The viewport has severe rendering issues when constrain aspect ratio is applied and a post process material is affecting the scene set to "After Tonemapping" in it's blendable location

  1. In a new project create a camera (either standard or cine).
  2. Create a post process volume and add a post process material to it (I used a copy of the M_NPRPostProcess material from the archviz tutorial (I changed the blendable location to After tonemapping).
  3. Constrain the aspect ratio of the camera.
  4. Play the Project and Either adjust the Viewport in the editor or change the aspect ratio.
  5. there will now be glitched sections of the Viewports.
  6. the viewport looks like it has shifted if you disable the post process the image shifts the amount of the glitch back into the view.
    it looks like the glitched area is “outside of the viewport and rendering nothing”

There was a similar issue UE-85019 but I’ve spent a little while digging into the issue and have more information, the issue affects both cine and standard camera.

The post processing can be either attached to the camera or to a post processing volume.

It took me a while to reproduce the issue but after some testing it seemed to only be an issue when “After tonemapping” was set as the blendable option in the material.

I took the arch viz tutorial M_NPRPostProcess material and simple tweaked the blendable location and the issue can be seen.

And with the post processing off.


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