bevy/crates/bevy_gizmos/src/arcs.rs
Robert Walter 210c79c9f9
Gizmos: arc_2d utility helpers (#14932)
# Objective

Since https://github.com/bevyengine/bevy/pull/14731 is merged, it
unblocked a few utility methods for 2D arcs. In 2D the pendant to
`long_arc_3d_between` and `short_arc_3d_between` are missing. Since
`arc_2d` can be a bit hard to use, this PR is trying to plug some holes
in the `arcs` API.

## Solution

Implement

- `long_arc_2d_between(center, from, tp, color)`
- `short_arc_2d_between(center, from, tp, color)`

## Testing

- There are new doc tests
- The `2d_gizmos` example has been extended a bit to include a few more
arcs which can easily be checked with respect to the grid

---

## Showcase


![image](https://github.com/user-attachments/assets/b90ad8b1-86c2-4304-a481-4f9a5246c457)

Code related to the screenshot (from outer = first line to inner = last
line)

```rust
    my_gizmos.arc_2d(Isometry2d::IDENTITY, FRAC_PI_2, 80.0, ORANGE_RED);
    my_gizmos.short_arc_2d_between(Vec2::ZERO, Vec2::X * 40.0, Vec2::Y * 40.0, ORANGE_RED);
    my_gizmos.long_arc_2d_between(Vec2::ZERO, Vec2::X * 20.0, Vec2::Y * 20.0, ORANGE_RED);
```
2024-08-28 11:33:11 +00:00

