Initial implementation for Area Lights (#16078)

Added initial implementation of Area Lights. Initial light type supported is RectAreaLight and support is only available in Standard and PBR shaders.  

---------

Co-authored-by: Gary Hsu <[email protected]>
Co-authored-by: Popov72 <[email protected]>

packages/dev/core/src/Lights/LTC/ltcTextureTool.ts

@@ -0,0 +1,45 @@
+import type { BaseTexture } from "core/Materials/Textures/baseTexture";
+import { Tools } from "core/Misc/tools";
+import type { Tuple } from "core/types";
+
+/**
+ * Linearly transformed cosine textures that are used in the Area Lights shaders.
+ */
+export type ILTCTextures = {
+    /**
+     * Linearly transformed cosine texture BRDF Approximation.
+     */
+    LTC1: BaseTexture;
+
+    /**
+     * Linearly transformed cosine texture Fresnel Approximation.
+     */
+    LTC2: BaseTexture;
+};
+
+/**
+ * Loads LTC texture data from Babylon.js CDN.
+ * @returns Promise with data for LTC1 and LTC2 textures for area lights.
+ */
+export async function DecodeLTCTextureDataAsync(): Promise<Tuple<Uint16Array, 2>> {
+    const ltc1 = new Uint16Array(64 * 64 * 4);
+    const ltc2 = new Uint16Array(64 * 64 * 4);
+    const file = await Tools.LoadFileAsync(Tools.GetAssetUrl("https://assets.babylonjs.com/core/areaLights/areaLightsLTC.bin"));
+    const ltcEncoded = new Uint16Array(file);
+
+    const pixelCount = ltcEncoded.length / 8;
+
+    for (let pixelIndex = 0; pixelIndex < pixelCount; pixelIndex++) {
+        ltc1[pixelIndex * 4] = ltcEncoded[pixelIndex * 8];
+        ltc1[pixelIndex * 4 + 1] = ltcEncoded[pixelIndex * 8 + 1];
+        ltc1[pixelIndex * 4 + 2] = ltcEncoded[pixelIndex * 8 + 2];
+        ltc1[pixelIndex * 4 + 3] = ltcEncoded[pixelIndex * 8 + 3];
+
+        ltc2[pixelIndex * 4] = ltcEncoded[pixelIndex * 8 + 4];
+        ltc2[pixelIndex * 4 + 1] = ltcEncoded[pixelIndex * 8 + 5];
+        ltc2[pixelIndex * 4 + 2] = ltcEncoded[pixelIndex * 8 + 6];
+        ltc2[pixelIndex * 4 + 3] = ltcEncoded[pixelIndex * 8 + 7];
+    }
+
+    return [ltc1, ltc2];
+}

