DRW: Use USHORT for vertex color and upload them in linear color to the GPU

This way we remove the need for the srgb boolean uniform and a lot of code complexity. However, mesh update is going to be a bit slower.

I did not benchmark the performance impact.

This also fix a typo in draw_cache_impl_particles.c and fix hair not using vertex color in workbench.

Reviewed By: jbakker

Differential Revision: https://developer.blender.org/D6610

1 files changed, 9 insertions, 12 deletions

diff --git a/source/blender/draw/engines/workbench/shaders/workbench_prepass_vert.glsl b/source/blender/draw/engines/workbench/shaders/workbench_prepass_vert.glsl
index 04dd9ab85bb..0a3252f0b9b 100644
--- a/source/blender/draw/engines/workbench/shaders/workbench_prepass_vert.glsl
+++ b/source/blender/draw/engines/workbench/shaders/workbench_prepass_vert.glsl
@@ -4,13 +4,18 @@ in vec3 pos;
 in vec3 nor;
 in vec2 au; /* active texture layer */
 #  ifdef V3D_SHADING_VERTEX_COLOR
-in vec3 ac; /* active color */
+in vec4 ac; /* active color */
 #  endif
 #  define uv au
 #else /* HAIR_SHADER */
+
 #  ifdef V3D_SHADING_TEXTURE_COLOR
 uniform samplerBuffer au; /* active texture layer */
 #  endif
+#  ifdef V3D_SHADING_VERTEX_COLOR
+uniform samplerBuffer ac; /* active color layer */
+#  endif
+
 flat out float hair_rand;
 #endif /* HAIR_SHADER */
 
@@ -37,16 +42,6 @@ float integer_noise(int n)
   return (float(nn) / 1073741824.0);
 }
 
-#ifdef V3D_SHADING_VERTEX_COLOR
-vec3 srgb_to_linear_attr(vec3 c)
-{
-  c = max(c, vec3(0.0));
-  vec3 c1 = c * (1.0 / 12.92);
-  vec3 c2 = pow((c + 0.055) * (1.0 / 1.055), vec3(2.4));
-  return mix(c1, c2, step(vec3(0.04045), c));
-}
-#endif
-
 vec3 workbench_hair_hair_normal(vec3 tan, vec3 binor, float rand)
 {
   /* To "simulate" anisotropic shading, randomize hair normal per strand. */
@@ -90,7 +85,9 @@ void main()
 
 #ifdef V3D_SHADING_VERTEX_COLOR
 #  ifndef HAIR_SHADER
-  vertexColor = srgb_to_linear_attr(ac);
+  vertexColor = ac.rgb;
+#  else
+  vertexColor = hair_get_customdata_vec4(ac).rgb;
 #  endif
 #endif