531 lines
17 KiB
Rust

//! Additional [`Gizmos`] Functions -- Arcs
//!
//! Includes the implementation of [`Gizmos::arc_2d`],
//! and assorted support items.
use crate::circles::DEFAULT_CIRCLE_RESOLUTION;
use crate::prelude::{GizmoConfigGroup, Gizmos};
use bevy_color::Color;
use bevy_math::{Isometry2d, Isometry3d, Quat, Rot2, Vec2, Vec3};
use std::f32::consts::{FRAC_PI_2, TAU};
// === 2D ===
impl<'w, 's, Config, Clear> Gizmos<'w, 's, Config, Clear>
where
Config: GizmoConfigGroup,
Clear: 'static + Send + Sync,
{
/// Draw an arc, which is a part of the circumference of a circle, in 2D.
///
/// This should be called for each frame the arc needs to be rendered.
///
/// # Arguments
/// - `isometry` defines the translation and rotation of the arc.
/// - the translation specifies the center of the arc
/// - the rotation is counter-clockwise starting from `Vec2::Y`
/// - `arc_angle` sets the length of this arc, in radians.
/// - `radius` controls the distance from `position` to this arc, and thus its curvature.
/// - `color` sets the color to draw the arc.
///
/// # Example
/// ```
/// # use bevy_gizmos::prelude::*;
/// # use bevy_math::prelude::*;
/// # use std::f32::consts::FRAC_PI_4;
/// # use bevy_color::palettes::basic::{GREEN, RED};
/// fn system(mut gizmos: Gizmos) {
/// gizmos.arc_2d(Isometry2d::IDENTITY, FRAC_PI_4, 1., GREEN);
///
/// // Arcs have 32 line-segments by default.
/// // You may want to increase this for larger arcs.
/// gizmos
/// .arc_2d(Isometry2d::IDENTITY, FRAC_PI_4, 5., RED)
/// .resolution(64);
/// }
/// # bevy_ecs::system::assert_is_system(system);
/// ```
#[inline]
pub fn arc_2d(
&mut self,
isometry: Isometry2d,
arc_angle: f32,
radius: f32,
color: impl Into<Color>,
) -> Arc2dBuilder<'_, 'w, 's, Config, Clear> {
Arc2dBuilder {
gizmos: self,
isometry,
arc_angle,
radius,
color: color.into(),
resolution: None,
}
}
}
/// A builder returned by [`Gizmos::arc_2d`].
pub struct Arc2dBuilder<'a, 'w, 's, Config, Clear>
where
Config: GizmoConfigGroup,
Clear: 'static + Send + Sync,
{
gizmos: &'a mut Gizmos<'w, 's, Config, Clear>,
isometry: Isometry2d,
arc_angle: f32,
radius: f32,
color: Color,
resolution: Option<u32>,
}
impl<Config, Clear> Arc2dBuilder<'_, '_, '_, Config, Clear>
where
Config: GizmoConfigGroup,
Clear: 'static + Send + Sync,
{
/// Set the number of lines used to approximate the geometry of this arc.
pub fn resolution(mut self, resolution: u32) -> Self {
self.resolution.replace(resolution);
self
}
}
impl<Config, Clear> Drop for Arc2dBuilder<'_, '_, '_, Config, Clear>
where
Config: GizmoConfigGroup,
Clear: 'static + Send + Sync,
{
fn drop(&mut self) {
if !self.gizmos.enabled {
return;
}
let resolution = self
.resolution
.unwrap_or_else(|| resolution_from_angle(self.arc_angle));
let positions =
arc_2d_inner(self.arc_angle, self.radius, resolution).map(|vec2| self.isometry * vec2);
self.gizmos.linestrip_2d(positions, self.color);
}
}
fn arc_2d_inner(arc_angle: f32, radius: f32, resolution: u32) -> impl Iterator<Item = Vec2> {
(0..=resolution)
.map(move |n| arc_angle * n as f32 / resolution as f32)
.map(|angle| angle + FRAC_PI_2)
.map(f32::sin_cos)
.map(|(sin, cos)| Vec2::new(cos, sin))
.map(move |vec2| vec2 * radius)
}
// === 3D ===
impl<'w, 's, Config, Clear> Gizmos<'w, 's, Config, Clear>
where
Config: GizmoConfigGroup,
Clear: 'static + Send + Sync,
{
/// Draw an arc, which is a part of the circumference of a circle, in 3D. For default values
/// this is drawing a standard arc. A standard arc is defined as
///
/// - an arc with a center at `Vec3::ZERO`
/// - starting at `Vec3::X`
/// - embedded in the XZ plane
/// - rotates counterclockwise
///
/// This should be called for each frame the arc needs to be rendered.
///
/// # Arguments
/// - `angle`: sets how much of a circle circumference is passed, e.g. PI is half a circle. This
/// value should be in the range (-2 * PI..=2 * PI)
/// - `radius`: distance between the arc and its center point
/// - `isometry` defines the translation and rotation of the arc.
/// - the translation specifies the center of the arc
/// - the rotation is counter-clockwise starting from `Vec3::Y`
/// - `color`: color of the arc
///
/// # Builder methods
/// The resolution of the arc (i.e. the level of detail) can be adjusted with the
/// `.resolution(...)` method.
///
/// # Example
/// ```
/// # use bevy_gizmos::prelude::*;
/// # use bevy_math::prelude::*;
/// # use std::f32::consts::PI;
/// # use bevy_color::palettes::css::ORANGE;
/// fn system(mut gizmos: Gizmos) {
/// // rotation rotates normal to point in the direction of `Vec3::NEG_ONE`
/// let rotation = Quat::from_rotation_arc(Vec3::Y, Vec3::NEG_ONE.normalize());
///
/// gizmos
/// .arc_3d(
/// 270.0_f32.to_radians(),
/// 0.25,
/// Isometry3d::new(Vec3::ONE, rotation),
/// ORANGE
/// )
/// .resolution(100);
/// }
/// # bevy_ecs::system::assert_is_system(system);
/// ```
#[inline]
pub fn arc_3d(
&mut self,
angle: f32,
radius: f32,
isometry: Isometry3d,
