[unity] Fixed errors in URP blend mode shaders when main and additional lights are disabled. Closes #2592.

spine-unity/Modules/com.esotericsoftware.spine.urp-shaders/Shaders/BlendModes/Spine-Skeleton-Additive-URP.shader

@@ -63,6 +63,44 @@
 			ENDHLSL
 	 	}
 
-		UsePass "Universal Render Pipeline/Spine/Skeleton/SHADOWCASTER"
+		// UsePass "Universal Render Pipeline/Spine/Skeleton/SHADOWCASTER"
+		// Note: UsePass above fails when both main and additional lights are disabled, thus inlined below.
+		Pass
+		{
+			Name "ShadowCaster"
+			Tags{"LightMode" = "ShadowCaster"}
+
+			ZWrite On
+			ColorMask 0
+			ZTest LEqual
+			Cull Off
+
+			HLSLPROGRAM
+			// Required to compile gles 2.0 with standard srp library
+			#pragma prefer_hlslcc gles
+			#pragma exclude_renderers d3d11_9x
+			#pragma target 2.0
+
+			// -------------------------------------
+			// Material Keywords
+			#pragma shader_feature _ALPHATEST_ON
+
+			//--------------------------------------
+			// GPU Instancing
+			#pragma multi_compile_instancing
+			#pragma shader_feature _SMOOTHNESS_TEXTURE_ALBEDO_CHANNEL_A
+
+			#pragma vertex ShadowPassVertexSkeletonLit
+			#pragma fragment ShadowPassFragmentSkeletonLit
+
+			#define USE_URP
+			#define fixed4 half4
+			#define fixed3 half3
+			#define fixed half
+			#include "../Include/Spine-Input-URP.hlsl"
+			#include "../Include/Spine-SkeletonLit-ShadowCasterPass-URP.hlsl"
+
+			ENDHLSL
+		}
 	}
 }

spine-unity/Modules/com.esotericsoftware.spine.urp-shaders/Shaders/BlendModes/Spine-Skeleton-Multiply-URP.shader

@@ -63,6 +63,44 @@
 			ENDHLSL
 	 	}
 
-		UsePass "Universal Render Pipeline/Spine/Skeleton/SHADOWCASTER"
+		// UsePass "Universal Render Pipeline/Spine/Skeleton/SHADOWCASTER"
+		// Note: UsePass above fails when both main and additional lights are disabled, thus inlined below.
+		Pass
+		{
+			Name "ShadowCaster"
+			Tags{"LightMode" = "ShadowCaster"}
+
+			ZWrite On
+			ColorMask 0
+			ZTest LEqual
+			Cull Off
+
+			HLSLPROGRAM
+			// Required to compile gles 2.0 with standard srp library
+			#pragma prefer_hlslcc gles
+			#pragma exclude_renderers d3d11_9x
+			#pragma target 2.0
+
+			// -------------------------------------
+			// Material Keywords
+			#pragma shader_feature _ALPHATEST_ON
+
+			//--------------------------------------
+			// GPU Instancing
+			#pragma multi_compile_instancing
+			#pragma shader_feature _SMOOTHNESS_TEXTURE_ALBEDO_CHANNEL_A
+
+			#pragma vertex ShadowPassVertexSkeletonLit
+			#pragma fragment ShadowPassFragmentSkeletonLit
+
+			#define USE_URP
+			#define fixed4 half4
+			#define fixed3 half3
+			#define fixed half
+			#include "../Include/Spine-Input-URP.hlsl"
+			#include "../Include/Spine-SkeletonLit-ShadowCasterPass-URP.hlsl"
+
+			ENDHLSL
+		}
 	}
 }

spine-unity/Modules/com.esotericsoftware.spine.urp-shaders/Shaders/BlendModes/Spine-Skeleton-Screen-URP.shader

@@ -63,6 +63,44 @@
 			ENDHLSL
 	 	}
 
-		UsePass "Universal Render Pipeline/Spine/Skeleton/SHADOWCASTER"
+		// UsePass "Universal Render Pipeline/Spine/Skeleton/SHADOWCASTER"
+		// Note: UsePass above fails when both main and additional lights are disabled, thus inlined below.
+		Pass
+		{
+			Name "ShadowCaster"
+			Tags{"LightMode" = "ShadowCaster"}
+
+			ZWrite On
+			ColorMask 0
+			ZTest LEqual
+			Cull Off
+
+			HLSLPROGRAM
+			// Required to compile gles 2.0 with standard srp library
+			#pragma prefer_hlslcc gles
+			#pragma exclude_renderers d3d11_9x
+			#pragma target 2.0
+
+			// -------------------------------------
+			// Material Keywords
+			#pragma shader_feature _ALPHATEST_ON
+
+			//--------------------------------------
+			// GPU Instancing
+			#pragma multi_compile_instancing
+			#pragma shader_feature _SMOOTHNESS_TEXTURE_ALBEDO_CHANNEL_A
+
+			#pragma vertex ShadowPassVertexSkeletonLit
+			#pragma fragment ShadowPassFragmentSkeletonLit
+
+			#define USE_URP
+			#define fixed4 half4
+			#define fixed3 half3
+			#define fixed half
+			#include "../Include/Spine-Input-URP.hlsl"
+			#include "../Include/Spine-SkeletonLit-ShadowCasterPass-URP.hlsl"
+
+			ENDHLSL
+		}
 	}
 }

spine-unity/Modules/com.esotericsoftware.spine.urp-shaders/package.json

@@ -2,7 +2,7 @@
   "name": "com.esotericsoftware.spine.urp-shaders",
   "displayName": "Spine Universal RP Shaders",
   "description": "This plugin provides universal render pipeline (URP) shaders for the spine-unity runtime.\n\nPrerequisites:\nIt requires a working installation of the spine-unity runtime, version 4.2.\n(See http://esotericsoftware.com/git/spine-runtimes/spine-unity)",
-  "version": "4.2.36",
+  "version": "4.2.37",
   "unity": "2019.3",
   "author": {
     "name": "Esoteric Software",