const PI = Math.PI
const PI2 = PI * 2
const PIH = PI * 0.5
const cosFromSin = (sin, angle) => {
    const pih = PI / 2;
    const pi2 = PI * 2
    const cos = Math.sqrt(1.0 - sin * sin);
    const a = angle + PIH;
    const b = a - parseInt(a / PI2) * PI2;
    if (b < 0.0)
        b = PIH + b;
    if (b >= PI)
        return -cos;
    return cos;
} 

export class Mat4 {

    constructor() {
        this.data = [
            0, 0, 0, 0,
            0, 0, 0, 0,
            0, 0, 0, 0,
            0, 0, 0, 0
        ]
    }

    set(m00, m01, m02, m03, m10, m11, m12, m13, m20, m21, m22, m23, m30, m31, m32, m33) {
        const d = this.data
        d[0] = m00; d[1] = m01; d[2] = m02; d[3] = m03;
        d[4] = m10; d[5] = m11; d[6] = m12; d[7] = m13;
        d[8] = m20; d[9] = m21; d[10] = m22; d[11] = m23;
        d[12] = m30; d[13] = m31; d[14] = m32; d[15] = m33;
        return this
    }

    clone() {
        return new Mat4().arr(this.da)
    }

    arr(arr, offset = 0) {
        for(let i = 0; i < 16; i++) {
            this.data[i] = arr[i + offset]
        }
        return this
    }

    identity() {
        this.set(
            1, 0, 0, 0,
            0, 1, 0, 0,
            0, 0, 1, 0,
            0, 0, 0, 1
        )
        return this
    }

    copy(m) {
        const d = this.data
        const o = m.data
        d[0] = o[0]; d[1] = o[1]; d[2] = o[2]; d[3] = o[3];
        d[4] = o[4]; d[5] = o[5]; d[6] = o[6]; d[7] = o[7];
        d[8] = o[8]; d[9] = o[9]; d[10] = o[10]; d[11] = o[11];
        d[12] = o[12]; d[13] = o[13]; d[14] = o[14]; d[15] = o[15];
        return this
    }

    pos(v) {
        const d = this.data

        const m30 = d[0] * v.x + d[4] * v.y + d[8] * v.z;
        const m31 = d[1] * v.x + d[5] * v.y + d[9] * v.z;
        const m32 = d[2] * v.x + d[6] * v.y + d[10] * v.z;
        const m33 = d[3] * v.x + d[7] * v.y + d[11] * v.z; 

		d[3] += m30;
        d[7] += m31;
        d[11] += m32;
        d[15] += m33;
		return this;
	}

    rot(v) {
        this.rotX(v.x)
        this.rotY(v.y)
        this.rotZ(v.z)

        return this
    }

    rotX(a) {
        const s = Math.sin(a), c = cosFromSin(s, a);
        const d = this.data;

        d[5] = c
        d[6] = s
        d[9] = -s
        d[10] = c

        return this
    }

    rotY(a) {
        const s = Math.sin(a), c = cosFromSin(s, a);
        const d = this.data;
        
        d[0] = c
        d[3] = -s
        d[8] = c
        d[10] = c

        return this
    }

    rotZ(a) {
        const s = Math.sin(a), c = cosFromSin(s, a);
        const d = this.data;
        
        d[0] = c
        d[1] = s
        d[4] = -s
        d[5] = c

        return this
    }

    scale(v) {
		const d = this.data;

		d[0] *= v.x; d[1] *= v.y; d[2] *= v.z;
		d[4] *= v.x; d[5] *= v.y; d[6] *= v.z;
		d[8] *= v.x; d[9] *= v.y; d[10] *= v.z;
		d[12] *= v.x; d[13] *= v.y; d[14] *= v.z;

		return this;
	}

    get() {
        return new Float32Array(this.data)
    }
}