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pub mod line_segment;
pub mod polygon;
pub mod rect;
pub mod triangle;
pub mod vec2;
pub use self::line_segment::*;
pub use self::polygon::*;
pub use self::rect::*;
pub use self::triangle::*;
pub use self::vec2::*;
use nalgebra::Scalar;
use std::cmp::Ordering;
/// Trait that describes an area in the vector space on the field of T
pub trait Surface<T: Scalar + Copy> {
/// Checks if a point lies on this surface.
fn contains_point(&self, point: &Vec2<T>) -> bool;
/// Checks if a line segment is entirely contained by this surface.
fn contains_line_segment(&self, line_segment: &LineSegment<T>) -> bool;
/// Checks if a rectangle is entirely contained inside this surface.
fn contains_rect(&self, rect: &Rect<T>) -> bool;
/// Checks if a polygon is contained wholly by this surface.
fn contains_polygon(&self, polygon: &Polygon<T>) -> bool;
}
/// Round a floating point number to the nearest step given by the step argument. For instance, if
/// the step is 0.5, then all numbers from 0.0 to 0.24999... will be 0., while all numbers from
/// 0.25 to 0.74999... will be 0.5 and so on.
pub fn round(num: f32, step: f32) -> f32 {
// Only positive steps will be accepted.
assert!(step > 0.);
let lower_bound = ((num / step) as i32) as f32 * step;
let upper_bound = lower_bound + step;
// Compare the distances and prefer the smaller. If they are the same, prefer the upper bound.
if (num - lower_bound) < (upper_bound - num) {
lower_bound
} else {
upper_bound
}
}
/// Works like `std::cmp::max`, however also allows partial comparisons. It is specifically
/// designed so functions that should be able to use f32 and f64 work, eventhough these do not
/// implement Ord. The downside of this function however is, that its behaviour is undefined when
/// `f32::NaN` for instance were to be passed.
pub(crate) fn partial_max<T>(a: T, b: T) -> T
where
T: PartialOrd,
{
match a.partial_cmp(&b) {
Some(Ordering::Greater) => a,
_ => b,
}
}
/// Like `partial_max`, but for minimum values. Comes with the same downside, too.
pub(crate) fn partial_min<T>(a: T, b: T) -> T
where
T: PartialOrd,
{
match a.partial_cmp(&b) {
Some(Ordering::Less) => a,
_ => b,
}
}
#[cfg(test)]
mod test {
#[test]
fn partial_max() {
assert_eq!(super::partial_max(0., 0.), 0.);
assert_eq!(super::partial_max(-1., 1.), 1.);
assert_eq!(super::partial_max(-2., -1.), -1.);
assert_eq!(super::partial_max(2., 1.), 2.);
}
#[test]
fn partial_min() {
assert_eq!(super::partial_min(0., 0.), 0.);
assert_eq!(super::partial_min(-1., 1.), -1.);
assert_eq!(super::partial_min(-2., -1.), -2.);
assert_eq!(super::partial_min(2., 1.), 1.);
}
}
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