rotate function

List<double>? rotate(List<double> out, List<double> a, double rad, dynamic axis,)

Rotates a mat4 by the given angle around the given axis

@param {mat4} out the receiving matrix @param {ReadonlyMat4} a the matrix to rotate @param {Number} rad the angle to rotate the matrix by @param {ReadonlyVec3} axis the axis to rotate around @returns {mat4} out

Implementation

List<double>? rotate(List<double> out, List<double> a, double rad, axis) {
  double x = axis[0], y = axis[1], z = axis[2];
  double len = hypot([x, y, z]);
  double s, c, t;
  double a00, a01, a02, a03;
  double a10, a11, a12, a13;
  double a20, a21, a22, a23;
  double b00, b01, b02;
  double b10, b11, b12;
  double b20, b21, b22;

  if (len < GlMatrix.EPSILON) {
    return null;
  }

  len = 1 / len;
  x *= len;
  y *= len;
  z *= len;

  s = math.sin(rad);
  c = math.cos(rad);
  t = 1 - c;

  a00 = a[0];
  a01 = a[1];
  a02 = a[2];
  a03 = a[3];
  a10 = a[4];
  a11 = a[5];
  a12 = a[6];
  a13 = a[7];
  a20 = a[8];
  a21 = a[9];
  a22 = a[10];
  a23 = a[11];

  // Construct the elements of the rotation matrix
  b00 = x * x * t + c;
  b01 = y * x * t + z * s;
  b02 = z * x * t - y * s;
  b10 = x * y * t - z * s;
  b11 = y * y * t + c;
  b12 = z * y * t + x * s;
  b20 = x * z * t + y * s;
  b21 = y * z * t - x * s;
  b22 = z * z * t + c;

  // Perform rotation-specific matrix multiplication
  out[0] = a00 * b00 + a10 * b01 + a20 * b02;
  out[1] = a01 * b00 + a11 * b01 + a21 * b02;
  out[2] = a02 * b00 + a12 * b01 + a22 * b02;
  out[3] = a03 * b00 + a13 * b01 + a23 * b02;
  out[4] = a00 * b10 + a10 * b11 + a20 * b12;
  out[5] = a01 * b10 + a11 * b11 + a21 * b12;
  out[6] = a02 * b10 + a12 * b11 + a22 * b12;
  out[7] = a03 * b10 + a13 * b11 + a23 * b12;
  out[8] = a00 * b20 + a10 * b21 + a20 * b22;
  out[9] = a01 * b20 + a11 * b21 + a21 * b22;
  out[10] = a02 * b20 + a12 * b21 + a22 * b22;
  out[11] = a03 * b20 + a13 * b21 + a23 * b22;

  if (a != out) {
    // If the source and destination differ, copy the unchanged last row
    out[12] = a[12];
    out[13] = a[13];
    out[14] = a[14];
    out[15] = a[15];
  }
  return out;
}