color: impl Into<Color>,
) -> Arc3dBuilder<'_, 'w, 's, Config, Clear> {
Arc3dBuilder {
gizmos: self,
start_vertex: Vec3::X,
isometry,
angle,
radius,
color: color.into(),
resolution: None,
}
}
/// Draws the shortest arc between two points (`from` and `to`) relative to a specified `center` point.
///
/// # Arguments
///
/// - `center`: The center point around which the arc is drawn.
/// - `from`: The starting point of the arc.
/// - `to`: The ending point of the arc.
/// - `color`: color of the arc
///
/// # Builder methods
/// The resolution of the arc (i.e. the level of detail) can be adjusted with the
/// `.resolution(...)` method.
///
/// # Examples
/// ```
/// # use bevy_gizmos::prelude::*;
/// # use bevy_math::prelude::*;
/// # use bevy_color::palettes::css::ORANGE;
/// fn system(mut gizmos: Gizmos) {
/// gizmos.short_arc_3d_between(
/// Vec3::ONE,
/// Vec3::ONE + Vec3::NEG_ONE,
/// Vec3::ZERO,
/// ORANGE
/// )
/// .resolution(100);
/// }
/// # bevy_ecs::system::assert_is_system(system);
/// ```
///
/// # Notes
/// - This method assumes that the points `from` and `to` are distinct from `center`. If one of
/// the points is coincident with `center`, nothing is rendered.
/// - The arc is drawn as a portion of a circle with a radius equal to the distance from the
/// `center` to `from`. If the distance from `center` to `to` is not equal to the radius, then
/// the results will behave as if this were the case
#[inline]
pub fn short_arc_3d_between(
&mut self,
center: Vec3,
from: Vec3,
to: Vec3,
color: impl Into<Color>,
) -> Arc3dBuilder<'_, 'w, 's, Config, Clear> {
self.arc_from_to(center, from, to, color, |x| x)
}
/// Draws the longest arc between two points (`from` and `to`) relative to a specified `center` point.
///
/// # Arguments
/// - `center`: The center point around which the arc is drawn.
/// - `from`: The starting point of the arc.
/// - `to`: The ending point of the arc.
/// - `color`: color of the arc
///
/// # Builder methods
/// The resolution of the arc (i.e. the level of detail) can be adjusted with the
/// `.resolution(...)` method.
///
/// # Examples
/// ```
/// # use bevy_gizmos::prelude::*;
/// # use bevy_math::prelude::*;
/// # use bevy_color::palettes::css::ORANGE;
/// fn system(mut gizmos: Gizmos) {
/// gizmos.long_arc_3d_between(
/// Vec3::ONE,
/// Vec3::ONE + Vec3::NEG_ONE,
/// Vec3::ZERO,
/// ORANGE
/// )
/// .resolution(100);
/// }
/// # bevy_ecs::system::assert_is_system(system);
/// ```
///
/// # Notes
/// - This method assumes that the points `from` and `to` are distinct from `center`. If one of
/// the points is coincident with `center`, nothing is rendered.
/// - The arc is drawn as a portion of a circle with a radius equal to the distance from the
/// `center` to `from`. If the distance from `center` to `to` is not equal to the radius, then
/// the results will behave as if this were the case.
#[inline]
pub fn long_arc_3d_between(
&mut self,
center: Vec3,
from: Vec3,
to: Vec3,
color: impl Into<Color>,
) -> Arc3dBuilder<'_, 'w, 's, Config, Clear> {
self.arc_from_to(center, from, to, color, |angle| {
if angle > 0.0 {
TAU - angle
} else if angle < 0.0 {
-TAU - angle
} else {
0.0
}
})
}
#[inline]
fn arc_from_to(
&mut self,
center: Vec3,
from: Vec3,
to: Vec3,
color: impl Into<Color>,
angle_fn: impl Fn(f32) -> f32,
) -> Arc3dBuilder<'_, 'w, 's, Config, Clear> {
// `from` and `to` can be the same here since in either case nothing gets rendered and the
// orientation ambiguity of `up` doesn't matter
let from_axis = (from - center).normalize_or_zero();
let to_axis = (to - center).normalize_or_zero();
let (up, angle) = Quat::from_rotation_arc(from_axis, to_axis).to_axis_angle();
let angle = angle_fn(angle);
let radius = center.distance(from);
let rotation = Quat::from_rotation_arc(Vec3::Y, up);
let start_vertex = rotation.inverse() * from_axis;
Arc3dBuilder {
gizmos: self,
start_vertex,
isometry: Isometry3d::new(center, rotation),
angle,
radius,
color: color.into(),
resolution: None,
}
}
/// Draws the shortest arc between two points (`from` and `to`) relative to a specified `center` point.
///
/// # Arguments
///
/// - `center`: The center point around which the arc is drawn.
/// - `from`: The starting point of the arc.
/// - `to`: The ending point of the arc.
/// - `color`: color of the arc
///
/// # Builder methods
/// The resolution of the arc (i.e. the level of detail) can be adjusted with the
/// `.resolution(...)` method.
///
/// # Examples
/// ```
/// # use bevy_gizmos::prelude::*;
/// # use bevy_math::prelude::*;
/// # use bevy_color::palettes::css::ORANGE;
/// fn system(mut gizmos: Gizmos) {
/// gizmos.short_arc_2d_between(
/// Vec2::ZERO,
/// Vec2::X,
/// Vec2::Y,
/// ORANGE
/// )
/// .resolution(100);
/// }
/// # bevy_ecs::system::assert_is_system(system);
/// ```
///
/// # Notes
/// - This method assumes that the points `from` and `to` are distinct from `center`. If one of
/// the points is coincident with `center`, nothing is rendered.
