mesh_edge_roundifier.py

        # to origin position and then perform calculations
        # At least that is my understanding :) <komi3D>

        # V1 V2 stores Local Coordinates
        V1, V2, edgeVector, edgeLength, edgeCenter = self.getEdgeInfo(edge)

        debugPrintNew(d_Plane, "PLANE: " + parameters["plane"])
        lineAB = self.calc.getLineCoefficientsPerpendicularToVectorInPoint(
                                                edgeCenter, edgeVector,
                                                parameters["plane"]
                                                )
        circleMidPoint = V1
        circleMidPointOnPlane = self.calc.getCircleMidPointOnPlane(
                                                V1, parameters["plane"]
                                                )
        radius = parameters["radius"]

        angle = 0
        if (parameters["entryMode"] == 'Angle'):
            if (parameters["angleEnum"] != 'Other'):
                radius, angle = self.CalculateRadiusAndAngleForAnglePresets(
                                                parameters["angleEnum"], radius,
                                                angle, edgeLength
                                                )
            else:
                radius, angle = self.CalculateRadiusAndAngle(edgeLength)
        debugPrintNew(d_Radius_Angle, "RADIUS = " + str(radius) + "  ANGLE = " + str(angle))
        roots = None
        if angle != pi:  # mode other than 180
            if lineAB is None:
                roots = self.calc.getLineCircleIntersectionsWhenXPerpendicular(
                                                edgeCenter, circleMidPointOnPlane,
                                                radius, parameters["plane"]
                                                )
            else:
                roots = self.calc.getLineCircleIntersections(
                                                lineAB, circleMidPointOnPlane, radius
                                                )

            if roots is None:
                debugPrintNew(True,
                             "[Edge Roundifier]: No centers were found. Change radius to higher value")
                return None
            roots = self.addMissingCoordinate(roots, V1, parameters["plane"])  # adds X, Y or Z coordinate
        else:
            roots = [edgeCenter, edgeCenter]
        debugPrintNew(d_Roots, "roots=" + str(roots))

        refObjectLocation = None
        objectLocation = bpy.context.active_object.location  # Origin Location

        if parameters["refObject"] == "ORG":
            refObjectLocation = [0, 0, 0]
        elif parameters["refObject"] == "CUR":
            refObjectLocation = bpy.context.scene.cursor.location - objectLocation
        else:
            refObjectLocation = self.calc.getEdgeReference(edge, edgeCenter, parameters["plane"])

        debugPrintNew(d_RefObject, parameters["refObject"], refObjectLocation)
        chosenSpinCenter, otherSpinCenter = self.getSpinCenterClosestToRefCenter(
                                                            refObjectLocation, roots
                                                            )

        if (parameters["entryMode"] == "Radius"):
            halfAngle = self.calc.getAngle(edgeCenter, chosenSpinCenter, circleMidPoint)
            angle = 2 * halfAngle[0]  # in radians
            self.a = degrees(angle)   # in degrees

        spinAxis = self.getSpinAxis(parameters["plane"])
        steps = parameters["segments"]
        angle = -angle  # rotate clockwise by default

        return [chosenSpinCenter, otherSpinCenter, spinAxis, angle, steps, refObjectLocation]

    def drawSpin(self, edge, edgeCenter, roundifyParams, parameters, bm, mesh):
        [chosenSpinCenter, otherSpinCenter, spinAxis, angle, steps, refObjectLocation] = roundifyParams

        v0org, v1org = (edge.verts[0], edge.verts[1])

        if parameters["flip"]:
            angle = -angle
            spinCenterTemp = chosenSpinCenter
            chosenSpinCenter = otherSpinCenter
            otherSpinCenter = spinCenterTemp

        if(parameters["invertAngle"]):
            if angle < 0:
                angle = two_pi + angle
            elif angle > 0:
                angle = -two_pi + angle
            else:
                angle = two_pi

        if(parameters["fullCircles"]):
            angle = two_pi

        v0 = bm.verts.new(v0org.co)

        result = bmesh.ops.spin(
                        bm, geom=[v0], cent=chosenSpinCenter, axis=spinAxis,
                        angle=angle, steps=steps, use_duplicate=False
                        )

