@three.ez/instanced-mesh/src/core/utils/GLInstancedBufferAttribute.js

Enhanced InstancedMesh with frustum culling, fast raycasting (using BVH), sorting, visibility management and more.

import { GLBufferAttribute } from 'three';
/**
 * A class that extends `GLBufferAttribute` to handle instanced buffer attributes.
 * This class was specifically created to allow updating instanced buffer attributes during the `onBeforeRender` callback,
 * providing an efficient way to modify the buffer data dynamically before rendering.
 */
export class GLInstancedBufferAttribute extends GLBufferAttribute {
    /**
     * @param gl The WebGL2RenderingContext used to create the buffer.
     * @param type The type of data in the attribute.
     * @param itemSize The number of elements per attribute.
     * @param elementSize The size of individual elements in the array.
     * @param array The data array that holds the attribute values.
     * @param meshPerAttribute The number of meshes that share the same attribute data.
     */
    constructor(gl, type, itemSize, elementSize, array, meshPerAttribute = 1) {
        const buffer = gl.createBuffer();
        super(buffer, type, itemSize, elementSize, array.length / itemSize);
        /**
         * Indicates if this is an `isGLInstancedBufferAttribute`.
         */
        this.isGLInstancedBufferAttribute = true;
        /** @internal */ this._needsUpdate = false;
        // HACK TO MAKE IT WORK WITHOUT UPDATE CORE
        /** @internal */ this.isInstancedBufferAttribute = true;
        this.meshPerAttribute = meshPerAttribute;
        this.array = array;
        this._cacheArray = array;
        gl.bindBuffer(gl.ARRAY_BUFFER, buffer);
        gl.bufferData(gl.ARRAY_BUFFER, array, gl.DYNAMIC_DRAW);
    }
    /**
     * Updates the buffer data.
     * This method is designed to be called during the `onBeforeRender` callback.
     * It ensures that the attribute data is updated just before the rendering process begins.
     * @param renderer The WebGLRenderer used to render the scene.
     * @param count The number of elements to update in the buffer.
     */
    update(renderer, count) {
        if (!this._needsUpdate || count === 0)
            return;
        const gl = renderer.getContext();
        gl.bindBuffer(gl.ARRAY_BUFFER, this.buffer);
        if (this.array === this._cacheArray) {
            gl.bufferSubData(gl.ARRAY_BUFFER, 0, this.array, 0, count);
        }
        else {
            gl.bufferData(gl.ARRAY_BUFFER, this.array, gl.DYNAMIC_DRAW);
            this._cacheArray = this.array;
        }
        this._needsUpdate = false;
    }
    /** @internal */
    clone() {
        // This method is intentionally empty but necessary to avoid exceptions when cloning geometry.
        return this;
    }
}
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