[unity] PMA textures now have sRGB (Color Texture) disabled by default to prevent border artifacts with mipmaps. Closes #2187.

CHANGELOG.md

@@ -91,6 +91,7 @@
   * Added Spine Preferences setting `Prefabs` - `Optimize Preview Meshes`. When enabled, Spine prefab preview meshes will be removed in a pre-build step to reduce build size. This increases build time as all prefabs in the project will be processed. Defaults to false to not slow down builds substantially every time.
   * Added Spine Preferences setting `Reload SkeletonData after Play`. When enabled, the shared `SkeletonData` of all skeletons in the active scene is reloaded (from the `.json` or `.skel.bytes` file) after exiting play-mode. You can disable this setting to avoid the reloading delay if you can ensure that there are no (accidental) modifications to the shared `SkeletonData` during play-mode (otherwise it would carry over its effect into subsequent plays). Defaults to `true` (the safe setting), which maintains existing behaviour. 
   * Added `SkeletonAnimationMulti` sample component methods `SetActiveSkeleton(int index)` and getter property `SkeletonAnimations` to more easily apply changes at all SkeletonAnimation instances instead of only the active one.
+  * PMA textures now have `sRGB (Color Texture)` disabled by default, the preset template `PMATexturePreset.preset` has been adjusted accordingly. As PMA textures are only allowed with Gamma color space, `sRGB (Color Texture)` shall be disabled to prevent border artifacts when mipmaps are enabled. In Gamma color space having this setting disabled has no drawbacks, only benefits.
  
 * **Breaking changes**
   * Made `SkeletonGraphic.unscaledTime` parameter protected, use the new property `UnscaledTime` instead.

spine-unity/Assets/Spine/Editor/spine-unity/Editor/ImporterPresets/PMAPresetTemplate.png.meta

@@ -8,7 +8,7 @@ TextureImporter:
   mipmaps:
     mipMapMode: 0
     enableMipMap: 0
-    sRGBTexture: 1
+    sRGBTexture: 0
     linearTexture: 0
     fadeOut: 0
     borderMipMap: 0

spine-unity/Assets/Spine/Editor/spine-unity/Editor/ImporterPresets/PMATexturePreset.preset

@@ -26,7 +26,7 @@ Preset:
     objectReference: {fileID: 0}
   - target: {fileID: 0}
     propertyPath: m_sRGBTexture
-    value: 1
+    value: 0
     objectReference: {fileID: 0}
   - target: {fileID: 0}
     propertyPath: m_LinearTexture

spine-unity/Assets/Spine/Editor/spine-unity/Editor/Utility/AssetUtility.cs

@@ -884,6 +884,7 @@ namespace Spine.Unity.Editor {
 				return false;
 			}
 
+			texImporter.sRGBTexture = false; // as PMA is the default, prevent any border issues that may arise when enabling mipmaps later.
 			texImporter.textureCompression = TextureImporterCompression.Uncompressed;
 			texImporter.alphaSource = TextureImporterAlphaSource.FromInput;
 			texImporter.mipmapEnabled = false;