Add convenience methods

docs/api/en/core/BufferAttribute.html

@@ -113,6 +113,18 @@
 
 		<h2>Methods</h2>
 
+		<h3>[method:this applyMatrix3]( [param:Matrix3 m] )</h3>
+		<p>Applies matrix [page:Matrix3 m] to every Vector3 element of this BufferAttribute.</p>
+
+		<h3>[method:this applyMatrix4]( [param:Matrix4 m] )</h3>
+		<p>Applies matrix [page:Matrix4 m] to every Vector3 element of this BufferAttribute.</p>
+
+		<h3>[method:this applyNormalMatrix]( [param:Matrix3 m] )</h3>
+		<p>Applies normal matrix [page:Matrix3 m] to every Vector3 element of this BufferAttribute.</p>
+
+		<h3>[method:this transformDirection]( [param:Matrix4 m] )</h3>
+		<p>Applies matrix [page:Matrix4 m] to every Vector3 element of this BufferAttribute, interpreting the elements as a direction vectors.</p>
+
 		<h3>[method:BufferAttribute clone]() </h3>
 		<p>Return a copy of this bufferAttribute.</p>
 

src/core/BufferAttribute.d.ts

@@ -43,6 +43,10 @@ export class BufferAttribute {
 	copyVector4sArray(
 		vectors: { x: number; y: number; z: number; w: number }[]
 	): this;
+	applyMatrix3( m: Matrix3 ): this;
+	applyMatrix4( m: Matrix4 ): this;
+	applyNormalMatrix( m: Matrix3 ): this;
+	transformDirection( m: Matrix4 ): this;
 	set(
 		value: ArrayLike<number> | ArrayBufferView,
 		offset?: number

src/core/BufferAttribute.js

@@ -8,6 +8,8 @@ import { StaticDrawUsage } from '../constants.js';
  * @author mrdoob / http://mrdoob.com/
  */
 
+var _vector = new Vector3();
+
 function BufferAttribute( array, itemSize, normalized ) {
 
 	if ( Array.isArray( array ) ) {
@@ -191,6 +193,78 @@ Object.assign( BufferAttribute.prototype, {
 
 	},
 
+	applyMatrix3: function ( m ) {
+
+		for ( var i = 0, l = this.count; i < l; i ++ ) {
+
+			_vector.x = this.getX( i );
+			_vector.y = this.getY( i );
+			_vector.z = this.getZ( i );
+
+			_vector.applyMatrix3( m );
+
+			this.setXYZ( i, _vector.x, _vector.y, _vector.z );
+
+		}
+
+		return this;
+
+	},
+
+	applyMatrix4: function ( m ) {
+
+		for ( var i = 0, l = this.count; i < l; i ++ ) {
+
+			_vector.x = this.getX( i );
+			_vector.y = this.getY( i );
+			_vector.z = this.getZ( i );
+
+			_vector.applyMatrix4( m );
+
+			this.setXYZ( i, _vector.x, _vector.y, _vector.z );
+
+		}
+
+		return this;
+
+	},
+
+	applyNormalMatrix: function ( m ) {
+
+		for ( var i = 0, l = this.count; i < l; i ++ ) {
+
+			_vector.x = this.getX( i );
+			_vector.y = this.getY( i );
+			_vector.z = this.getZ( i );
+
+			_vector.applyNormalMatrix( m );
+
+			this.setXYZ( i, _vector.x, _vector.y, _vector.z );
+
+		}
+
+		return this;
+
+	},
+
+	transformDirection: function ( m ) {
+
+		for ( var i = 0, l = this.count; i < l; i ++ ) {
+
+			_vector.x = this.getX( i );
+			_vector.y = this.getY( i );
+			_vector.z = this.getZ( i );
+
+			_vector.transformDirection( m );
+
+			this.setXYZ( i, _vector.x, _vector.y, _vector.z );
+
+		}
+
+		return this;
+
+	},
+
 	set: function ( value, offset ) {
 
 		if ( offset === undefined ) offset = 0;