From d7aa7cc8ca75425d7175c854a67ea42fa34ab2b9 Mon Sep 17 00:00:00 2001
From: Nathan Vegdahl <cessen@cessen.com>
Date: Sat, 9 Apr 2022 13:20:31 -0700
Subject: [PATCH] Add UV margin setting.

It's a little hacky, but mostly works.
---
 __init__.py        | 36 ++++++++++++++++++++++++++++++++----
 uv_island_utils.py | 37 -------------------------------------
 uv_utils.py        | 10 ++++++++++
 3 files changed, 42 insertions(+), 41 deletions(-)
 delete mode 100644 uv_island_utils.py
 create mode 100644 uv_utils.py

diff --git a/__init__.py b/__init__.py
index cf721f9..0d14465 100644
--- a/__init__.py
+++ b/__init__.py
@@ -36,6 +36,7 @@ from .node_groups import \
     ensure_footage_group, \
     ensure_camera_project_group, \
     ensure_feathered_square_group
+from .uv_utils import leftmost_u
 
 MAIN_NODE_NAME = "Compify Footage"
 BAKE_IMAGE_NODE_NAME = "Baked Lighting"
@@ -99,6 +100,7 @@ class CompifyPanel(bpy.types.Panel):
         layout.separator(factor=1.0)
 
         layout.use_property_split = True
+        layout.prop(context.scene.compify_config, "bake_uv_margin")
         layout.prop(context.scene.compify_config, "bake_image_res")
 
         layout.separator(factor=1.0)
@@ -301,13 +303,29 @@ class CompifyPrepScene(bpy.types.Operator):
         bpy.ops.mesh.select_all(action='SELECT')
         bpy.ops.uv.smart_project(
             angle_limit=(math.pi/180)*60, # 60 degrees
-            island_margin=0.005,
+            island_margin=0.001,
             area_weight=0.0,
             correct_aspect=False,
-            scale_to_bounds=True,
+            scale_to_bounds=False,
         )
         bpy.ops.object.mode_set(mode='OBJECT')
 
+        # We have to do the UV island margins twice, because Blender's
+        # `island_margin` is stupid beyond belief and corresponds to
+        # nothing absolute that we can depend on.  So what we're doing
+        # here is saying, "Hey, what was the actual margin achieved
+        # with `island_margin=0.001`?  Okay, now let's redo it based on
+        # that result."  It's still not 100% precise even with this,
+        # but with a bit of buffer it's close enough.
+        actual_margin = leftmost_u(context.selected_objects, UV_LAYER_NAME)
+        actual_margin_pixels = actual_margin * context.scene.compify_config.bake_image_res
+        target_margin_with_buffer = context.scene.compify_config.bake_uv_margin * (5.0 / 4.0)
+        correction_factor = target_margin_with_buffer / actual_margin_pixels
+        bpy.ops.object.mode_set(mode='EDIT')
+        bpy.ops.uv.select_all(action='SELECT') 
+        bpy.ops.uv.pack_islands(rotate=False, margin = 0.001 * correction_factor)
+        bpy.ops.object.mode_set(mode='OBJECT')
+
         return {'FINISHED'}
 
 
@@ -333,7 +351,8 @@ class CompifyBake(bpy.types.Operator):
             and context.scene.compify_config.footage != None \
             and context.scene.compify_config.camera != None \
             and context.scene.compify_config.geo_collection != None \
-            and len(context.scene.compify_config.geo_collection.all_objects) > 0
+            and len(context.scene.compify_config.geo_collection.all_objects) > 0 \
+            and compify_mat_name(context) in bpy.data.materials
 
     def execute(self, context):
         # Clear operator fields.  Not strictly necessary, since they
@@ -421,7 +440,7 @@ class CompifyBake(bpy.types.Operator):
                     # filepath='',
                     # width=512,
                     # height=512,
-                    margin=4,
+                    margin=context.scene.compify_config.bake_uv_margin,
                     margin_type='EXTEND',
                     use_selected_to_active=False,
                     max_ray_distance=0.0,
@@ -534,6 +553,15 @@ class CompifyFootageConfig(bpy.types.PropertyGroup):
         type=bpy.types.Collection,
         name="Footage Lights Collection",
     )
+    bake_uv_margin: bpy.props.IntProperty(
+        name="Bake UV Margin",
+        subtype='PIXEL',
+        options=set(), # Not animatable.
+        default=4,
+        min=0,
+        max=2**16,
+        soft_max=32,
+    )
     bake_image_res: bpy.props.IntProperty(
         name="Bake Resolution",
         subtype='PIXEL',
diff --git a/uv_island_utils.py b/uv_island_utils.py
deleted file mode 100644
index 4938d59..0000000
--- a/uv_island_utils.py
+++ /dev/null
@@ -1,37 +0,0 @@
-from math import inf
-from bpy_extras.mesh_utils import mesh_linked_uv_islands
-
-
-def uv_island_bbox_area_sum_multi_object(mesh_objects, uv_layer_name):
-    area_sum = 0.0
-    for obj in mesh_objects:
-        area_sum += uv_island_bbox_area_sum(obj.data, uv_layer_name)
-    return area_sum
-
-
-def uv_island_bbox_area_sum(mesh, uv_layer_name):
-    """ Returns the sum of the area of the bounding boxes of all the UV
-        islands in the given mesh for the given uv layer.
-    """
-    uvs = mesh.uv_layers[uv_layer_name].data
-    islands = mesh_linked_uv_islands(mesh)
-
-    bbox_area_sum = 0.0
-    for island in islands:
-        # Calculate the island's bounding box.
-        min_u = inf
-        max_u = -inf
-        min_v = inf
-        max_v = -inf
-        for face_idx in island:
-            for loop_idx in mesh.polygons[face_idx].loop_indices:
-                uv = uvs[mesh.loops[loop_idx].vertex_index].uv
-                min_u = min(min_u, uv[0])
-                max_u = max(max_u, uv[0])
-                min_v = min(min_v, uv[1])
-                max_v = max(max_v, uv[1])
-
-        # Add it's area to the sum.
-        bbox_area_sum += ((max_u - min_u) * (max_v - min_v))**0.5
-
-    return bbox_area_sum
diff --git a/uv_utils.py b/uv_utils.py
new file mode 100644
index 0000000..76db207
--- /dev/null
+++ b/uv_utils.py
@@ -0,0 +1,10 @@
+from math import inf
+
+
+def leftmost_u(mesh_objects, uv_layer_name):
+    leftmost = inf
+    for obj in mesh_objects:
+        uvs = obj.data.uv_layers[uv_layer_name].data
+        for uv in uvs:
+            leftmost = min(leftmost, uv.uv[0])
+    return leftmost