Rename PLYReader to TrimeshReader

We're going to repurpose this plug-in to read other file formats as well.
Currently it still only registers itself as PLY file reader. But I'm about to change that.

Contributes to issue CURA-6739.

plugins/TrimeshReader/TrimeshReader.py

@@ -0,0 +1,81 @@
+# Copyright (c) 2019 Ultimaker B.V., fieldOfView
+# Cura is released under the terms of the LGPLv3 or higher.
+
+# The _toMeshData function is taken from the AMFReader class which was built by fieldOfView.
+
+import numpy  # To create the mesh data.
+import os.path  # To create the mesh name for the resulting mesh.
+import trimesh  # To load the files into a Trimesh.
+
+from UM.Mesh.MeshData import MeshData, calculateNormalsFromIndexedVertices  # To construct meshes from the Trimesh data.
+from UM.Mesh.MeshReader import MeshReader  # The plug-in type we're extending.
+from UM.MimeTypeDatabase import MimeTypeDatabase, MimeType  # To add file types that we can open.
+
+from cura.CuraApplication import CuraApplication
+from cura.Scene.BuildPlateDecorator import BuildPlateDecorator  # Added to the resulting scene node.
+from cura.Scene.CuraSceneNode import CuraSceneNode  # To create a node in the scene after reading the file.
+from cura.Scene.SliceableObjectDecorator import SliceableObjectDecorator  # Added to the resulting scene node.
+
+##  Class that leverages Trimesh to import files.
+class Trimesh(MeshReader):
+    def __init__(self) -> None:
+        super().__init__()
+
+        self._supported_extensions = [".ply"]
+        MimeTypeDatabase.addMimeType(
+            MimeType(
+                name = "application/x-ply",  # Wikipedia lists the MIME type as "text/plain" but that won't do as it's not unique to PLY files.
+                comment = "Stanford Triangle Format",
+                suffixes = ["ply"]
+            )
+        )
+
+    ##  Reads a file using Trimesh.
+    #   \param file_name The file path. This is assumed to be one of the file
+    #   types that Trimesh can read. It will not be checked again.
+    #   \return A scene node that contains the file's contents.
+    def _read(self, file_name: str) -> CuraSceneNode:
+        mesh = trimesh.load(file_name)
+        mesh.merge_vertices()
+        mesh.remove_unreferenced_vertices()
+        mesh.fix_normals()
+        mesh_data = self._toMeshData(mesh)
+
+        file_base_name = os.path.basename(file_name)
+        new_node = CuraSceneNode()
+        new_node.setMeshData(mesh_data)
+        new_node.setSelectable(True)
+        new_node.setName(file_base_name)
+        new_node.addDecorator(BuildPlateDecorator(CuraApplication.getInstance().getMultiBuildPlateModel().activeBuildPlate))
+        new_node.addDecorator(SliceableObjectDecorator())
+        return new_node
+
+    ##  Converts a Trimesh to Uranium's MeshData.
+    #   \param tri_node A Trimesh containing the contents of a file that was
+    #   just read.
+    #   \return Mesh data from the Trimesh in a way that Uranium can understand
+    #   it.
+    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

plugins/TrimeshReader/__init__.py

@@ -0,0 +1,21 @@
+# Copyright (c) 2019 Ultimaker
+# Cura is released under the terms of the LGPLv3 or higher.
+
+from . import TrimeshReader
+
+from UM.i18n import i18nCatalog
+i18n_catalog = i18nCatalog("uranium")
+
+
+def getMetaData():
+    return {
+        "mesh_reader": [
+            {
+                "extension": "ply",
+                "description": i18n_catalog.i18nc("@item:inlistbox", "PLY File")
+            }
+        ]
+    }
+
+def register(app):
+    return {"mesh_reader": TrimeshReader.TrimeshReader()}

plugins/TrimeshReader/plugin.json

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+{
+    "name": "Trimesh Reader",
+    "author": "Ultimaker B.V.",
+    "version": "1.0.0",
+    "description": "Provides support for reading model files.",
+    "api": "6.0.0"
+}