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use crate::*;
use core::cmp::Ordering;
use core::convert::TryInto;
///Convenience function to create a ray.
pub fn ray<N>(point: Vec2<N>, dir: Vec2<N>) -> Ray<N> {
Ray { point, dir }
}
///A Ray.
#[derive(Default,Debug, Copy, Clone)]
#[must_use]
pub struct Ray<N> {
pub point: Vec2<N>,
pub dir: Vec2<N>,
}
impl<B: Copy> Ray<B> {
#[inline(always)]
pub fn inner_as<C: 'static + Copy>(&self) -> Ray<C>
where
B: num_traits::AsPrimitive<C>,
{
ray(self.point.inner_as(), self.dir.inner_as())
}
}
impl<N: Copy + core::ops::Add<Output = N> + core::ops::Mul<Output = N>> Ray<N> {
#[inline(always)]
pub fn point_at_tval(&self, tval: N) -> Vec2<N> {
self.point + self.dir * tval
}
}
impl<S> Ray<S> {
#[inline(always)]
pub fn inner_into<A>(self) -> Ray<A>
where
S: Into<A>,
{
let point = self.point.inner_into();
let dir = self.dir.inner_into();
Ray { point, dir }
}
#[inline(always)]
pub fn inner_try_into<A>(self) -> Result<Ray<A>, S::Error>
where
S: TryInto<A>,
{
let point = self.point.inner_try_into();
let dir = self.dir.inner_try_into();
match (point, dir) {
(Ok(point), Ok(dir)) => Ok(Ray { point, dir }),
(Err(e), Ok(_)) => Err(e),
(Ok(_), Err(e)) => Err(e),
(Err(e), Err(_)) => Err(e),
}
}
}
impl<N: PartialOrd + Copy> Ray<N> {
#[inline(always)]
pub fn range_side(&self, axis: impl Axis, range: &Range<N>) -> Ordering {
let v = if axis.is_xaxis() {
self.point.x
} else {
self.point.y
};
range.contains_ext(v)
}
}
///Describes if a ray hit a rectangle.
#[derive(Copy, Clone, Debug, PartialEq, Eq)]
#[must_use]
pub enum CastResult<N> {
Hit(N),
NoHit,
}
impl<N> CastResult<N> {
#[inline(always)]
pub fn map<X>(self, mut func: impl FnMut(N) -> X) -> CastResult<X> {
match self {
CastResult::Hit(a) => CastResult::Hit(func(a)),
CastResult::NoHit => CastResult::NoHit,
}
}
#[inline(always)]
pub fn unwrap(self) -> N {
match self {
CastResult::Hit(a) => a,
CastResult::NoHit => panic!("unwrapped a NoHit in CastResult"),
}
}
}
#[cfg(feature = "std")]
pub mod foo {
use super::*;
use roots;
use roots::*;
impl<N: num_traits::float::FloatCore + roots::FloatType> Ray<N> {
///Checks if a ray intersects a circle.
pub fn cast_to_circle(&self, center: Vec2<N>, radius: N) -> CastResult<N> {
//https://math.stackexchange.com/questions/311921/get-location-of-vector-circle-intersection
//circle
//(x-center.x)^2+(y-center.y)^2=r2
//ray
//x(t)=ray.dir.x*t+ray.point.x
//y(t)=ray.dir.y*t+ray.point.y
//
//solve for t.
