First commit with code.

Just the skeleton so far, with a bit of code that makes a
useless node-based material.

__init__.py

@@ -0,0 +1,151 @@
+#====================== BEGIN GPL LICENSE BLOCK ======================
+#
+#  This program is free software; you can redistribute it and/or
+#  modify it under the terms of the GNU General Public License
+#  as published by the Free Software Foundation; either version 2
+#  of the License, or (at your option) any later version.
+#
+#  This program is distributed in the hope that it will be useful,
+#  but WITHOUT ANY WARRANTY; without even the implied warranty of
+#  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+#  GNU General Public License for more details.
+#
+#  You should have received a copy of the GNU General Public License
+#  along with this program; if not, write to the Free Software Foundation,
+#  Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+#
+#======================= END GPL LICENSE BLOCK ========================
+
+bl_info = {
+    "name": "GI Comp",
+    "version": (0, 1, 0),
+    "author": "Nathan Vegdahl, Ian Hubert",
+    "blender": (3, 0, 0),
+    "description": "Composite CG elements into your footage with GI lighting",
+    "location": "Scene properties",
+    # "doc_url": "",
+    "category": "Compositing",
+}
+
+import re
+import math
+
+import bpy
+
+MATERIAL_NAME_PREFIX = "GICompFootage"
+
+
+#========================================================
+
+
+class GICompPanel(bpy.types.Panel):
+    """Composite with GI lighting."""
+    bl_label = "GI Comp"
+    bl_idname = "DATA_PT_gi_comp"
+    bl_space_type = 'PROPERTIES'
+    bl_region_type = 'WINDOW'
+    bl_context = "scene"
+
+    @classmethod
+    def poll(cls, context):
+        return True
+
+    def draw(self, context):
+        wm = context.window_manager
+        layout = self.layout
+
+        col = layout.column()
+        col.operator("material.gi_comp_material_new")
+
+
+#========================================================
+
+
+# Builds a material with the GI Comp footage configuration..
+def make_gi_comp_material(name, context):
+    # Create a new completely empty node-based material.
+    mat = bpy.data.materials.new(name)
+    mat.use_nodes = True
+    for node in mat.node_tree.nodes:
+        mat.node_tree.nodes.remove(node)
+
+    # Create the nodes we need.
+    output = mat.node_tree.nodes.new(type='ShaderNodeOutputMaterial')
+    footage = mat.node_tree.nodes.new(type='ShaderNodeTexImage')
+    lighting_bake = mat.node_tree.nodes.new(type='ShaderNodeTexImage')
+    diffuse = mat.node_tree.nodes.new(type='ShaderNodeBsdfDiffuse')
+    delight_group = mat.node_tree.nodes.new(type='ShaderNodeGroup')
+    delight_group.node_tree = ensure_delight_bake_group()
+
+
+# Ensures that the Delight Bake shader group exists.
+#
+# It will create it if it doesn't exist, and returns the group.
+def ensure_delight_baker_group():
+    NAME = "Delight Baker"
+    if NAME in bpy.data.node_groups:
+        return bpy.data.node_groups[NAME]
+    else:
+        group = bpy.data.node_groups.new(NAME, type='ShaderNodeTree')
+        for node in group.nodes:
+            group.nodes.remove(node)
+
+        # Create the nodes.
+        input = group.nodes.new(type='NodeGroupInput')
+        output = group.nodes.new(type='NodeGroupOutput')
+        lightpath = group.nodes.new(type='ShaderNodeLightPath')
+        diffuse = group.nodes.new(type='ShaderNodeBsdfDiffuse')
+        mix = group.nodes.new(type='ShaderNodeMixShader')
+
+        # Position the nodes.
+        input.location = (-400.0, 0.0)
+        output.location = (200.0, 0.0)
+        lightpath.location = (-200.0, 400.0)
+        diffuse.location = (-200.0, -100.0)
+        mix.location = (0.0, 0.0)
+
+        # Configure the nodes.
+        group.inputs.new(type="NodeSocketShader", name="Shader")
+        group.outputs.new(type="NodeSocketShader", name="Shader")
+        diffuse.inputs['Color'].default_value = [1.0, 1.0, 1.0, 1.0]
+        diffuse.inputs['Roughness'].default_value = 0.0
+
+        # Hook up the nodes.
+        group.links.new(lightpath.outputs['Is Camera Ray'], mix.inputs['Fac'])
+        group.links.new(input.outputs['Shader'], mix.inputs[1])
+        group.links.new(diffuse.outputs['BSDF'], mix.inputs[2])
+        group.links.new(mix.outputs['Shader'], output.inputs['Shader'])
+
+        return group
+
+
+class GICompMaterialNew(bpy.types.Operator):
+    """Creates a new GI Comp material"""
+    bl_idname = "material.gi_comp_material_new"
+    bl_label = "New GI Comp material"
+    bl_options = {'UNDO'}
+
+    @classmethod
+    def poll(cls, context):
+        return True
+
+    def execute(self, context):
+        make_gi_comp_material(MATERIAL_NAME_PREFIX, context)
+        return {'FINISHED'}
+
+
+#========================================================
+
+
+def register():
+    bpy.utils.register_class(GICompPanel)
+    bpy.utils.register_class(GICompMaterialNew)
+
+
+def unregister():
+    bpy.utils.unregister_class(GICompPanel)
+    bpy.utils.unregister_class(GICompMaterialNew)
+
+
+if __name__ == "__main__":
+    register()