Mesa (master): draw: fix points with negative w coords for d3d style point clipping
Roland Scheidegger
sroland at kemper.freedesktop.org
Tue Jan 21 16:49:24 UTC 2014
Module: Mesa
Branch: master
Commit: e23e4f67bed51a8dfd182eae6c7e8e23a7d2cb0e
URL: http://cgit.freedesktop.org/mesa/mesa/commit/?id=e23e4f67bed51a8dfd182eae6c7e8e23a7d2cb0e
Author: Roland Scheidegger <sroland at vmware.com>
Date: Tue Jan 21 17:47:08 2014 +0100
draw: fix points with negative w coords for d3d style point clipping
Even with depth clipping disabled, vertices which have negative w coords
must be discarded. And since we don't have a proper guardband implementation
yet (relying on driver to handle all values except infs/nans in rasterization
for such points) we need to kill them off manually (as they can end up with
coordinates inside viewport otherwise).
v2: use 0.0f instead of 0 (spotted by Brian).
Reviewed-by: Jose Fonseca <jfonseca at vmware.com>
Reviewed-by: Brian Paul <brianp at vmware.com>
---
src/gallium/auxiliary/draw/draw_pipe_clip.c | 8 ++++++--
1 file changed, 6 insertions(+), 2 deletions(-)
diff --git a/src/gallium/auxiliary/draw/draw_pipe_clip.c b/src/gallium/auxiliary/draw/draw_pipe_clip.c
index 8bdb882..de354e9 100644
--- a/src/gallium/auxiliary/draw/draw_pipe_clip.c
+++ b/src/gallium/auxiliary/draw/draw_pipe_clip.c
@@ -635,8 +635,13 @@ clip_point_guard_xy( struct draw_stage *stage,
clipmask &= ~(1 << plane_idx); /* turn off this plane's bit */
/* TODO: this should really do proper guardband clipping,
* currently just throw out infs/nans.
+ * Also note that vertices with negative w values MUST be tossed
+ * out (not sure if proper guardband clipping would do this
+ * automatically). These would usually be captured by depth clip
+ * too but this can be disabled.
*/
- if (util_is_inf_or_nan(header->v[0]->clip[0]) ||
+ if (header->v[0]->clip[3] <= 0.0f ||
+ util_is_inf_or_nan(header->v[0]->clip[0]) ||
util_is_inf_or_nan(header->v[0]->clip[1]))
return;
}
@@ -645,7 +650,6 @@ clip_point_guard_xy( struct draw_stage *stage,
}
-
static void
clip_first_point( struct draw_stage *stage,
struct prim_header *header )
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