/// - The arc is drawn as a portion of a circle with a radius equal to the distance from the
/// `center` to `from`. If the distance from `center` to `to` is not equal to the radius, then
/// the results will behave as if this were the case
#[inline]
pub fn short_arc_2d_between(
&mut self,
center: Vec2,
from: Vec2,
to: Vec2,
color: impl Into<Color>,
) -> Arc2dBuilder<'_, 'w, 's, Config, Clear> {
self.arc_2d_from_to(center, from, to, color, std::convert::identity)
}
/// Draws the longest arc between two points (`from` and `to`) relative to a specified `center` point.
///
/// # Arguments
/// - `center`: The center point around which the arc is drawn.
/// - `from`: The starting point of the arc.
/// - `to`: The ending point of the arc.
/// - `color`: color of the arc
///
/// # Builder methods
/// The resolution of the arc (i.e. the level of detail) can be adjusted with the
/// `.resolution(...)` method.
///
/// # Examples
/// ```
/// # use bevy_gizmos::prelude::*;
/// # use bevy_math::prelude::*;
/// # use bevy_color::palettes::css::ORANGE;
/// fn system(mut gizmos: Gizmos) {
/// gizmos.long_arc_2d_between(
/// Vec2::ZERO,
/// Vec2::X,
/// Vec2::Y,
/// ORANGE
/// )
/// .resolution(100);
/// }
/// # bevy_ecs::system::assert_is_system(system);
/// ```
///
/// # Notes
/// - This method assumes that the points `from` and `to` are distinct from `center`. If one of
/// the points is coincident with `center`, nothing is rendered.
/// - The arc is drawn as a portion of a circle with a radius equal to the distance from the
/// `center` to `from`. If the distance from `center` to `to` is not equal to the radius, then
/// the results will behave as if this were the case.
#[inline]
pub fn long_arc_2d_between(
&mut self,
center: Vec2,
from: Vec2,
to: Vec2,
color: impl Into<Color>,
) -> Arc2dBuilder<'_, 'w, 's, Config, Clear> {
self.arc_2d_from_to(center, from, to, color, |angle| angle - TAU)
}
#[inline]
fn arc_2d_from_to(
&mut self,
center: Vec2,
from: Vec2,
to: Vec2,
color: impl Into<Color>,
angle_fn: impl Fn(f32) -> f32,
) -> Arc2dBuilder<'_, 'w, 's, Config, Clear> {
// `from` and `to` can be the same here since in either case nothing gets rendered and the
// orientation ambiguity of `up` doesn't matter
let from_axis = (from - center).normalize_or_zero();
let to_axis = (to - center).normalize_or_zero();
let rotation = Vec2::Y.angle_to(from_axis);
let arc_angle_raw = from_axis.angle_to(to_axis);
let arc_angle = angle_fn(arc_angle_raw);
let radius = center.distance(from);
Arc2dBuilder {
gizmos: self,
isometry: Isometry2d::new(center, Rot2::radians(rotation)),
arc_angle,
radius,
color: color.into(),
resolution: None,
}
}
}
/// A builder returned by [`Gizmos::arc_2d`].
pub struct Arc3dBuilder<'a, 'w, 's, Config, Clear>
where
Config: GizmoConfigGroup,
Clear: 'static + Send + Sync,
{
gizmos: &'a mut Gizmos<'w, 's, Config, Clear>,
// this is the vertex the arc starts on in the XZ plane. For the normal arc_3d method this is
// always starting at Vec3::X. For the short/long arc methods we actually need a way to start
// at the from position and this is where this internal field comes into play. Some implicit
// assumptions:
//
// 1. This is always in the XZ plane
// 2. This is always normalized
//
// DO NOT expose this field to users as it is easy to mess this up
start_vertex: Vec3,
isometry: Isometry3d,
angle: f32,
radius: f32,
color: Color,
resolution: Option<u32>,
}
impl<Config, Clear> Arc3dBuilder<'_, '_, '_, Config, Clear>
where
Config: GizmoConfigGroup,
Clear: 'static + Send + Sync,
{
/// Set the number of lines for this arc.
pub fn resolution(mut self, resolution: u32) -> Self {
self.resolution.replace(resolution);
self
}
}
impl<Config, Clear> Drop for Arc3dBuilder<'_, '_, '_, Config, Clear>
where
Config: GizmoConfigGroup,
Clear: 'static + Send + Sync,
{
fn drop(&mut self) {
if !self.gizmos.enabled {
return;
}
let resolution = self
.resolution
.unwrap_or_else(|| resolution_from_angle(self.angle));
let positions = arc_3d_inner(
self.start_vertex,
self.isometry,
self.angle,
self.radius,
resolution,
);
self.gizmos.linestrip(positions, self.color);
}
}
fn arc_3d_inner(
start_vertex: Vec3,
isometry: Isometry3d,
angle: f32,
radius: f32,
resolution: u32,
) -> impl Iterator<Item = Vec3> {
// drawing arcs bigger than TAU degrees or smaller than -TAU degrees makes no sense since
// we won't see the overlap and we would just decrease the level of details since the resolution
// would be larger
let angle = angle.clamp(-TAU, TAU);
(0..=resolution)
.map(move |frac| frac as f32 / resolution as f32)
.map(move |percentage| angle * percentage)
.map(move |frac_angle| Quat::from_axis_angle(Vec3::Y, frac_angle) * start_vertex)
.map(move |vec3| vec3 * radius)
.map(move |vec3| isometry * vec3)
}
// helper function for getting a default value for the resolution parameter
fn resolution_from_angle(angle: f32) -> u32 {
((angle.abs() / TAU) * DEFAULT_CIRCLE_RESOLUTION as f32).ceil() as u32
}