Near the borders a bubble's refraction (liquid) or reflection (metal) sample
lands outside the layer. sample_bilinear returns transparent there, so the
pale stand-in colour for transparent pixels showed through, a band of washed-out
bubbles along every edge. Sample with edge pixels repeated instead, on the CPU
and in the GPU kernel; the pale colour stays for genuinely transparent pixels.
The CC Bubbles golden hashes are re-pinned (the half-resolution cases pad the
buffer with transparent pixels and are unchanged).
Shuvra Basak