Physical-pixel framebuffer size derived from the effective size, DPR,
and framebuffer limit. Render targets and the mega-shader / bloom /
FXAA passes are all sized here so they match the renderer's canvas
backbuffer AND what materials read from renderer.getDrawingBufferSize().
At DPR > 1 a mismatch would silently brighten the scene via over-coverage.
Physical-pixel framebuffer size derived from the effective size, DPR, and framebuffer limit. Render targets and the mega-shader / bloom / FXAA passes are all sized here so they match the renderer's canvas backbuffer AND what materials read from
renderer.getDrawingBufferSize(). At DPR > 1 a mismatch would silently brighten the scene via over-coverage.