@xeokit/xeokit-sdk/src/viewer/scene/math/Frustum.js

3D BIM IFC Viewer SDK for AEC engineering applications. Open Source JavaScript Toolkit based on pure WebGL for top performance, real-world coordinates and full double precision

import {math} from "./math.js";

const tempVec3a = math.vec3();
const tempVec3b = math.vec3();
const tempMat4a = math.mat4();

/**
 * @private
 */
class FrustumPlane {

    constructor() {
        this.normal = math.vec3();
        this.offset = 0;
        this.testVertex = math.vec3();
    }

    set(nx, ny, nz, offset) {
        const s = 1.0 / Math.sqrt(nx * nx + ny * ny + nz * nz);
        this.normal[0] = nx * s;
        this.normal[1] = ny * s;
        this.normal[2] = nz * s;
        this.offset = offset * s;
        this.testVertex[0] = (this.normal[0] >= 0.0) ? 1 : 0;
        this.testVertex[1] = (this.normal[1] >= 0.0) ? 1 : 0;
        this.testVertex[2] = (this.normal[2] >= 0.0) ? 1 : 0;
    }
}

/**
 * @private
 */
class Frustum {
    constructor() {
        this.planes = [
            new FrustumPlane(), new FrustumPlane(), new FrustumPlane(),
            new FrustumPlane(), new FrustumPlane(), new FrustumPlane()
        ];
    }
}

Frustum.INSIDE = 0;
Frustum.INTERSECT = 1;
Frustum.OUTSIDE = 2;

/** @private */
function setFrustum(frustum, viewMat, projMat) {

    const m = math.mulMat4(projMat, viewMat, tempMat4a);

    const m0 = m[0];
    const m1 = m[1];
    const m2 = m[2];
    const m3 = m[3];
    const m4 = m[4];
    const m5 = m[5];
    const m6 = m[6];
    const m7 = m[7];
    const m8 = m[8];
    const m9 = m[9];
    const m10 = m[10];
    const m11 = m[11];
    const m12 = m[12];
    const m13 = m[13];
    const m14 = m[14];
    const m15 = m[15];

    frustum.planes[0].set(m3 - m0, m7 - m4, m11 - m8, m15 - m12);
    frustum.planes[1].set(m3 + m0, m7 + m4, m11 + m8, m15 + m12);
    frustum.planes[2].set(m3 - m1, m7 - m5, m11 - m9, m15 - m13);
    frustum.planes[3].set(m3 + m1, m7 + m5, m11 + m9, m15 + m13);
    frustum.planes[4].set(m3 - m2, m7 - m6, m11 - m10, m15 - m14);
    frustum.planes[5].set(m3 + m2, m7 + m6, m11 + m10, m15 + m14);
}

/** @private */
function frustumIntersectsAABB3(frustum, aabb) {

    let ret = Frustum.INSIDE;

    const min = tempVec3a;
    const max = tempVec3b;

    min[0] = aabb[0];
    min[1] = aabb[1];
    min[2] = aabb[2];
    max[0] = aabb[3];
    max[1] = aabb[4];
    max[2] = aabb[5];

    const bminmax = [min, max];

    for (let i = 0; i < 6; ++i) {
        const plane = frustum.planes[i];
        if (((plane.normal[0] * bminmax[plane.testVertex[0]][0]) +
            (plane.normal[1] * bminmax[plane.testVertex[1]][1]) +
            (plane.normal[2] * bminmax[plane.testVertex[2]][2]) +
            (plane.offset)) < 0.0) {
            return Frustum.OUTSIDE;
        }

        if (((plane.normal[0] * bminmax[1 - plane.testVertex[0]][0]) +
            (plane.normal[1] * bminmax[1 - plane.testVertex[1]][1]) +
            (plane.normal[2] * bminmax[1 - plane.testVertex[2]][2]) +
            (plane.offset)) < 0.0) {
            ret = Frustum.INTERSECT;
        }
    }

    return ret;
}

export {
    Frustum,
    FrustumPlane,
    frustumIntersectsAABB3,
    setFrustum
};