gpu-blend-factor

enum gpu-blend-factor {
  zero,
  one,
  src,
  one-minus-src,
  src-alpha,
  one-minus-src-alpha,
  dst,
  one-minus-dst,
  dst-alpha,
  one-minus-dst-alpha,
  src-alpha-saturated,
  constant,
  one-minus-constant,
  src1,
  one-minus-src1,
  src1-alpha,
  one-minus-src1-alpha,
}