Add support for using BC5 and EAC_RG compressed textures as normal maps.

src/constants.js

@@ -1280,6 +1280,30 @@
  */
 export const SRGBTransfer = 'srgb';
 
+/**
+ * No normal map packing.
+ * 
+ * @type {string}
+ * @constant
+ */
+export const NoNormalPacking = '';
+
+/**
+ * Normal RG packing.
+ * 
+ * @type {string}
+ * @constant
+ */
+export const NormalRGPacking = 'rg';
+
+/**
+ * Normal GA packing.
+ * 
+ * @type {string}
+ * @constant
+ */
+export const NormalGAPacking = 'ga';
+
 /**
  * Sets the stencil buffer value to `0`.
  *

src/nodes/accessors/MaterialNode.js

@@ -235,6 +235,12 @@ class MaterialNode extends Node {
 				node = normalMap( this.getTexture( 'normal' ), this.getCache( 'normalScale', 'vec2' ) );
 				node.normalMapType = material.normalMapType;
 
+				if ( material.normalMap.userData?.unpackNormal ) {
+
+					node.unpackNormal = material.normalMap.userData.unpackNormal;
+
+				}
+
 			} else if ( material.bumpMap ) {
 
 				node = bumpMap( this.getTexture( 'bump' ).r, this.getFloat( 'bumpScale' ) );

src/nodes/display/NormalMapNode.js

@@ -2,9 +2,10 @@
 
 import { normalView, transformNormalToView } from '../accessors/Normal.js';
 import { TBNViewMatrix } from '../accessors/AccessorsUtils.js';
-import { nodeProxy, vec3 } from '../tsl/TSLBase.js';
+import { nodeProxy, vec3, float } from '../tsl/TSLBase.js';
+import { dot, sqrt, saturate } from '../math/MathNode.js';
 
-import { TangentSpaceNormalMap, ObjectSpaceNormalMap } from '../../constants.js';
+import { TangentSpaceNormalMap, ObjectSpaceNormalMap, NoNormalPacking, NormalRGPacking, NormalGAPacking } from '../../constants.js';
 import { directionToFaceDirection } from './FrontFacingNode.js';
 
 /**
@@ -57,14 +58,48 @@
 		 */
 		this.normalMapType = TangentSpaceNormalMap;
 
+		/**
+		 * Controls how to unpack the sampled normal map values.
+		 *
+		 * @type {string}
+		 * @default NoNormalPacking
+		 */
+		this.unpackNormal = NoNormalPacking;
+
 	}
 
 	setup( { material } ) {
 
-		const { normalMapType, scaleNode } = this;
+		const { normalMapType, scaleNode, unpackNormal } = this;
 
 		let normalMap = this.node.mul( 2.0 ).sub( 1.0 );
 
+		if ( normalMapType === TangentSpaceNormalMap ) {
+
+			if ( unpackNormal == NormalRGPacking ) {
+
+				normalMap = unpackRGNormal( normalMap );
+
+			} else if ( unpackNormal == NormalGAPacking ) {
+
+				normalMap = unpackGANormal( normalMap );
+
+			} else if ( unpackNormal != NoNormalPacking ) {
+
+				console.error( `THREE.NodeMaterial: Unexpected unpack normal mode: ${ unpackNormal }` );
+
+			}
+
+		} else {
+
+			if ( unpackNormal != NoNormalPacking ) {
+
+				console.error( `THREE.NodeMaterial: Normal map type '${ normalMapType }' is not compatible with unpack normal mode '${ unpackNormal }'` );
+
+			}
+
+		}
+
 		if ( scaleNode !== null ) {
 
 			let scale = scaleNode;

src/nodes/utils/Packing.js

@@ -19,3 +19,25 @@
  * @return {Node<vec3>} The direction.
  */
 export const colorToDirection = ( node ) => nodeObject( node ).mul( 2.0 ).sub( 1 );
+
+/**
+ * Unpacks RG-packed normals by reconstructing their Z component by projecting it to the hemisphere.
+ * The XY coordinates of the input normal are expected to be in the [-1, 1] range.
+ *
+ * @tsl
+ * @function
+ * @param {Node<vec3>} node - The packed normal to unpack.
+ * @return {Node<vec3>} The unpacked normal.
+ */
+export const unpackRGNormal = ( normal ) => vec3( normal.xy, sqrt( saturate( float( 1.0 ).sub( dot( normal.xy, normal.xy ) ) ) ) );
+
+/**
+ * Unpacks GA-packed normals by reconstructing their Z component by projecting it to the hemisphere. 
+ * The XY coordinates of the input normal are expected to be in the [-1, 1] range.
+ *
+ * @tsl
+ * @function
+ * @param {Node<vec3>} node - The packed normal to unpack.
+ * @return {Node<vec3>} The unpacked normal.
+ */
+export const unpackGANormal = ( normal ) => vec3( normal.yw, sqrt( saturate( float( 1.0 ).sub( dot( normal.yw, normal.yw ) ) ) ) );