Screen-space GI

import { Camera, Environment, PostProcessStack } from "ignifx";import { bootExample } from "../_kit/boot.ts";import { metres, twoPlaces } from "../_kit/format.ts";import { attachOrbit } from "../_kit/orbit.ts";import { bind, readout, slider, toggle } from "../_kit/panel.ts";import { loadEnvironment } from "../_kit/stage.ts";import { createSet, FOCUS, SHOT, START_EXPOSURE } from "./scene.ts";import type { PanelBinding } from "../_kit/panel.ts";/** * Screen-space contact shadows and screen-space global illumination (SSGI), two records on the * camera's `PostProcessStack`. * * Both need `rendering.features.postProcessing` and both read the shared scene depth. They run on * the scene colour right after the scene pass, before the HDR output pass and the rest of the * chain; under `rendering.hdr`, which this example turns on, that colour is linear, so the bounce * is added in light rather than in display values. Every field is live: toggling a record or * `ssgi.halfResolution` rebuilds its pass, the rest is written onto the pass each frame. * * **SSGI is beta and desktop tier.** It traces rays through the depth buffer and adds one bounce of * whatever lit colour they reach, which costs far more than anything else on this page, and it only * sees what is on screen: turn the camera until the red wall leaves the frame and its colour leaves * the floor. Because the probe already adds its own diffuse light, `ssgi.environmentDiffuse` keeps * only part of it while SSGI runs, so the bounce is not counted twice; that needs `rendering.hdr` * (or the `materialPlugins` feature). * * The bounce is noisy: each pixel traces a handful of rays and nothing averages them over time, * so more samples and full resolution buy a smoother result at a steep price. This example opens * at sixteen samples and full resolution; "Half resolution" and fewer samples show the cheap end. * * Contact shadows march a short way towards the first shadow-casting directional light from every * pixel. They fill in the thin dark line where an object meets the floor, which a shadow map is too * coarse to resolve — look at the steel rods lying on the floor. *//** Whether the two passes start on; also what the poster shows. */const START = { contactShadows: true, ssgi: true, ssgiIntensity: 0.6, ssgiSamples: 16 } as const;bootExample({  title: "Screen-space GI",  settings: {    rendering: {      clearColor: { r: 0.04, g: 0.045, b: 0.055, a: 1 },      hdr: true,      features: { postProcessing: true, shadows: true },    },  },  async setup({ app, panel, afterStart }) {    const eye = app.world.createEntity("Main Camera");    eye.addComponent(Camera, { near: 0.05, far: 100, fov: SHOT.fov });    attachOrbit(app, eye, {      yaw: SHOT.yaw,      pitch: SHOT.pitch,      distance: SHOT.distance,      target: FOCUS,      minDistance: 1.5,      maxDistance: 12,    });    const studio = loadEnvironment(app, "studio");    await studio.promise;    const sky = app.world.createEntity("Environment").addComponent(Environment, { environment: studio });    sky.imageProcessing.exposure = START_EXPOSURE;    sky.imageProcessing.toneMapping = "agx";    const sun = createSet(app);    const post = eye.addComponent(PostProcessStack);    // Full resolution and sixteen samples: the engine's defaults (half, eight) are cheaper and    // visibly grainy, since nothing denoises the bounce over time. Halve both for a laptop.    post.ssgi.intensity = START.ssgiIntensity;    post.ssgi.samples = START.ssgiSamples;    post.ssgi.halfResolution = false;    afterStart((): void => {      post.contactShadows.enabled = START.contactShadows;      post.ssgi.enabled = START.ssgi;    });    /**     * Binds a toggle to a record's `enabled`, opening at the start value: the record itself reads     * `false` until `afterStart` switches it on.     *     * @param record - The `contactShadows` or `ssgi` record.     * @param start - The value the page opens with.     * @returns The binding.     */    const enabled = (record: { enabled: boolean }, start: boolean): PanelBinding<boolean> => ({      value: start,      change: (on: boolean): void => {        record.enabled = on;      },      read: (): boolean => record.enabled,    });    panel({      title: "Screen-space GI",      groups: [        {          label: "SSGI (beta)",          controls: [            toggle("Enabled", enabled(post.ssgi, START.ssgi)),            slider("Intensity", { min: 0, max: 4, step: 0.1, format: twoPlaces }, bind(post.ssgi, "intensity")),            slider("Radius", { min: 0.25, max: 6, step: 0.25, format: metres }, bind(post.ssgi, "radius")),            slider("Samples", { min: 2, max: 32, step: 1 }, bind(post.ssgi, "samples")),            toggle("Half resolution", bind(post.ssgi, "halfResolution")),            slider(              "Probe diffuse kept",              { min: 0, max: 1, step: 0.05, format: twoPlaces },              bind(post.ssgi, "environmentDiffuse"),            ),          ],        },        {          label: "Contact shadows",          controls: [            toggle("Enabled", enabled(post.contactShadows, START.contactShadows)),            slider(              "Intensity",              { min: 0, max: 4, step: 0.1, format: twoPlaces },              bind(post.contactShadows, "intensity"),            ),            slider("Length", { min: 0.05, max: 1.5, step: 0.05, format: metres }, bind(post.contactShadows, "length")),            slider(              "Thickness",              { min: 0.02, max: 1, step: 0.02, format: metres },              bind(post.contactShadows, "thickness"),            ),            slider("Samples", { min: 2, max: 32, step: 1 }, bind(post.contactShadows, "samples")),          ],        },        {          label: "Lighting",          collapsed: true,          controls: [            toggle("Sun", bind(sun, "enabled")),            slider("Sun intensity", { min: 0, max: 6, step: 0.1, format: twoPlaces }, bind(sun, "intensity")),            slider("Exposure", { min: 0.2, max: 3, step: 0.05, format: twoPlaces }, bind(sky.imageProcessing, "exposure")),          ],        },        {          label: "Frame",          collapsed: true,          controls: [readout("Draw calls", (): string => String(app.renderer.drawCalls))],        },      ],    });  },});