packages/dev/core/src/Lights/areaLight.ts

@@ -0,0 +1,114 @@
+import type { Vector3 } from "core/Maths/math.vector";
+import { RawTexture } from "core/Materials/Textures/rawTexture";
+import { Texture } from "core/Materials/Textures/texture";
+import { Constants } from "core/Engines/constants";
+import { Light } from "core/Lights/light";
+import type { Effect } from "core/Materials/effect";
+import type { ILTCTextures } from "core/Lights/LTC/ltcTextureTool";
+import { DecodeLTCTextureDataAsync } from "core/Lights/LTC/ltcTextureTool";
+import type { Scene } from "core/scene";
+import { Logger } from "core/Misc/logger";
+
+declare module "../scene" {
+    export interface Scene {
+        /**
+         * @internal
+         */
+        _ltcTextures?: ILTCTextures;
+    }
+}
+
+function CreateSceneLTCTextures(scene: Scene): void {
+    const useDelayedTextureLoading = scene.useDelayedTextureLoading;
+    scene.useDelayedTextureLoading = false;
+
+    const previousState = scene._blockEntityCollection;
+    scene._blockEntityCollection = false;
+
+    scene._ltcTextures = {
+        LTC1: RawTexture.CreateRGBATexture(null, 64, 64, scene.getEngine(), false, false, Constants.TEXTURE_LINEAR_LINEAR, Constants.TEXTURETYPE_HALF_FLOAT, 0, false, true),
+        LTC2: RawTexture.CreateRGBATexture(null, 64, 64, scene.getEngine(), false, false, Constants.TEXTURE_LINEAR_LINEAR, Constants.TEXTURETYPE_HALF_FLOAT, 0, false, true),
+    };
+
+    scene._blockEntityCollection = previousState;
+
+    scene._ltcTextures.LTC1.wrapU = Texture.CLAMP_ADDRESSMODE;
+    scene._ltcTextures.LTC1.wrapV = Texture.CLAMP_ADDRESSMODE;
+
+    scene._ltcTextures.LTC2.wrapU = Texture.CLAMP_ADDRESSMODE;
+    scene._ltcTextures.LTC2.wrapV = Texture.CLAMP_ADDRESSMODE;
+
+    scene.useDelayedTextureLoading = useDelayedTextureLoading;
+
+    DecodeLTCTextureDataAsync()
+        .then((textureData) => {
+            if (scene._ltcTextures) {
+                const ltc1 = scene._ltcTextures?.LTC1 as RawTexture;
+                ltc1.update(textureData[0]);
+
+                const ltc2 = scene._ltcTextures?.LTC2 as RawTexture;
+                ltc2.update(textureData[1]);
+
+                scene.onDisposeObservable.addOnce(() => {
+                    scene._ltcTextures?.LTC1.dispose();
+                    scene._ltcTextures?.LTC2.dispose();
+                });
+            }
+        })
+        .catch((error) => {
+            Logger.Error(`Area Light fail to get LTC textures data. Error: ${error}`);
+        });
+}
+
+/**
+ * Abstract Area Light class that servers as parent for all Area Lights implementations.
+ * The light is emitted from the area in the -Z direction.
+ */
+export abstract class AreaLight extends Light {
+    /**
+     * Area Light position.
+     */
+    public position: Vector3;
+
+    /**
+     * Creates a area light object.
+     * Documentation : https://doc.babylonjs.com/features/featuresDeepDive/lights/lights_introduction
+     * @param name The friendly name of the light
+     * @param position The position of the area light.
+     * @param scene The scene the light belongs to
+     */
+    constructor(name: string, position: Vector3, scene?: Scene) {
+        super(name, scene);
+        this.position = position;
+
+        if (!this._scene._ltcTextures) {
+            CreateSceneLTCTextures(this._scene);
+        }
+    }
+
+    public override transferTexturesToEffect(effect: Effect): Light {
+        if (this._scene._ltcTextures) {
+            effect.setTexture("areaLightsLTC1Sampler", this._scene._ltcTextures.LTC1);
+            effect.setTexture("areaLightsLTC2Sampler", this._scene._ltcTextures.LTC2);
+        }
+        return this;
+    }
+
+    /**
+     * Prepares the list of defines specific to the light type.
+     * @param defines the list of defines
+     * @param lightIndex defines the index of the light for the effect
+     */
+    public prepareLightSpecificDefines(defines: any, lightIndex: number): void {
+        defines["AREALIGHT" + lightIndex] = true;
+        defines["AREALIGHTUSED"] = true;
+    }
+
+    public override _isReady(): boolean {
+        if (this._scene._ltcTextures) {
+            return this._scene._ltcTextures.LTC1.isReady() && this._scene._ltcTextures.LTC2.isReady();
+        }
+
+        return false;
+    }
+}

packages/dev/core/src/Lights/index.ts

@@ -6,4 +6,6 @@ export * from "./directionalLight";
 export * from "./hemisphericLight";
 export * from "./pointLight";
 export * from "./spotLight";
+export * from "./areaLight";
+export * from "./rectAreaLight";
 export * from "./IES/iesLoader";

packages/dev/core/src/Lights/light.ts

@@ -106,6 +106,11 @@ export abstract class Light extends Node implements ISortableLight {
      */
     public static readonly LIGHTTYPEID_HEMISPHERICLIGHT = LightConstants.LIGHTTYPEID_HEMISPHERICLIGHT;
 
