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i965: Implement guardband clipping on Sandybridge.

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Improves performance in Citybench:
- 320x240:  19.8008% +/- 0.937818%
- 1280x480: 6.53856% +/- 0.859083%

No apparent difference in OpenArena nor Xonotic.

Signed-off-by: Kenneth Graunke <kenneth@whitecape.org>
Reviewed-by: Eric Anholt <eric@anholt.net>
This commit is contained in:
Kenneth Graunke 2012-05-04 17:06:38 -07:00
parent 5994a641d8
commit 85cd30406f
2 changed files with 15 additions and 10 deletions
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1
src/mesa/drivers/dri/i965/gen6_clip_state.c
View file

@ -74,6 +74,7 @@ upload_clip_state(struct brw_context *brw)
GEN6_CLIP_MODE_NORMAL |
nonperspective_barycentric_enable_flag |
GEN6_CLIP_XY_TEST |
GEN6_CLIP_GB_TEST |
userclip << GEN6_USER_CLIP_CLIP_DISTANCES_SHIFT |
depth_clamp |
provoking);

24
src/mesa/drivers/dri/i965/gen6_viewport_state.c
View file

@ -33,31 +33,35 @@
/* The clip VP defines the guardband region where expensive clipping is skipped
* and fragments are allowed to be generated and clipped out cheaply by the SF.
*
* By setting it to NDC bounds of [-1,1], we don't do GB clipping. It's
* supposed to cause seams to become visible in apps due to shared edges taking
* different clip/no clip paths depending on whether the rest of the prim ends
* up in the guardband or not.
*/
static void
gen6_upload_clip_vp(struct brw_context *brw)
{
struct gl_context *ctx = &brw->intel.ctx;
struct brw_clipper_viewport *vp;
vp = brw_state_batch(brw, AUB_TRACE_CLIP_VP_STATE,
sizeof(*vp), 32, &brw->clip.vp_offset);
vp->xmin = -1.0;
vp->xmax = 1.0;
vp->ymin = -1.0;
vp->ymax = 1.0;
/* According to the Sandybridge PRM, Volume 2, Part 1, Section 6.3.8
* "Vertex X,Y Clamping and Quantization", the screen-aligned 2D
* bounding-box of an object must not exceed 16K pixels in either X or Y.
*/
const float maximum_post_clamp_delta = 16384;
float gbx = maximum_post_clamp_delta / (float) ctx->Viewport.Width;
float gby = maximum_post_clamp_delta / (float) ctx->Viewport.Height;
vp->xmin = -gbx;
vp->xmax = gbx;
vp->ymin = -gby;
vp->ymax = gby;
brw->state.dirty.cache |= CACHE_NEW_CLIP_VP;
}
const struct brw_tracked_state gen6_clip_vp = {
.dirty = {
.mesa = 0,
.mesa = _NEW_VIEWPORT,
.brw = BRW_NEW_BATCH,
.cache = 0,
},