Fix T42492, Shading error with fresnel weight node.

Orthographic case needs different handling.

1 files changed, 4 insertions, 2 deletions

diff --git a/source/blender/gpu/shaders/gpu_shader_material.glsl b/source/blender/gpu/shaders/gpu_shader_material.glsl
index 39e8b31197f..4e910cd220a 100644
--- a/source/blender/gpu/shaders/gpu_shader_material.glsl
+++ b/source/blender/gpu/shaders/gpu_shader_material.glsl
@@ -2274,10 +2274,12 @@ void node_layer_weight(float blend, vec3 N, vec3 I, out float fresnel, out float
 {
 	/* fresnel */
 	float eta = max(1.0 - blend, 0.00001);
-	fresnel = fresnel_dielectric(normalize(I), N, (gl_FrontFacing)? 1.0/eta : eta );
+	vec3 I_view = (gl_ProjectionMatrix[3][3] == 0.0)? normalize(I): vec3(0.0, 0.0, -1.0);
+
+	fresnel = fresnel_dielectric(I_view, N, (gl_FrontFacing)? 1.0/eta : eta );
 
 	/* facing */
-	facing = abs(dot(normalize(I), N));
+	facing = abs(dot(I_view, N));
 	if(blend != 0.5) {
 		blend = clamp(blend, 0.0, 0.99999);
 		blend = (blend < 0.5)? 2.0*blend: 0.5/(1.0 - blend);