Added a check to BVH::Compact for the root node being a leaf node.

This fixes a crash that happens when compacting a bvh that cannot be compacted more.
jbikker · Feb 24, 2025 · 8391653 · 8391653
1 parent 89c7bb0
commit 8391653
Showing 1 changed file with 30 additions and 24 deletions.
diff --git a/tiny_bvh.h b/tiny_bvh.h
@@ -2656,18 +2656,21 @@ void BVH::Compact()
 	memcpy( tmp, bvhNode, 2 * sizeof( BVHNode ) );
 	newNodePtr = 2;
 	uint32_t nodeIdx = 0, stack[128], stackPtr = 0;
-	while (1)
-	{
-		BVHNode& node = tmp[nodeIdx];
-		const BVHNode& left = bvhNode[node.leftFirst];
-		const BVHNode& right = bvhNode[node.leftFirst + 1];
-		tmp[newNodePtr] = left, tmp[newNodePtr + 1] = right;
-		const uint32_t todo1 = newNodePtr, todo2 = newNodePtr + 1;
-		node.leftFirst = newNodePtr, newNodePtr += 2;
-		if (!left.isLeaf()) stack[stackPtr++] = todo1;
-		if (!right.isLeaf()) stack[stackPtr++] = todo2;
-		if (!stackPtr) break;
-		nodeIdx = stack[--stackPtr];
+	if (!tmp[nodeIdx].isLeaf())
+	{ // If the root node is a leaf the BVH is already as compact as it can be.
+		while (1)
+		{
+			BVHNode& node = tmp[nodeIdx];
+			const BVHNode& left = bvhNode[node.leftFirst];
+			const BVHNode& right = bvhNode[node.leftFirst + 1];
+			tmp[newNodePtr] = left, tmp[newNodePtr + 1] = right;
+			const uint32_t todo1 = newNodePtr, todo2 = newNodePtr + 1;
+			node.leftFirst = newNodePtr, newNodePtr += 2;
+			if (!left.isLeaf()) stack[stackPtr++] = todo1;
+			if (!right.isLeaf()) stack[stackPtr++] = todo2;
+			if (!stackPtr) break;
+			nodeIdx = stack[--stackPtr];
+		}
 	}
 	usedNodes = newNodePtr;
 	AlignedFree( bvhNode );
@@ -2812,18 +2815,21 @@ void BVH_Verbose::Compact()
 	BVHNode* tmp = (BVHNode*)AlignedAlloc( sizeof( BVHNode ) * usedNodes );
 	memcpy( tmp, bvhNode, 2 * sizeof( BVHNode ) );
 	uint32_t newNodePtr = 2, nodeIdx = 0, stack[64], stackPtr = 0;
-	while (1)
-	{
-		BVHNode& node = tmp[nodeIdx];
-		const BVHNode& left = bvhNode[node.left];
-		const BVHNode& right = bvhNode[node.right];
-		tmp[newNodePtr] = left, tmp[newNodePtr + 1] = right;
-		const uint32_t todo1 = newNodePtr, todo2 = newNodePtr + 1;
-		node.left = newNodePtr++, node.right = newNodePtr++;
-		if (!left.isLeaf()) stack[stackPtr++] = todo1;
-		if (!right.isLeaf()) stack[stackPtr++] = todo2;
-		if (!stackPtr) break;
-		nodeIdx = stack[--stackPtr];
+	if (!tmp[nodeIdx].isLeaf())
+	{ // If the root node is a leaf the BVH is already as compact as it can be.
+		while (1)
+		{
+			BVHNode& node = tmp[nodeIdx];
+			const BVHNode& left = bvhNode[node.left];
+			const BVHNode& right = bvhNode[node.right];
+			tmp[newNodePtr] = left, tmp[newNodePtr + 1] = right;
+			const uint32_t todo1 = newNodePtr, todo2 = newNodePtr + 1;
+			node.left = newNodePtr++, node.right = newNodePtr++;
+			if (!left.isLeaf()) stack[stackPtr++] = todo1;
+			if (!right.isLeaf()) stack[stackPtr++] = todo2;
+			if (!stackPtr) break;
+			nodeIdx = stack[--stackPtr];
+		}
 	}
 	usedNodes = newNodePtr;
 	AlignedFree( bvhNode );