@woosh/meep-engine/src/engine/graphics/ecs/camera/FrustumProjector.js

Pure JavaScript game engine. Fully featured and production ready.

import { Vector3 as ThreeVector3 } from 'three';


const corners = [
    new ThreeVector3(-1, -1, 0),
    new ThreeVector3(-1, -1, 0),

    new ThreeVector3(-1, 1, 0),
    new ThreeVector3(-1, 1, 0),

    new ThreeVector3(1, -1, 0),
    new ThreeVector3(1, -1, 0),

    new ThreeVector3(1, 1, 0),
    new ThreeVector3(1, 1, 0)
];


/**
 *
 * @param {Number} nearZ
 * @param {Number} farZ
 * @param {THREE.Camera} camera
 * @param {THREE.Matrix4} matrixWorldInverse
 * @param {AABB3} result
 */
function project(nearZ, farZ, camera, matrixWorldInverse, result) {
    corners[0].set(-1, -1, nearZ);
    corners[1].set(-1, -1, farZ);

    corners[2].set(-1, 1, nearZ);
    corners[3].set(-1, 1, farZ);

    corners[4].set(1, -1, nearZ);
    corners[5].set(1, -1, farZ);

    corners[6].set(1, 1, nearZ);
    corners[7].set(1, 1, farZ);

    //compute corners of view frustum in light space
    let x0 = Number.POSITIVE_INFINITY;
    let y0 = Number.POSITIVE_INFINITY;
    let z0 = Number.POSITIVE_INFINITY;

    let x1 = Number.NEGATIVE_INFINITY;
    let y1 = Number.NEGATIVE_INFINITY;
    let z1 = Number.NEGATIVE_INFINITY;


    for (let i = 0; i < 8; i++) {
        const corner = corners[i];
        corner.unproject(camera);
        corner.applyMatrix4(matrixWorldInverse);

        if (corner.x < x0) {
            x0 = corner.x;
        }
        if (corner.x > x1) {
            x1 = corner.x;
        }

        if (corner.y < y0) {
            y0 = corner.y;
        }
        if (corner.y > y1) {
            y1 = corner.y;
        }

        if (corner.z < z0) {
            z0 = corner.z;
        }
        if (corner.z > z1) {
            z1 = corner.z;
        }
    }

    result.setBounds(x0, y0, z0, x1, y1, z1);
}


export default {
    /**
     * @deprecated use non-threejs specific code
     */
    project,
};