Function scaleAndAdd

scaleAndAdd(out: vec4, a: ReadonlyVec4, b: ReadonlyVec4, scale: number): vec4
Adds two vec4's after scaling the second operand by a scalar value
Parameters
- out: vec4
  the receiving vector
- a: ReadonlyVec4
  the first operand
- b: ReadonlyVec4
  the second operand
- scale: number
  the amount to scale b by before adding
Returns vec4
out