ft: 12: movable camera + camera init overhaul

src/camera.rs

@@ -1,6 +1,6 @@
-use std::cmp::max;
+use std::f32::consts::PI;
 
-use log::info;
+use log::{info, warn};
 
 use crate::{
     objects::{hit::Hit, traits::Hittable},
@@ -8,50 +8,129 @@ use crate::{
     vec3::{Colour, Vec3},
 };
 
+#[derive(Debug)]
 pub struct Camera {
+    // output
     image_width: u32,
     image_height: u32,
+
+    // raytracing
     anti_alias_rate: u32,
     max_depth: u32,
-    center: Vec3,
     pixel00_loc: Vec3,
     pixel_delta_u: Vec3,
     pixel_delta_v: Vec3,
+
+    // camera
+    dirty: bool,
+    fov: f32,
+    look_from: Vec3,
+    look_at: Vec3,
+    vup: Vec3,
+
+    // camera helpers
+    u: Vec3,
+    v: Vec3,
+    w: Vec3,
+}
+
+// FIXME: kinda out of place in this file.
+fn deg_to_rad(deg: f32) -> f32 {
+    deg * PI / 180.
 }
 
 impl Camera {
-    pub fn new(aspect_ratio: f32, image_width: u32, anti_alias_rate: u32, max_depth: u32) -> Self {
-        let image_height = max(1, (image_width as f32 / aspect_ratio) as u32);
-
-        //camera
-        let focal_length = 1.;
-        let viewport_height = 2.;
-        let viewport_width = viewport_height * (image_width as f32 / image_height as f32);
-        let camera_center = Vec3::nil();
-
-        //viewport
-        let viewport_u = Vec3::new(viewport_width as f32, 0., 0.);
-        let viewport_v = Vec3::new(0., -viewport_height as f32, 0.);
-
-        let pixel_delta_u = viewport_u / image_width as f32;
-        let pixel_delta_v = viewport_v / image_height as f32;
-
-        let pixel00_loc =
-            camera_center - Vec3::new(0., 0., focal_length) - viewport_u / 2 - viewport_v / 2;
-
+    pub fn new(image_width: u32, image_height: u32) -> Self {
         Self {
             image_width: image_width,
             image_height: image_height,
-            anti_alias_rate: anti_alias_rate,
-            max_depth: max_depth,
-            center: camera_center,
-            pixel00_loc: pixel00_loc,
-            pixel_delta_u: pixel_delta_u,
-            pixel_delta_v: pixel_delta_v,
+            anti_alias_rate: 1,
+            max_depth: 10,
+            dirty: true,
+            fov: 60.,
+            pixel00_loc: Vec3::nil(),
+            pixel_delta_u: Vec3::nil(),
+            pixel_delta_v: Vec3::nil(),
+            look_from: Vec3::nil(),
+            look_at: Vec3::new(0., 0., -1.),
+            vup: Vec3::new(0., 1., 0.),
+            u: Vec3::nil(),
+            v: Vec3::nil(),
+            w: Vec3::nil(),
         }
     }
 
-    pub fn render<T: Hittable>(&self, hittables: &Vec<T>) {
+    fn init(&mut self) {
+        // camera
+        let focal_length = (self.look_from - self.look_at).length();
+        let theta = deg_to_rad(self.fov);
+        let h = (theta / 2.).tan();
+        self.w = (self.look_from - self.look_at).get_unit();
+        self.u = self.vup.cross(&self.w).get_unit();
+        self.v = self.w.cross(&self.u);
+
+        // viewport
+        let viewport_height = 2. * h * focal_length;
+        let viewport_width = viewport_height * (self.image_width as f32 / self.image_height as f32);
+        let viewport_u = viewport_width * self.u;
+        let viewport_v = viewport_height * -self.v;
+
+        // variables
+        self.pixel_delta_u = viewport_u / self.image_width as f32;
+        self.pixel_delta_v = viewport_v / self.image_height as f32;
+        self.pixel00_loc =
+            self.look_from - (focal_length * self.w) - viewport_u / 2. - viewport_v / 2.;
+        self.dirty = false;
+    }
+
+    pub fn set_fov(&mut self, fov: f32) {
+        if self.fov != fov {
+            self.fov = fov;
+            self.dirty = true;
+        }
+    }
+
+    pub fn set_max_depth(&mut self, depth: u32) {
+        if self.max_depth != depth {
+            self.max_depth = depth;
+            self.dirty = true;
+        }
+    }
+
+    pub fn set_anti_alias_rate(&mut self, rate: u32) {
+        if self.anti_alias_rate != rate {
+            self.anti_alias_rate = rate;
+            self.dirty = true;
+        }
+    }
+
+    pub fn set_look_from(&mut self, look_from: Vec3) {
+        if self.look_from != look_from {
+            self.look_from = look_from;
+            self.dirty = true;
+        }
+    }
+
+    pub fn set_look_at(&mut self, look_at: Vec3) {
+        if self.look_at != look_at {
+            self.look_at = look_at;
+            self.dirty = true;
+        }
+    }
+
+    pub fn set_vup(&mut self, vup: Vec3) {
+        if self.vup != vup {
+            self.vup = vup;
+            self.dirty = true;
+        }
+    }
+
+    pub fn render<T: Hittable>(&mut self, hittables: &Vec<T>) {
+        if self.dirty {
+            self.init()
+        }
+        warn!("{}", format!("{self:#?}"));
+
         let mut imgbuf = image::ImageBuffer::new(self.image_width, self.image_height);
 
         // render
@@ -67,8 +146,8 @@ impl Camera {
                         let pixel_loc = pixel_tl
                             + (x * self.pixel_delta_u / (self.anti_alias_rate + 1) as f32)
                             + (y * self.pixel_delta_v / (self.anti_alias_rate + 1) as f32);
-                        let ray_dir = pixel_loc - self.center;
-                        let r = Ray::new(self.center, ray_dir);
+                        let ray_dir = pixel_loc - self.look_from;
+                        let r = Ray::new(self.look_from, ray_dir);
                         pixel_colour += self.ray_colour(&hittables, &r, self.max_depth);
                     }
                 }

src/main.rs

@@ -37,6 +37,12 @@ fn main() {
     world.push(Sphere::xyz(1., 0., -1.0, 0.5, right.clone()));
     world.push(Sphere::xyz(0., 0.7, -0.4, 0.2, blue.clone()));
 
-    let c = Camera::new(16. / 9., 1920, 3, 50);
+    let mut c = Camera::new(400, 300);
+    // let mut c = Camera::new(1920, 1080);
+    c.set_fov(20.);
+    c.set_anti_alias_rate(2);
+    c.set_max_depth(90);
+    c.set_look_from(Vec3::new(-2., 2., 1.));
+    c.set_look_at(Vec3::new(0., 0., -1.));
     c.render(&world);
 }

src/vec3.rs

@@ -6,7 +6,7 @@ use std::{
     ops::{Add, AddAssign, Div, DivAssign, Mul, MulAssign, Neg, Sub, SubAssign},
 };
 
-#[derive(Copy, Clone)]
+#[derive(Copy, Clone, Debug)]
 pub struct Vec3 {
     r: f32,
     g: f32,