src/viewer/scene/webgl/occlusion/OcclusionLayer.js

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

class OcclusionLayer {

    constructor(scene, origin) {

        this.scene = scene;
        this.aabb = math.AABB3();
        this.origin = math.vec3(origin);
        this.originHash = this.origin.join();
        this.numMarkers = 0;
        this.markers = {};
        this.markerList = [];                  // Ordered array of Markers
        this.markerIndices = {};               // ID map of Marker indices in _markerList
        this.positions = [];                   // Packed array of World-space marker positions
        this.indices = [];                     // Indices corresponding to array above
        this.positionsBuf = null;
        this.lenPositionsBuf = 0;
        this.indicesBuf = null;
        this.sectionPlanesActive = [];
        this.culledBySectionPlanes = false;
        this.occlusionTestList = [];           // List of
        this.lenOcclusionTestList = 0;
        this.pixels = [];
        this.aabbDirty = false;
        this.markerListDirty = false;
        this.positionsDirty = true;
        this.occlusionTestListDirty = false;
    }

    addMarker(marker) {
        this.markers[marker.id] = marker;
        this.markerListDirty = true;
        this.numMarkers++;
    }

    markerWorldPosUpdated(marker) {
        if (!this.markers[marker.id]) { // Not added
            return;
        }
        const i = this.markerIndices[marker.id];
        this.positions[i * 3 + 0] = marker.worldPos[0];
        this.positions[i * 3 + 1] = marker.worldPos[1];
        this.positions[i * 3 + 2] = marker.worldPos[2];
        this.positionsDirty = true; // TODO: avoid reallocating VBO each time
    }

    removeMarker(marker) {
        delete this.markers[marker.id];
        this.markerListDirty = true;
        this.numMarkers--;
    }

    update() {
        if (this.markerListDirty) {
            this._buildMarkerList();
            this.markerListDirty = false;
            this.positionsDirty = true;
            this.occlusionTestListDirty = true;
        }
        if (this.positionsDirty) { //////////////  TODO: Don't rebuild this when positions change, very wasteful
            this._buildPositions();
            this.positionsDirty = false;
            this.aabbDirty = true;
            this.vbosDirty = true;
        }
        if (this.aabbDirty) {
            this._buildAABB();
            this.aabbDirty = false;
        }
        if (this.vbosDirty) {
            this._buildVBOs();
            this.vbosDirty = false;
        }
        if (this.occlusionTestListDirty) {
            this._buildOcclusionTestList();
        }
        this._updateActiveSectionPlanes();
    }

    _buildMarkerList() {
        this.numMarkers = 0;
        for (var id in this.markers) {
            if (this.markers.hasOwnProperty(id)) {
                this.markerList[this.numMarkers] = this.markers[id];
                this.markerIndices[id] = this.numMarkers;
                this.numMarkers++;
            }
        }
        this.markerList.length = this.numMarkers;
    }

    _buildPositions() {
        let j = 0;
        for (let i = 0; i < this.numMarkers; i++) {
            if (this.markerList[i]) {
                const marker = this.markerList[i];
                const worldPos = marker.worldPos;
                this.positions[j++] = worldPos[0];
                this.positions[j++] = worldPos[1];
                this.positions[j++] = worldPos[2];
                this.indices[i] = i;
            }
        }
        this.positions.length = this.numMarkers * 3;
        this.indices.length = this.numMarkers;
    }

    _buildAABB() {
        const aabb = this.aabb;
        math.collapseAABB3(aabb);
        math.expandAABB3Points3(aabb, this.positions);
        const origin = this.origin;
        aabb[0] += origin[0];
        aabb[1] += origin[1];
        aabb[2] += origin[2];
        aabb[3] += origin[0];
        aabb[4] += origin[1];
        aabb[5] += origin[2];
    }

    _buildVBOs() {
        if (this.positionsBuf) {
            if (this.lenPositionsBuf === this.positions.length) { // Just updating buffer elements, don't need to reallocate
                this.positionsBuf.setData(this.positions); // Indices don't need updating
                return;
            }
            this.positionsBuf.destroy();
            this.positionsBuf = null;
            this.indicesBuf.destroy();
            this.indicesBuf = null;
        }
        const gl = this.scene.canvas.gl;
        const lenPositions = this.numMarkers * 3;
        const lenIndices = this.numMarkers;
        this.positionsBuf = new ArrayBuf(gl, gl.ARRAY_BUFFER, new Float32Array(this.positions), lenPositions, 3, gl.STATIC_DRAW);
        this.indicesBuf = new ArrayBuf(gl, gl.ELEMENT_ARRAY_BUFFER, new Uint16Array(this.indices), lenIndices, 1, gl.STATIC_DRAW);
        this.lenPositionsBuf = this.positions.length;
    }

    _buildOcclusionTestList() {
        const canvas = this.scene.canvas;
        const near = this.scene.camera.perspective.near; // Assume near enough to ortho near
        const boundary = canvas.boundary;
        const canvasWidth = boundary[2];
        const canvasHeight = boundary[3];
        let lenPixels = 0;
        this.lenOcclusionTestList = 0;
        for (let i = 0; i < this.numMarkers; i++) {
            const marker = this.markerList[i];
            const viewPos = marker.viewPos;
            if (viewPos[2] > -near) { // Clipped by near plane
                marker._setVisible(false);
                continue;
            }
            const canvasPos = marker.canvasPos;
            const canvasX = canvasPos[0];
            const canvasY = canvasPos[1];
            if ((canvasX + 10) < 0 || (canvasY + 10) < 0 || (canvasX - 10) > canvasWidth || (canvasY - 10) > canvasHeight) {
                marker._setVisible(false);
                continue;
            }
            if (marker.entity && !marker.entity.visible) {
                marker._setVisible(false);
                continue;
            }
            if (marker.occludable) {
                this.occlusionTestList[this.lenOcclusionTestList++] = marker;
                this.pixels[lenPixels++] = canvasX;
                this.pixels[lenPixels++] = canvasY;
                continue;
            }
            marker._setVisible(true);
        }
    }

    _updateActiveSectionPlanes() {
        const sectionPlanes = this.scene._sectionPlanesState.sectionPlanes;
        const numSectionPlanes = sectionPlanes.length;
        if (numSectionPlanes > 0) {
            for (let i = 0; i < numSectionPlanes; i++) {
                const sectionPlane = sectionPlanes[i];
                if (!sectionPlane.active) {
                    this.sectionPlanesActive[i] = false;
                } else {
                    const intersect = math.planeAABB3Intersect(sectionPlane.dir, sectionPlane.dist, this.aabb);
                    const outside = (intersect === -1);
                    if (outside) {
                        this.culledBySectionPlanes = true;
                        return;
                    }
                    const intersecting = (intersect === 0);
                    this.sectionPlanesActive[i] = intersecting;
                }
            }
        }
        this.culledBySectionPlanes = false;
    }

    destroy() {
        this.markers = {};
        this.markerList.length = 0;
        if (this.positionsBuf) {
            this.positionsBuf.destroy();
        }
        if (this.indicesBuf) {
            this.indicesBuf.destroy();
        }
    }
}


export {OcclusionLayer};