Images: change alpha settings to support channel packing

This also replaces the Use Alpha setting. We now have these alpha modes:

* Straight: store RGB and alpha channels separately with alpha acting as a
  mask, also known as unassociated alpha.
* Premultiplied: transparent RGB pixels are multiplied by the alpha channel.
  The natural format for renders.
* Channel Packed: different images are packed in the RGB and alpha channels,
  and they should not influence each other. Channel packing is commonly used
  by game engines to save memory.
* None: ignore alpha channel from the file and make image fully opaque.

Cycles OSL does not correctly support Channel Packed and None yet, we are
missing fine control over the OpenImageIO texture cache to do that.

Fixes T53672

1 files changed, 2 insertions, 2 deletions

diff --git a/intern/cycles/render/nodes.h b/intern/cycles/render/nodes.h
index 3dd84ad8dca..6b21be88663 100644
--- a/intern/cycles/render/nodes.h
+++ b/intern/cycles/render/nodes.h
@@ -100,10 +100,10 @@ class ImageTextureNode : public ImageSlotTextureNode {
   }
 
   /* Parameters. */
-  bool use_alpha;
   ustring filename;
   void *builtin_data;
   ustring colorspace;
+  ImageAlphaType alpha_type;
   NodeImageProjection projection;
   InterpolationType interpolation;
   ExtensionType extension;
@@ -141,10 +141,10 @@ class EnvironmentTextureNode : public ImageSlotTextureNode {
   }
 
   /* Parameters. */
-  bool use_alpha;
   ustring filename;
   void *builtin_data;
   ustring colorspace;
+  ImageAlphaType alpha_type;
   NodeEnvironmentProjection projection;
   InterpolationType interpolation;
   bool animated;