gl program showing nothing on screen

nacio · 04-05-2007, 04:16 PM

Hi,

I've made a small program to test the speed of OpenGL 2D graphics. I'm working under linux/X11. My program works... when dri is not enabled. When it is, the program runs naturally faster, but it displays nothing on screen! I'm confused, is it that I forgot to call some initialization routine? Then why does it work when dri is disabled?

Here's the code:

Code:

#include <time.h>
#include <stdlib.h>
#include <stdio.h>

#include <GL/gl.h>
#include <GL/glut.h>


int glutWin;


void videoInit(int argc, char *argv[]) {
        glutInitWindowSize(800, 600);
        glutInitWindowPosition(1, 1);
        glutInit( &argc, argv);
        glutInitDisplayMode( GLUT_SINGLE | GLUT_RGB |  GLUT_DEPTH );

        glutWin = glutCreateWindow("GL 2D speed test");
        glShadeModel(GL_FLAT);

        glClearColor(0.00, 0.00, 0.00, 0.00);

        glClearDepth(1.0f);

        glEnable(GL_DEPTH_TEST);

        glDepthFunc(GL_LEQUAL);

        glViewport(0, 0, 800, 600);
        glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
        glLoadIdentity();
        glOrtho(0.00, 1.00, 0.00, 1.00, 0.00, 1.00 );
}


void videoClose(void)
{
    glutDestroyWindow(glutWin);
}

//fill in the buffer with random colors
void randomize(char *p, int qty) {
        int i;
        for (i=0; i<qty; i++)
                *p++ = rand() & 0xFF;
}
int main(int argc, char *argv[]) {
        clock_t t;
        int i;
        void *p;

        videoInit(argc, argv);

        p  = malloc(800*600*4);
        if (!p) {
                fprintf(stderr, "can't get enough memory!\n");
                return 1;
        }
        randomize(p, 800*600*4);

        t = clock();
        for (i=0; i<1000; i++) {
            //this line is to see something moving on screen
            //so that we see that the buffer is actually being redrawn
            *(int *) (p+i) = 0;

            //and now we actually draw
            glDrawPixels(800, 600, GL_RGBA, GL_UNSIGNED_BYTE, p);
            glFlush();
        }
        printf("Time: %i\n", clock() - t );

        videoClose();
}