Cura/plugins/CuraEngineBackend/SupportMeshCreator.py

# Copyright (c) 2018 fieldOfView
# The Blackbelt plugin is released under the terms of the LGPLv3 or higher.

import numpy
import math
import trimesh

from UM.Extension import Extension
from UM.Application import Application
from UM.Logger import Logger

from UM.Mesh.MeshData import MeshData, calculateNormalsFromIndexedVertices
from UM.Math.Vector import Vector

from UM.i18n import i18nCatalog
catalog = i18nCatalog("cura")

class SupportMeshCreator():
    def __init__(self,
                    support_angle = None,
                    filter_upwards_facing_faces = True,
                    down_vector = numpy.array([0, -1, 0]),
                    bottom_cut_off = 0,
                    minimum_island_area = 0
                ):
        self._support_angle = support_angle
        if self._support_angle is None:
            global_container_stack = Application.getInstance().getGlobalContainerStack()
            if global_container_stack:
                support_extruder_nr = global_container_stack.getExtruderPositionValueWithDefault("support_extruder_nr")
                support_angle_stack = Application.getInstance().getExtruderManager().getExtruderStack(support_extruder_nr)
                self._support_angle = support_angle_stack.getProperty("support_angle", "value")
            else:
                self._support_angle = 50

        self._filter_upwards_facing_faces = filter_upwards_facing_faces
        self._minimum_island_area = minimum_island_area
        self._down_vector = down_vector
        self._bottom_cut_off = bottom_cut_off

    def createSupportMeshForNode(self, node):
        # convert node meshdata to trimesh
        node_name = node.getName()
        mesh_data = node.getMeshData().getTransformed(node.getWorldTransformation())

        node_vertices = mesh_data.getVertices()
        node_indices = mesh_data.getIndices()
        if node_indices is None:
            # some file formats (eg 3mf) don't supply indices, but have unique vertices per face
            node_indices = numpy.arange(len(node_vertices)).reshape(-1, 3)

        support_mesh = self.createSupportMesh(node_name, node_vertices, node_indices)
        if support_mesh is not None:
            # convert resulting trimesh into meshdata
            mesh_data = self._toMeshData(support_mesh)
            return mesh_data

    def createSupportMesh(self, node_name, node_vertices, node_indices):
        tri_mesh = trimesh.base.Trimesh(vertices=node_vertices, faces=node_indices)
        # make sure normals are sane
        tri_mesh.fix_normals()

        cos_support_angle = math.cos(math.radians(90 - self._support_angle))

        # get indices of faces that face down more than support_angle
        cos_angle_between_normal_down = numpy.dot(tri_mesh.face_normals, self._down_vector)
        faces_needing_support = numpy.argwhere(cos_angle_between_normal_down >= cos_support_angle).flatten()
        # filter out faces that point upwards
        if len(faces_needing_support) == 0 and self._filter_upwards_facing_faces:
            faces_facing_down = numpy.argwhere(tri_mesh.face_normals[:,1] < 0)
            faces_needing_support = numpy.intersect1d(faces_facing_down, faces_needing_support)
        if len(faces_needing_support) == 0:
            Logger.log("d", "Node %s doesn't need support" % node_name)
            return None
        roof_indices = node_indices[faces_needing_support]

        # filter out faces that are coplanar with the bottom
        non_bottom_indices = numpy.where(numpy.any(node_vertices[roof_indices].take(1, axis=2) > self._bottom_cut_off, axis=1))[0].flatten()
        roof_indices = roof_indices[non_bottom_indices]
        if len(roof_indices) == 0:
            Logger.log("d", "Node %s doesn't need support" % node_name)
            return None

        roof = trimesh.base.Trimesh(vertices=node_vertices, faces=roof_indices)
        roof.remove_unreferenced_vertices()
        roof.process()

        if self._minimum_island_area > 0:
            # filter out all islands that would result in small towers
            scale_matrix = trimesh.transformations.scale_matrix(0, direction=[0,1,0])
            roof_elements = roof.split(only_watertight=False)
            roof = trimesh.base.Trimesh()
            for roof_element in roof_elements:
                xy_element = roof_element.copy()
                xy_element.apply_transform(scale_matrix)
                if xy_element.area >= self._minimum_island_area:
                    roof = roof + roof_element

        num_roof_vertices = len(roof.vertices)
        if num_roof_vertices == 0:
            Logger.log("d", "All surfaces of node %s that need support are smaller than %d" % (node_name, self._minimum_island_area))
            return None

        connecting_faces = []

        roof_outline = roof.outline()
        for entity in roof_outline.entities:
            entity_points = entity.points
            outline = roof_outline.vertices[entity_points]

            # numpy magic to find indices for each outline vertex
            outline_indices = numpy.where((roof.vertices==outline[:,None]).all(-1))[1]

            num_outline_vertices = len(outline)
            for i in range(0, num_outline_vertices - 1):
                connecting_faces.append([outline_indices[i], outline_indices[i + 1] + num_roof_vertices, outline_indices[i] + num_roof_vertices])
                connecting_faces.append([outline_indices[i], outline_indices[i + 1], outline_indices[i + 1] + num_roof_vertices])

        support_vertices = numpy.concatenate((roof.vertices, roof.vertices * [1,0,1]))
        support_faces = numpy.concatenate((roof.faces, roof.faces + len(roof.vertices), connecting_faces))

        support_mesh = trimesh.base.Trimesh(vertices=support_vertices, faces=support_faces)
        support_mesh.fix_normals()

        return support_mesh

    def _toMeshData(self, tri_node: trimesh.base.Trimesh) -> MeshData:
        tri_faces = tri_node.faces
        tri_vertices = tri_node.vertices

        indices = []
        vertices = []

        index_count = 0
        face_count = 0
        for tri_face in tri_faces:
            face = []
            for tri_index in tri_face:
                vertices.append(tri_vertices[tri_index])
                face.append(index_count)
                index_count += 1
            indices.append(face)
            face_count += 1

        vertices = numpy.asarray(vertices, dtype=numpy.float32)
        indices = numpy.asarray(indices, dtype=numpy.int32)
        normals = calculateNormalsFromIndexedVertices(vertices, indices, face_count)

        mesh_data = MeshData(vertices=vertices, indices=indices, normals=normals)
        return mesh_data