From fcc2ca008907a897286d1dfcd9c9105677f71ea8 Mon Sep 17 00:00:00 2001 From: Sergey Sharybin Date: Fri, 31 Oct 2014 12:15:38 +0100 Subject: [PATCH] Fix T42401: Gaussian blur node is visibly squared-off at larger sizes The root of the issue comes to the way how we sample the gaussian filter in RE_filter_value(). We need to scale x to -3*sigma..3*sigma segment in order to get the whole bell. The old code tried to do it, but failed dramatically, plus it used some weird gaussian sampling formula. Replaced it with much more clear one, which gives proper blur now. There's no visible different in AA sampling in BI render tho. Other filters like Mitchell still tends to give wrong square shaped blurs, but they're much more difficult to resolve because they're just wrong in the code -- for some reason smaller kernel size means more blur. Let's solve this later. --- source/blender/render/intern/source/initrender.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) diff --git a/source/blender/render/intern/source/initrender.c b/source/blender/render/intern/source/initrender.c index 353ba5d5caa..4bb5dc154a6 100644 --- a/source/blender/render/intern/source/initrender.c +++ b/source/blender/render/intern/source/initrender.c @@ -164,8 +164,11 @@ float RE_filter_value(int type, float x) return 1.0f - x; case R_FILTER_GAUSS: - x *= gaussfac; - return (1.0f / expf(x * x) - 1.0f / expf(gaussfac * gaussfac * 2.25f)); + { + const float two_gaussfac2 = 2.0f * gaussfac * gaussfac; + x *= 3.0f * gaussfac; + return 1.0f / sqrtf(M_PI * two_gaussfac2) * expf(-x*x / two_gaussfac2); + } case R_FILTER_MITCH: return filt_mitchell(x * gaussfac);