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use nalgebra::{Point2, SMatrix};
use crate::{
algebra::subspace::Plane,
algebra::{Point, Scalar, Vector, N},
};
pub struct Camera {
plane: Plane,
up: Vector,
origin: Point,
world_to_screen_space: SMatrix<Scalar, 2, N>,
screen_space_to_world: SMatrix<Scalar, N, 2>,
}
impl Camera {
pub fn new(origin: Point, up: Vector, right: Vector) -> Self {
assert!(
up.dot(&right) == 0.0,
"Up and right vectors must be orthogonal"
);
let plane = Plane::new(origin, [up, right]);
let screen_space_to_world = SMatrix::<Scalar, N, 2>::from_columns(&[right, up]);
let world_to_screen_space = screen_space_to_world.pseudo_inverse(0.001).unwrap();
Self {
plane,
up,
origin,
world_to_screen_space,
screen_space_to_world,
}
}
pub fn world_to_screen_space(&self, point: Point) -> Point2<Scalar> {
let projected = self.plane.project_point(point);
let in_screen_space = self.world_to_screen_space * (projected - self.origin);
in_screen_space.into()
}
pub fn screen_space_to_world(&self, point: Point2<Scalar>) -> Point {
(self.screen_space_to_world * point) + self.origin.coords
}
}
#[cfg(test)]
mod tests {
use crate::algebra::{Point, Vector};
use super::Camera;
#[test]
fn test_projection() {
let camera = Camera::new(
Point::new(1.0, 0.0),
Vector::new(1.0, 2.0),
Vector::new(2.0, -1.0),
);
let point = Point::new(3.0, 1.0);
let diff = camera.world_to_screen_space * point - Point::new(1.0, 1.0);
assert!(
diff.norm() < 0.001,
"Camera translated point into screen_space incorrectly"
);
}
}
|
