diff --git a/spine-ue4/Plugins/SpinePlugin/Source/SpinePlugin/Private/SpineSkeletonRendererComponent.cpp b/spine-ue4/Plugins/SpinePlugin/Source/SpinePlugin/Private/SpineSkeletonRendererComponent.cpp
index e52e8fa35..7b9eeedba 100644
--- a/spine-ue4/Plugins/SpinePlugin/Source/SpinePlugin/Private/SpineSkeletonRendererComponent.cpp
+++ b/spine-ue4/Plugins/SpinePlugin/Source/SpinePlugin/Private/SpineSkeletonRendererComponent.cpp
@@ -348,15 +348,39 @@ void USpineSkeletonRendererComponent::UpdateMesh(Skeleton *Skeleton) {
 			indices.Add(idx + attachmentIndices[j]);
 		}
 
-		FVector normal = FVector(0, -1, 0);
-		if (numVertices > 2 &&
-			FVector::CrossProduct(
-					vertices[indices[firstIndex + 2]] - vertices[indices[firstIndex]],
-					vertices[indices[firstIndex + 1]] - vertices[indices[firstIndex]])
-							.Y > 0.f) {
-			normal.Y = 1;
+
+		//Calculate total triangle to add on this loof.
+
+		int TriangleInitialCount = firstIndex / 3;
+
+		int TriangleToAddNum = indices.Num() / 3 - TriangleInitialCount;
+
+		int FirstVertexIndex = vertices.Num() - numVertices;
+
+		//loof through all the triangles and resolve to be reversed if the triangle has winding order as CCW.
+
+		for (int j = 0; j < TriangleToAddNum; j++) {
+
+			const int TargetTringleIndex = firstIndex + j * 3;
+
+			if (FVector::CrossProduct(
+						vertices[indices[TargetTringleIndex + 2]] - vertices[indices[TargetTringleIndex]],
+						vertices[indices[TargetTringleIndex + 1]] - vertices[indices[TargetTringleIndex]])
+						.Y < 0.f) {
+
+				const int32 targetVertex = indices[TargetTringleIndex];
+				indices[TargetTringleIndex] = indices[TargetTringleIndex + 2];
+				indices[TargetTringleIndex + 2] = targetVertex;
+			}
 		}
+
+
+		FVector normal = FVector(0, 1, 0);
+
+		//Add normals for vertices.
+
 		for (int j = 0; j < numVertices; j++) {
+
 			normals.Add(normal);
 		}
 
@@ -370,4 +394,4 @@ void USpineSkeletonRendererComponent::UpdateMesh(Skeleton *Skeleton) {
 	clipper.clipEnd();
 }
 
-#undef LOCTEXT_NAMESPACE
+#undef LOCTEXT_NAMESPACE
\ No newline at end of file
diff --git a/spine-unity/Assets/Spine/Editor/spine-unity/Editor/Components/SkeletonGraphicInspector.cs b/spine-unity/Assets/Spine/Editor/spine-unity/Editor/Components/SkeletonGraphicInspector.cs
index c6a402943..8fe4c60bd 100644
--- a/spine-unity/Assets/Spine/Editor/spine-unity/Editor/Components/SkeletonGraphicInspector.cs
+++ b/spine-unity/Assets/Spine/Editor/spine-unity/Editor/Components/SkeletonGraphicInspector.cs
@@ -60,7 +60,7 @@ namespace Spine.Unity.Editor {
 		SerializedProperty initialFlipX, initialFlipY;
 		SerializedProperty meshGeneratorSettings;
 		SerializedProperty allowMultipleCanvasRenderers, separatorSlotNames, enableSeparatorSlots, updateSeparatorPartLocation;
-		SerializedProperty raycastTarget;
+		SerializedProperty raycastTarget, maskable;
 
 		readonly GUIContent UnscaledTimeLabel = new GUIContent("Unscaled Time",
 			"If enabled, AnimationState uses unscaled game time (Time.unscaledDeltaTime), " +
@@ -107,6 +107,7 @@ namespace Spine.Unity.Editor {
 			material = so.FindProperty("m_Material");
 			color = so.FindProperty("m_Color");
 			raycastTarget = so.FindProperty("m_RaycastTarget");
+			maskable = so.FindProperty("m_Maskable");
 
 			// SkeletonRenderer
 			additiveMaterial = so.FindProperty("additiveMaterial");
@@ -295,6 +296,7 @@ namespace Spine.Unity.Editor {
 			EditorGUILayout.Space();
 			EditorGUILayout.LabelField("UI", EditorStyles.boldLabel);
 			EditorGUILayout.PropertyField(raycastTarget);
+			if (maskable != null) EditorGUILayout.PropertyField(maskable);
 
 			EditorGUILayout.BeginHorizontal(GUILayout.Height(EditorGUIUtility.singleLineHeight + 5));
 			EditorGUILayout.PrefixLabel("Match RectTransform with Mesh");
diff --git a/spine-unity/Assets/Spine/Editor/spine-unity/Editor/Utility/SpineBuildProcessor.cs b/spine-unity/Assets/Spine/Editor/spine-unity/Editor/Utility/SpineBuildProcessor.cs
index 12d836ea5..4ed661539 100644
--- a/spine-unity/Assets/Spine/Editor/spine-unity/Editor/Utility/SpineBuildProcessor.cs
+++ b/spine-unity/Assets/Spine/Editor/spine-unity/Editor/Utility/SpineBuildProcessor.cs
@@ -36,7 +36,14 @@
 #define HAS_ON_POSTPROCESS_PREFAB
 #endif
 