+    /**
+     * Light type const id of the area light.
+     */
+    public static readonly LIGHTTYPEID_RECT_AREALIGHT = LightConstants.LIGHTTYPEID_RECT_AREALIGHT;
+
     /**
      * Diffuse gives the basic color to an object.
      */
@@ -923,4 +928,11 @@ export abstract class Light extends Node implements ISortableLight {
      * @param lightIndex defines the index of the light for the effect
      */
     public abstract prepareLightSpecificDefines(defines: any, lightIndex: number): void;
+
+    /**
+     * @internal
+     */
+    public _isReady() {
+        return true;
+    }
 }

packages/dev/core/src/Lights/lightConstants.ts

@@ -86,6 +86,11 @@ export class LightConstants {
      */
     public static readonly LIGHTTYPEID_HEMISPHERICLIGHT = 3;
 
+    /**
+     * Light type const id of the area light.
+     */
+    public static readonly LIGHTTYPEID_RECT_AREALIGHT = 4;
+
     /**
      * Sort function to order lights for rendering.
      * @param a First Light object to compare to second.

packages/dev/core/src/Lights/rectAreaLight.ts

@@ -0,0 +1,142 @@
+import { Vector3 } from "../Maths/math.vector";
+import { Node } from "../node";
+import { Light } from "./light";
+import type { Effect } from "core/Materials/effect";
+import { RegisterClass } from "core/Misc/typeStore";
+import { serialize } from "../Misc/decorators";
+import type { Scene } from "core/scene";
+import { AreaLight } from "./areaLight";
+
+Node.AddNodeConstructor("Light_Type_4", (name, scene) => {
+    return () => new RectAreaLight(name, Vector3.Zero(), 1, 1, scene);
+});
+
+/**
+ * A rectangular area light defined by an unique point in world space, a width and a height.
+ * The light is emitted from the rectangular area in the -Z direction.
+ */
+export class RectAreaLight extends AreaLight {
+    private readonly _width: Vector3;
+    private readonly _height: Vector3;
+    protected readonly _pointTransformedPosition: Vector3;
+    protected readonly _pointTransformedWidth: Vector3;
+    protected readonly _pointTransformedHeight: Vector3;
+
+    /**
+     * Rect Area Light width.
+     */
+    @serialize()
+    public get width(): number {
+        return this._width.x;
+    }
+    /**
+     * Rect Area Light width.
+     */
+    public set width(value: number) {
+        this._width.x = value;
+    }
+
+    /**
+     * Rect Area Light height.
+     */
+    @serialize()
+    public get height(): number {
+        return this._height.y;
+    }
+    /**
+     * Rect Area Light height.
+     */
+    public set height(value: number) {
+        this._height.y = value;
+    }
+
+    /**
+     * Creates a rectangular area light object.
+     * Documentation : https://doc.babylonjs.com/features/featuresDeepDive/lights/lights_introduction
+     * @param name The friendly name of the light
+     * @param position The position of the area light.
+     * @param width The width of the area light.
+     * @param height The height of the area light.
+     * @param scene The scene the light belongs to
+     */
+    constructor(name: string, position: Vector3, width: number, height: number, scene?: Scene) {
+        super(name, position, scene);
+        this._width = new Vector3(width, 0, 0);
+        this._height = new Vector3(0, height, 0);
+        this._pointTransformedPosition = Vector3.Zero();
+        this._pointTransformedWidth = Vector3.Zero();
+        this._pointTransformedHeight = Vector3.Zero();
+    }
+
+    /**
+     * Returns the string "RectAreaLight"
+     * @returns the class name
+     */
+    public override getClassName(): string {
+        return "RectAreaLight";
+    }
+
+    /**
+     * Returns the integer 4.
+     * @returns The light Type id as a constant defines in Light.LIGHTTYPEID_x
+     */
+    public override getTypeID(): number {
+        return Light.LIGHTTYPEID_RECT_AREALIGHT;
+    }
+
+    protected _buildUniformLayout(): void {
+        this._uniformBuffer.addUniform("vLightData", 4);
+        this._uniformBuffer.addUniform("vLightDiffuse", 4);
+        this._uniformBuffer.addUniform("vLightSpecular", 4);
+        this._uniformBuffer.addUniform("vLightWidth", 4);
+        this._uniformBuffer.addUniform("vLightHeight", 4);
+        this._uniformBuffer.addUniform("shadowsInfo", 3);
+        this._uniformBuffer.addUniform("depthValues", 2);
+        this._uniformBuffer.create();
+    }
+
+    protected _computeTransformedInformation(): boolean {
+        if (this.parent && this.parent.getWorldMatrix) {
+            Vector3.TransformCoordinatesToRef(this.position, this.parent.getWorldMatrix(), this._pointTransformedPosition);
+            Vector3.TransformNormalToRef(this._width, this.parent.getWorldMatrix(), this._pointTransformedWidth);
+            Vector3.TransformNormalToRef(this._height, this.parent.getWorldMatrix(), this._pointTransformedHeight);
+            return true;
+        }
+
+        return false;
+    }
+
+    /**
+     * Sets the passed Effect "effect" with the PointLight transformed position (or position, if none) and passed name (string).
+     * @param effect The effect to update
+     * @param lightIndex The index of the light in the effect to update
+     * @returns The point light
+     */
+    public transferToEffect(effect: Effect, lightIndex: string): RectAreaLight {
+        if (this._computeTransformedInformation()) {
+            this._uniformBuffer.updateFloat4("vLightData", this._pointTransformedPosition.x, this._pointTransformedPosition.y, this._pointTransformedPosition.z, 0, lightIndex);
+            this._uniformBuffer.updateFloat4("vLightWidth", this._pointTransformedWidth.x / 2, this._pointTransformedWidth.y / 2, this._pointTransformedWidth.z / 2, 0, lightIndex);
+            this._uniformBuffer.updateFloat4(
+                "vLightHeight",
+                this._pointTransformedHeight.x / 2,
+                this._pointTransformedHeight.y / 2,
+                this._pointTransformedHeight.z / 2,
+                0,
+                lightIndex
+            );
+        } else {
+            this._uniformBuffer.updateFloat4("vLightData", this.position.x, this.position.y, this.position.z, 0.0, lightIndex);
+            this._uniformBuffer.updateFloat4("vLightWidth", this._width.x / 2, this._width.y / 2, this._width.z / 2, 0.0, lightIndex);
+            this._uniformBuffer.updateFloat4("vLightHeight", this._height.x / 2, this._height.y / 2, this._height.z / 2, 0.0, lightIndex);
+        }
+        return this;
+    }
+
+    public transferToNodeMaterialEffect(effect: Effect, lightDataUniformName: string) {
+        // TO DO: Implement this to add support for NME.
+        return this;
+    }
+}
+
+// Register Class Name
+RegisterClass("BABYLON.RectAreaLight", RectAreaLight);

