fix for [#28012] Mat ID messy with shader nodes

Issue was that the Shader tree execution changed the ShaderInput.
Changes are that the UI is updated that only the main material will have the pass_index this is displayed in the "render pipeline options" panel.
When the material is not a node material the pass_index will be shown at the "options" panel

To test enable nodes on the material
Add a new input material
change the pass_index of the material (render pipeline options)
Enable RenderPass material ID and use the compositor to read out the material pass

Jeroen

release/scripts/startup/bl_ui/properties_material.py

@@ -174,6 +174,7 @@ class MATERIAL_PT_pipeline(MaterialButtonsPanel, bpy.types.Panel):
         row.prop(mat, "use_transparency")
         sub = row.column()
         sub.prop(mat, "offset_z")
+
         sub.active = mat_type and mat.use_transparency and mat.transparency_method == 'Z_TRANSPARENCY'
 
         row = layout.row()
@@ -199,6 +200,7 @@ class MATERIAL_PT_pipeline(MaterialButtonsPanel, bpy.types.Panel):
         col.prop(mat, "shadow_cast_alpha", text="Casting Alpha")
         col.prop(mat, "use_cast_buffer_shadows")
         col.prop(mat, "use_cast_approximate")
+        col.prop(mat, "pass_index")
 
 
 class MATERIAL_PT_diffuse(MaterialButtonsPanel, bpy.types.Panel):
@@ -729,7 +731,8 @@ class MATERIAL_PT_options(MaterialButtonsPanel, bpy.types.Panel):
         col.prop(mat, "use_vertex_color_paint")
         col.prop(mat, "use_vertex_color_light")
         col.prop(mat, "use_object_color")
-        col.prop(mat, "pass_index")
+        if simple_material(base_mat):
+            col.prop(mat, "pass_index")
 
 
 class MATERIAL_PT_shadow(MaterialButtonsPanel, bpy.types.Panel):