Allow to set view perspective (#1991)

Author: dnicolodi

cadquery/vis.py

@@ -410,6 +410,7 @@ def show(
     xpos: Union[int, float] = 0,
     ypos: Union[int, float] = 0,
     fxaa: bool = True,
+    orthographic: bool = False,
 ):
     """
     Show CQ objects using VTK. This functions optionally allows to make screenshots.
@@ -506,6 +507,9 @@ def show(
     # set camera
     camera = renderer.GetActiveCamera()
 
+    # set perspective or parallel (orthographic) projection
+    camera.SetParallelProjection(orthographic)
+
     # Update camera position with user provided absolute positions
     if viewup:
         camera.SetViewUp(*viewup)

tests/test_vis.py

@@ -234,3 +234,8 @@ def test_camera_position(wp, patch_vtk):
 def test_frustrum_clipping_range(wp, patch_vtk):
 
     show(wp, zoom=2.0, clipping_range=(1, 100))
+
+
+def test_orthographic(wp, patch_vtk):
+
+    show(wp, orthographic=True)