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use crate::math::*;
///
/// A bounding box that aligns with the x, y and z axes.
///
#[derive(Debug, Copy, Clone)]
pub struct AxisAlignedBoundingBox {
min: Vec3,
max: Vec3,
}
impl AxisAlignedBoundingBox {
fn empty() -> Self {
Self {
min: vec3(std::f32::INFINITY, std::f32::INFINITY, std::f32::INFINITY),
max: vec3(
std::f32::NEG_INFINITY,
std::f32::NEG_INFINITY,
std::f32::NEG_INFINITY,
),
}
}
///
/// Constructs a new bounding box and expands it such that all of the given positions are contained inside the bounding box.
/// A position consisting of an x, y and z coordinate corresponds to three consecutive value in the positions array.
///
pub fn new_with_positions(positions: &[f32]) -> Self {
let mut aabb = Self::empty();
aabb.expand(positions);
aabb
}
///
/// Constructs a new bounding box and expands it such that all of the given positions transformed with the given transformation are contained inside the bounding box.
/// A position consisting of an x, y and z coordinate corresponds to three consecutive value in the positions array.
///
pub fn new_with_transformed_positions(positions: &[f32], transformation: &Mat4) -> Self {
let mut aabb = Self::empty();
aabb.expand_with_transformation(positions, transformation);
aabb
}
///
/// Get the minimum coordinate of the bounding box.
///
pub fn min(&self) -> &Vec3 {
&self.min
}
///
/// Get the maximum coordinate of the bounding box.
///
pub fn max(&self) -> &Vec3 {
&self.max
}
///
/// Expands the bounding box such that all of the given positions are contained inside the bounding box.
/// A position consisting of an x, y and z coordinate corresponds to three consecutive value in the positions array.
///
pub fn expand(&mut self, positions: &[f32]) {
for i in 0..positions.len() {
match i % 3 {
0 => {
self.min.x = f32::min(positions[i], self.min.x);
self.max.x = f32::max(positions[i], self.max.x);
}
1 => {
self.min.y = f32::min(positions[i], self.min.y);
self.max.y = f32::max(positions[i], self.max.y);
}
2 => {
self.min.z = f32::min(positions[i], self.min.z);
self.max.z = f32::max(positions[i], self.max.z);
}
_ => {
unreachable!()
}
};
}
}
///
/// Expands the bounding box such that all of the given positions transformed with the given transformation are contained inside the bounding box.
/// A position consisting of an x, y and z coordinate corresponds to three consecutive value in the positions array.
///
pub fn expand_with_transformation(&mut self, positions: &[f32], transformation: &Mat4) {
for i in 0..positions.len() / 3 {
let pos = transformation
* vec4(
positions[i * 3],
positions[i * 3 + 1],
positions[i * 3 + 2],
1.0,
);
self.min.x = f32::min(pos.x, self.min.x);
self.max.x = f32::max(pos.x, self.max.x);
self.min.y = f32::min(pos.y, self.min.y);
self.max.y = f32::max(pos.y, self.max.y);
self.min.z = f32::min(pos.z, self.min.z);
self.max.z = f32::max(pos.z, self.max.z);
}
}
///
/// Expand the bounding box such that it also contains the given other bounding box.
///
pub fn expand_with_aabb(&mut self, other: &AxisAlignedBoundingBox) {
self.min = vec3(
f32::min(self.min.x, other.min.x),
f32::min(self.min.y, other.min.y),
f32::min(self.min.z, other.min.z),
);
self.max = vec3(
f32::max(self.max.x, other.max.x),
f32::max(self.max.y, other.max.y),
f32::max(self.max.z, other.max.z),
);
}
///
/// Transforms the bounding box by the given transformation.
///
/// **Note:** Use [new_with_transformed_positions](crate::AxisAlignedBoundingBox::new_with_transformed_positions) instead of
/// [new_with_positions](crate::AxisAlignedBoundingBox::new_with_positions) followed by this method to create a smaller bounding box.
///
pub fn transform(&mut self, transformation: &Mat4) {
let aabb = Self::new_with_transformed_positions(
&[
self.min.x, self.min.y, self.min.z, self.max.x, self.min.y, self.min.z, self.min.x,
self.max.y, self.min.z, self.min.x, self.min.y, self.max.z, self.min.x, self.max.y,
self.max.z, self.max.x, self.min.y, self.max.z, self.max.x, self.max.y, self.min.z,
self.max.x, self.max.y, self.max.z,
],
transformation,
);
self.min = aabb.min;
self.max = aabb.max;
}
}