From f628cfd2970a8c215aa4366e76a642cfec3c43ca Mon Sep 17 00:00:00 2001
From: Luca Rood <dev@lucarood.com>
Date: Wed, 17 May 2017 16:41:42 +0200
Subject: [PATCH] Fix T51535: View vector inverting in pespective/ortho

---
 .../draw/engines/clay/shaders/particle_strand_frag.glsl        | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/source/blender/draw/engines/clay/shaders/particle_strand_frag.glsl b/source/blender/draw/engines/clay/shaders/particle_strand_frag.glsl
index 396cc5b7e81..b4dff283b18 100644
--- a/source/blender/draw/engines/clay/shaders/particle_strand_frag.glsl
+++ b/source/blender/draw/engines/clay/shaders/particle_strand_frag.glsl
@@ -9,6 +9,7 @@ layout(std140) uniform material_block {
 	Material shader_param[MAX_MATERIAL];
 };
 
+uniform mat4 ProjectionMatrix;
 uniform sampler2DArray matcaps;
 uniform int mat_id;
 
@@ -116,7 +117,7 @@ void hue_sat(float hue, float sat, float value, inout vec3 col)
 
 void main()
 {
-	vec3 viewvec = normalize(viewPosition);
+	vec3 viewvec = (ProjectionMatrix[3][3] == 0.0) ? normalize(viewPosition) : vec3(0.0, 0.0, -1.0);
 	vec3 ortho = normalize(cross(viewPosition, tangent));
 	vec3 norm = normalize(cross(ortho, tangent));