From 6892b2dc2b223dc8ed8a4953137cf826e27a6532 Mon Sep 17 00:00:00 2001
From: ira <JustTheCoolDude@gmail.com>
Date: Mon, 21 Nov 2022 13:19:43 +0000
Subject: [PATCH] Add `Transform::look_to` (#6692)

Add a method to rotate a transform to point towards a direction.

Also updated the docs to link to `forward` and `up` instead of mentioning local negative `Z` and local `Y`.

Unfortunately, links to methods don't work in rust-analyzer :(

Co-authored-by: Devil Ira <justthecooldude@gmail.com>
---
 .../src/components/transform.rs               | 27 ++++++++++++++-----
 1 file changed, 21 insertions(+), 6 deletions(-)

diff --git a/crates/bevy_transform/src/components/transform.rs b/crates/bevy_transform/src/components/transform.rs
index 439f3c53a1e05..a94ff06bda17a 100644
--- a/crates/bevy_transform/src/components/transform.rs
+++ b/crates/bevy_transform/src/components/transform.rs
@@ -117,9 +117,8 @@ impl Transform {
         }
     }
 
-    /// Updates and returns this [`Transform`] by rotating it so that its unit
-    /// vector in the local negative `Z` direction is toward `target` and its
-    /// unit vector in the local `Y` direction is toward `up`.
+    /// Returns this [`Transform`] with a new rotation so that [`Transform::forward`]
+    /// points towards the `target` position and [`Transform::up`] points towards `up`.
     #[inline]
     #[must_use]
     pub fn looking_at(mut self, target: Vec3, up: Vec3) -> Self {
@@ -127,6 +126,15 @@ impl Transform {
         self
     }
 
+    /// Returns this [`Transform`] with a new rotation so that [`Transform::forward`]
+    /// points in the given `direction` and [`Transform::up`] points towards `up`.
+    #[inline]
+    #[must_use]
+    pub fn looking_to(mut self, direction: Vec3, up: Vec3) -> Self {
+        self.look_to(direction, up);
+        self
+    }
+
     /// Returns this [`Transform`] with a new translation.
     #[inline]
     #[must_use]
@@ -314,11 +322,18 @@ impl Transform {
         self.rotate(rotation);
     }
 
-    /// Rotates this [`Transform`] so that its local negative `Z` direction is toward
-    /// `target` and its local `Y` direction is toward `up`.
+    /// Rotates this [`Transform`] so that [`Transform::forward`] points towards the `target` position,
+    /// and [`Transform::up`] points towards `up`.
     #[inline]
     pub fn look_at(&mut self, target: Vec3, up: Vec3) {
-        let forward = Vec3::normalize(self.translation - target);
+        self.look_to(target - self.translation, up);
+    }
+
+    /// Rotates this [`Transform`] so that [`Transform::forward`] points in the given `direction`
+    /// and [`Transform::up`] points towards `up`.
+    #[inline]
+    pub fn look_to(&mut self, direction: Vec3, up: Vec3) {
+        let forward = -direction.normalize();
         let right = up.cross(forward).normalize();
         let up = forward.cross(right);
         self.rotation = Quat::from_mat3(&Mat3::from_cols(right, up, forward));