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# <pep8 compliant>

#for full docs see...
# http://mediawiki.blender.org/index.php/Scripts/Manual/UV_Calculate/Follow_active_quads

import bpy


def extend(obj, operator, EXTEND_MODE):
    me = obj.data
    me_verts = me.verts
    # script will fail without UVs
    if not me.active_uv_texture:
        me.add_uv_texture()


    # Toggle Edit mode
    is_editmode = (obj.mode == 'EDIT')
    if is_editmode:
        bpy.ops.object.mode_set(mode='OBJECT')

    #t = sys.time()
    edge_average_lengths = {}

    OTHER_INDEX = 2, 3, 0, 1
    FAST_INDICIES = 0, 2, 1, 3 # order is faster

    def extend_uvs(face_source, face_target, edge_key):
        '''
        Takes 2 faces,
        Projects its extends its UV coords onto the face next to it.
        Both faces must share an edge
        '''

        def face_edge_vs(vi):
            # assume a quad
            return [(vi[0], vi[1]), (vi[1], vi[2]), (vi[2], vi[3]), (vi[3], vi[0])]

        vidx_source = face_source.verts
        vidx_target = face_target.verts

        faceUVsource = me.active_uv_texture.data[face_source.index]
        uvs_source = [faceUVsource.uv1, faceUVsource.uv2, faceUVsource.uv3, faceUVsource.uv4]

        faceUVtarget = me.active_uv_texture.data[face_target.index]
        uvs_target = [faceUVtarget.uv1, faceUVtarget.uv2, faceUVtarget.uv3, faceUVtarget.uv4]

        # vertex index is the key, uv is the value

        uvs_vhash_source = {vindex: uvs_source[i] for i, vindex in enumerate(vidx_source)}

        uvs_vhash_target = {vindex: uvs_target[i] for i, vindex in enumerate(vidx_target)}

        edge_idxs_source = face_edge_vs(vidx_source)
        edge_idxs_target = face_edge_vs(vidx_target)

        source_matching_edge = -1
        target_matching_edge = -1

        edge_key_swap = edge_key[1], edge_key[0]

        try:
            source_matching_edge = edge_idxs_source.index(edge_key)
        except:
            source_matching_edge = edge_idxs_source.index(edge_key_swap)
        try:
            target_matching_edge = edge_idxs_target.index(edge_key)
        except:
            target_matching_edge = edge_idxs_target.index(edge_key_swap)


        edgepair_inner_source = edge_idxs_source[source_matching_edge]
        edgepair_inner_target = edge_idxs_target[target_matching_edge]
        edgepair_outer_source = edge_idxs_source[OTHER_INDEX[source_matching_edge]]
        edgepair_outer_target = edge_idxs_target[OTHER_INDEX[target_matching_edge]]

        if edge_idxs_source[source_matching_edge] == edge_idxs_target[target_matching_edge]:
            iA = 0 # Flipped, most common
            iB = 1
        else: # The normals of these faces must be different
            iA = 1
            iB = 0


        # Set the target UV's touching source face, no tricky calc needed,
        uvs_vhash_target[edgepair_inner_target[0]][:] = uvs_vhash_source[edgepair_inner_source[iA]]
        uvs_vhash_target[edgepair_inner_target[1]][:] = uvs_vhash_source[edgepair_inner_source[iB]]


        # Set the 2 UV's on the target face that are not touching
        # for this we need to do basic expaning on the source faces UV's
        if EXTEND_MODE == 'LENGTH':

            try: # divide by zero is possible
                '''
                measure the length of each face from the middle of each edge to the opposite
                allong the axis we are copying, use this
                '''
                i1a = edgepair_outer_target[iB]
                i2a = edgepair_inner_target[iA]
                if i1a > i2a:
                    i1a, i2a = i2a, i1a

                i1b = edgepair_outer_source[iB]
                i2b = edgepair_inner_source[iA]
                if i1b > i2b:
                    i1b, i2b = i2b, i1b
                # print edge_average_lengths
                factor = edge_average_lengths[i1a, i2a][0] / edge_average_lengths[i1b, i2b][0]
            except:
                # Div By Zero?
                factor = 1.0

            uvs_vhash_target[edgepair_outer_target[iB]][:] = uvs_vhash_source[edgepair_inner_source[0]] + factor * (uvs_vhash_source[edgepair_inner_source[0]] - uvs_vhash_source[edgepair_outer_source[1]])
            uvs_vhash_target[edgepair_outer_target[iA]][:] = uvs_vhash_source[edgepair_inner_source[1]] + factor * (uvs_vhash_source[edgepair_inner_source[1]] - uvs_vhash_source[edgepair_outer_source[0]])