//
//
//we get:
//
//𝑎𝑡^2+𝑏𝑡+𝑐=0
//
//
//
//
let ray = self;
let zz = <N as FloatType>::zero();
let two = <N as FloatType>::one() + <N as FloatType>::one();
let a = ray.dir.x.powi(2) + ray.dir.y.powi(2);
let b = two * ray.dir.x * (ray.point.x - center.x)
+ two * ray.dir.y * (ray.point.y - center.y);
let c = (ray.point.x - center.x).powi(2) + (ray.point.y - center.y).powi(2)
- radius.powi(2);
match find_roots_quadratic(a, b, c) {
Roots::No(_) => CastResult::NoHit,
Roots::One([a]) => {
if a < zz {
CastResult::NoHit
} else {
CastResult::Hit(a)
}
}
Roots::Two([a, b]) => {
let (closer, further) = if a < b { (a, b) } else { (b, a) };
if closer < zz && further < zz {
CastResult::NoHit
} else if closer < zz && further > zz {
CastResult::Hit(<N as FloatType>::zero())
} else {
CastResult::Hit(closer)
}
}
_ => unreachable!(),
}
}
}
}
impl<N: num_traits::Num + num_traits::Signed + PartialOrd + Copy + core::fmt::Debug> Ray<N> {
//if axis is x, then the line is top to bottom
//if axis is y, then the line is left to right
pub fn cast_to_aaline<A: Axis>(&self, a: A, line: N) -> CastResult<N> {
let ray = self;
let tval = if a.is_xaxis() {
if ray.dir.x == N::zero() {
return CastResult::NoHit;
}
(line - ray.point.x) / ray.dir.x
} else {
if ray.dir.y == N::zero() {
return CastResult::NoHit;
}
(line - ray.point.y) / ray.dir.y
};
if tval > N::zero() {
CastResult::Hit(tval)
} else {
CastResult::NoHit
}
}
fn prune_rect_axis<A: Axis>(&self, tval: N, rect: &Rect<N>, axis: A) -> CastResult<N> {
use CastResult::*;
if axis.is_xaxis() {
let xx = self.point.x + self.dir.x * tval;
if rect.x.contains(xx) {
Hit(tval)
} else {
NoHit
}
} else {
let yy = self.point.y + self.dir.y * tval;
if rect.y.contains(yy) {
Hit(tval)
} else {
NoHit
}
}
}
pub fn cast_to_rect(&self, rect: &Rect<N>) -> CastResult<N> {
if rect.contains_point(self.point) {
return CastResult::Hit(N::zero());
}
/*
https://gamedev.stackexchange.com/questions/18436/most-efficient-aabb-vs-ray-collision-algorithms
Nobody described the algorithm here, but the Graphics Gems algorithm is simply:
Using your ray's direction vector, determine which 3 of the 6 candidate planes would be hit first. If your (unnormalized) ray direction vector is (-1, 1, -1), then the 3 planes that are possible to be hit are +x, -y, and +z.
Of the 3 candidate planes, do find the t-value for the intersection for each. Accept the plane that gets the largest t value as being the plane that got hit, and check that the hit is within the box. The diagram in the text makes this clear:
*/
let &Rect {
x: Range {
start: startx,
end: endx,
},
y: Range {
start: starty,
end: endy,
},
} = rect;
let x = if self.dir.x >= N::zero() {
startx
} else {
endx
};
let y = if self.dir.y >= N::zero() {
starty
} else {
endy
};
let tval1 = self.cast_to_aaline(XAXIS, x);
let tval2 = self.cast_to_aaline(YAXIS, y);
use CastResult::*;
match (tval1, tval2) {
(Hit(a), Hit(b)) => {
//xaxis hit
if a > b {
self.prune_rect_axis(a, rect, YAXIS)
} else {
self.prune_rect_axis(b, rect, XAXIS)
}
}
(Hit(a), NoHit) => self.prune_rect_axis(a, rect, YAXIS),
(NoHit, Hit(b)) => self.prune_rect_axis(b, rect, XAXIS),
(NoHit, NoHit) => NoHit,
}
}
/*
pub fn find_candidate_planes(&self,rect:&Rect<N>)->[bool;4]{
//In cases where the ray is directly vertical or horizant,
//we technically only need to check one side of the rect.
//but these cases are so rare, and it doesnt hurt much to check
//one extra side. So we condense these cases into cases
//where we check two sides.
let x=self.dir.x>N::zero();
let y=self.dir.y>N::zero();
match (x,y){
(true,true)=>{
//left top
},
(true,false)=>{
//left bottom
},
(false,true)=>{
//right top
},
(false,false)=>{
//right bottom
}
}
//Observation to make is that in each case, there was on x and one y coordinate.
todo!()
}
*/
}