From f867979437ea10b5c3f59e04b7e6806b79167c42 Mon Sep 17 00:00:00 2001
From: Nick Fox-Gieg <nick@fox-gieg.com>
Date: Mon, 13 Jul 2026 11:33:02 -0400
Subject: [PATCH] fix vertex colors

Update stop_motion_obj.py
---
 src/panels.py          |  2 ++
 src/stop_motion_obj.py | 33 ++++++++++++++++++++++++++++++++-
 2 files changed, 34 insertions(+), 1 deletion(-)

diff --git a/src/panels.py b/src/panels.py
index 3705a3e..5c05a2f 100644
--- a/src/panels.py
+++ b/src/panels.py
@@ -389,6 +389,7 @@ def copyImportSettings(self, source, dest):
         dest.ply_use_scene_unit = source.ply_use_scene_unit
         dest.ply_merge_verts = source.ply_merge_verts
         dest.ply_import_colors = source.ply_import_colors
+        dest.ply_import_attributes = source.ply_import_attributes
         
         dest.stl_global_scale = source.stl_global_scale
         dest.stl_use_scene_unit = source.stl_use_scene_unit
@@ -445,6 +446,7 @@ def draw(self, context):
             layout.prop(op.importSettings, 'ply_use_scene_unit')
             layout.prop(op.importSettings, 'ply_merge_verts')
             layout.prop(op.importSettings, 'ply_import_colors')
+            layout.prop(op.importSettings, 'ply_import_attributes')
         elif op.sequenceSettings.fileFormat == 'x3d':
             # if the x3d/wrl addon is not installed, inform the user
             if not x3dWrlInstalled:
diff --git a/src/stop_motion_obj.py b/src/stop_motion_obj.py
index a877e37..9c6c890 100644
--- a/src/stop_motion_obj.py
+++ b/src/stop_motion_obj.py
@@ -487,7 +487,8 @@ class MeshIO(bpy.types.PropertyGroup):
          name="Import Vertex color attributes",
          items=(('NONE', "None", "Do not import/export color attributes"),
                 ('SRGB', "sRGB", "Vertex colors in the file are in sRGB color space"),
-                ('LINEAR', "Linear", "Vertex colors in the file are in linear color space")))
+                ('LINEAR', "Linear", "Vertex colors in the file are in linear color space")),
+         default='SRGB')
     ply_import_attributes: bpy.props.BoolProperty(
         name="Import Attributes",
         description="Import custom vertex attributes",
@@ -602,6 +603,7 @@ def exportOBJ(self, filePath):
                 export_selected_objects=True,
                 export_animation=False,
                 export_triangulated_mesh=False,
+                export_colors=True,
                 forward_axis=newForwardAxisStr,
                 global_scale=self.obj_global_scale,
                 up_axis=newUpAxisStr)
@@ -823,6 +825,27 @@ def deleteLinkedMeshMaterials(mesh, maxMaterialUsers=1, maxImageUsers=0):
     mesh.materials.clear()
 
 
+def ensureVertexColorMaterial(mesh):
+    # only create a material if the mesh has vertex colors but no material to display them
+    if len(mesh.color_attributes) == 0 or len(mesh.materials) > 0:
+        return
+
+    matName = 'SMO_VertexColors'
+    material = bpy.data.materials.get(matName)
+    if material is None:
+        material = bpy.data.materials.new(matName)
+        material.use_nodes = True
+        nodes = material.node_tree.nodes
+        bsdf = next((node for node in nodes if node.type == 'BSDF_PRINCIPLED'), None)
+        if bsdf is not None:
+            colorNode = nodes.new('ShaderNodeAttribute')
+            colorNode.attribute_name = 'Col'
+            colorNode.location = (bsdf.location.x - 250, bsdf.location.y)
+            material.node_tree.links.new(colorNode.outputs['Color'], bsdf.inputs['Base Color'])
+
+    mesh.materials.append(material)
+
+
 def newMeshSequence():
     theMesh = bpy.data.meshes.new(createUniqueName('emptyMesh', bpy.data.meshes))
     theObj = bpy.data.objects.new(createUniqueName('sequence', bpy.data.objects), theMesh)
@@ -945,6 +968,9 @@ def loadSequenceFromMeshFiles(_obj, _dir, _file):
         if numFrames >= 1 and mss.perFrameMaterial is False:
             deleteLinkedMeshMaterials(tmpMesh)
 
+        # if the mesh has vertex colors but no material, create one that displays them
+        ensureVertexColorMaterial(tmpMesh)
+
         newMeshNameElement = mss.meshNameArray.add()
         newMeshNameElement.key = tmpMesh.name
         newMeshNameElement.basename = os.path.basename(file)
@@ -1150,6 +1176,7 @@ def setFrameObjStreamed(obj, frameNum, forceLoad=False, deleteMaterials=False):
         if deleteMaterials is True:
             nextMesh = getMeshFromIndex(obj, idx)
             deleteLinkedMeshMaterials(nextMesh)
+            ensureVertexColorMaterial(nextMesh)
 
     # if the mesh is in memory, show it
     if nextMeshProp.inMemory is True:
@@ -1238,6 +1265,10 @@ def importStreamedFile(obj, idx):
     # we want to make sure the cached meshes are saved to the .blend file
     tmpMesh.use_fake_user = True
     tmpMesh.inMeshSequence = True
+
+    # if the mesh has vertex colors but no material, create one that displays them
+    ensureVertexColorMaterial(tmpMesh)
+
     mss.meshNameArray[idx].key = tmpMesh.name
     mss.meshNameArray[idx].inMemory = True
     mss.numMeshesInMemory += 1