Add support for 32 bit indices for the terrain chunk geometry

Content/Editor/MaterialTemplates/Terrain.shader

@@ -269,24 +269,16 @@ float CalcLOD(float2 xy, float4 morph)
 	if ((xy.x + xy.y) > 1)
 	{
 		if (xy.x < xy.y)
-		{
 			lod = lodCalculated.w;
-		}
 		else
-		{
 			lod = lodCalculated.z;
-		}
 	}
 	else
 	{
 		if (xy.x < xy.y)
-		{
 			lod = lodCalculated.y;
-		}
 		else
-		{
 			lod = lodCalculated.x;
-		}
 	}
 
 	return lod;

Source/Editor/Tools/Terrain/CreateTerrainDialog.cs

@@ -26,7 +26,9 @@ namespace FlaxEditor.Tools.Terrain
             _31 = 31,
             _63 = 63,
             _127 = 127,
+            _254 = 254,
             _255 = 255,
+            _511 = 511,
         }
 
         private class Options
@@ -34,7 +36,7 @@ namespace FlaxEditor.Tools.Terrain
             [EditorOrder(100), EditorDisplay("Layout", "Number Of Patches"), DefaultValue(typeof(Int2), "1,1"), Limit(0, 512), Tooltip("Amount of terrain patches in each direction (X and Z). Each terrain patch contains a grid of 16 chunks. Patches can be later added or removed from terrain using a terrain editor tool.")]
             public Int2 NumberOfPatches = new Int2(1, 1);
 
-            [EditorOrder(110), EditorDisplay("Layout"), DefaultValue(ChunkSizes._127), Tooltip("The size of the chunk (amount of quads per edge for the highest LOD). Must be power of two minus one (eg. 63).")]
+            [EditorOrder(110), EditorDisplay("Layout"), DefaultValue(ChunkSizes._127), Tooltip("The size of the chunk (amount of quads per edge for the highest LOD).")]
             public ChunkSizes ChunkSize = ChunkSizes._127;
 
             [EditorOrder(120), EditorDisplay("Layout", "LOD Count"), DefaultValue(6), Limit(1, FlaxEngine.Terrain.MaxLODs), Tooltip("The maximum Level Of Details count. The actual amount of LODs may be lower due to provided chunk size (each LOD has 4 times less quads).")]

Source/Engine/Terrain/TerrainManager.cpp

@@ -98,10 +98,12 @@ bool TerrainManager::GetChunkGeometry(DrawCall& drawCall, int32 chunkSize, int32
     // Prepare
     const int32 vertexCount = (chunkSize + 1) >> lodIndex;
     chunkSize = vertexCount - 1;
+    const bool indexUse16bits = chunkSize * chunkSize * vertexCount < MAX_uint16;
+    const int32 indexSize = indexUse16bits ? sizeof(uint16) : sizeof(uint32);
     const int32 indexCount = chunkSize * chunkSize * 2 * 3;
     const int32 vertexCount2 = vertexCount * vertexCount;
     const int32 vbSize = sizeof(TerrainVertex) * vertexCount2;
-    const int32 ibSize = sizeof(uint16) * indexCount;
+    const int32 ibSize = indexSize * indexCount;
     TempData.Clear();
     TempData.EnsureCapacity(Math::Max(vbSize, ibSize));
 
@@ -140,26 +142,51 @@ bool TerrainManager::GetChunkGeometry(DrawCall& drawCall, int32 chunkSize, int32
 
     // Create index buffer
     auto ib = GPUDevice::Instance->CreateBuffer(TEXT("TerrainChunk.IB"));
-    auto index = (uint16*)TempData.Get();
+    if (indexUse16bits)
-    for (int32 z = 0; z < chunkSize; z++)
     {
-        for (int32 x = 0; x < chunkSize; x++)
+        auto index = (uint16*)TempData.Get();
+        for (int32 z = 0; z < chunkSize; z++)
         {
-            const uint16 i00 = (x + 0) + (z + 0) * vertexCount;
+            for (int32 x = 0; x < chunkSize; x++)
-            const uint16 i10 = (x + 1) + (z + 0) * vertexCount;
+            {
-            const uint16 i11 = (x + 1) + (z + 1) * vertexCount;
+                const uint16 i00 = (x + 0) + (z + 0) * vertexCount;
-            const uint16 i01 = (x + 0) + (z + 1) * vertexCount;
+                const uint16 i10 = (x + 1) + (z + 0) * vertexCount;
+                const uint16 i11 = (x + 1) + (z + 1) * vertexCount;
+                const uint16 i01 = (x + 0) + (z + 1) * vertexCount;
 
-            *index++ = i00;
+                *index++ = i00;
-            *index++ = i11;
+                *index++ = i11;
-            *index++ = i10;
+                *index++ = i10;
 
-            *index++ = i00;
+                *index++ = i00;
-            *index++ = i01;
+                *index++ = i01;
-            *index++ = i11;
+                *index++ = i11;
+            }
         }
     }
-    desc = GPUBufferDescription::Index(sizeof(uint16), indexCount, TempData.Get());
+    else
+    {
+        auto index = (uint32*)TempData.Get();
+        for (int32 z = 0; z < chunkSize; z++)
+        {
+            for (int32 x = 0; x < chunkSize; x++)
+            {
+                const uint32 i00 = (x + 0) + (z + 0) * vertexCount;
+                const uint32 i10 = (x + 1) + (z + 0) * vertexCount;
+                const uint32 i11 = (x + 1) + (z + 1) * vertexCount;
+                const uint32 i01 = (x + 0) + (z + 1) * vertexCount;
+
+                *index++ = i00;
+                *index++ = i11;
+                *index++ = i10;
+
+                *index++ = i00;
+                *index++ = i01;
+                *index++ = i11;
+            }
+        }
+    }
+    desc = GPUBufferDescription::Index(indexSize, indexCount, TempData.Get());
     if (ib->Init(desc))
     {
         vb->ReleaseGPU();