From 13e24cd87e7d9373e3eaf429b6aa7990d0156c4d Mon Sep 17 00:00:00 2001 From: Pablo Delgado Date: Wed, 4 Jan 2023 17:20:43 +0100 Subject: [PATCH] Fix missing basis orthogonalizations in GLSL backend (#1177) I've encountered shading artifacts in normal mapped MaterialX materials, and upon closer inspection I believe that these are caused by the missing basis orthogonalizations @Tellusim brought to attention in PR #1049. However, instead of using a second normalize(cross(..)) call, I've applied the Gram-Schmidt algorithm. --- libraries/pbrlib/genglsl/lib/mx_environment_fis.glsl | 4 ++-- libraries/pbrlib/genglsl/mx_conductor_bsdf.glsl | 3 ++- libraries/pbrlib/genglsl/mx_dielectric_bsdf.glsl | 3 ++- libraries/pbrlib/genglsl/mx_generalized_schlick_bsdf.glsl | 3 ++- 4 files changed, 8 insertions(+), 5 deletions(-) diff --git a/libraries/pbrlib/genglsl/lib/mx_environment_fis.glsl b/libraries/pbrlib/genglsl/lib/mx_environment_fis.glsl index b39697fea4..d66f3a8cfb 100644 --- a/libraries/pbrlib/genglsl/lib/mx_environment_fis.glsl +++ b/libraries/pbrlib/genglsl/lib/mx_environment_fis.glsl @@ -13,8 +13,8 @@ float mx_latlong_compute_lod(vec3 dir, float pdf, float maxMipLevel, int envSamp vec3 mx_environment_radiance(vec3 N, vec3 V, vec3 X, vec2 alpha, int distribution, FresnelData fd) { // Generate tangent frame. - vec3 Y = normalize(cross(N, X)); - X = cross(Y, N); + X = normalize(X - dot(X, N) * N); + vec3 Y = cross(N, X); mat3 tangentToWorld = mat3(X, Y, N); // Transform the view vector to tangent space. diff --git a/libraries/pbrlib/genglsl/mx_conductor_bsdf.glsl b/libraries/pbrlib/genglsl/mx_conductor_bsdf.glsl index 1b1069298d..532550554a 100644 --- a/libraries/pbrlib/genglsl/mx_conductor_bsdf.glsl +++ b/libraries/pbrlib/genglsl/mx_conductor_bsdf.glsl @@ -11,7 +11,8 @@ void mx_conductor_bsdf_reflection(vec3 L, vec3 V, vec3 P, float occlusion, float N = mx_forward_facing_normal(N, V); - vec3 Y = normalize(cross(N, X)); + X = normalize(X - dot(X, N) * N); + vec3 Y = cross(N, X); vec3 H = normalize(L + V); float NdotL = clamp(dot(N, L), M_FLOAT_EPS, 1.0); diff --git a/libraries/pbrlib/genglsl/mx_dielectric_bsdf.glsl b/libraries/pbrlib/genglsl/mx_dielectric_bsdf.glsl index 69445b2875..0150d308d9 100644 --- a/libraries/pbrlib/genglsl/mx_dielectric_bsdf.glsl +++ b/libraries/pbrlib/genglsl/mx_dielectric_bsdf.glsl @@ -9,7 +9,8 @@ void mx_dielectric_bsdf_reflection(vec3 L, vec3 V, vec3 P, float occlusion, floa N = mx_forward_facing_normal(N, V); - vec3 Y = normalize(cross(N, X)); + X = normalize(X - dot(X, N) * N); + vec3 Y = cross(N, X); vec3 H = normalize(L + V); float NdotL = clamp(dot(N, L), M_FLOAT_EPS, 1.0); diff --git a/libraries/pbrlib/genglsl/mx_generalized_schlick_bsdf.glsl b/libraries/pbrlib/genglsl/mx_generalized_schlick_bsdf.glsl index 11d1568fd6..ce0fb8ea48 100644 --- a/libraries/pbrlib/genglsl/mx_generalized_schlick_bsdf.glsl +++ b/libraries/pbrlib/genglsl/mx_generalized_schlick_bsdf.glsl @@ -9,7 +9,8 @@ void mx_generalized_schlick_bsdf_reflection(vec3 L, vec3 V, vec3 P, float occlus N = mx_forward_facing_normal(N, V); - vec3 Y = normalize(cross(N, X)); + X = normalize(X - dot(X, N) * N); + vec3 Y = cross(N, X); vec3 H = normalize(L + V); float NdotL = clamp(dot(N, L), M_FLOAT_EPS, 1.0);