Matrix4.premultipy()

The premultipy method of the Matrix4 class in three.js is used to multiply a matrix with another matrix in the left-multiplication form.

Syntax

premultiply(matrix: Matrix4): this

Parameters

• matrix: The matrix to be multiplied with.

Return Value

The this keyword, which refers to the Matrix4 object that is being modified.

Description

The premultipy method is used to multiply a matrix with another matrix in the left multiplication form. The matrix passed as an argument is multiplied in the order matrix * this, where matrix is the argument and this refers to the current Matrix4 object.

This method updates the current object, and returns a reference to the same object. Therefore, this method can be chained with other methods on the Matrix4 object.

Examples

const matrix1 = new THREE.Matrix4().makeScale(2, 2, 2);
const matrix2 = new THREE.Matrix4().makeRotationY(Math.PI / 2);

matrix1.premultiply(matrix2);

console.log(matrix1.toArray());
// [ 0, 0, -2, 0, 0, 2, 0, 0, 2, 0, 0, 0, 0, 0, 0, 1 ]

const matrix1 = new THREE.Matrix4().makeScale(2, 2, 2);
const matrix2 = new THREE.Matrix4().makeRotationY(Math.PI / 2);
const matrix3 = new THREE.Matrix4().makeTranslation(1, 2, 3);

matrix1.premultiply(matrix2).premultiply(matrix3);

console.log(matrix1.toArray());
// [ 0, 0, -2, 3, 0, 2, 0, 4, 2, 0, 0, 0, 0, 0, 0, 1 ]

See Also

• Matrix4.multiply()
• Matrix4.makeRotationY()
• Matrix4.makeScale()