Added arc_2d function for gizmos

crates/bevy_gizmos/src/gizmos.rs

@@ -459,6 +459,51 @@ impl<'s> Gizmos<'s> {
  }
  }
 
+ /// Draw an arc, which is a part of the circumference of a circle.
+ ///
+ /// # Arguments
+ /// - `position` sets the center of this circle.
+ /// - `radius` controls the distance from `position` to this arc, and thus its curvature.
+ /// - `direction_angle` sets the angle in radians between `position` and the midpoint of the arc.
+ /// -`arc_angle` sets the length of this arc, in radians.
+ ///
+ /// # Example
+ /// ```
+ /// # use bevy_gizmos::prelude::*;
+ /// # use bevy_render::prelude::*;
+ /// # use bevy_math::prelude::*;
+ /// # use std::f32::consts::PI;
+ /// fn system(mut gizmos: Gizmos) {
+ /// gizmos.arc_2d(Vec2::ZERO, 0., PI / 4., 1., Color::GREEN);
+ ///
+ /// // Arcs have 32 line-segments by default.
+ /// // You may want to increase this for larger arcs.
+ /// gizmos
+ /// .arc_2d(Vec2::ZERO, 0., PI / 4., 5., Color::RED)
+ /// .segments(64);
+ /// }
+ /// # bevy_ecs::system::assert_is_system(system);
+ /// ```
+ #[inline]
+ pub fn arc_2d(
+ &mut self,
+ position: Vec2,
+ direction_angle: f32,
+ arc_angle: f32,
+ radius: f32,
+ color: Color,
+ ) -> Arc2dBuilder<'_, 's> {
+ Arc2dBuilder {
+ gizmos: self,
+ position,
+ direction_angle,
+ arc_angle,
+ radius,
+ color,
+ segments: None,
+ }
+ }
+
  /// Draw a wireframe rectangle.
  ///
  /// # Example
@@ -589,6 +634,54 @@ impl Drop for Circle2dBuilder<'_, '_> {
  }
 }
 
+/// A builder returned by [`Gizmos::arc_2d`].
+pub struct Arc2dBuilder<'a, 's> {
+ gizmos: &'a mut Gizmos<'s>,
+ position: Vec2,
+ direction_angle: f32,
+ arc_angle: f32,
+ radius: f32,
+ color: Color,
+ segments: Option<usize>,
+}
+
+impl Arc2dBuilder<'_, '_> {
+ /// Set the number of line-segements for this arc.
+ pub fn segments(mut self, segments: usize) -> Self {
+ self.segments = Some(segments);
+ self
+ }
+}
+
+impl Drop for Arc2dBuilder<'_, '_> {
+ fn drop(&mut self) {
+ let segments = match self.segments {
+ Some(segments) => segments,
+ // Do a linear interpolation between 1 and `DEFAULT_CIRCLE_SEGMENTS`
+ // using the arc angle as scalar.
+ None => ((self.arc_angle.abs() / TAU) * DEFAULT_CIRCLE_SEGMENTS as f32).ceil() as usize,
+ };
+
+ let positions = arc_inner(self.direction_angle, self.arc_angle, self.radius, segments)
+ .map(|vec2| (vec2 + self.position));
+ self.gizmos.linestrip_2d(positions, self.color);
+ }
+}
+
+fn arc_inner(
+ direction_angle: f32,
+ arc_angle: f32,
+ radius: f32,
+ segments: usize,
+) -> impl Iterator<Item = Vec2> {
+ (0..segments + 1).map(move |i| {
+ let start = direction_angle - arc_angle / 2.;
+
+ let angle = start + (i as f32 * (arc_angle / segments as f32));
+ Vec2::from(angle.sin_cos()) * radius
+ })
+}
+
 fn circle_inner(radius: f32, segments: usize) -> impl Iterator<Item = Vec2> {
  (0..segments + 1).map(move |i| {
  let angle = i as f32 * TAU / segments as f32;

examples/2d/2d_gizmos.rs

@@ -1,5 +1,7 @@
 //! This example demonstrates Bevy's immediate mode drawing API intended for visual debugging.
 
+use std::f32::consts::PI;
+
 use bevy::prelude::*;
 
 fn main() {
@@ -38,4 +40,8 @@ fn system(mut gizmos: Gizmos, time: Res<Time>) {
  gizmos.circle_2d(Vec2::ZERO, 120., Color::BLACK);
  // You may want to increase this for larger circles.
  gizmos.circle_2d(Vec2::ZERO, 300., Color::NAVY).segments(64);
+
+ // Arcs default amount of segments is linerarly interpolated between
+ // 1 and 32, using the arc length as scalar.
+ gizmos.arc_2d(Vec2::ZERO, sin / 10., PI / 2., 350., Color::ORANGE_RED);
 }