        else:
            # same as above but with no factors
            uvs_vhash_target[edgepair_outer_target[iB]][:] = uvs_vhash_source[edgepair_inner_source[0]] + (uvs_vhash_source[edgepair_inner_source[0]] - uvs_vhash_source[edgepair_outer_source[1]])
            uvs_vhash_target[edgepair_outer_target[iA]][:] = uvs_vhash_source[edgepair_inner_source[1]] + (uvs_vhash_source[edgepair_inner_source[1]] - uvs_vhash_source[edgepair_outer_source[0]])


    if me.active_uv_texture == None:
        me.add_uv_texture

    face_act = me.faces.active
    if face_act == -1:
        operator.report({'ERROR'}, "No active face.")
        return

    face_sel = [f for f in me.faces if len(f.verts) == 4 and f.select]

    face_act_local_index = -1
    for i, f in enumerate(face_sel):
        if f.index == face_act:
            face_act_local_index = i
            break

    if face_act_local_index == -1:
        operator.report({'ERROR'}, "Active face not selected.")
        return



    # Modes
    # 0 unsearched
    # 1:mapped, use search from this face. - removed!!
    # 2:all siblings have been searched. dont search again.
    face_modes = [0] * len(face_sel)
    face_modes[face_act_local_index] = 1 # extend UV's from this face.


    # Edge connectivty
    edge_faces = {}
    for i, f in enumerate(face_sel):
        for edkey in f.edge_keys:
            try:
                edge_faces[edkey].append(i)
            except:
                edge_faces[edkey] = [i]

    #SEAM = me.edges.seam

    if EXTEND_MODE == 'LENGTH':
        edge_loops = me.edge_loops_from_faces(face_sel, [ed.key for ed in me.edges if ed.seam])
        me_verts = me.verts
        for loop in edge_loops:
            looplen = [0.0]
            for ed in loop:
                edge_average_lengths[ed] = looplen
                looplen[0] += (me_verts[ed[0]].co - me_verts[ed[1]].co).length
            looplen[0] = looplen[0] / len(loop)


    # remove seams, so we dont map accross seams.
    for ed in me.edges:
        if ed.seam:
            # remove the edge pair if we can
            try:
                del edge_faces[ed.key]
            except:
                pass
    # Done finding seams


    # face connectivity - faces around each face
    # only store a list of indicies for each face.
    face_faces = [[] for i in range(len(face_sel))]

    for edge_key, faces in edge_faces.items():
        if len(faces) == 2: # Only do edges with 2 face users for now
            face_faces[faces[0]].append((faces[1], edge_key))
            face_faces[faces[1]].append((faces[0], edge_key))


    # Now we know what face is connected to what other face, map them by connectivity
    ok = True
    while ok:
        ok = False
        for i in range(len(face_sel)):
            if face_modes[i] == 1: # searchable
                for f_sibling, edge_key in face_faces[i]:
                    if face_modes[f_sibling] == 0:
                        face_modes[f_sibling] = 1 # mapped and search from.
                        extend_uvs(face_sel[i], face_sel[f_sibling], edge_key)
                        face_modes[i] = 1 # we can map from this one now.
                        ok = True # keep searching

                face_modes[i] = 2 # dont search again

    if is_editmode:
        bpy.ops.object.mode_set(mode='EDIT')
    else:
        me.update()


def main(context, operator):
    obj = context.active_object

    extend(obj, operator, operator.properties.mode)


class FollowActiveQuads(bpy.types.Operator):
    '''Follow UVs from active quads along continuous face loops'''
    bl_idname = "uv.follow_active_quads"
    bl_label = "Follow Active Quads"
    bl_options = {'REGISTER', 'UNDO'}

    mode = bpy.props.EnumProperty(items=(("EVEN", "Even", "Space all UVs evently"), ("LENGTH", "Length", "Average space UVs edge length of each loop")),
                        name="Edge Length Mode",
                        description="Method to space UV edge loops",
                        default="LENGTH")

    def poll(self, context):
        obj = context.active_object
        return (obj is not None and obj.type == 'MESH')

    def execute(self, context):
        main(context, self)
        return {'FINISHED'}


# Add to a menu
menu_func = (lambda self, context: self.layout.operator(FollowActiveQuads.bl_idname))


def register():
    bpy.types.register(FollowActiveQuads)
    bpy.types.VIEW3D_MT_uv_map.append(menu_func)


def unregister():
    bpy.types.unregister(FollowActiveQuads)
    bpy.types.VIEW3D_MT_uv_map.remove(menu_func)

if __name__ == "__main__":
    register()
