Refactored codebase, Added sdl2 along with some shortcuts to switch between different renders and save them on disk in ppm format

ria-weekend/examples/ppm.rs

@@ -1,13 +0,0 @@
-extern crate ria_weekend;
-
-use ria_weekend::{ppm, demo::Demo};
-
-fn main() {
-    let demo = Demo::new("ppm_sample");
-    let dimensions = demo.dimensions();
-    let mut buf = String::new();
-
-    ppm::create_sample(&mut buf, dimensions);
-
-    demo.save_as_ppm(buf);
-}

ria-weekend/examples/ray_demo.rs

@@ -1,38 +0,0 @@
-extern crate ria_weekend;
-extern crate sdl2;
-
-use ria_weekend::{demo::Demo, ray, ray::Ray, vec3::Vec3};
-use sdl2::{pixels, rect::Rect};
-
-fn main() {
-    let (width, height): (usize, usize) = (500, 500);
-    let mut demo = Demo::new("ray_demo", width, height).expect("error occurred");
-
-    let texture_creator = demo.canvas.texture_creator();
-
-    // linear interpolation based on y coordinate
-    // top to down
-    let linear_interpolate_y = |ray: Ray| -> Vec3 {
-        let unit_direction = ray.direction().unit_vector();
-        let t = 0.5 * (unit_direction.y() + 1.0);
-        // (1.0 - t) * start blend_color + t * end color
-        Vec3::new(1.0, 1.0, 1.0) * (1.0 - t) + Vec3::new(0.0, 0.0, 0.0) * t
-    };
-    let mut texture = texture_creator
-        .create_texture_streaming(pixels::PixelFormatEnum::RGB888, width as u32, height as u32)
-        .map_err(|e| e.to_string())
-        .expect("error in creating texture");
-    let mut buf = Vec::new();
-    ray::create_ray_demo(
-        &mut buf,
-        (width as u32, height as u32),
-        linear_interpolate_y,
-    );
-
-    texture.update(Rect::new(0, 0, width as u32, height as u32), &buf, 20);
-
-    demo.canvas.copy(&texture, None, None).unwrap();
-    demo.canvas.present();
-    demo.save_as_ppm(&buf);
-    demo.start().unwrap();
-}

ria-weekend/examples/surface_normal_sphere.rs

@@ -0,0 +1,54 @@
+extern crate ria_weekend;
+
+use ria_weekend::{demo::Demo, ray, ray::Ray, vec3::Vec3};
+
+fn main() {
+    let demo = Demo::new("surface_normal_sphere");
+    let dimensions = demo.dimensions();
+
+    let mut buf = String::new();
+    // linear interpolation based on y coordinate
+    // top to down
+    let color = |ray: Ray| -> Vec3 {
+        // center at z=-1. xy axis cuts sphere in half
+        // blending parameter
+        let t = ray_hit_sphere(Vec3::new(0.0, 0.0, 1.0), 0.5, &ray);
+        if t > 0.0 {
+            // For all rays that hit sphere, return red color
+            // This will result in a sphere that is red in color
+            let N = ray.point_at_parameter(t) - Vec3::new(0.0, 0.0, -1.0);
+            return Vec3::new(N.x() + 1.0, N.y() + 1.0, N.z() + 1.0) * 0.5;
+        }
+        let unit_direction = ray.direction().unit_vector();
+        // For rays that don't hit sphere, It'll paint the gradient as the background
+        // Linear gradient depends on y
+        let t = 0.5 * (unit_direction.y() + 1.0);
+
+        // start color + end color
+        Vec3::new(1.0, 1.0, 1.0) * (1.0 - t) + Vec3::new(0.0, 0.0, 0.0) * t
+    };
+
+    ray::create_ray_demo(&mut buf, dimensions, color);
+
+    demo.save_as_ppm(buf);
+}
+
+fn ray_hit_sphere(center: Vec3, radius: f32, ray: &Ray) -> f32 {
+    // dot(A + t*B - C, A + t*B - C) =  R*R
+    // when expanded we get
+    // t * t * dot(B, B) + 2 * t * dot(B, A-C) + dot(A-C, A-C) - R*R = 0
+
+    // A-C
+    let ac = ray.origin() - center;
+    let a = ray.direction().dot(&ray.direction());
+    let b = 2.0 * ac.dot(&ray.direction());
+    let c = ac.dot(&ac) - radius * radius;
+    let discriminant = b * b - 4.0 * a * c;
+
+    if discriminant >= 0.0 {
+        // return quadratic root
+        (-b + discriminant.sqrt()) / (2.0 * a)
+    } else {
+        -1.0
+    }
+}

