package.rotateX.js Maven / Gradle / Ivy
module.exports = rotateX;
/**
* Rotates a matrix by the given angle around the X axis
*
* @param {mat4} out the receiving matrix
* @param {mat4} a the matrix to rotate
* @param {Number} rad the angle to rotate the matrix by
* @returns {mat4} out
*/
function rotateX(out, a, rad) {
var s = Math.sin(rad),
c = Math.cos(rad),
a10 = a[4],
a11 = a[5],
a12 = a[6],
a13 = a[7],
a20 = a[8],
a21 = a[9],
a22 = a[10],
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;
};