[unity] Fixed `Outline` shaders 4 and 8 neighbourhood outline thickness consistency. There was an obvious bug in the shader, dividing through the wrong number of samples. Closes #1864.

CHANGELOG.md

@@ -51,6 +51,7 @@
   * `Skin.Attachments` now replaces `Skin.GetAttachments()`, returning an `ICollection<SkinEntry>`. This makes access more consistent and intuitive. To fix any compile errors, replace any occurrances of `skin.GetAttachments()` by `skin.Attachments`.
   * Reverted changes: `BoneFollower` property `followLocalScale` has intermediately been renamed to `followScale` but was renamed back to `followLocalScale`. Serialized values (scenes and prefabs) will automatically be upgraded, only code accessing `followScale` needs to be adapted.
   * Corrected blending behaviour of all `Sprite` shaders in `Premultiply Alpha` blend mode (including URP and LWRP packages). Previously vertex color alpha was premultiplied again, even though `Premultiply Alpha` blend mode assumes PMA texture and PMA vertex color input. Slot-alpha blending will thus be correctly lighter after upgrading to 4.0. If you have compensated this problem by disabling `Advanced - PMA Vertex Colors` you can now re-enable this parameter, also allowing for rendering Additive slots in a single pass.
+  * Corrected all `Outline` shaders outline thickness when `Advanced - Sample 8 Neighbourhood` is disabled (thus using `4 Neighbourhood`). Previously weighting was incorrectly thick (4x as thick) compared to 8 neighbourhood, now it is more consistent. This might require adjustment of all your outline materials where `Sample 8 Neighbourhood` is disabled to restore the previous outline thickness, by adjusting the `Outline Threshold` parameter through adding a `/4` to make the threshold 4 times smaller.
 
 * **Additions**
   * Additional **Fix Draw Order** parameter at SkeletonRenderer, defaults to `disabled` (previous behaviour).

spine-unity/Assets/Spine/Runtime/spine-unity/Shaders/CGIncludes/Spine-Outline-Common.cginc

@@ -31,7 +31,7 @@ float4 computeOutlinePixel(sampler2D mainTexture, float2 mainTextureTexelSize,
 		pixelTopLeft + pixelTopRight + pixelBottomLeft + pixelBottomRight)
 		* vertexColorAlpha / numSamples;
 #else // 4 neighbourhood
-	float numSamples = 1;
+	float numSamples = 4;
 	float average = (pixelTop + pixelBottom + pixelLeft + pixelRight) * vertexColorAlpha / numSamples;
 #endif
 	float thresholdStart = ThresholdEnd * (1.0 - OutlineSmoothness);