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Fix #1091: Prevent legacy Principled BSDF from rendering as mesh lights #1093

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Merged
howetuft merged 1 commit into from
Sep 18, 2026
Merged

Fix #1091: Prevent legacy Principled BSDF from rendering as mesh lights #1093

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26 changes: 25 additions & 1 deletion export/cycles_node_reader.py
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Original file line number Diff line number Diff line change
Expand Up @@ -171,8 +171,32 @@ def _node(node, output_socket, props, material, luxcore_name=None, obj_name="",
}

# Attach these props to the right-most material node (regardless if it's glass, disney or a mix mat)

# Fix for issue #1091: Only add emission if actually used
# Blender 3.6 uses "Emission", Blender 4.0+ renamed it to "Emission Color"
emission_color_socket_name = "Emission Color" if "Emission Color" in node.inputs else "Emission"
emission_color_socket = node.inputs[emission_color_socket_name]
emission_strength_socket = node.inputs["Emission Strength"]

emission_update = {}
color_is_linked = emission_color_socket.is_linked
strength_is_linked = emission_strength_socket.is_linked
color_default = list(emission_color_socket.default_value)[:3]
color_is_nonzero = any(c > 0 for c in color_default)
strength_is_nonzero = emission_strength_socket.default_value > 0

if color_is_linked or strength_is_linked or (color_is_nonzero and strength_is_nonzero):
emission_color = _socket(emission_color_socket, props, material, obj_name, group_node_stack)
emission_strength = _socket(emission_strength_socket, props, material, obj_name, group_node_stack)
emission_tex_name = luxcore_name + "_em"
props.Set(utils.luxutils.create_props(
"scene.textures." + emission_tex_name + ".",
{"type": "scale", "texture1": emission_strength, "texture2": emission_color},
))
emission_update["emission"] = emission_tex_name

definitions.update({
"emission": _socket(node.inputs["Emission Strength"], props, material, obj_name, group_node_stack),
**emission_update,
"transparency": _socket(node.inputs["Alpha"], props, material, obj_name, group_node_stack),
"bumptex": _socket(node.inputs["Normal"], props, material, obj_name, group_node_stack),
})
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