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Fix dangling node crash by iterating nodes by name #4

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Fix dangling node crash by iterating nodes by name #4

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51515c6
Fix dangling node crash by iterating nodes by name
ppenenko Dec 2, 2025
05e3a94
Remove manually optimized genglsl BSDF graphs to test automatic optim…
ppenenko Jan 6, 2026
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28 changes: 17 additions & 11 deletions source/MaterialXGenShader/ShaderGraph.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -1070,23 +1070,29 @@ void ShaderGraph::optimize(GenContext& context)
_nodeOrder = usedNodesVec;
}

// we take a copy of the node list because we might modify it during the optimization
// We store node names (not raw pointers) because optimization may call
// removeNode(), which deletes nodes via shared_ptr. Raw pointers would dangle.
if (context.getOptions().optReplaceBsdfMixWithLinearCombination)
{
const vector<ShaderNode*> nodeList = getNodes();
for (ShaderNode* node : nodeList)
vector<string> mixBsdfNodeNames;
for (ShaderNode* node : getNodes())
{
// first check the node is still in the graph, and hasn't been removed by a
// prior optimization
if (!getNode(node->getName()))
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@ppenenko ppenenko Dec 2, 2025

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This crashed for me - apparently because optimizeMixMixBsdf can delete not just the node we pass to it but also another mix node down the node order.

if (node->hasClassification(ShaderNode::Classification::MIX_BSDF))
{
mixBsdfNodeNames.push_back(node->getName());
}
}

for (const string& name : mixBsdfNodeNames)
{
// Look up fresh each iteration - node may have been removed by prior optimization
ShaderNode* node = getNode(name);
if (!node)
continue;

if (node->hasClassification(ShaderNode::Classification::MIX_BSDF))
if (!optimizeMixMixBsdf(node, context))
{
if (!optimizeMixMixBsdf(node, context))
{
optimizeMixBsdf(node, context);
}
optimizeMixBsdf(node, context);
}
}
}
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