Implement From translation and rotation for isometries (#15733)

# Objective

Several of our APIs (namely gizmos and bounding) use isometries on
current Bevy main. This is nicer than separate properties in a lot of
cases, but users have still expressed usability concerns.

One problem is that in a lot of cases, you only care about e.g.
translation, so you end up with this:

```rust
gizmos.cross_2d(
    Isometry2d::from_translation(Vec2::new(-160.0, 120.0)),
    12.0,
    FUCHSIA,
);
```

The isometry adds quite a lot of length and verbosity, and isn't really
that relevant since only the translation is important here.

It would be nice if you could use the translation directly, and only
supply an isometry if both translation and rotation are needed. This
would make the following possible:

```rust
gizmos.cross_2d(Vec2::new(-160.0, 120.0), 12.0, FUCHSIA);
```

removing a lot of verbosity.

## Solution

Implement `From<Vec2>` and `From<Rot2>` for `Isometry2d`, and
`From<Vec3>`, `From<Vec3A>`, and `From<Quat>` for `Isometry3d`. These
are lossless conversions that fit the semantics of `From`.

This makes the proposed API possible! The methods must now simply take
an `impl Into<IsometryNd>`, and this works:

```rust
gizmos.cross_2d(Vec2::new(-160.0, 120.0), 12.0, FUCHSIA);
```

crates/bevy_gizmos/src/arcs.rs

@@ -50,14 +50,14 @@ where
  #[inline]
  pub fn arc_2d(
  &mut self,
- isometry: Isometry2d,
+ isometry: impl Into<Isometry2d>,
  arc_angle: f32,
  radius: f32,
  color: impl Into<Color>,
  ) -> Arc2dBuilder<'_, 'w, 's, Config, Clear> {
  Arc2dBuilder {
  gizmos: self,
- isometry,
+ isometry: isometry.into(),
  arc_angle,
  radius,
  color: color.into(),
@@ -176,13 +176,13 @@ where
  &mut self,
  angle: f32,
  radius: f32,
- isometry: Isometry3d,
+ isometry: impl Into<Isometry3d>,
  color: impl Into<Color>,
  ) -> Arc3dBuilder<'_, 'w, 's, Config, Clear> {
  Arc3dBuilder {
  gizmos: self,
  start_vertex: Vec3::X,
- isometry,
+ isometry: isometry.into(),
  angle,
  radius,
  color: color.into(),

crates/bevy_gizmos/src/circles.rs

@@ -51,13 +51,13 @@ where
  #[inline]
  pub fn ellipse(
  &mut self,
- isometry: Isometry3d,
+ isometry: impl Into<Isometry3d>,
  half_size: Vec2,
  color: impl Into<Color>,
  ) -> EllipseBuilder<'_, 'w, 's, Config, Clear> {
  EllipseBuilder {
  gizmos: self,
- isometry,
+ isometry: isometry.into(),
  half_size,
  color: color.into(),
  resolution: DEFAULT_CIRCLE_RESOLUTION,
@@ -92,13 +92,13 @@ where
  #[inline]
  pub fn ellipse_2d(
  &mut self,
- isometry: Isometry2d,
+ isometry: impl Into<Isometry2d>,
  half_size: Vec2,
  color: impl Into<Color>,
  ) -> Ellipse2dBuilder<'_, 'w, 's, Config, Clear> {
  Ellipse2dBuilder {
  gizmos: self,
- isometry,
+ isometry: isometry.into(),
  half_size,
  color: color.into(),
  resolution: DEFAULT_CIRCLE_RESOLUTION,
@@ -131,13 +131,13 @@ where
  #[inline]
  pub fn circle(
  &mut self,
- isometry: Isometry3d,
+ isometry: impl Into<Isometry3d>,
  radius: f32,
  color: impl Into<Color>,
  ) -> EllipseBuilder<'_, 'w, 's, Config, Clear> {
  EllipseBuilder {
  gizmos: self,
- isometry,
+ isometry: isometry.into(),
  half_size: Vec2::splat(radius),
  color: color.into(),
  resolution: DEFAULT_CIRCLE_RESOLUTION,
@@ -172,13 +172,13 @@ where
  #[inline]
  pub fn circle_2d(
  &mut self,
- isometry: Isometry2d,
+ isometry: impl Into<Isometry2d>,
  radius: f32,
  color: impl Into<Color>,
  ) -> Ellipse2dBuilder<'_, 'w, 's, Config, Clear> {
  Ellipse2dBuilder {
  gizmos: self,
- isometry,
+ isometry: isometry.into(),
  half_size: Vec2::splat(radius),
  color: color.into(),
  resolution: DEFAULT_CIRCLE_RESOLUTION,
@@ -214,14 +214,14 @@ where
  #[inline]
  pub fn sphere(
  &mut self,
- isometry: Isometry3d,
+ isometry: impl Into<Isometry3d>,
  radius: f32,
  color: impl Into<Color>,
  ) -> SphereBuilder<'_, 'w, 's, Config, Clear> {
  SphereBuilder {
  gizmos: self,
  radius,
- isometry,
+ isometry: isometry.into(),
  color: color.into(),
  resolution: DEFAULT_CIRCLE_RESOLUTION,
  }

