[KayBee]

Hi Again Devs,

Learning graphics programming on my O2 has been a tough start. So I was excited to find some examples in this SGI document:

Graphics Library Programming Guide Volume I 
Document Number 007-1210-060

In it I found an animation example and typed it in:

Code:

#include <stdio.h>
#include <stdlib.h>
#include <math.h>
#include <gl/gl.h>
#include <gl/device.h>
#define RGB_BLACK 0x000000
#define RGB_WHITE 0xffffff
#define X        0
#define Y        1
#define XY        2
#define SIZE    0.05
#define BOUNDS    (1.0 + SIZE)
#define EDGE    (1.1 * BOUNDS)

float boundary[4][XY] = {
    {-BOUNDS, -BOUNDS},
    {-BOUNDS, BOUNDS},
    { BOUNDS, BOUNDS},
    { BOUNDS, -BOUNDS}
};

struct ball_s {
    float pos[XY];
    float delta[XY];
    unsigned long col;
};

void main(int argc, char *argv[])
{
    int i, j;
    int nballs;
    struct ball_s *balls;
    short val;
    if (getgdesc(GD_BITS_NORM_DBL_RED) == 0) {
        fprintf(stderr,"Double buffered RGB not available on this machine\n");
        return 1;
    }
    if(argc!=2){
        fprintf(stderr, "Usage: bounce <ball count>");
        return 1;
    }
    nballs = atoi(argv[1]);
    if (!(balls = (struct ball_s *)malloc(nballs * sizeof(struct ball_s)))) {
    fprintf(stderr, "bounce: malloc failed\n");
    return 1;
    }
    for(i=0;i<nballs;i++){
        for(j=0;j<XY;j++){
            balls[i].pos[j] = 2.0 * (drand48() - 0.5);
            balls[i].delta[j] = 2.0 * (drand48() - 0.5) / 50.0;
        }
        balls[i].col = drand48() * 0xffffff;
    }
    prefsize(400, 400);
    winopen("bounce");
    doublebuffer();
    RGBmode();
    gconfig();
    shademodel(FLAT);
    qdevice(ESCKEY);
    ortho2(-EDGE, EDGE, -EDGE, EDGE);
    while (!(qtest() && qread(&val) == ESCKEY && val == 0)) {
        for(i=0;i<nballs;i++){
            for(j=0;j<XY;j++){
                balls[i].pos[j] += balls[i].delta[j];
                if ((balls[i].pos[j] >= 1.0) || (balls[i].pos[j] <= -1.0))
                    balls[i].delta[j] = -balls[i].delta[j];
                }
            }
            cpack(RGB_BLACK);
            clear();
            cpack(RGB_WHITE);
            bgnclosedline();
            for(i=0;i<4;i++)
                v2f(boundary[i]);
            endclosedline();
            for(i=0;i<nballs;i++){
                cpack(balls[i].col);
                sboxf(balls[i].pos[X]-SIZE, balls[i].pos[Y]-SIZE,
                        balls[i].pos[X]+SIZE, balls[i].pos[Y]+SIZE);
            }
            swapbuffers();
        }
        gexit();
        return 0;
    }

Compiling this code via: cc -n32 animation.c -lgl
yields 4 errors, each identifying one of the returns and the accompanying number and stating for example:
      return 1;
An expression appears after a "return" in a "void" function

Could you knowledgable folks give it a go and let me know what is going on?

Thanks as always.

KB