Fix T64625: Eevee image textures with alpha have dark edges

Now texture storage of images is defined by the alpha mode of the image. The
downside of this is that there can be artifacts near alpha edges where pixels
with zero alpha bleed in. It also adds more code complexity since image textures
are no longer all stored the same way.

This changes allows us to keep using sRGB texture formats, which have edge
darkening when stored with premultiplied alpha. Game engines seems to generally
do the same thing, and we want to be compatible with them.

1 files changed, 2 insertions, 0 deletions

diff --git a/source/blender/draw/engines/workbench/workbench_materials.c b/source/blender/draw/engines/workbench/workbench_materials.c
index 6ca55d48681..d570fda9dac 100644
--- a/source/blender/draw/engines/workbench/workbench_materials.c
+++ b/source/blender/draw/engines/workbench/workbench_materials.c
@@ -296,6 +296,8 @@ void workbench_material_shgroup_uniform(WORKBENCH_PrivateData *wpd,
       V3D_SHADING_TEXTURE_COLOR) {
     GPUTexture *tex = GPU_texture_from_blender(material->ima, material->iuser, GL_TEXTURE_2D);
     DRW_shgroup_uniform_texture(grp, "image", tex);
+    DRW_shgroup_uniform_bool_copy(
+        grp, "imagePremultiplied", (material->ima->alpha_mode == IMA_ALPHA_PREMUL));
     DRW_shgroup_uniform_bool_copy(grp, "imageNearest", (interp == SHD_INTERP_CLOSEST));
   }
   else {