@woosh/meep-engine/src/engine/graphics/sh3/path_tracer/material/StandardMaterial.js

Pure JavaScript game engine. Fully featured and production ready.

import { v3_dot } from "../../../../../core/geom/vec3/v3_dot.js";
import { PI_RECIPROCAL } from "../../../../../core/math/PI_RECIPROCAL.js";
import { one_pixel_sampler_uint8 } from "../../../texture/sampler/one_pixel_sampler_uint8.js";
import { StandardTexture } from "./StandardTexture.js";

const DEFAULT_DIFFUSE = one_pixel_sampler_uint8([255, 255, 255, 255]);
const DEFAULT_NORMAL = one_pixel_sampler_uint8([127, 127, 255]);
const DEFAULT_EMISSIVE = one_pixel_sampler_uint8([0, 0, 0]);
const DEFAULT_ROUGHNESS = one_pixel_sampler_uint8([255]);
const DEFAULT_METALNESS = one_pixel_sampler_uint8([0]);

let id_counter = 0;

export class StandardMaterial {
    id = id_counter++;

    diffuse = StandardTexture.from(DEFAULT_DIFFUSE)
    normal = StandardTexture.from(DEFAULT_NORMAL)
    emissive = StandardTexture.from(DEFAULT_EMISSIVE)
    roughness = StandardTexture.from(DEFAULT_ROUGHNESS)
    metalness = StandardTexture.from(DEFAULT_METALNESS)

    /**
     *
     * @param {number} incoming_direction_x
     * @param {number} incoming_direction_y
     * @param {number} incoming_direction_z
     * @param {number} normal_x
     * @param {number} normal_y
     * @param {number} normal_z
     * @param {number} outgoing_x
     * @param {number}  outgoing_y
     * @param {number} outgoing_z
     * @returns {number}
     */
    scattering_pdf(
        incoming_direction_x, incoming_direction_y, incoming_direction_z,
        normal_x, normal_y, normal_z,
        outgoing_x, outgoing_y, outgoing_z,
    ) {
        const cos_theta = v3_dot(
            normal_x, normal_y, normal_z,
            outgoing_x, outgoing_y, outgoing_z
        );

        if (cos_theta < 0) {
            // clamp rays below horizon
            return 0;
        }

        return cos_theta * PI_RECIPROCAL;
    }
}