Getting the wrong preview resolution in a render plugin

Hello,

I’m following this example to write a render plugin:
https://docs.blender.org/api/blender_python_api_2_77_0/bpy.types.RenderEngine.html

Everything is working fine except one thing: When editing material parameters, a preview render is triggered as expected, but scene.render.resolution_x and scene.render.resolution_y are somehow both always equal to 32 and the preview doesn’t get updated. However, when a preview render is triggered by e.g. resizing the property panel, the resolution is correct and the preview is properly updated.

Is there anything obvious I’m missing?

Franz

Sounds like the render you are looking at is the one for the material preview.

Just a guess…