gaussianRenderScale

Gaussian-splat offscreen render scale in (0, 1]. Values < 1 draw all splat tiles into a reduced-resolution target and composite-upsample — splat rendering is blended-fill bound, so 0.5 costs ~1/4 the GPU fragment work at slightly softer splat edges. 1.0 restores direct full-resolution drawing. See DrawableGaussianPass.