modeling/src/maths/mat4/fromXRotation.js

  1. const { sin, cos } = require('../utils/trigonometry')
  3. /**
  4.  * Creates a matrix from the given angle around the X axis.
  5.  * This is equivalent to (but much faster than):
  6.  *
  7.  *     mat4.identity(dest)
  8.  *     mat4.rotateX(dest, dest, radians)
  9.  *
  10.  * @param {mat4} out - receiving matrix
  11.  * @param {Number} radians - angle to rotate the matrix by
  12.  * @returns {mat4} out
  13.  * @alias module:modeling/maths/mat4.fromXRotation
  14.  * @example
  15.  * let matrix = fromXRotation(create(), TAU / 4)
  16.  */
  17. const fromXRotation = (out, radians) => {
  18.   const s = sin(radians)
  19.   const c = cos(radians)
  21.   // Perform axis-specific matrix multiplication
  22.   out[0] = 1
  23.   out[1] = 0
  24.   out[2] = 0
  25.   out[3] = 0
  26.   out[4] = 0
  27.   out[5] = c
  28.   out[6] = s
  29.   out[7] = 0
  30.   out[8] = 0
  31.   out[9] = -s
  32.   out[10] = c
  33.   out[11] = 0
  34.   out[12] = 0
  35.   out[13] = 0
  36.   out[14] = 0
  37.   out[15] = 1
  38.   return out
  39. }
  41. module.exports = fromXRotation