Am 16.04.2013 21:41, schrieb Brian Paul: > On 04/16/2013 01:07 PM, srol...@vmware.com wrote: >> From: Roland Scheidegger<srol...@vmware.com> >> >> This will calculate rho correctly as >> sqrt(max((ds/dx)^2 + (dt/dx)^2 + (dr/dx)^2), (ds/dx)^2 + (dt/dx)^2 + >> (dr/dx)^2)) >> instead of max(|ds/dx|,|dt/dx|,|dr/dx|,|ds/dy|,|dt/dy,|dr/dy|) >> (for 3 coords - 2 coords work analogous, for 1 coord there's no point >> doing >> the exact version), for both implicit and explicit derivatives. >> While such approximation seems to be allowed in OpenGL some APIs may >> be less >> forgiving, and the error can be quite large (sqrt(2) for 2 coords, >> sqrt(3) for >> 3 coords so wrong by nearly one mip level in the latter case). >> This also helps to single out "real" bugs from "expected" ones, so it >> is debug >> only (though at least combined with no_brilinear I didn't really see >> much of a >> performance difference but only tested with a debug build - at least with >> implicit mipmaps the instruction count is almost exactly the same >> though the >> instructions are more complex (1 sqrt and mul/adds instead of and/max >> mostly). >> The code when the option isn't set stays exactly the same. > > It sounds like a better name for the option would be something like > "sqrt_rho" because you're just computing rho with more precision. Hmm I wanted to name this somewhat along the lines of "no_brilinear" (which ultimately clamps the rho value to exact mip levels whereas this makes rho calculation itself more accurate) but I guess it's not a very good name. Maybe "no_rho_approx" would be better? I'd like to have a somewhat consistent naming for all switches which disable somewhat fishy (but enabled by default) optimizations, and "sqrt_rho" doesn't quite fit that bill. I could live with it though.
> > >> --- >> src/gallium/auxiliary/gallivm/lp_bld_debug.h | 3 +- >> src/gallium/auxiliary/gallivm/lp_bld_init.c | 1 + >> src/gallium/auxiliary/gallivm/lp_bld_sample.c | 299 >> +++++++++++++++---------- >> 3 files changed, 185 insertions(+), 118 deletions(-) >> >> diff --git a/src/gallium/auxiliary/gallivm/lp_bld_debug.h >> b/src/gallium/auxiliary/gallivm/lp_bld_debug.h >> index da873f3..b65a1f7 100644 >> --- a/src/gallium/auxiliary/gallivm/lp_bld_debug.h >> +++ b/src/gallium/auxiliary/gallivm/lp_bld_debug.h >> @@ -42,7 +42,8 @@ >> #define GALLIVM_DEBUG_NO_OPT (1<< 3) >> #define GALLIVM_DEBUG_PERF (1<< 4) >> #define GALLIVM_DEBUG_NO_BRILINEAR (1<< 5) >> -#define GALLIVM_DEBUG_GC (1<< 6) >> +#define GALLIVM_DEBUG_NO_RHO_OPT (1<< 6) > > GALLIVM_DEBUG_SQRT_RHO? Yes, should be the same as the as the env var name. Roland > > Looks good otherwise. > > -Brian > _______________________________________________ mesa-dev mailing list mesa-dev@lists.freedesktop.org http://lists.freedesktop.org/mailman/listinfo/mesa-dev
