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#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#define GL_GLEXT_PROTOTYPES
#include <GL/glut.h>
#include <unistd.h>
#include <signal.h>
unsigned show_fps = 0;
unsigned int frame_cnt = 0;
void alarmhandler(int);
static const char *filename = NULL;
static void usage(char *name)
{
fprintf(stderr, "usage: %s [ options ] shader_filename\n", name);
fprintf(stderr, "\n" );
fprintf(stderr, "options:\n");
fprintf(stderr, " -fps show frames per second\n");
}
void alarmhandler (int sig)
{
if (sig == SIGALRM) {
printf("%d frames in 5.0 seconds = %.3f FPS\n", frame_cnt,
frame_cnt / 5.0);
frame_cnt = 0;
}
signal(SIGALRM, alarmhandler);
alarm(5);
}
static void args(int argc, char *argv[])
{
GLint i;
for (i = 1; i < argc; i++) {
if (strcmp(argv[i], "-fps") == 0) {
show_fps = 1;
}
else if (i == argc - 1) {
filename = argv[i];
}
else {
usage(argv[0]);
exit(1);
}
}
if (!filename) {
usage(argv[0]);
exit(1);
}
}
static void Init( void )
{
GLint errno;
GLuint prognum;
char buf[4096];
GLuint sz;
FILE *f;
if ((f = fopen(filename, "r")) == NULL) {
fprintf(stderr, "Couldn't open %s\n", filename);
exit(1);
}
sz = fread(buf, 1, sizeof(buf), f);
if (!feof(f)) {
fprintf(stderr, "file too long\n");
exit(1);
}
fprintf(stderr, "%.*s\n", sz, buf);
if (!glutExtensionSupported("GL_ARB_fragment_program")) {
printf("Error: GL_ARB_fragment_program not supported!\n");
exit(1);
}
printf("GL_RENDERER = %s\n", (char *) glGetString(GL_RENDERER));
/* Setup the fragment program */
glGenProgramsARB(1, &prognum);
glBindProgramARB(GL_FRAGMENT_PROGRAM_ARB, prognum);
glProgramStringARB(GL_FRAGMENT_PROGRAM_ARB, GL_PROGRAM_FORMAT_ASCII_ARB,
sz, (const GLubyte *)buf);
errno = glGetError();
printf("glGetError = 0x%x\n", errno);
if (errno != GL_NO_ERROR) {
GLint errorpos;
glGetIntegerv(GL_PROGRAM_ERROR_POSITION_ARB, &errorpos);
printf("errorpos: %d\n", errorpos);
printf("glError(GL_PROGRAM_ERROR_STRING_ARB) = %s\n",
(char *) glGetString(GL_PROGRAM_ERROR_STRING_ARB));
}
glEnable(GL_FRAGMENT_PROGRAM_ARB);
glClearColor(.3, .3, .3, 0);
}
static void Reshape(int width, int height)
{
glViewport(0, 0, (GLint)width, (GLint)height);
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
glOrtho(-1.0, 1.0, -1.0, 1.0, -0.5, 1000.0);
glMatrixMode(GL_MODELVIEW);
}
static void Key(unsigned char key, int x, int y)
{
switch (key) {
case 27:
exit(1);
default:
return;
}
glutPostRedisplay();
}
static void Display(void)
{
glClear(GL_COLOR_BUFFER_BIT);
glBegin(GL_TRIANGLES);
glColor3f(0,0,1);
glVertex3f( 0.9, -0.9, -30.0);
glColor3f(1,0,0);
glVertex3f( 0.9, 0.9, -30.0);
glColor3f(0,1,0);
glVertex3f(-0.9, 0.0, -30.0);
glEnd();
glFlush();
if (show_fps) {
++frame_cnt;
glutPostRedisplay();
}
}
int main(int argc, char **argv)
{
glutInit(&argc, argv);
glutInitWindowPosition(0, 0);
glutInitWindowSize(250, 250);
glutInitDisplayMode(GLUT_RGB | GLUT_SINGLE | GLUT_DEPTH);
glutCreateWindow(argv[0]);
glutReshapeFunc(Reshape);
glutKeyboardFunc(Key);
glutDisplayFunc(Display);
args(argc, argv);
Init();
if (show_fps) {
signal(SIGALRM, alarmhandler);
alarm(5);
}
glutMainLoop();
return 0;
}
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