@woosh/meep-engine/src/engine/physics/fluid/FluidField.js

Pure JavaScript game engine. Fully featured and production ready.

class FluidAttribute {
    name = "unnamed"
    /**
     *
     * @type {Float32Array}
     */
    data = null
}

/**
 * Represents a space where fluid simulation happens
 *
 * @see 2019 GDC talk by Runard Rupert "Wind Simulation in God of War" https://www.youtube.com/watch?v=dDgyBKkSf7A
 * @see Inspired by GDC talk "Interactive Wind and Vegetation in 'God of War'" - https://www.youtube.com/watch?v=MKX45_riWQA
 */
export class FluidField {

    #attributes = [];


    #size = [0, 0, 0]
    #resolution = [0, 0, 0]

    buffer = null;

    addAttribute(name) {
        const attribute = new FluidAttribute();
        attribute.name = name;

        const index = this.#attributes.length;

        this.#attributes.push(attribute);

        return index;
    }

    #findAttribute(name) {
        return this.#attributes.find(a => a.name === name);
    }

    /**
     *
     * @param {string} name
     * @return {Float32Array}
     */
    getAttributeData(name) {
        return this.#findAttribute(name)?.data;
    }

    getAttributeCount() {
        return this.#attributes.length;
    }

    /**
     *
     * @param {ArrayBuffer} buffer
     * @param {number} offset
     */
    attachBuffer(buffer, offset = 0) {

        const attribute_count = this.#attributes.length;

        const cell_count = this.#resolution[0] * this.#resolution[1] * this.#resolution[2];

        for (let i = 0; i < attribute_count; i++) {
            const attribute = this.#attributes[i];

            const array = new Float32Array(buffer, offset + i * cell_count * 4, cell_count);


            attribute.data = array;
        }

        this.buffer = buffer;
    }

    setAttributeAt(attribute_index, x, y, z, value) {

        const attribute = this.#attributes[attribute_index];

        const data = attribute.data;

        data[z * this.#resolution[0] * this.#resolution[1] + y * this.#resolution[0] + x] = value;

    }

    build() {
        const attribute_count = this.#attributes.length;

        const cell_count = this.#resolution[0] * this.#resolution[1] * this.#resolution[2];

        const data_buffer = new ArrayBuffer(cell_count * attribute_count * 4);

        this.attachBuffer(data_buffer);
    }

    set size(v) {
        const width = v[0];
        const height = v[1];
        const depth = v[2];

        this.#size[0] = width;
        this.#size[1] = height;
        this.#size[2] = depth
    }

    set resolution(v) {
        const width = v[0];
        const height = v[1];
        const depth = v[2];

        this.#resolution[0] = width;
        this.#resolution[1] = height;
        this.#resolution[2] = depth
    }

    get resolution() {
        return this.#resolution;
    }
}