Linearly interpolates between two values within the visual shader graph.
mix(a, b, weight) in the shader language.
OP_TYPE_SCALAR = 0 --- A scalar type.
OP_TYPE_VECTOR = 1 --- A vector type.
OP_TYPE_VECTOR_SCALAR = 2 --- A vector type.
weightport is using a scalar type.
OP_TYPE_MAX = 3 --- Represents the size of the OpType enum.