Matrix3f

        public Matrix3f mul(Matrix3f otherMatrix){
    Matrix3f res = new Matrix3f();

    for(int i = 0; i < 3; i++){
        for(int j = 0; j < 3; j++){
        res.set(i, j,
            m[i][0] * otherMatrix.get(0, j) +
            m[i][1] * otherMatrix.get(1, j) +
            m[i][2] * otherMatrix.get(2, j));
        }
    }
    return res;
    }
    public Matrix3f initIdentity(){
    m[0][0] = 1; m[0][1] = 0; m[0][2] = 0;
    m[1][0] = 0; m[1][1] = 1; m[1][2] = 0;
    m[2][0] = 0; m[2][1] = 0; m[2][2] = 1;
    return this;
    }

    public Matrix3f initTranslationIdentity(float x, float y) {
    m[0][0] = 1; m[0][1] = 0; m[0][2] = x;
    m[1][0] = 0; m[1][1] = 1; m[1][2] = y;
    m[2][0] = 0; m[2][1] = 0; m[2][2] = 1;
    return this;
    }

    public Matrix3f initRotationIdentity(double angle) {
    float cos = (float) Math.cos(angle);
    float sin = (float) Math.sin(angle);
    m[0][0] = cos;  m[0][1] = sin; m[0][2] = 0;
    m[1][0] = -sin; m[1][1] = cos; m[1][2] = 0;
    m[2][0] = 0;    m[2][1] = 0;   m[2][2] = 1;
    return this;
    }

    public Matrix3f initScaleIdentity(float x, float y) {
    m[0][0] = x; m[0][1] = 0; m[0][2] = 0;
    m[1][0] = 0; m[1][1] = y; m[1][2] = 0;
    m[2][0] = 0; m[2][1] = 0; m[2][2] = 1;
    return this;
    }

    public Matrix3f initShearXIdentity(float shearX) {
    m[0][0] = 1; m[0][1] = shearX; m[0][2] = 0;
    m[1][0] = 0; m[1][1] = 1; m[1][2] = 0;
    m[2][0] = 0; m[2][1] = 0; m[2][2] = 1;
    return this;
    }

    public Matrix3f initShearYIdentity(float shearY) {
    m[0][0] = 1;      m[0][1] = 0; m[0][2] = 0;
    m[1][0] = shearY; m[1][1] = 1; m[1][2] = 0;
    m[2][0] = 0;      m[2][1] = 0; m[2][2] = 1;
    return this;
    }