From f07b1396ee52aa6fd8063d327e96a1dbcde79ac3 Mon Sep 17 00:00:00 2001
From: ycw <ycw7788@gmail.com>
Date: Thu, 23 Feb 2023 12:20:02 +0800
Subject: [PATCH] LineCurve/LineCurve3: Override `getTangent()` and
 `getTangentAt()`. (#25544)

* add tests `.getTangentAt`

* override `.getTangent*`

* use `.subVectors`

* revert unused fn par `_t` to `t`
---
 src/extras/curves/LineCurve.js                 | 10 ++++++----
 src/extras/curves/LineCurve3.js                | 13 +++++++++++++
 test/unit/src/extras/curves/LineCurve.tests.js |  7 ++++++-
 3 files changed, 25 insertions(+), 5 deletions(-)

diff --git a/src/extras/curves/LineCurve.js b/src/extras/curves/LineCurve.js
index 4b14d5edb6aad8..0a636898ce30cb 100644
--- a/src/extras/curves/LineCurve.js
+++ b/src/extras/curves/LineCurve.js
@@ -42,13 +42,15 @@ class LineCurve extends Curve {
 
 	}
 
-	getTangent( t, optionalTarget ) {
+	getTangent( t, optionalTarget = new Vector2() ) {
 
-		const tangent = optionalTarget || new Vector2();
+		return optionalTarget.subVectors( this.v2, this.v1 ).normalize();
 
-		tangent.copy( this.v2 ).sub( this.v1 ).normalize();
+	}
+
+	getTangentAt( u, optionalTarget ) {
 
-		return tangent;
+		return this.getTangent( u, optionalTarget );
 
 	}
 
diff --git a/src/extras/curves/LineCurve3.js b/src/extras/curves/LineCurve3.js
index c315c3869f3024..f83a63914fed22 100644
--- a/src/extras/curves/LineCurve3.js
+++ b/src/extras/curves/LineCurve3.js
@@ -39,6 +39,19 @@ class LineCurve3 extends Curve {
 		return this.getPoint( u, optionalTarget );
 
 	}
+
+	getTangent( t, optionalTarget = new Vector3() ) {
+
+		return optionalTarget.subVectors( this.v2, this.v1 ).normalize();
+
+	}
+
+	getTangentAt( u, optionalTarget ) {
+
+		return this.getTangent( u, optionalTarget );
+
+	}
+
 	copy( source ) {
 
 		super.copy( source );
diff --git a/test/unit/src/extras/curves/LineCurve.tests.js b/test/unit/src/extras/curves/LineCurve.tests.js
index 04ce06a6b02d26..3fff1b3f477e1f 100644
--- a/test/unit/src/extras/curves/LineCurve.tests.js
+++ b/test/unit/src/extras/curves/LineCurve.tests.js
@@ -106,7 +106,7 @@ export default QUnit.module( 'Extras', () => {
 
 			} );
 
-			QUnit.test( 'getTangent', ( assert ) => {
+			QUnit.test( 'getTangent/getTangentAt', ( assert ) => {
 
 				const curve = _curve;
 				const tangent = new Vector2();
@@ -117,6 +117,11 @@ export default QUnit.module( 'Extras', () => {
 				assert.numEqual( tangent.x, expectedTangent, 'tangent.x correct' );
 				assert.numEqual( tangent.y, expectedTangent, 'tangent.y correct' );
 
+				curve.getTangentAt( 0, tangent );
+
+				assert.numEqual( tangent.x, expectedTangent, 'tangentAt.x correct' );
+				assert.numEqual( tangent.y, expectedTangent, 'tangentAt.y correct' );
+
 			} );
 
 			QUnit.todo( 'copy', ( assert ) => {