[unity] Fixed URP and LWRP shaders Sprite and SkeletonLit not handling shadows correctly after 180 degree rotation (normal needs to be flipped for bias direction). Now URP shaders no longer require Advanced - Add Normals enabled to receive shadows. Closes #1842.

CHANGELOG.md

@@ -252,6 +252,7 @@
   * Sprite shaders now provide four `Diffuse Ramp` modes as an Inspector Material parameter: `Hard`, `Soft`, `Old Hard` and `Old Soft`. In spine-unity 3.8 it defaults to `Old Hard` to keep the behaviour of existing projects unchanged. Note that `Old Hard` and `Old Soft` ramp versions were using only the right half of the ramp texture, and additionally multiplying the light intensity by 2, both leading to brighter lighting than without a ramp texture active. The new ramp modes `Hard` and `Soft` use the full ramp texture and do not modify light intensity, being consistent with lighting without a ramp texture active.
   * Added **native support for slot blend modes** `Additive`, `Multiply` and `Screen` with automatic assignment at newly imported skeleton assets. `BlendModeMaterialAssets` are now obsolete and replaced by the native properties at `SkeletonDataAsset`. The `SkeletonDataAsset` Inspector provides a new `Blend Modes - Upgrade` button to upgrade an obsolete `BlendModeMaterialAsset` to the native blend modes properties. This upgrade will be performed automatically on imported and re-imported assets in Unity 2020.1 and newer to prevent reported `BlendModeMaterialAsset` issues in these Unity versions. spine-unity 4.0 and newer will automatically perform this upgrade regardless of the Unity version.
   * `BoneFollower` and `BoneFollowerGraphic` components now provide better support for following bones when the skeleton's Transform is not the parent of the follower's Transform. Previously e.g. rotating a common parent Transform did not lead to the desired result, as well as negatively scaling a skeleton's Transform when it is not a parent of the follower's Transform.
+  * URP and LWRP `Sprite` and `SkeletonLit` shaders no longer require `Advanced - Add Normals` enabled to properly cast and receive shadows. It is recommended to disable `Add Normals` if normals are otherwise not needed.
 
 * **Changes of default values**
   * `SkeletonMecanim`'s `Layer Mix Mode` now defaults to `MixMode.MixNext` instead of `MixMode.MixAlways`.

spine-unity/Assets/Spine/Runtime/spine-unity/Utility/MaterialChecks.cs

@@ -66,10 +66,6 @@ namespace Spine.Unity {
 			"\nWarning: 'Add Normals' required when not using 'Fixed Normals'!\n\nPlease\n"
 			+ "a) enable 'Add Normals' at the SkeletonRenderer/SkeletonAnimation component under 'Advanced' or\n"
 			+ "b) enable 'Fixed Normals' at the Material.\n";
-		public static readonly string kAddNormalsRequiredForURPShadowsMessage =
-			"\nWarning: 'Add Normals' required on URP shader to receive shadows!\n\nPlease\n"
-			+ "a) enable 'Add Normals' at the SkeletonRenderer/SkeletonAnimation component under 'Advanced' or\n"
-			+ "b) disable 'Receive Shadows' at the Material.\n";
 		public static readonly string kSolveTangentsMessage =
 			"\nWarning: 'Solve Tangents' required when using a Normal Map!\n\nPlease\n"
 			+ "a) enable 'Solve Tangents' at the SkeletonRenderer/SkeletonAnimation component under 'Advanced' or\n"
@@ -119,10 +115,6 @@ namespace Spine.Unity {
 					isProblematic = true;
 					errorMessage += kTintBlackMessage;
 				}
-				if (IsURP3DMaterial(material) && !AreShadowsDisabled(material) && renderer.addNormals == false) {
-					isProblematic = true;
-					errorMessage += kAddNormalsRequiredForURPShadowsMessage;
-				}
 			}
 			return isProblematic;
 		}

spine-unity/Modules/com.esotericsoftware.spine.lwrp-shaders/Shaders/CGIncludes/Spine-SkeletonLit-ShadowCasterPass-LW.hlsl

@@ -22,11 +22,9 @@ struct VaryingsSpine
 	float4 texcoordAndAlpha: TEXCOORD0;
 };
 
