[Bf-blender-cvs] [e1e772a8024] master: Cleanup: add comment explaining reason for volume texture swizzling

[Brecht Van Lommel]

Commit: e1e772a80243f3c279fcd076c8311301e8885d41
Author: Brecht Van Lommel
Date:   Wed Mar 11 14:52:55 2020 +0100
Branches: master
https://developer.blender.org/rBe1e772a80243f3c279fcd076c8311301e8885d41

Cleanup: add comment explaining reason for volume texture swizzling

===================================================================

M	source/blender/gpu/intern/gpu_draw_smoke.c

===================================================================

diff --git a/source/blender/gpu/intern/gpu_draw_smoke.c b/source/blender/gpu/intern/gpu_draw_smoke.c
index aa7789b3342..546faadbda4 100644
--- a/source/blender/gpu/intern/gpu_draw_smoke.c
+++ b/source/blender/gpu/intern/gpu_draw_smoke.c
@@ -124,6 +124,8 @@ static GPUTexture *create_transfer_function(int type, const struct ColorBand *co
 
 static void swizzle_texture_channel_single(GPUTexture *tex)
 {
+  /* Swizzle texture channels so that we get useful RGBA values when sampling
+   * a texture with fewer channels, e.g. when using density as color. */
   GPU_texture_bind(tex, 0);
   GPU_texture_swizzle_channel_auto(tex, 1);
   GPU_texture_unbind(tex);