chore: share a single sphere mesh; dedup primitive UV logic (#9614)

Author: dalkia

Explorer/Assets/DCL/Infrastructure/ECS/Unity/PrimitiveRenderer/MeshPrimitive/SpherePrimitive.cs

@@ -5,13 +5,22 @@ namespace ECS.Unity.PrimitiveRenderer.MeshPrimitive
 {
     public class SpherePrimitive : IPrimitiveMesh
     {
+        // Sphere geometry is constant (fixed radius and tessellation) and is never mutated per instance
+        // (MeshSetupSphere.Execute is a no-op), so every sphere shares this single immutable mesh.
+        private static Mesh? sharedMesh;
+
         public Mesh Mesh { get; }
 
         public SpherePrimitive()
+        {
+            Mesh = sharedMesh ??= CreateSharedMesh();
+        }
+
+        private static Mesh CreateSharedMesh()
         {
             var newMesh = new Mesh();
             SphereFactory.Create(ref newMesh);
-            Mesh = newMesh;
+            return newMesh;
         }
     }
 }

Explorer/Assets/DCL/Infrastructure/ECS/Unity/PrimitiveRenderer/Tests/InstantiatePrimitiveRenderingSystemShould.cs

@@ -91,6 +91,12 @@ public void UpdateInvalidatedRenderer(PBMeshRenderer input, PBMeshRenderer.MeshO
             system.Update(0);
 
             //Act
+            // Sphere primitives share a single immutable mesh, so the re-instantiated mesh is the same
+            // object as the initial one. Clear the recorded calls so the assertion below counts only the
+            // Execute triggered by re-instantiation and not the initial setup (which the mesh argument can
+            // no longer disambiguate).
+            setupMeshes[input.MeshCase].ClearReceivedCalls();
+
             input.IsDirty = true;
             world.Get<PrimitiveMeshRendererComponent>(entity).PrimitiveMesh = null;
             system.Update(0);

Explorer/Assets/DCL/Infrastructure/Utility/Primitives/BoxFactory.cs

@@ -232,10 +232,7 @@ public static void Create(ref Mesh mesh)
 
         public static void UpdateMesh(ref Mesh mesh, RepeatedField<float> boxUVs = null)
         {
-            if (boxUVs is { Count: > 0 })
-                mesh.SetUVs(0, PrimitivesUtility.FloatArrayToV2List(boxUVs, mesh.uv), 0, VERTICES_NUM);
-            else
-                mesh.SetUVs(0, defaultUVs, 0, VERTICES_NUM);
+            PrimitivesUtility.ApplyUVs(mesh, boxUVs, defaultUVs, VERTICES_NUM);
         }
     }
 }

Explorer/Assets/DCL/Infrastructure/Utility/Primitives/PlaneFactory.cs

@@ -28,7 +28,6 @@ public static void Create(ref Mesh mesh)
             vertices[6] = new Vector3(-halfSize.x, halfSize.y, 0);
             vertices[7] = new Vector3(-halfSize.x, -halfSize.y, 0);
 
-            Vector2[] uvs = PrimitivesBuffersPool.UVS.Rent(VERTICES_NUM);
             defaultUVs = new Vector2[VERTICES_NUM];
 
             defaultUVs[0] = new Vector2(0f, 0f);
@@ -85,10 +84,7 @@ public static void Create(ref Mesh mesh)
 
         public static void UpdateMesh(ref Mesh mesh, RepeatedField<float> planeUvs)
         {
-            if (planeUvs is { Count: > 0 })
-                mesh.SetUVs(0, PrimitivesUtility.FloatArrayToV2List(planeUvs, mesh.uv), 0, VERTICES_NUM);
-            else
-                mesh.SetUVs(0, defaultUVs, 0, VERTICES_NUM);
+            PrimitivesUtility.ApplyUVs(mesh, planeUvs, defaultUVs, VERTICES_NUM);
         }
     }
 }

Explorer/Assets/DCL/Infrastructure/Utility/Primitives/PrimitivesUtility.cs

@@ -14,5 +14,14 @@ public static Vector2[] FloatArrayToV2List(IList<float> uvs, Vector2[] uvsResult
 
             return uvsResult;
         }
+
+        // Writes UV channel 0: the scene-provided UVs when present, otherwise the primitive's default set
+        public static void ApplyUVs(Mesh mesh, IList<float>? customUVs, Vector2[] defaultUVs, int verticesNum)
+        {
+            if (customUVs is { Count: > 0 })
+                mesh.SetUVs(0, FloatArrayToV2List(customUVs, mesh.uv), 0, verticesNum);
+            else
+                mesh.SetUVs(0, defaultUVs, 0, verticesNum);
+        }
     }
 }