- for (i = 3; i < nr; i += 2) {
- setup->triangle( setup,
- get_vert(vertex_buffer, indices[i-3], stride),
- get_vert(vertex_buffer, indices[i-2], stride),
- get_vert(vertex_buffer, indices[i-0], stride) );
- setup->triangle( setup,
- get_vert(vertex_buffer, indices[i-1], stride),
- get_vert(vertex_buffer, indices[i-3], stride),
- get_vert(vertex_buffer, indices[i-0], stride) );
+ /* GL quad strips don't follow provoking vertex convention */
+ if (flatshade_first) {
+ /* emit last quad vertex as first triangle vertex */
+ for (i = 3; i < nr; i += 2) {
+ setup->triangle( setup,
+ get_vert(vertex_buffer, indices[i-0], stride),
+ get_vert(vertex_buffer, indices[i-3], stride),
+ get_vert(vertex_buffer, indices[i-2], stride) );
+ setup->triangle( setup,
+ get_vert(vertex_buffer, indices[i-0], stride),
+ get_vert(vertex_buffer, indices[i-1], stride),
+ get_vert(vertex_buffer, indices[i-3], stride) );
+ }
+ }
+ else {
+ /* emit last quad vertex as last triangle vertex */
+ for (i = 3; i < nr; i += 2) {
+ setup->triangle( setup,
+ get_vert(vertex_buffer, indices[i-3], stride),
+ get_vert(vertex_buffer, indices[i-2], stride),
+ get_vert(vertex_buffer, indices[i-0], stride) );
+ setup->triangle( setup,
+ get_vert(vertex_buffer, indices[i-1], stride),
+ get_vert(vertex_buffer, indices[i-3], stride),
+ get_vert(vertex_buffer, indices[i-0], stride) );
+ }