.0;
+ GLfloat fps = Frames / seconds;
+ printf("%d frames in %6.3f seconds = %6.3f FPS\n",
+ Frames, seconds, fps);
+ T0 = t;
+ Frames = 0;
+ }
+ }
+}
+
+
+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, 5.0, 25.0);
+ glMatrixMode(GL_MODELVIEW);
+ glLoadIdentity();
+ glTranslatef(0.0, 0.0, -8.0);
+}
+
+
+static void
+Key(unsigned char key, int x, int y)
+{
+ const GLfloat step = 3.0;
+ (void) x;
+ (void) y;
+ switch (key) {
+ case 's':
+ SwapBuffers = !SwapBuffers;
+ break;
+ case 'a':
+ Anim = !Anim;
+ if (Anim)
+ glutIdleFunc(Idle);
+ else
+ glutIdleFunc(NULL);
+ break;
+ case 'z':
+ Zrot -= step;
+ break;
+ case 'Z':
+ Zrot += step;
+ break;
+ case 27:
+ glutDestroyWindow(Win);
+ 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
+quad(float x, float y, float z, float *v)
+{
+ int k = 0;
+
+ /* color */
+ v[k++] = x * 0.5 + 0.5;
+ v[k++] = y * 0.5 + 0.5;
+ v[k++] = z * 0.5 + 0.5;
+ /* vert */
+ v[k++] = x;
+ v[k++] = y;
+ v[k++] = z;
+
+ /* color */
+ v[k++] = -x * 0.5 + 0.5;
+ v[k++] = -y * 0.5 + 0.5;
+ v[k++] = z * 0.5 + 0.5;
+ /* vert */
+ v[k++] = -x;
+ v[k++] = -y;
+ v[k++] = z;
+
+ /* color */
+ v[k++] = -x * 0.5 + 0.5;
+ v[k++] = -y * 0.5 + 0.5;
+ v[k++] = -z * 0.5 + 0.5;
+ /* vert */
+ v[k++] = -x;
+ v[k++] = -y;
+ v[k++] = -z;
+
+ /* color */
+ v[k++] = x * 0.5 + 0.5;
+ v[k++] = y * 0.5 + 0.5;
+ v[k++] = -z * 0.5 + 0.5;
+ /* vert */
+ v[k++] = x;
+ v[k++] = y;
+ v[k++] = -z;
+}
+
+static void
+gen_quads(GLfloat *buf)
+{
+ float *v = buf;
+ float r = 1.0;
+ int i;
+
+ for (i = 0; i < NUM_QUADS; i++) {
+ float angle = i / (float) NUM_QUADS * M_PI;
+ float x = r * cos(angle);
+ float y = r * sin(angle);
+ float z = 1.10;
+ quad(x, y, z, v);
+ v += 24;
+ }
+
+ if (0) {
+ float *p = buf;
+ for (i = 0; i < NUM_QUADS * 4 * 2; i++) {
+ printf("%d: %f %f %f\n", i, p[0], p[1], p[2]);
+ p += 3;
+ }
+ }
+}
+
+
+static void
+Init(void)
+{
+ int bytes = NUM_QUADS * 4 * 2 * 3 * sizeof(float);
+ GLfloat *f;
+
+#if 1
+ glGenBuffers(1, &Vbuffer);
+ glBindBuffer(GL_ARRAY_BUFFER, Vbuffer);
+ glBufferData(GL_ARRAY_BUFFER_ARB, bytes, NULL, GL_STATIC_DRAW_ARB);
+ f = (float *) glMapBuffer(GL_ARRAY_BUFFER_ARB, GL_WRITE_ONLY_ARB);
+ gen_quads(f);
+ glUnmapBuffer(GL_ARRAY_BUFFER_ARB);
+ glColorPointer(3, GL_FLOAT, 6*sizeof(float), (void *) 0);
+ glVertexPointer(3, GL_FLOAT, 6*sizeof(float), (void *) 12);
+#else
+ f = buf;
+ gen_quads(f);
+ glColorPointer(3, GL_FLOAT, 6*sizeof(float), buf);
+ glVertexPointer(3, GL_FLOAT, 6*sizeof(float), buf + 3);
+#endif
+
+ glEnableClientState(GL_COLOR_ARRAY);
+ glEnableClientState(GL_VERTEX_ARRAY);
+
+ glEnable(GL_DEPTH_TEST);
+
+ glClearColor(0.5, 0.5, 0.5, 0.0);
+}
+
+
+int
+main(int argc, char *argv[])
+{
+ glutInit(&argc, argv);
+ glutInitWindowPosition(0, 0);
+ glutInitWindowSize(600, 600);
+ glutInitDisplayMode(GLUT_RGB | GLUT_DOUBLE | GLUT_DEPTH);
+ Win = glutCreateWindow(argv[0]);
+ glutReshapeFunc(Reshape);
+ glutKeyboardFunc(Key);
+ glutSpecialFunc(SpecialKey);
+ glutDisplayFunc(Draw);
+ if (Anim)
+ glutIdleFunc(Idle);
+ Init();
+ glutMainLoop();
+ return 0;
+}