        # it seems there is something wrong with last index of this spin
        # I need to calculate the last index manually here
        vertsLength = len(bm.verts)
        bm.verts.ensure_lookup_table()
        lastVertIndex = bm.verts[vertsLength - 1].index
        lastSpinVertIndices = self.getLastSpinVertIndices(steps, lastVertIndex)

        self.sel.refreshMesh(bm, mesh)

        alternativeLastSpinVertIndices = []
        bothSpinVertices = []
        spinVertices = []
        alternate = False

        if ((angle == pi or angle == -pi) and not parameters["bothSides"]):

            midVertexIndex = lastVertIndex - round(steps / 2)
            bm.verts.ensure_lookup_table()
            midVert = bm.verts[midVertexIndex].co

            midVertexDistance = (Vector(refObjectLocation) - Vector(midVert)).length
            midEdgeDistance = (Vector(refObjectLocation) - Vector(edgeCenter)).length

            if ((parameters["invertAngle"]) or (parameters["flip"])):
                if (midVertexDistance > midEdgeDistance):
                    alternativeLastSpinVertIndices = self.alternateSpin(
                                                        bm, mesh, angle, chosenSpinCenter,
                                                        spinAxis, steps, v0, v1org, lastSpinVertIndices
                                                        )
            else:
                if (midVertexDistance < midEdgeDistance):
                    alternativeLastSpinVertIndices = self.alternateSpin(
                                                        bm, mesh, angle, chosenSpinCenter,
                                                        spinAxis, steps, v0, v1org, lastSpinVertIndices
                                                        )
        elif (angle != two_pi):  # to allow full circles
            if (result['geom_last'][0].co - v1org.co).length > SPIN_END_THRESHOLD:
                alternativeLastSpinVertIndices = self.alternateSpin(
                                                        bm, mesh, angle, chosenSpinCenter,
                                                        spinAxis, steps, v0, v1org, lastSpinVertIndices
                                                        )
                alternate = True

        self.sel.refreshMesh(bm, mesh)
        if alternativeLastSpinVertIndices != []:
            lastSpinVertIndices = alternativeLastSpinVertIndices

        if lastSpinVertIndices.stop <= len(bm.verts):  # make sure arc was added to bmesh
            spinVertices = [bm.verts[i] for i in lastSpinVertIndices]
            if alternativeLastSpinVertIndices != []:
                spinVertices = spinVertices + [v0]
            else:
                spinVertices = [v0] + spinVertices

        if (parameters["bothSides"]):
            # do some more testing here!!!
            if (angle == pi or angle == -pi):
                alternativeLastSpinVertIndices = self.alternateSpinNoDelete(
                                                        bm, mesh, -angle, chosenSpinCenter,
                                                        spinAxis, steps, v0, v1org, []
                                                        )
            elif alternate:
                alternativeLastSpinVertIndices = self.alternateSpinNoDelete(
                                                        bm, mesh, angle, otherSpinCenter,
                                                        spinAxis, steps, v0, v1org, []
                                                        )
            elif not alternate:
                alternativeLastSpinVertIndices = self.alternateSpinNoDelete(
                                                        bm, mesh, -angle, otherSpinCenter,
                                                        spinAxis, steps, v0, v1org, []
                                                        )
            bothSpinVertices = [bm.verts[i] for i in lastSpinVertIndices]
            alternativeSpinVertices = [bm.verts[i] for i in alternativeLastSpinVertIndices]
            bothSpinVertices = [v0] + bothSpinVertices + alternativeSpinVertices
            spinVertices = bothSpinVertices

