Merge pull request #564 from signmotion/chaotic-crash-decal

Will go ahead and merge this in on the grounds that while it may not technically be possible to make this problem occur(at least no one seems to have been able to reproduce it), having the clamping of values is generally a smart move on principle and prevents even the weird outliers from happening.

Engine/source/T3D/decal/decalManager.cpp

@@ -1235,8 +1235,30 @@ void DecalManager::prepRenderImage( SceneRenderState* state )
          currentBatch = &batches.last();
          currentBatch->startDecal = i;
          currentBatch->decalCount = 1;
-         currentBatch->iCount = decal->mIndxCount;
-         currentBatch->vCount = decal->mVertCount;
+
+         // Shrink and warning: preventing a potential crash.
+         currentBatch->iCount =
+             (decal->mIndxCount > smMaxIndices) ? smMaxIndices : decal->mIndxCount;
+         currentBatch->vCount =
+             (decal->mVertCount > smMaxVerts) ? smMaxVerts : decal->mVertCount;
+#ifdef TORQUE_DEBUG
+         // we didn't mean send a spam to the console
+         static U32 countMsgIndx = 0;
+         if ( (decal->mIndxCount > smMaxIndices) && ((countMsgIndx++ % 1024) == 0) ) {
+            Con::warnf(
+               "DecalManager::prepRenderImage() - Shrinked indices of decal."
+               " Lost %u.",  (decal->mIndxCount - smMaxIndices)
+            );
+         }
+         static U32 countMsgVert = 0;
+         if ( (decal->mVertCount > smMaxVerts) && ((countMsgVert++ % 1024) == 0) ) {
+            Con::warnf(
+               "DecalManager::prepRenderImage() - Shrinked vertices of decal."
+               " Lost %u.",  (decal->mVertCount - smMaxVerts)
+            );
+         }
+#endif
+
          currentBatch->mat = mat;
          currentBatch->matInst = decal->mDataBlock->getMaterialInstance();
          currentBatch->priority = decal->getRenderPriority();         
@@ -1299,15 +1321,21 @@ void DecalManager::prepRenderImage( SceneRenderState* state )
       {
          DecalInstance *dinst = mDecalQueue[j];
 
-         for ( U32 k = 0; k < dinst->mIndxCount; k++ )
+         const U32 indxCount =
+             (dinst->mIndxCount > currentBatch.iCount) ?
+             currentBatch.iCount : dinst->mIndxCount;
+         for ( U32 k = 0; k < indxCount; k++ )
          {
             *( pbPtr + ioffset + k ) = dinst->mIndices[k] + voffset;            
          }
 
-         ioffset += dinst->mIndxCount;
+         ioffset += indxCount;
 
-         dMemcpy( vpPtr + voffset, dinst->mVerts, sizeof( DecalVertex ) * dinst->mVertCount );
-         voffset += dinst->mVertCount;
+         const U32 vertCount =
+             (dinst->mVertCount > currentBatch.vCount) ?
+             currentBatch.vCount : dinst->mVertCount;
+         dMemcpy( vpPtr + voffset, dinst->mVerts, sizeof( DecalVertex ) * vertCount );
+         voffset += vertCount;
 
          // Ugly hack for ProjectedShadow!
          if ( (dinst->mFlags & CustomDecal) && dinst->mCustomTex != NULL )
@@ -1357,8 +1385,10 @@ void DecalManager::prepRenderImage( SceneRenderState* state )
       pb->lock( &pbPtr );
 
       // Memcpy from system to video memory.
-      dMemcpy( vpPtr, vertData, sizeof( DecalVertex ) * currentBatch.vCount );
-      dMemcpy( pbPtr, indexData, sizeof( U16 ) * currentBatch.iCount );
+      const U32 vpCount = sizeof( DecalVertex ) * currentBatch.vCount;
+      dMemcpy( vpPtr, vertData, vpCount );
+      const U32 pbCount = sizeof( U16 ) * currentBatch.iCount;
+      dMemcpy( pbPtr, indexData, pbCount );
 
       pb->unlock();
       vb->unlock();