We found that we had need for this as well.
Since it’s not built in, we added it.
It’s not a terribly difficult thing to add.
Add orthographic properties to SceneCapture2DComponent.
We just mimicked CameraComponent properties, and defaults.
ProjectionMode=Perspective, OrthoWidth = 512, OrthoNearPlane=0, and OrthoFarPlane=WORLD_MAX.
work to create projection matrix is then in CreateSceneRenderer in SceneCaptureRendering.
If ortho is specified for SceneCapture2DComponent create a FReversedZOrthMatrix, or FOrthoMatrix rather than creating Perspective matrix.
There is a good example of creating one in CameraStackTypes.cpp
Look for CalculatProjectionMatrixGivenView function line 137ish.
Hope that helps
Jason Calvert
Cyan Inc.