Unwrap Constraint

unwrap_constraint.py

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#  as published by the Free Software Foundation; either version 2
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import bpy
import bmesh
from bpy.props import BoolProperty, EnumProperty, FloatProperty


bl_info = {
    "name": "Unwrap Constraint",
    "author": "Nutti",
    "version": (0, 1),
    "blender": (2, 77, 0),
    "location": "View3D > U",
    "description": "Unwrap while keeping uv coordinate",
    "warning": "",
    "support": "COMMUNITY",
    "wiki_url": "",
    "tracker_url": "",
    "category": "UV"
}


class UnwrapConstraint(bpy.types.Operator):
    bl_idname = "uv.unwrap_constraint"
    bl_label = "Unwrap Constraint"
    bl_description = "Unwrap while keeping uv coordinate"
    bl_options = {'REGISTER', 'UNDO'}

    # property for original unwrap
    method = EnumProperty(
        name="Method",
        description="Unwrapping method",
        items=[
            ('ANGLE_BASED', 'Angle Based', 'Angle Based'),
            ('CONFORMAL', 'Conformal', 'Conformal')],
        default='ANGLE_BASED')
    
    fill_holes = BoolProperty(
        name="Fill Holes",
        description="Virtual fill holes in meshes before unwrapping",
        default=True)

    correct_aspect = BoolProperty(
        name="Correct Aspect",
        description="Map UVs taking image aspect ratio into account",
        default=True)

    use_subsurf_data = BoolProperty(
        name="Use Subsurf Modifier",
        description="Map UVs taking vertex position after subsurf into account",
        default=False)
    
    margin = FloatProperty(
        name="Margin",
        description="Space between islands",
        max=1.0,
        min=0.0,
        default=0.001)

    # property for this operation
    x_const = BoolProperty(
        name="X-Constraint",
        description="Keep UV X-axis coordinate",
        default=False)
    
    y_const = BoolProperty(
        name="Y-Constraint",
        description="Keep UV Y-axis coordinate",
        default=False)
    

    
    def execute(self, context):
        obj = bpy.context.active_object
        bm = bmesh.from_edit_mesh(obj.data)
        
        bm.faces.ensure_lookup_table()
        
        if not bm.loops.layers.uv:
            self.report(
                {'WARNING'}, "Object must have more than one UV map")
            return {'CANCELLED'}
        uv_layer = bm.loops.layers.uv.verify()
        
        # get original UV coordinate
        faces = [f for f in bm.faces if f.select]
        uv_list = []
        for f in faces:
            uvs = [l[uv_layer].uv.copy() for l in f.loops]
            uv_list.append(uvs)
        
        # unwrap
        bpy.ops.uv.unwrap(
            method=self.method,
            fill_holes=self.fill_holes,
            correct_aspect=self.correct_aspect,
            use_subsurf_data=self.use_subsurf_data,
            margin=self.margin)
        
        # when X/Y-Constraint is checked, revert original coordinate
        for f, uvs in zip(faces, uv_list):
            for l, uv in zip(f.loops, uvs):
                if self.x_const:
                    l[uv_layer].uv.x = uv.x
                if self.y_const:
                    l[uv_layer].uv.y = uv.y
        
        # update mesh
        bmesh.update_edit_mesh(obj.data)
    
        return {'FINISHED'}


def view3d_uvmap_menu_fn(self, context):
    self.layout.separator()
    self.layout.operator(UnwrapConstraint.bl_idname, icon="PLUGIN")


def register():
    bpy.utils.register_module(__name__)
    bpy.types.VIEW3D_MT_uv_map.append(view3d_uvmap_menu_fn)


def unregister():
    bpy.utils.unregister_module(__name__)
    bpy.types.VIEW3D_MT_uv_map.remove(view3d_uvmap_menu_fn)


if __name__ == "__main__":
    register()