[unity] Allow empty slots as separators.

spine-unity/Assets/spine-unity/Mesh Generation/SpineMesh.cs

@@ -38,7 +38,6 @@ using System.Collections.Generic;
 
 namespace Spine.Unity {
 	public static class SpineMesh {
-
 		internal const HideFlags MeshHideflags = HideFlags.DontSaveInBuild | HideFlags.DontSaveInEditor;
 
 		/// <summary>Factory method for creating a new mesh for use in Spine components. This can be called in field initializers.</summary>
@@ -132,6 +131,8 @@ namespace Spine.Unity {
 		[NonSerialized] ExposedList<Vector2> uv3;
 		#endregion
 
+		public int VertexCount { get { return vertexBuffer.Count; } }
+
 		#region Step 1 : Generate Instructions
 		public static void GenerateSingleSubmeshInstruction (SkeletonRendererInstruction instructionOutput, Skeleton skeleton, Material material) {
 			ExposedList<Slot> drawOrder = skeleton.drawOrder;
@@ -295,7 +296,7 @@ namespace Spine.Unity {
 				}
 
 				if (noRender) {
-					if (current.forceSeparate && current.rawVertexCount > 0 && generateMeshOverride) {
+					if (current.forceSeparate && generateMeshOverride && current.rawVertexCount > 0) {
 						{ // Add
 							current.endSlot = i;
 							current.preActiveClippingSlotSource = lastPreActiveClipping;
@@ -305,6 +306,7 @@ namespace Spine.Unity {
 
 							submeshIndex++;
 						}
+
 						current.startSlot = i;
 						lastPreActiveClipping = clippingAttachmentSource;
 						#if SPINE_TRIANGLECHECK
@@ -327,7 +329,7 @@ namespace Spine.Unity {
 					Material material = (rendererObject.GetType() == typeof(Material)) ? (Material)rendererObject : (Material)((AtlasRegion)rendererObject).page.rendererObject;
 					#endif
 
-					if (current.rawVertexCount > 0 && (current.forceSeparate || !System.Object.ReferenceEquals(current.material, material))) { // Material changed. Add the previous submesh.
+					if (current.forceSeparate || (current.rawVertexCount > 0 && !System.Object.ReferenceEquals(current.material, material))) { // Material changed. Add the previous submesh.
 						{ // Add
 							current.endSlot = i;
 							current.preActiveClippingSlotSource = lastPreActiveClipping;

spine-unity/Assets/spine-unity/Modules/SkeletonRenderSeparator/SkeletonPartsRenderer.cs

@@ -104,12 +104,18 @@ namespace Spine.Unity.Modules {
 
 			// STEP 3: modify mesh.
 			var mesh = smartMesh.mesh;
-			meshGenerator.FillVertexData(mesh);
-			if (updateTriangles) {
-				meshGenerator.FillTriangles(mesh);
-				meshRenderer.sharedMaterials = buffers.GetUpdatedShaderdMaterialsArray();
-			} else if (buffers.MaterialsChangedInLastUpdate()) {
-				meshRenderer.sharedMaterials = buffers.GetUpdatedShaderdMaterialsArray();
+
+			if (meshGenerator.VertexCount <= 0) { // Clear an empty mesh
+				updateTriangles = false;
+				mesh.Clear();
+			} else {
+				meshGenerator.FillVertexData(mesh);
+				if (updateTriangles) {
+					meshGenerator.FillTriangles(mesh);
+					meshRenderer.sharedMaterials = buffers.GetUpdatedShaderdMaterialsArray();
+				} else if (buffers.MaterialsChangedInLastUpdate()) {
+					meshRenderer.sharedMaterials = buffers.GetUpdatedShaderdMaterialsArray();
+				}
 			}
 
 			meshFilter.sharedMesh = mesh;