        if (parameters["fullCircles"]):
            v1 = bm.verts.new(v1org.co)
            spinVertices = spinVertices + [v1]

        if (parameters['drawArcCenters']):
            centerVert = bm.verts.new(chosenSpinCenter)
            spinVertices.append(centerVert)

        return spinVertices, [chosenSpinCenter, otherSpinCenter, spinAxis, angle, steps, refObjectLocation]

    def deleteSpinVertices(self, bm, mesh, lastSpinVertIndices):
        verticesForDeletion = []
        bm.verts.ensure_lookup_table()
        for i in lastSpinVertIndices:
            vi = bm.verts[i]
            vi.select = True
            debugPrintNew(True, str(i) + ") " + str(vi))
            verticesForDeletion.append(vi)

        bmesh.ops.delete(bm, geom=verticesForDeletion, context = 'VERTS')
        bmesh.update_edit_mesh(mesh, loop_triangles=True)
        bpy.ops.object.mode_set(mode='OBJECT')
        bpy.ops.object.mode_set(mode='EDIT')

    def alternateSpinNoDelete(self, bm, mesh, angle, chosenSpinCenter,
                              spinAxis, steps, v0, v1org, lastSpinVertIndices):
        v0prim = v0

        result2 = bmesh.ops.spin(bm, geom=[v0prim], cent=chosenSpinCenter, axis=spinAxis,
                                 angle=angle, steps=steps, use_duplicate=False)
        vertsLength = len(bm.verts)
        bm.verts.ensure_lookup_table()
        lastVertIndex2 = bm.verts[vertsLength - 1].index

        lastSpinVertIndices2 = self.getLastSpinVertIndices(steps, lastVertIndex2)
        return lastSpinVertIndices2

    def alternateSpin(self, bm, mesh, angle, chosenSpinCenter,
                      spinAxis, steps, v0, v1org, lastSpinVertIndices):

        self.deleteSpinVertices(bm, mesh, lastSpinVertIndices)
        v0prim = v0

        result2 = bmesh.ops.spin(
                        bm, geom=[v0prim], cent=chosenSpinCenter, axis=spinAxis,
                        angle=-angle, steps=steps, use_duplicate=False
                        )
        # it seems there is something wrong with last index of this spin
        # I need to calculate the last index manually here
        vertsLength = len(bm.verts)
        bm.verts.ensure_lookup_table()
        lastVertIndex2 = bm.verts[vertsLength - 1].index

        lastSpinVertIndices2 = self.getLastSpinVertIndices(steps, lastVertIndex2)
        # second spin also does not hit the v1org
        if (result2['geom_last'][0].co - v1org.co).length > SPIN_END_THRESHOLD:

            self.deleteSpinVertices(bm, mesh, lastSpinVertIndices2)
            self.deleteSpinVertices(bm, mesh, range(v0.index, v0.index + 1))
            return []
        else:
            return lastSpinVertIndices2

    def getLastSpinVertIndices(self, steps, lastVertIndex):
        arcfirstVertexIndex = lastVertIndex - steps + 1
        lastSpinVertIndices = range(arcfirstVertexIndex, lastVertIndex + 1)
        return lastSpinVertIndices

    def rotateArcAroundSpinAxis(self, bm, mesh, vertices, parameters, edgeCenter):
        axisAngle = parameters["axisAngle"]
        plane = parameters["plane"]
        # compensate rotation center
        objectLocation = bpy.context.active_object.location
        center = objectLocation + edgeCenter

        rot = Euler((0.0, 0.0, radians(axisAngle)), 'XYZ').to_matrix()
        if plane == YZ:
            rot = Euler((radians(axisAngle), 0.0, 0.0), 'XYZ').to_matrix()
        if plane == XZ:
            rot = Euler((0.0, radians(axisAngle), 0.0), 'XYZ').to_matrix()

        indexes = [v.index for v in vertices]