-float4 GetShadowPositionHClip(AttributesSpine input)
+float4 GetShadowPositionHClip(float3 positionOS, half3 normalWS)
 {
-	float3 positionWS = TransformObjectToWorld(input.positionOS.xyz);
-	float3 normalWS = TransformObjectToWorldNormal(input.normalOS);
-
+	float3 positionWS = TransformObjectToWorld(positionOS);
 	float4 positionCS = TransformWorldToHClip(ApplyShadowBias(positionWS, normalWS, _LightDirection));
 
 #if UNITY_REVERSED_Z
@@ -44,7 +42,19 @@ VaryingsSpine ShadowPassVertexSkeletonLit(AttributesSpine input)
 	UNITY_SETUP_INSTANCE_ID(input);
 
 	output.texcoordAndAlpha.xyz = float3(TRANSFORM_TEX(input.texcoord, _MainTex).xy, 0);
-	output.positionCS = GetShadowPositionHClip(input);
+
+	half3 fixedNormalOS = half3(0, 0, -1);
+	half3 normalWS = normalize(TransformObjectToWorldNormal(fixedNormalOS));
+#ifdef _DOUBLE_SIDED_LIGHTING
+	// flip normal for shadow bias if necessary
+	// unfortunately we have to compute the sign here in the vertex shader
+	// instead of using VFACE in fragment shader stage.
+	half3 viewDirWS = UNITY_MATRIX_V[2].xyz;
+	half faceSign = sign(dot(viewDirWS, normalWS));
+	normalWS *= faceSign;
+#endif
+
+	output.positionCS = GetShadowPositionHClip(input.positionOS.xyz, normalWS);
 	output.texcoordAndAlpha.a = input.vertexColor.a;
 	return output;
 }

spine-unity/Modules/com.esotericsoftware.spine.lwrp-shaders/Shaders/CGIncludes/Spine-Sprite-ShadowCasterPass-LW.hlsl

@@ -21,11 +21,9 @@ struct VaryingsSpine
 	float4 texcoordAndAlpha: TEXCOORD0;
 };
 
-float4 GetShadowPositionHClip(AttributesSpine input)
+float4 GetShadowPositionHClip(float3 positionOS, half3 normalWS)
 {
-	float3 positionWS = TransformObjectToWorld(input.positionOS.xyz);
-	float3 normalWS = TransformObjectToWorldNormal(input.normalOS);
-
+	float3 positionWS = TransformObjectToWorld(positionOS);
 	float4 positionCS = TransformWorldToHClip(ApplyShadowBias(positionWS, normalWS, _LightDirection));
 
 #if UNITY_REVERSED_Z
@@ -43,7 +41,17 @@ VaryingsSpine ShadowPassVertexSprite(AttributesSpine input)
 	UNITY_SETUP_INSTANCE_ID(input);
 
 	output.texcoordAndAlpha.xyz = float3(TRANSFORM_TEX(input.texcoord, _MainTex).xy, 0);
-	output.positionCS = GetShadowPositionHClip(input);
+
+	half3 fixedNormalOS = half3(0, 0, -1);
+	half3 normalWS = normalize(TransformObjectToWorldNormal(fixedNormalOS));
+	// flip normal for shadow bias if necessary
+	// unfortunately we have to compute the sign here in the vertex shader
+	// instead of using VFACE in fragment shader stage.
+	half3 viewDirWS = UNITY_MATRIX_V[2].xyz;
+	half faceSign = sign(dot(viewDirWS, normalWS));
+	normalWS *= faceSign;
+
+	output.positionCS = GetShadowPositionHClip(input.positionOS.xyz, normalWS);
 	output.texcoordAndAlpha.a = input.vertexColor.a * _Color.a;
 	return output;
 }

spine-unity/Modules/com.esotericsoftware.spine.lwrp-shaders/Shaders/Spine-SkeletonLit-LW.shader

@@ -102,6 +102,7 @@ Shader "Lightweight Render Pipeline/Spine/Skeleton Lit" {
 			// GPU Instancing
 			#pragma multi_compile_instancing
 			#pragma shader_feature _SMOOTHNESS_TEXTURE_ALBEDO_CHANNEL_A
+			#pragma shader_feature _ _DOUBLE_SIDED_LIGHTING
 
 			#pragma vertex ShadowPassVertexSkeletonLit
 			#pragma fragment ShadowPassFragmentSkeletonLit

spine-unity/Modules/com.esotericsoftware.spine.urp-shaders/Shaders/Include/Spine-SkeletonLit-ShadowCasterPass-URP.hlsl

