On Mon, Nov 6, 2017 at 8:48 AM, Ilia Mirkin <imir...@alum.mit.edu> wrote: > On Mon, Nov 6, 2017 at 6:21 AM, Nicolai Hähnle <nhaeh...@gmail.com> wrote: >> On 06.11.2017 05:22, Ilia Mirkin wrote: >>> >>> Radeonsi also sets this flag. >>> >>> Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=103544 >>> Signed-off-by: Ilia Mirkin <imir...@alum.mit.edu> >>> --- >>> >>> This needs testing with the fbo-float-nan piglit that was recently added. >>> Just >>> guessing that this is the right flag to set here. >> >> >> Assuming that the test passes: > > Well, the test can't pass or fail. The behavior is undefined. But Dave > ran it last night to see what would happen. It appears that with the > current code, if you have a float RB with a infinity or nan in it, and > then you set the dst blend factor to GL_ZERO, then you'll still end up > with a NaN in the result. > > With this change, you'll end up with what most people would expect > with a GL_ZERO dst blend factor. Unless your src blend factor is e.g. > GL_DST_ALPHA, the dst op is multiplied. So if e.g. the RB has > (0,0,0,infinity), and shader output is (0,0,0,infinity), then src * > GL_DST_ALPHA + dst * GL_ZERO = (nan, nan, nan, nan). However src * > GL_SRC_ALPHA + dst + GL_ZERO = (0, 0, 0, infinity).
Ugh. I managed to confuse myself. With the patch and src = dst = (0,0,0,infinity): src * GL_DST_ALPHA + dst * GL_ZERO = (nan, nan, nan, nan). src * GL_SRC_ALPHA + dst * GL_ZERO = (nan, nan, nan, infinity) > > Perhaps there's another flag which controls 0 * inf = 0 vs NaN thing > for blending, but it wasn't immediately apparent from the docs. NVIDIA > blob drivers configure the hw for 0 * inf = 0. > >> >> Reviewed-by: Nicolai Hähnle <nicolai.haeh...@amd.com> > > Let me know if this stands, given the above info. > >> >> >> >>> >>> src/gallium/drivers/r600/evergreen_state.c | 1 + >>> src/gallium/drivers/r600/r600_state.c | 1 + >>> 2 files changed, 2 insertions(+) >>> >>> diff --git a/src/gallium/drivers/r600/evergreen_state.c >>> b/src/gallium/drivers/r600/evergreen_state.c >>> index 96eb35a9818..131778dea9f 100644 >>> --- a/src/gallium/drivers/r600/evergreen_state.c >>> +++ b/src/gallium/drivers/r600/evergreen_state.c >>> @@ -1211,6 +1211,7 @@ static void >>> evergreen_set_color_surface_common(struct r600_context *rctx, >>> S_028C70_COMP_SWAP(swap) | >>> S_028C70_BLEND_CLAMP(blend_clamp) | >>> S_028C70_BLEND_BYPASS(blend_bypass) | >>> + S_028C70_SIMPLE_FLOAT(1) | >>> S_028C70_NUMBER_TYPE(ntype) | >>> S_028C70_ENDIAN(endian); >>> diff --git a/src/gallium/drivers/r600/r600_state.c >>> b/src/gallium/drivers/r600/r600_state.c >>> index c21e8dabb1f..0c331537460 100644 >>> --- a/src/gallium/drivers/r600/r600_state.c >>> +++ b/src/gallium/drivers/r600/r600_state.c >>> @@ -898,6 +898,7 @@ static void r600_init_color_surface(struct >>> r600_context *rctx, >>> S_0280A0_COMP_SWAP(swap) | >>> S_0280A0_BLEND_BYPASS(blend_bypass) | >>> S_0280A0_BLEND_CLAMP(blend_clamp) | >>> + S_0280A0_SIMPLE_FLOAT(1) | >>> S_0280A0_NUMBER_TYPE(ntype) | >>> S_0280A0_ENDIAN(endian); >>> >> >> >> >> -- >> Lerne, wie die Welt wirklich ist, >> Aber vergiss niemals, wie sie sein sollte. _______________________________________________ mesa-dev mailing list mesa-dev@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/mesa-dev