crates/bevy_gizmos/src/cross.rs

@@ -30,7 +30,13 @@ where
  /// }
  /// # bevy_ecs::system::assert_is_system(system);
  /// ```
- pub fn cross(&mut self, isometry: Isometry3d, half_size: f32, color: impl Into<Color>) {
+ pub fn cross(
+ &mut self,
+ isometry: impl Into<Isometry3d>,
+ half_size: f32,
+ color: impl Into<Color>,
+ ) {
+ let isometry = isometry.into();
  let color: Color = color.into();
  [Vec3::X, Vec3::Y, Vec3::Z]
  .map(|axis| axis * half_size)
@@ -59,7 +65,13 @@ where
  /// }
  /// # bevy_ecs::system::assert_is_system(system);
  /// ```
- pub fn cross_2d(&mut self, isometry: Isometry2d, half_size: f32, color: impl Into<Color>) {
+ pub fn cross_2d(
+ &mut self,
+ isometry: impl Into<Isometry2d>,
+ half_size: f32,
+ color: impl Into<Color>,
+ ) {
+ let isometry = isometry.into();
  let color: Color = color.into();
  [Vec2::X, Vec2::Y]
  .map(|axis| axis * half_size)

crates/bevy_gizmos/src/gizmos.rs

@@ -482,10 +482,11 @@ where
  /// # bevy_ecs::system::assert_is_system(system);
  /// ```
  #[inline]
- pub fn rect(&mut self, isometry: Isometry3d, size: Vec2, color: impl Into<Color>) {
+ pub fn rect(&mut self, isometry: impl Into<Isometry3d>, size: Vec2, color: impl Into<Color>) {
  if !self.enabled {
  return;
  }
+ let isometry = isometry.into();
  let [tl, tr, br, bl] = rect_inner(size).map(|vec2| isometry * vec2.extend(0.));
  self.linestrip([tl, tr, br, bl, tl], color);
  }
@@ -709,10 +710,16 @@ where
  /// # bevy_ecs::system::assert_is_system(system);
  /// ```
  #[inline]
- pub fn rect_2d(&mut self, isometry: Isometry2d, size: Vec2, color: impl Into<Color>) {
+ pub fn rect_2d(
+ &mut self,
+ isometry: impl Into<Isometry2d>,
+ size: Vec2,
+ color: impl Into<Color>,
+ ) {
  if !self.enabled {
  return;
  }
+ let isometry = isometry.into();
  let [tl, tr, br, bl] = rect_inner(size).map(|vec2| isometry * vec2);
  self.linestrip_2d([tl, tr, br, bl, tl], color);
  }

crates/bevy_gizmos/src/grid.rs

@@ -218,14 +218,14 @@ where
  /// ```
  pub fn grid(
  &mut self,
- isometry: Isometry3d,
+ isometry: impl Into<Isometry3d>,
  cell_count: UVec2,
  spacing: Vec2,
  color: impl Into<Color>,
  ) -> GridBuilder2d<'_, 'w, 's, Config, Clear> {
  GridBuilder2d {
  gizmos: self,
- isometry,
+ isometry: isometry.into(),
  spacing,
  cell_count,
  skew: Vec2::ZERO,
@@ -272,14 +272,14 @@ where
  /// ```
  pub fn grid_3d(
  &mut self,
- isometry: Isometry3d,
+ isometry: impl Into<Isometry3d>,
  cell_count: UVec3,
  spacing: Vec3,
  color: impl Into<Color>,
  ) -> GridBuilder3d<'_, 'w, 's, Config, Clear> {
  GridBuilder3d {
  gizmos: self,
- isometry,
+ isometry: isometry.into(),
  spacing,
  cell_count,
  skew: Vec3::ZERO,
@@ -326,11 +326,12 @@ where
  /// ```
  pub fn grid_2d(
  &mut self,
- isometry: Isometry2d,
+ isometry: impl Into<Isometry2d>,
  cell_count: UVec2,
  spacing: Vec2,
  color: impl Into<Color>,
  ) -> GridBuilder2d<'_, 'w, 's, Config, Clear> {
+ let isometry = isometry.into();
  GridBuilder2d {
  gizmos: self,
  isometry: Isometry3d::new(

crates/bevy_gizmos/src/light.rs

@@ -41,20 +41,10 @@ fn point_light_gizmo(
 ) {
  let position = transform.translation();
  gizmos
- .primitive_3d(
- &Sphere {
- radius: point_light.radius,
- },
- Isometry3d::from_translation(position),
- color,
- )
+ .primitive_3d(&Sphere::new(point_light.radius), position, color)
  .resolution(16);
  gizmos
- .sphere(
- Isometry3d::from_translation(position),
- point_light.range,
- color,
- )
+ .sphere(position, point_light.range, color)
  .resolution(32);
 }
 
@@ -68,13 +58,7 @@ fn spot_light_gizmo(
 ) {
  let (_, rotation, translation) = transform.to_scale_rotation_translation();
  gizmos
- .primitive_3d(
- &Sphere {
- radius: spot_light.radius,
- },
- Isometry3d::from_translation(translation),
- color,
- )
+ .primitive_3d(&Sphere::new(spot_light.radius), translation, color)
  .resolution(16);
 
  // Offset the tip of the cone to the light position.