+ glReadPixels(0, 0, win_width, win_height, GL_RGB, GL_UNSIGNED_BYTE, pixels);
+
+ for(i=0; i<grid_rows; i++) {
+ for(j=0; j<grid_cols; j++) {
+ tilepix = pixels + (i * win_width + j) * tilesz * 3;
+
+ sprintf(fname, "tile-%02d%02d.ppm", j, i);
+ save_tile(fname, tilepix, tilesz, tilesz, win_width * 3);
+ }
+ }
+}
+
+int save_tile(const char *fname, unsigned char *pixptr, int xsz, int ysz, int pitch)
+{
+ int i, j;
+ FILE *fp;
+
+ printf("saving tile: %s\n", fname);
+
+ if(!(fp = fopen(fname, "wb"))) {
+ fprintf(stderr, "failed to open %s for writing: %s\n", fname, strerror(errno));
+ return -1;
+ }
+
+ pixptr += ysz * pitch;
+ fprintf(fp, "P6\n%d %d\n255\n", xsz, ysz);
+ for(i=0; i<ysz; i++) {
+ pixptr -= pitch;
+ for(j=0; j<xsz; j++) {
+ int r = pixptr[j * 3];
+ int g = pixptr[j * 3 + 1];
+ int b = pixptr[j * 3 + 2];
+ fputc(r, fp);
+ fputc(g, fp);
+ fputc(b, fp);
+ }
+ }
+
+ fclose(fp);
+ return 0;