How to use GetViewProjMatrix().TransformVector(LineDirection) in UE4?

Development Programming & Scripting C++
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1

I try to project a 3D vector (a direction, not a position) in screen space, but it does not return satisfying results:

 FVector LineDirectionOnScreen = 
   EdMode->ViewMatrices.GetViewProjMatrix().TransformVector(LineDirection);
 FVector2D LineDirectionOnScreen2D(
   LineDirectionOnScreen.X * 0.5f * (float)EdMode->ViewRect.Width(), 
   LineDirectionOnScreen.Y * 0.5f * (float)EdMode->ViewRect.Height());

When LineDirection is (0,0,1) it always returns a something like (0,Y) (Y can be anything), no matter how the camera is rotated.

What is wrong with my code?

2

Hi, EdMode what type of object is it ?

3

Hi, EdMode is my custom FEdMode object, but ViewMatrices are matrices of the FSceneView.