Image-based lighting

import { Camera, Environment, ENVIRONMENT_ASSET_TYPE } from "ignifx";import { bootExample } from "../_kit/boot.ts";import { attachOrbit } from "../_kit/orbit.ts";import { bind, readout, select, slider } from "../_kit/panel.ts";import { createStudioFloor } from "../_kit/stage.ts";import {  createSphereGrid,  degrees,  GRID,  percent,  START_BLUR,  START_EXPOSURE,  START_ROTATION,  twoPlaces,} from "./scene.ts";import type { AssetHandle, EnvironmentAsset } from "ignifx";/** * Image-based lighting: a prefiltered environment is the **only** light in this scene. * * There is no `Light` component anywhere below. Every highlight, every gradient and every * reflection comes from one `.env` file — a cube map that was convolved offline into a mip chain, * one level per roughness, plus the spherical harmonics that carry the diffuse term. That is what * `Environment` installs, and it is why a metal sphere in ignifx looks like metal without anyone * placing a lamp. * * Two rows of spheres, because a probe shows itself differently in each. The front row is metal * (`metallic: 1`): it has no diffuse colour at all, so what you see *is* the environment — three * softbox panels in a dark room, sharp at roughness zero and diffused into a soft wash by the time * roughness reaches one. The back row is dielectric (`metallic: 0`): the same probe arrives as a * broad diffuse tint with a bright rim where the grazing reflection climbs. * * ## Switching probes, and the two things that do not follow * * An `.env` is installed **onto the scene** by the asset loader, because that is the only shape * Lite's `loadEnvironment` has. So all three are loaded before `app.start()` and their handles are * kept: assigning one to `Environment.environment` installs it, the diffuse term changes on that * frame, and the reflections follow on the next coalesced renderable rebuild — a frame or two, and * switching back costs nothing at all. * * Two things do not follow a switch. The **background** does not: Lite builds the skybox inside * `loadEnvironment` as a renderable it owns and offers no way to remove or re-aim one, so all three * `.environment.json` files here load with `skyboxEnabled: false`, the frame is cleared to a flat * near-black, and this example draws a floor instead of a sky. And **`Environment.skybox`** is not a * live control: setting it asks for something the installed environment cannot deliver and logs * `IGX-0711`. `rotation`, `blur`, the exposure and the contrast *are* live, and they are what a game * actually reaches for. *//** * The vendored environments, by the label the panel shows them under. * * @remarks * Three probes that disagree about everything a probe can disagree about: a neutral softbox studio * with almost no colour in it, a warm canal at San Giuseppe bridge with a low sun, and the cool * overcast square in front of Ulm Minster. Switch between them and the whole frame changes * temperature, because the probe is the only light there is. */const ENVIRONMENTS: Readonly<Record<string, string>> = {  Studio: "environments/studio.environment.json",  Bridge: "environments/sanGiuseppeBridge.environment.json",  Cathedral: "environments/ulmerMuenster.environment.json",};/** The label the example opens on, and the one every capture shows. */const START_ENVIRONMENT = "Studio";/** * The panel label for an installed environment's address. * * @param address - The address `Environment.installed` reports, or an empty string. * @returns The label {@link ENVIRONMENTS} shows it under, or `"none"`. */function probeName(address: string): string {  return Object.keys(ENVIRONMENTS).find((label: string) => ENVIRONMENTS[label] === address) ?? "none";}bootExample({  title: "Image-based lighting",  settings: {    rendering: {      clearColor: { r: 0.02, g: 0.025, b: 0.035, a: 1 },      msaaSamples: 4,    },    time: { fixedDeltaTime: 1 / 60 },  },  async setup({ app, panel }) {    const focus = { x: 0, y: GRID.height, z: 0 };    const eye = app.world.createEntity("Main Camera");    eye.addComponent(Camera, { near: 0.05, far: 100, fov: 38 });    attachOrbit(app, eye, { yaw: 0, pitch: 15, distance: 8, target: focus, minDistance: 2, maxDistance: 24 });    // Every probe is loaded and awaited **before** `app.start()`, for two reasons. A load that    // finishes before the loop runs settles at once, while one awaited afterwards waits for a    // frame's `PreUpdate`; and an environment loaded after start gets no background at all, which    // would make the three disagree about more than their lighting. Each `.env` also pulls the BRDF    // lookup table Lite requires, from the `rendering.brdfLut` default address, once.    const probes = new Map<string, AssetHandle<EnvironmentAsset>>();    for (const [label, address] of Object.entries(ENVIRONMENTS)) {      probes.set(label, app.assets.load<EnvironmentAsset>(address, { type: ENVIRONMENT_ASSET_TYPE }));    }    await Promise.all([...probes.values()].map((handle: AssetHandle<EnvironmentAsset>) => handle.promise));    const environment = probes.get(START_ENVIRONMENT) ?? null;    // One `Environment` per world; a second logs `IGX-0705`. Its `imageProcessing` record is the    // exposure and tone-mapping path the PBR shaders themselves compile, which is why changing the    // curve recompiles a pipeline and changing the exposure is nearly free.    const sky = app.world.createEntity("Environment").addComponent(Environment, { environment });    sky.blur = START_BLUR;    sky.rotation = START_ROTATION;    sky.imageProcessing.exposure = START_EXPOSURE;    sky.imageProcessing.toneMapping = "aces";    // Switching a probe is one assignment. The handles stay retained for the page's life, so the    // GPU resources of the one you switched away from are still there when you switch back.    const install = (label: string): void => {      sky.environment = probes.get(label) ?? null;    };    createStudioFloor(app, { size: 160, environmentIntensity: 0.6, roughness: 0.42 });    createSphereGrid(app);    panel({      title: "Image-based lighting",      groups: [        {          label: "Environment",          controls: [            select("Probe", Object.keys(ENVIRONMENTS), { value: START_ENVIRONMENT, change: install }),            // Rotating the probe moves every reflection at once: the cheapest lighting control a            // game can offer, and blurring it is the second.            slider(              "Rotation",              { min: 0, max: 360, step: 1, format: degrees },              {                value: START_ROTATION,                change: (value: number): void => {                  sky.rotation = value;                },              },            ),            slider("Blur", { min: 0, max: 1, step: 0.02, format: percent }, bind(sky, "blur")),          ],        },        {          label: "Grading",          controls: [            slider(              "Exposure",              { min: 0.2, max: 3, step: 0.05, format: twoPlaces },              bind(sky.imageProcessing, "exposure"),            ),            slider(              "Contrast",              { min: 0.5, max: 2, step: 0.05, format: twoPlaces },              bind(sky.imageProcessing, "contrast"),            ),          ],        },        {          label: "Frame",          collapsed: true,          controls: [            // `installed` is the asset the *scene* is actually lit by, which is the honest readout:            // it only changes once the install has happened, not when the select was clicked.            readout("Installed", (): string => probeName(sky.installed?.address ?? "")),            readout("Draw calls", (): string => String(app.renderer.drawCalls)),            readout("Lights", (): string => "0"),          ],        },      ],    });  },});