diff options
| -rw-r--r-- | src/gallium/drivers/r300/r300_render.c | 31 |
1 files changed, 25 insertions, 6 deletions
diff --git a/src/gallium/drivers/r300/r300_render.c b/src/gallium/drivers/r300/r300_render.c index 11c7ce859d..2d70ec2ac9 100644 --- a/src/gallium/drivers/r300/r300_render.c +++ b/src/gallium/drivers/r300/r300_render.c @@ -83,15 +83,34 @@ static uint32_t r300_provoking_vertex_fixes(struct r300_context *r300, /* By default (see r300_state.c:r300_create_rs_state) color_control is * initialized to provoking the first vertex. * - * If we are provoking the first vertex, then there's a quirk in the - * specification for ARB_provoking_vertex that essentially makes the - * second vertex the correct one to provoke for triangle fans. + * Triangle fans must be reduced to the second vertex, not the first, in + * Gallium flatshade-first mode, as per the GL spec. * (http://www.opengl.org/registry/specs/ARB/provoking_vertex.txt) - * Otherwise, force the last vertex, as GL standard. */ + * + * Quads never provoke correctly in flatshade-first mode. The first + * vertex is never considered as provoking, so only the second, third, + * and fourth vertices can be selected, and both "third" and "last" modes + * select the fourth vertex. This is probably due to D3D lacking quads. + * + * Similarly, polygons reduce to the first, not the last, vertex, when in + * "last" mode, and all other modes start from the second vertex. + * + * ~ C. + */ if (r300->rs_state->rs.flatshade_first) { - if (mode == PIPE_PRIM_TRIANGLE_FAN) { - color_control |= R300_GA_COLOR_CONTROL_PROVOKING_VERTEX_SECOND; + switch (mode) { + case PIPE_PRIM_TRIANGLE_FAN: + color_control |= R300_GA_COLOR_CONTROL_PROVOKING_VERTEX_SECOND; + break; + case PIPE_PRIM_QUADS: + case PIPE_PRIM_QUAD_STRIP: + case PIPE_PRIM_POLYGON: + color_control |= R300_GA_COLOR_CONTROL_PROVOKING_VERTEX_LAST; + break; + default: + color_control |= R300_GA_COLOR_CONTROL_PROVOKING_VERTEX_FIRST; + break; } } else { color_control |= R300_GA_COLOR_CONTROL_PROVOKING_VERTEX_LAST; |