Update PreviewPass so that only slicable objects are rendered

cura/PreviewPass.py

@@ -2,27 +2,56 @@
 # Uranium is released under the terms of the LGPLv3 or higher.
 
 from UM.Application import Application
-from UM.View.RenderPass import RenderPass
+from UM.Resources import Resources
-from UM.Scene.Camera import Camera
 
-##  A render pass subclass that renders everything with default parameters, but can be used with a non-default camera
+from UM.View.RenderPass import RenderPass
+from UM.View.GL.OpenGL import OpenGL
+from UM.View.RenderBatch import RenderBatch
+
+
+from UM.Scene.Iterator.DepthFirstIterator import DepthFirstIterator
+
+from typing import Optional
+
+MYPY = False
+if MYPY:
+    from UM.Scene.Camera import Camera
+
+##  A render pass subclass that renders slicable objects with default parameters.
+#   It uses the active camera by default, but it can be overridden to use a different camera.
 #
 #   This is useful to get a preview image of a scene taken from a different location as the active camera.
 class PreviewPass(RenderPass):
-    def __init__(self, width, height):
+    def __init__(self, width: int, height: int):
         super().__init__("preview", width, height, 0)
 
-        self._camera = Application.getInstance().getController().getScene().getActiveCamera()
+        self._camera = None  # type: Optional[Camera]
+
         self._renderer = Application.getInstance().getRenderer()
 
-    #   Override the camera to be used for this render pass
+        self._shader = None
-    def setCamera(self, camera: Camera):
+        self._scene = Application.getInstance().getController().getScene()
+
+    #   Set the camera to be used by this render pass
+    #   if it's None, the active camera is used
+    def setCamera(self, camera: Optional["Camera"]):
         self._camera = camera
 
-    def render(self):
+    def render(self) -> None:
+        if not self._shader:
+            self._shader = OpenGL.getInstance().createShaderProgram(Resources.getPath(Resources.Shaders, "object.shader"))
+
+        # Create a new batch to be rendered
+        batch = RenderBatch(self._shader)
+
+        # Fill up the batch with objects that can be sliced. `
+        for node in DepthFirstIterator(self._scene.getRoot()):
+            if node.callDecoration("isSliceable") and node.getMeshData() and node.isVisible():
+                batch.addItem(node.getWorldTransformation(), node.getMeshData())
+
         self.bind()
-
+        if self._camera is None:
-        for batch in self._renderer.getBatches():
+            batch.render(Application.getInstance().getController().getScene().getActiveCamera())
+        else:
             batch.render(self._camera)
-
         self.release()