packages/dev/core/src/Materials/PBR/pbrBaseMaterial.ts

@@ -281,6 +281,7 @@ export class PBRMaterialDefines extends MaterialDefines implements IImageProcess
     public LOGARITHMICDEPTH = false;
     public CAMERA_ORTHOGRAPHIC = false;
     public CAMERA_PERSPECTIVE = false;
+    public AREALIGHTSUPPORTED = true;
 
     public FORCENORMALFORWARD = false;
 
@@ -1213,6 +1214,15 @@ export abstract class PBRBaseMaterial extends PushMaterial {
             }
         }
 
+        // Check if Area Lights have LTC texture.
+        if (defines["AREALIGHTUSED"]) {
+            for (let index = 0; index < mesh.lightSources.length; index++) {
+                if (!mesh.lightSources[index]._isReady()) {
+                    return false;
+                }
+            }
+        }
+
         if (!engine.getCaps().standardDerivatives && !mesh.isVerticesDataPresent(VertexBuffer.NormalKind)) {
             mesh.createNormals(true);
             Logger.Warn("PBRMaterial: Normals have been created for the mesh: " + mesh.name);
@@ -1497,6 +1507,8 @@ export abstract class PBRBaseMaterial extends PushMaterial {
             "oitDepthSampler",
             "oitFrontColorSampler",
             "icdfSampler",
+            "areaLightsLTC1Sampler",
+            "areaLightsLTC2Sampler",
         ];
 
         const uniformBuffers = ["Material", "Scene", "Mesh"];