+ vert_t *a_verts = (vert_t*)(((gfloat*)a)+2);
+ vert_t *b_verts = (vert_t*)(((gfloat*)b)+2);
+ gfloat a_sum = a_verts[0].xyz[2] + a_verts[1].xyz[2] + a_verts[2].xyz[2];
+ gfloat b_sum = b_verts[0].xyz[2] + b_verts[1].xyz[2] + b_verts[2].xyz[2];
+ return a_sum == b_sum ? 0 :
+ a_sum < b_sum ? 1 : -1;
+}
+
+static gfloat *sort_start()
+{
+ int size = 1000000;
+ gfloat *data = g_new0(gfloat, size);
+ glFeedbackBuffer(size, GL_3D_COLOR, data);
+ glRenderMode(GL_FEEDBACK);
+ g_print("1st = %f\n", data[0]);
+ return data;
+}
+
+static void sort_end(gfloat *data)
+{
+ int vertsize = sizeof(vert_t)/sizeof(gfloat);
+ int count = glRenderMode(GL_RENDER);
+
+ /* Set up screen coords */
+ gint view[4];
+ glGetIntegerv(GL_VIEWPORT, view);
+
+ glMatrixMode(GL_PROJECTION);
+ glLoadIdentity();
+ glOrtho(view[0],view[2], view[1],view[3], -10,10);
+
+ glMatrixMode(GL_MODELVIEW);
+ glLoadIdentity();
+ glDisable(GL_LIGHTING);
+
+ /* Sort the vertexes (this only works with all-triangles */
+ int trisize = 2*sizeof(gfloat) + 3*sizeof(vert_t);
+ int ntris = count / trisize;
+ g_print("%d, %d, %d\n", sizeof(gfloat), trisize, ntris);
+ qsort(data, ntris*4, trisize, sort_cmp);
+
+ /* Draw the data */
+ for (int i = 0; i < count;) {
+ gfloat token = data[i++];
+ if (token == GL_POLYGON_TOKEN) {
+ gfloat n = data[i++];
+ vert_t *verts = (vert_t*)&data[i];
+ i += n*vertsize;
+ //g_print("GL_POLYGON_TOKEN: %f\n", n);
+
+ /* Draw triangle */
+ glBegin(GL_TRIANGLES);
+ for (int j = 0; j < n; j++) {
+ //g_print("\t%f, %f, %f\n",
+ // verts[j].xyz[0],
+ // verts[j].xyz[1],
+ // verts[j].xyz[2]);
+ glColor4fv(verts[j].color);
+ glVertex3fv(verts[j].xyz);
+ }
+ glEnd();
+
+ /* Draw line */
+ glColor4f(1,1,1,1);
+ glBegin(GL_LINE_LOOP);
+ for (int j = 0; j < n; j++)
+ glVertex3fv(verts[j].xyz);
+ glEnd();
+ } else {
+ g_error("Unknown token: %f\n", token);
+ }
+ }