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/**
* Draw colored quads.
*/
#include <stdio.h>
#include <stdlib.h>
#include <math.h>
#include <GL/glew.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 doSwapBuffers = 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 (doSwapBuffers)
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':
doSwapBuffers = !doSwapBuffers;
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]);
glewInit();
glutReshapeFunc(Reshape);
glutKeyboardFunc(Key);
glutSpecialFunc(SpecialKey);
glutDisplayFunc(Draw);
if (Anim)
glutIdleFunc(Idle);
Init();
glutMainLoop();
return 0;
}
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