-#if UNITY_2020_3_OR_NEWER
+#if (UNITY_2020_3 && !(UNITY_2020_3_1 || UNITY_2020_3_2 || UNITY_2020_3_3 || UNITY_2020_3_4 || UNITY_2020_3_5 || UNITY_2020_3_6 || UNITY_2020_3_7 || UNITY_2020_3_8 || UNITY_2020_3_9 || UNITY_2020_3_10 || UNITY_2020_3_11 || UNITY_2020_3_12 || UNITY_2020_3_13 || UNITY_2020_3_14 || UNITY_2020_3_15))
+#define UNITY_2020_3_16_OR_NEWER
+#endif
+#if (UNITY_2021_1 && !(UNITY_2021_1_1 || UNITY_2021_1_2 || UNITY_2021_1_3 || UNITY_2021_1_4 || UNITY_2021_1_5 || UNITY_2021_1_6 || UNITY_2021_1_7 || UNITY_2021_1_8 || UNITY_2021_1_9 || UNITY_2021_1_10 || UNITY_2021_1_11 || UNITY_2021_1_12 || UNITY_2021_1_13 || UNITY_2021_1_14 || UNITY_2021_1_15 || UNITY_2021_1_16))
+#define UNITY_2021_1_17_OR_NEWER
+#endif
+
+#if UNITY_2020_3_16_OR_NEWER || UNITY_2021_1_17_OR_NEWER
 #define HAS_SAVE_ASSET_IF_DIRTY
 #endif
 
diff --git a/spine-unity/Modules/com.esotericsoftware.spine.urp-shaders/Shaders/Include/Spine-Sprite-ForwardPass-URP.hlsl b/spine-unity/Modules/com.esotericsoftware.spine.urp-shaders/Shaders/Include/Spine-Sprite-ForwardPass-URP.hlsl
index 7c39640cd..e526d3574 100644
--- a/spine-unity/Modules/com.esotericsoftware.spine.urp-shaders/Shaders/Include/Spine-Sprite-ForwardPass-URP.hlsl
+++ b/spine-unity/Modules/com.esotericsoftware.spine.urp-shaders/Shaders/Include/Spine-Sprite-ForwardPass-URP.hlsl
@@ -43,6 +43,22 @@ struct VertexOutputLWRP
 ///////////////////////////////////////////////////////////////////////////////
 //                  Vertex and Fragment functions                            //
 ///////////////////////////////////////////////////////////////////////////////
+#if defined(_ADDITIONAL_LIGHT_SHADOWS) && !defined(_RECEIVE_SHADOWS_OFF)
+half4 CalculateShadowMaskBackwardsCompatible(InputData inputData)
+{
+	// To ensure backward compatibility we have to avoid using shadowMask input, as it is not present in older shaders
+#if defined(SHADOWS_SHADOWMASK) && defined(LIGHTMAP_ON)
+	half4 shadowMask = inputData.shadowMask;
+#elif !defined (LIGHTMAP_ON)
+	half4 shadowMask = unity_ProbesOcclusion;
+#else
+	half4 shadowMask = half4(1, 1, 1, 1);
+#endif
+
+	return shadowMask;
+}
+#endif
+
 half3 LightweightLightVertexSimplified(float3 positionWS, half3 normalWS) {
 #ifdef _MAIN_LIGHT_VERTEX
 	Light mainLight = GetMainLight();
@@ -101,7 +117,12 @@ half4 LightweightFragmentPBRSimplified(InputData inputData, half4 texAlbedoAlpha
 	int pixelLightCount = GetAdditionalLightsCount();
 	for (int i = 0; i < pixelLightCount; ++i)
 	{
+#if defined(_ADDITIONAL_LIGHT_SHADOWS) && !defined(_RECEIVE_SHADOWS_OFF)
+		half4 shadowMask = CalculateShadowMaskBackwardsCompatible(inputData);
+		Light light = GetAdditionalLight(i, inputData.positionWS, shadowMask);
+#else
 		Light light = GetAdditionalLight(i, inputData.positionWS);
+#endif
 		finalColor += LightingPhysicallyBased(brdfData, light, inputData.normalWS, inputData.viewDirectionWS);
 	}
 #endif
@@ -142,7 +163,12 @@ half4 LightweightFragmentBlinnPhongSimplified(InputData inputData, half4 texDiff
 	int pixelLightCount = GetAdditionalLightsCount();
 	for (int i = 0; i < pixelLightCount; ++i)
 	{
+#if defined(_ADDITIONAL_LIGHT_SHADOWS) && !defined(_RECEIVE_SHADOWS_OFF)
+		half4 shadowMask = CalculateShadowMaskBackwardsCompatible(inputData);
+		Light light = GetAdditionalLight(i, inputData.positionWS, shadowMask);
+#else
 		Light light = GetAdditionalLight(i, inputData.positionWS);
+#endif
 		half3 attenuation = (light.distanceAttenuation * light.shadowAttenuation);
 		half3 attenuatedLightColor = light.color * attenuation;
 #ifndef _DIFFUSE_RAMP
diff --git a/spine-unity/Modules/com.esotericsoftware.spine.urp-shaders/package.json b/spine-unity/Modules/com.esotericsoftware.spine.urp-shaders/package.json
index bc6093559..b2776c014 100644
--- a/spine-unity/Modules/com.esotericsoftware.spine.urp-shaders/package.json
+++ b/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 4.1.\n(See http://esotericsoftware.com/git/spine-runtimes/spine-unity)",
-  "version": "4.1.2",
+  "version": "4.1.3",
   "unity": "2019.3",
   "author": {
     "name": "Esoteric Software",