rotateX function
Rotates a matrix by the given angle around the X axis
@param {mat4} out the receiving matrix @param {ReadonlyMat4} a the matrix to rotate @param {Number} rad the angle to rotate the matrix by @returns {mat4} out
Implementation
List<double> rotateX(List<double> out, List<double> a, double rad) {
final s = math.sin(rad);
final c = math.cos(rad);
final a10 = a[4];
final a11 = a[5];
final a12 = a[6];
final a13 = a[7];
final a20 = a[8];
final a21 = a[9];
final a22 = a[10];
final a23 = a[11];
if (a != out) {
// If the source and destination differ, copy the unchanged rows
out[0] = a[0];
out[1] = a[1];
out[2] = a[2];
out[3] = a[3];
out[12] = a[12];
out[13] = a[13];
out[14] = a[14];
out[15] = a[15];
}
// Perform axis-specific matrix multiplication
out[4] = a10 * c + a20 * s;
out[5] = a11 * c + a21 * s;
out[6] = a12 * c + a22 * s;
out[7] = a13 * c + a23 * s;
out[8] = a20 * c - a10 * s;
out[9] = a21 * c - a11 * s;
out[10] = a22 * c - a12 * s;
out[11] = a23 * c - a13 * s;
return out;
}