        bmesh.ops.rotate(
            bm,
            cent=center,
            matrix=rot,
            verts=vertices,
            space=bpy.context.edit_object.matrix_world
        )
        self.sel.refreshMesh(bm, mesh)
        bm.verts.ensure_lookup_table()
        rotatedVertices = [bm.verts[i] for i in indexes]

        return rotatedVertices

    def CalculateRadiusAndAngle(self, edgeLength):
        degAngle = self.a
        angle = radians(degAngle)
        self.r = radius = edgeLength / (2 * sin(angle / 2))
        return radius, angle

    def CalculateRadiusAndAngleForAnglePresets(self, angleEnum, initR, initA, edgeLength):
        radius = initR
        angle = initA
        try:
            # Note - define an integer string in the angleEnum
            angle_convert = int(angleEnum)
            self.a = angle_convert
        except:
            self.a = 180  # fallback
            debugPrintNew(True,
                          "CalculateRadiusAndAngleForAnglePresets problem with int conversion")

        return self.CalculateRadiusAndAngle(edgeLength)

    def getSpinCenterClosestToRefCenter(self, objLocation, roots):
        root0Distance = (Vector(objLocation) - Vector(roots[0])).length
        root1Distance = (Vector(objLocation) - Vector(roots[1])).length

        chosenId = 0
        rejectedId = 1
        if (root0Distance > root1Distance):
            chosenId = 1
            rejectedId = 0
        return roots[chosenId], roots[rejectedId]

    def addMissingCoordinate(self, roots, startVertex, plane):
        if roots is not None:
            a, b = roots[0]
            c, d = roots[1]
            if plane == XY:
                roots[0] = Vector((a, b, startVertex[2]))
                roots[1] = Vector((c, d, startVertex[2]))
            if plane == YZ:
                roots[0] = Vector((startVertex[0], a, b))
                roots[1] = Vector((startVertex[0], c, d))
            if plane == XZ:
                roots[0] = Vector((a, startVertex[1], b))
                roots[1] = Vector((c, startVertex[1], d))
        return roots

    def selectEdgesAfterRoundifier(self, context, edges):
        bpy.ops.object.mode_set(mode='OBJECT')
        bpy.ops.object.mode_set(mode='EDIT')
        mesh = context.view_layer.objects.active.data
        bmnew = bmesh.new()
        bmnew.from_mesh(mesh)

        self.deselectEdges(bmnew)
        for selectedEdge in edges:
            for e in bmnew.edges:
                if (e.verts[0].co - selectedEdge.verts[0].co).length <= self.threshold \
                   and (e.verts[1].co - selectedEdge.verts[1].co).length <= self.threshold:
                    e.select_set(True)

        bpy.ops.object.mode_set(mode='OBJECT')
        bmnew.to_mesh(mesh)
        bmnew.free()
        bpy.ops.object.mode_set(mode='EDIT')

    def deselectEdges(self, bm):
        for edge in bm.edges:
            edge.select_set(False)

    def getSpinAxis(self, plane):
        axis = (0, 0, 1)
        if plane == YZ:
            axis = (1, 0, 0)
        if plane == XZ:
            axis = (0, 1, 0)
        return axis


    @classmethod
    def poll(cls, context):
        return (context.view_layer.objects.active.type == 'MESH') and (context.view_layer.objects.active.mode == 'EDIT')

def draw_item(self, context):
    self.layout.operator_context = 'INVOKE_DEFAULT'
    self.layout.operator('mesh.edge_roundifier')


classes = (
           EdgeRoundifier,
           )

reg_cls, unreg_cls = bpy.utils.register_classes_factory(classes)


def register():
    reg_cls()
    bpy.types.VIEW3D_MT_edit_mesh_edges.append(draw_item)


def unregister():
    unreg_cls()
    bpy.types.VIEW3D_MT_edit_mesh_edges.remove(draw_item)

if __name__ == "__main__":
    register()