- // Lock patch_bottom_left_texel to an integer, so that we never get
- // any bilinear artifacts for the gradient.
- vec2 base = (round(patch_bottom_left_texel * image_size - vec2(0.5, 0.5)) + vec2(0.5, 0.5))
+ // Lock the patch center to an integer, so that we never get
+ // any bilinear artifacts for the gradient. (NOTE: This assumes an
+ // even patch size.) Then calculate the bottom-left texel of the patch.
+ vec2 base = (round(patch_center * image_size) - (0.5f * patch_size - 0.5f))