I have lots of objects consisting of many different meshes. Some of these meshes come with transparent materials applied to them. My goal is to modify the nodes list, add new nodes and change the links for the transparent materials. Based on this answer, I can detect the transparent materials (thanks to gandalf3) using the following Python script:
for obj in bpy.data.objects: if obj.type == 'MESH': for slot in obj.material_slots: if slot.material: mat = slot.material for node in mat.node_tree.nodes: if node.label == "Mix Color/Alpha": if node.inputs.default_value < 1: print("Material '%s' on object '%s' seems transparent" % (mat.name, obj.name))
I need to do this process for thousands of objects. I am pretty new to the concepts of nodes in Blender and do not know how modify the nodes and remove/add links to do what is being shown in the GIF image above. So I wonder, how can I add the math and mix shader nodes and add/remove the corresponding links using Python?
You can download this .obj file and load it in Blender to be able and make sure your code works. Just make sure you have selected Cycles before importing the obj file into Blender so that Blender creates the materials' nodes list automatically.
NOTE: I'm not sure how this helps but some of the meshes share the same materials. For instance, in the car example, the headlamps and the glasses (windshield, side windows) share the same material.
NOTE: Just loading the object and doing rendering will not get you the same Normal maps as shown here. The surface Normals of the object I provide here are incorrect. If you want to get the same surface Normals you need to do the following: join all the meshes. Then go edit mode and recalculate outside surface Normals of the downloaded object. Then turn off Auto Smooth.