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use std::f32;
use std::ops::{Add, Sub, Mul, Div, Neg, Index, IndexMut};
use linalg::{self, Vector};
#[derive(Debug, Copy, Clone, PartialEq, PartialOrd)]
pub struct Normal {
pub x: f32,
pub y: f32,
pub z: f32,
}
impl Normal {
pub fn new(x: f32, y: f32, z: f32) -> Normal {
Normal { x: x, y: y, z: z }
}
pub fn broadcast(x: f32) -> Normal {
Normal { x: x, y: x, z: x }
}
pub fn length_sqr(&self) -> f32 {
self.x * self.x + self.y * self.y + self.z * self.z
}
pub fn length(&self) -> f32 {
f32::sqrt(self.length_sqr())
}
pub fn normalized(&self) -> Normal {
let len = self.length();
Normal { x: self.x / len, y: self.y / len, z: self.z / len }
}
pub fn face_forward(&self, v: &Vector) -> Normal {
if linalg::dot(self, v) < 0f32 { -*self } else { *self }
}
}
impl Add for Normal {
type Output = Normal;
fn add(self, rhs: Normal) -> Normal {
Normal { x: self.x + rhs.x, y: self.y + rhs.y, z: self.z + rhs.z }
}
}
impl Sub for Normal {
type Output = Normal;
fn sub(self, rhs: Normal) -> Normal {
Normal { x: self.x - rhs.x, y: self.y - rhs.y, z: self.z - rhs.z }
}
}
impl Mul for Normal {
type Output = Normal;
fn mul(self, rhs: Normal) -> Normal {
Normal { x: self.x * rhs.x, y: self.y * rhs.y, z: self.z * rhs.z }
}
}
impl Mul<f32> for Normal {
type Output = Normal;
fn mul(self, rhs: f32) -> Normal {
Normal { x: self.x * rhs, y: self.y * rhs, z: self.z * rhs }
}
}
impl Mul<Normal> for f32 {
type Output = Normal;
fn mul(self, rhs: Normal) -> Normal {
Normal { x: self * rhs.x, y: self * rhs.y, z: self * rhs.z }
}
}
impl Div for Normal {
type Output = Normal;
fn div(self, rhs: Normal) -> Normal {
Normal { x: self.x / rhs.x, y: self.y / rhs.y, z: self.z / rhs.z }
}
}
impl Div<f32> for Normal {
type Output = Normal;
fn div(self, rhs: f32) -> Normal {
Normal { x: self.x / rhs, y: self.y / rhs, z: self.z / rhs }
}
}
impl Neg for Normal {
type Output = Normal;
fn neg(self) -> Normal {
Normal { x: -self.x, y: -self.y, z: -self.z }
}
}
impl Index<usize> for Normal {
type Output = f32;
fn index(&self, i: usize) -> &f32 {
match i {
0 => &self.x,
1 => &self.y,
2 => &self.z,
_ => panic!("Invalid index into normal"),
}
}
}
impl IndexMut<usize> for Normal {
fn index_mut(&mut self, i: usize) -> &mut f32 {
match i {
0 => &mut self.x,
1 => &mut self.y,
2 => &mut self.z,
_ => panic!("Invalid index into normal"),
}
}
}
#[test]
fn test_face_fwd() {
let n = Normal::new(1f32, 0f32, 0f32);
let v = Vector::new(-1f32, 0f32, 0f32);
let n_fwd = n.face_forward(&v);
assert!(n_fwd == Normal::new(-1f32, 0f32, 0f32));
}