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c285a69f76
# Objective I think the 'collide' function inside the 'bevy/crates/bevy_sprite/src/collide_aabb.rs' file should return 'Some' if the two rectangles are fully overlapping or one is inside the other. This can happen on low-end machines when a lot of time passes between two frames because of a stutter, so a bullet for example gets inside its target. I can also think of situations where this is a valid use case even without stutters. ## Solution I added an 'Inside' version to the Collision enum declared in the file. And I use it, when the two rectangles are overlapping, but we can't say from which direction it happened. I gave a 'penetration depth' of minus Infinity to these cases, so that this variant only appears, when the two rectangles overlap from each side fully. I am not sure if this is the right thing to do. Fixes #1980 Co-authored-by: Carter Anderson <mcanders1@gmail.com>
57 lines
2.1 KiB
Rust
57 lines
2.1 KiB
Rust
//! Utilities for detecting if and on which side two axis-aligned bounding boxes (AABB) collide.
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use bevy_math::{Vec2, Vec3};
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#[derive(Debug)]
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pub enum Collision {
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Left,
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Right,
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Top,
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Bottom,
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Inside,
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}
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// TODO: ideally we can remove this once bevy gets a physics system
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/// Axis-aligned bounding box collision with "side" detection
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/// * `a_pos` and `b_pos` are the center positions of the rectangles, typically obtained by
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/// extracting the `translation` field from a `Transform` component
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/// * `a_size` and `b_size` are the dimensions (width and height) of the rectangles.
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pub fn collide(a_pos: Vec3, a_size: Vec2, b_pos: Vec3, b_size: Vec2) -> Option<Collision> {
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let a_min = a_pos.truncate() - a_size / 2.0;
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let a_max = a_pos.truncate() + a_size / 2.0;
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let b_min = b_pos.truncate() - b_size / 2.0;
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let b_max = b_pos.truncate() + b_size / 2.0;
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// check to see if the two rectangles are intersecting
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if a_min.x < b_max.x && a_max.x > b_min.x && a_min.y < b_max.y && a_max.y > b_min.y {
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// check to see if we hit on the left or right side
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let (x_collision, x_depth) = if a_min.x < b_min.x && a_max.x > b_min.x && a_max.x < b_max.x
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{
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(Collision::Left, b_min.x - a_max.x)
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} else if a_min.x > b_min.x && a_min.x < b_max.x && a_max.x > b_max.x {
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(Collision::Right, a_min.x - b_max.x)
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} else {
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(Collision::Inside, -f32::INFINITY)
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};
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// check to see if we hit on the top or bottom side
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let (y_collision, y_depth) = if a_min.y < b_min.y && a_max.y > b_min.y && a_max.y < b_max.y
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{
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(Collision::Bottom, b_min.y - a_max.y)
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} else if a_min.y > b_min.y && a_min.y < b_max.y && a_max.y > b_max.y {
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(Collision::Top, a_min.y - b_max.y)
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} else {
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(Collision::Inside, -f32::INFINITY)
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};
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// if we had an "x" and a "y" collision, pick the "primary" side using penetration depth
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if y_depth.abs() < x_depth.abs() {
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Some(y_collision)
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} else {
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Some(x_collision)
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}
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} else {
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None
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}
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}
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