@@ -22,11 +22,9 @@ struct VaryingsSpine
 	float4 texcoordAndAlpha: TEXCOORD0;
 };
 
-float4 GetShadowPositionHClip(AttributesSpine input)
+float4 GetShadowPositionHClip(float3 positionOS, half3 normalWS)
 {
-	float3 positionWS = TransformObjectToWorld(input.positionOS.xyz);
-	float3 normalWS = TransformObjectToWorldNormal(input.normalOS);
-
+	float3 positionWS = TransformObjectToWorld(positionOS);
 	float4 positionCS = TransformWorldToHClip(ApplyShadowBias(positionWS, normalWS, _LightDirection));
 
 #if UNITY_REVERSED_Z
@@ -44,7 +42,19 @@ VaryingsSpine ShadowPassVertexSkeletonLit(AttributesSpine input)
 	UNITY_SETUP_INSTANCE_ID(input);
 
 	output.texcoordAndAlpha.xyz = float3(TRANSFORM_TEX(input.texcoord, _MainTex).xy, 0);
-	output.positionCS = GetShadowPositionHClip(input);
+
+	half3 fixedNormalOS = half3(0, 0, -1);
+	half3 normalWS = normalize(TransformObjectToWorldNormal(fixedNormalOS));
+#ifdef _DOUBLE_SIDED_LIGHTING
+	// flip normal for shadow bias if necessary
+	// unfortunately we have to compute the sign here in the vertex shader
+	// instead of using VFACE in fragment shader stage.
+	half3 viewDirWS = UNITY_MATRIX_V[2].xyz;
+	half faceSign = sign(dot(viewDirWS, normalWS));
+	normalWS *= faceSign;
+#endif
+
+	output.positionCS = GetShadowPositionHClip(input.positionOS.xyz, normalWS);
 	output.texcoordAndAlpha.a = input.vertexColor.a;
 	return output;
 }

spine-unity/Modules/com.esotericsoftware.spine.urp-shaders/Shaders/Include/Spine-Sprite-ShadowCasterPass-URP.hlsl

@@ -21,11 +21,9 @@ struct VaryingsSpine
 	float4 texcoordAndAlpha: TEXCOORD0;
 };
 
-float4 GetShadowPositionHClip(AttributesSpine input)
+float4 GetShadowPositionHClip(float3 positionOS, half3 normalWS)
 {
-	float3 positionWS = TransformObjectToWorld(input.positionOS.xyz);
-	float3 normalWS = TransformObjectToWorldNormal(input.normalOS);
-
+	float3 positionWS = TransformObjectToWorld(positionOS);
 	float4 positionCS = TransformWorldToHClip(ApplyShadowBias(positionWS, normalWS, _LightDirection));
 
 #if UNITY_REVERSED_Z
@@ -43,7 +41,17 @@ VaryingsSpine ShadowPassVertexSprite(AttributesSpine input)
 	UNITY_SETUP_INSTANCE_ID(input);
 
 	output.texcoordAndAlpha.xyz = float3(TRANSFORM_TEX(input.texcoord, _MainTex).xy, 0);
-	output.positionCS = GetShadowPositionHClip(input);
+
+	half3 fixedNormalOS = half3(0, 0, -1);
+	half3 normalWS = normalize(TransformObjectToWorldNormal(fixedNormalOS));
+	// flip normal for shadow bias if necessary
+	// unfortunately we have to compute the sign here in the vertex shader
+	// instead of using VFACE in fragment shader stage.
+	half3 viewDirWS = UNITY_MATRIX_V[2].xyz;
+	half faceSign = sign(dot(viewDirWS, normalWS));
+	normalWS *= faceSign;
+
+	output.positionCS = GetShadowPositionHClip(input.positionOS.xyz, normalWS);
 	output.texcoordAndAlpha.a = input.vertexColor.a * _Color.a;
 	return output;
 }

spine-unity/Modules/com.esotericsoftware.spine.urp-shaders/Shaders/Spine-SkeletonLit-URP.shader

@@ -96,6 +96,7 @@
 			// GPU Instancing
 			#pragma multi_compile_instancing
 			#pragma shader_feature _SMOOTHNESS_TEXTURE_ALBEDO_CHANNEL_A
+			#pragma shader_feature _ _DOUBLE_SIDED_LIGHTING
 
 			#pragma vertex ShadowPassVertexSkeletonLit
 			#pragma fragment ShadowPassFragmentSkeletonLit