Fix fast_trigonometry.inl

[ZvRzyan18]

fix glm::fastTan, glm::fastAsin, glm::fastAcos, glm::fastAtan, They should work much better now across their domains.

Other changes

• glm::wrapAngle, since fmod is slow so changed it into angle - trunc(angle / two_pi) * two_pi
• glm::fastSin, glm::fastCos improve accuracy

Implementation

it uses different approximated polynomials to minimize the error

sin_poly(x) ~ (sin(sqrt(x))-sqrt(x)) / (x * sqrt(x))
sin(x) ~ x * x3 * sin_poly(x2)

cos_poly(x) ~ cos(sqrt(x))
cos(x) ~ cos_poly(x2)

asin_poly(x) ~ (asin(sqrt(x))-sqrt(x)) / (x * sqrt(x))
asin(x) ~ x * x3 * asin_poly(x2)

atan_poly(x) ~ (atan(sqrt(x))-sqrt(x)) / (x * sqrt(x))
atan(x) ~ x * x3 * atan_poly(x2)

Identity

Polynomial approximation is only accurate within its interval, so trig identity solves that

• asin_poly(x) interval [0, 0.5]
  for x values [0.5, 1.0] asin(x) ~ pi/2 - 2 * asin_poly(sqrt((1 - x) / 2))
  for -x values asin(x) ~ -asin(abs(x))

• tan(x)
  for +-x -> inf x values tan(x) ~ sin(x)/cos(x)

• atan_poly(x) interval [0, 0.5]
  for x values [0.5, 1.0] atan(x) ~ atan_poly((x - 1) / (1 + x)) + pi/4
  for x values [1.0, inf] atan(x) ~ asin(x / sqrt(1 + x * x))
  alternative : atan(x) ~ pi/2 - atan(1 / x)
  for -x values atan(x) ~ -atan(abs(x))