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//! Implement collision shapes and handle collisions between them
use sdl2::rect::Rect;
/// Colliders that attach to GameObjects. Support Circle and Rect colliders
#[derive(Clone, Debug, PartialEq, Eq, PartialOrd, Ord)]
pub enum CollisionShape {
Circle {
center: (i32, i32),
radius: u32
}, Rect {
center: (i32, i32),
size: (u32, u32)
}, Polygon {
center: (i32, i32),
points: Vec<(i32, i32)>
}
}
impl CollisionShape {
pub fn collides_with(&self, other: &CollisionShape) -> bool {
match self {
CollisionShape::Circle { center, radius } => {
match other {
CollisionShape::Circle { center: other_center, radius: other_radius } => {
let a = other_center.0 - center.0;
let b = other_center.1 - center.1;
let c = other_radius + radius;
((a * a) + (b * b)) as u32 <= (c * c)
}, CollisionShape::Rect { center: other_center, size: other_size } => {
let mut test = center.clone();
let rect = Rect::new(
other_center.0 - other_size.0 as i32 / 2,
other_center.1 - other_size.1 as i32 / 2,
other_size.0,
other_size.1
);
if center.0 < rect.x {
test.0 = rect.x;
} else if center.0 > rect.x + rect.w {
test.0 = rect.x + rect.w;
}
if center.1 < rect.y {
test.1 = rect.y;
} else if center.1 > rect.y + rect.h {
test.1 = rect.y + rect.h;
}
let dist_lat = (center.0 - test.0, center.1 - test.1);
let dist_sqrd = (dist_lat.0 * dist_lat.0) + (dist_lat.1 * dist_lat.1);
dist_sqrd as u32 <= radius * radius
}, CollisionShape::Polygon { center: other_center, points } => {
for point in points.iter() {
let dists = (
other_center.0 + point.0 - center.0,
other_center.1 + point.1 - center.1
);
let dist_sqrd = dists.0 * dists.0 + dists.1 + dists.1;
if (dist_sqrd as u32) < radius * radius {
return true;
}
}
false
}
}
}, CollisionShape::Rect { center, size } => {
match other {
CollisionShape::Circle { center: other_center, radius: other_radius } => {
let mut test = other_center.clone();
let rect = Rect::new(
center.0 - size.0 as i32 / 2,
center.1 - size.1 as i32 / 2,
size.0,
size.1
);
if other_center.0 < rect.x {
test.0 = rect.x;
} else if other_center.0 > rect.x + rect.w {
test.0 = rect.x + rect.w;
}
if other_center.1 < rect.y {
test.1 = rect.y;
} else if other_center.1 > rect.y + rect.h {
test.1 = rect.y + rect.h;
}
let dist_lat = (other_center.0 - test.0, other_center.1 - test.1);
let dist_sqrd = (dist_lat.0 * dist_lat.0) + (dist_lat.1 * dist_lat.1);
dist_sqrd as u32 <= other_radius * other_radius
}, CollisionShape::Rect { center: other_center, size: other_size } => {
let r1 = Rect::new(
center.0 - size.0 as i32 / 2,
center.1 - size.1 as i32 / 2,
size.0,
size.1
);
let r2 = Rect::new(
other_center.0 - other_size.1 as i32 / 2,
other_center.1 - other_size.1 as i32 / 2,
other_size.0,
other_size.1
);
r1.x + r1.w >= r2.x
&& r1.x <= r2.x + r2.w
&& r1.y + r1.h >= r2.y
&& r1.y <= r2.y + r2.h
}, CollisionShape::Polygon { center: other_center, points } => {
for point in points.iter() {
let transformed_point = (
other_center.0 + point.0,
other_center.1 + point.1
);
let (left, right) = (
center.0 - size.0 as i32 / 2,
center.0 + size.0 as i32 / 2
);
let (top, bottom) = (
center.1 - size.1 as i32 / 2,
center.1 + size.1 as i32 / 2
);
if transformed_point.0 >= left
&& transformed_point.0 <= right
&& transformed_point.1 >= top
&& transformed_point.1 <= bottom {
return true;
}
}
false
}
}
}, CollisionShape::Polygon { center, points } => {
match other {
CollisionShape::Circle { center: other_center, radius } => {
for point in points.iter() {
let dists = (
center.0 + point.0 - other_center.0,
center.1 + point.1 - other_center.1
);
let dist_sqrd = dists.0 * dists.0 + dists.1 + dists.1;
if (dist_sqrd as u32) < radius * radius {
return true;
}
}
false
}, CollisionShape::Rect { center: other_center, size } => {
for point in points.iter() {
let transformed_point = (
center.0 + point.0,
center.1 + point.1
);
let (left, right) = (
other_center.0 - size.0 as i32 / 2,
other_center.0 + size.0 as i32 / 2
);
let (top, bottom) = (
other_center.1 - size.1 as i32 / 2,
other_center.1 + size.1 as i32 / 2
);
if transformed_point.0 >= left
&& transformed_point.0 <= right
&& transformed_point.1 >= top
&& transformed_point.1 <= bottom {
return true;
}
}
false
}, CollisionShape::Polygon { center: other_center, points: other_points } => {
// Iterate over each edge of the first polygon
for i in 0..points.len() {
let p1 = points[i];
let p2 = points[(i + 1) % points.len()];
// Calculate the normal of the edge
let normal = ((p2.1 - p1.1), -(p2.0 - p1.0));
// Project both polygons onto the normal
let (min1, max1) = project_polygon(&points, &normal, ¢er);
let (min2, max2) = project_polygon(
&other_points, &normal, &other_center
);
// Check for overlap on the projected axis
if max1 < min2 || max2 < min1 {
return false;
}
}
true
}
}
}
}
}
}
fn project_polygon(points: &[(i32, i32)], axis: &(i32, i32), center: &(i32, i32)) -> (i32, i32) {
let mut min = i32::MAX;
let mut max = i32::MIN;
for point in points.iter() {
let proj_point = (point.0 + center.0, point.1 + center.1);
let dot_prod = proj_point.0 * axis.0 + proj_point.1 * axis.1;
if dot_prod < min {
min = dot_prod;
}
if dot_prod > max {
max = dot_prod;
}
}
(min, max)
}