camera.rs
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//
// Basic geometric things...
//
// Georg Hopp <georg@steffers.org>
//
// Copyright © 2019 Georg Hopp
//
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program. If not, see <http://www.gnu.org/licenses/>.
//
use std::fmt::Debug;
use std::ops::{Add, Div, Mul, Neg, Sub};
use crate::easel::canvas::{Canvas, Vertex};
use crate::math::transform::{TMatrix, Transformable};
use crate::math::trigonometry::Trig;
use crate::math::vector::Vector;
use super::point::Point;
#[derive(Debug, Clone, Copy)]
pub struct Camera<T>
where T: Add + Sub + Neg + Mul + Div + Debug + Copy + Trig + From<i32> {
width :T,
height :T,
distance :T,
project :TMatrix<T>,
}
impl<T> Camera<T>
where T: Add<Output = T> + Sub<Output = T> + Neg<Output = T>
+ Mul<Output = T> + Div<Output = T>
+ PartialEq + Debug + Copy + Trig + From<i32> {
// This code assumes that the size of the viewport is always
// equal to the size of the physical screen… e.g. window/canvas thus some
// effects can't be done. See book for examples with different viewport
// and screen sizes.
pub fn new(c :&dyn Canvas<T>, angle :i32) -> Self {
let width :T = (c.width() as i32).into();
let height :T = (c.height() as i32).into();
let d :T = 1.into();
let fov = T::cot(angle) * width;
let wh = width / 2.into();
let hh = height / 2.into();
Camera { width: width
, height: height
, distance: d
, project: TMatrix::new(
( fov, 0.into(), wh, 0.into())
, (0.into(), fov, hh, 0.into())
, (0.into(), 0.into(), d, 1.into())
, (0.into(), 0.into(), 1.into(), 0.into()) ) }
}
pub fn get_distance(&self) -> T {
self.distance
}
pub fn get_projection(&self) -> TMatrix<T> {
self.project
}
pub fn project(&self, p :Point<T>) -> Vertex<T> {
let v :Vector<T> = p.transform(&self.project).into();
Vertex::new( T::round(&v.x())
, T::round(&v.y())
, v.z() - self.distance )
}
}