abs, sign, floor, ceil, mod, min, max
trunc(x) // nearest whole number not larger than the absolute value of x
round(x) // based on 0.5
// Returns a value equal to the nearest integer to x.
// The fractional part of 0.5 will round toward the nearest even integer.
// For example, both 3.5 and 4.5 will round to 4.0:
roundEven(x)
fract (x) // returns the fractional part
clamp(x, y, z) // returns x if it's between y and z, else returns y or z
mix (x, y, a) // returns the linear blend of x and y, as a varies from 0 to 1
step (edge, x) // returns 0.0 if x < edge, 1.0f otherwise
smoothstep (edge0, edge1, x) // returns 0 if x < edge0, 1 if x > edge1, interpolated otherwise