ria-weekend/src/demo.rs

@@ -1,91 +1,26 @@
-extern crate sdl2;
-
-use sdl2::{
-    event::Event,
-    keyboard::Keycode,
-    pixels::PixelFormatEnum,
-    rect::Rect,
-    render::{Canvas, Texture, TextureValueError},
-    video::Window,
-    EventPump, Sdl,
-};
 use std::error::Error;
 use std::fs::File;
-use std::{io, io::Write};
+use std::io::Write;
 
-pub struct Demo<'a> {
-    pub width: usize,
-    pub height: usize,
-    pub project_name: &'a str,
-    pub canvas: Canvas<Window>,
-    pub sdl_ctx: Sdl,
-}
+pub trait Demo {
+    fn render(&self, buf: &mut Vec<u8>, width: usize, height: usize);
+    fn name(&self) -> String;
 
-impl<'a> Demo<'a> {
-    pub fn new(project_name: &str, width: usize, height: usize) -> Result<Demo, String> {
-        let sdl_ctx = sdl2::init()?;
-        let video_subsys = sdl_ctx.video()?;
+    fn save_as_ppm(&self, buf: &[u8], width: usize, height: usize) {
+        let header = format!("P3\n{} {}\n255\n", width, height);
 
-        let window = video_subsys
-            .window(project_name, width as u32, height as u32)
-            .position_centered()
-            .build()
-            .map_err(|e| e.to_string())?;
-        let mut canvas = window
-            .into_canvas()
-            .target_texture()
-            .build()
-            .map_err(|e| e.to_string())?;
-
-        Ok(Demo {
-            width,
-            height,
-            canvas,
-            project_name,
-            sdl_ctx,
-        })
-    }
-
-    pub fn save_as_ppm(&self, buf: &[u8]) {
-        let mut header = format!("P3\n{} {}\n255\n", self.width, self.height);
-
-        let mut file = match File::create(&format!(
-            "{}-{}x{}.ppm",
-            self.project_name, self.width, self.height
-        )) {
+        let mut file = match File::create(&format!("{}-{}x{}.ppm", self.name(), width, height)) {
             Ok(file) => file,
-            Err(e) => panic!("couldn't create {}: {}", self.project_name, e.description()),
+            Err(e) => panic!("couldn't create {}: {}", self.name(), e.description()),
         };
         file.write(header.as_bytes())
             .expect("error in writing file header");
-        match file.write_all(&buf) {
-            Ok(_) => println!("Succesfully wrote to {}", self.project_name),
-            Err(e) => panic!(
-                "couldn't write to {}: {}",
-                self.project_name,
-                e.description()
-            ),
-        }
-    }
 
-    pub fn start(&mut self) -> Result<(), String> {
-        let mut event_pump = self.sdl_ctx.event_pump()?;
-
-        loop {
-            for event in event_pump.poll_iter() {
-                match event {
-                    Event::Quit { .. }
-                    | Event::KeyDown {
-                        keycode: Some(Keycode::Escape),
-                        ..
-                    } => return Ok(()),
-                    _ => {}
-                };
+        for i in buf.chunks(4) {
+            match file.write(&format!("{} {} {}\n", i[0], i[1], i[2]).as_bytes()) {
+                Ok(_) => (),
+                Err(e) => panic!("couldn't write to {}: {}", self.name(), e.description()),
             }
         }
     }
-
-    pub fn dimensions(&self) -> (usize, usize) {
-        (self.width, self.height)
-    }
 }

ria-weekend/src/lib.rs

@@ -1,5 +0,0 @@
-pub mod ppm;
-pub mod vec3;
-pub mod ray;
-pub mod demo;
-pub mod stage;

ria-weekend/src/linear_interpolation_y.rs

@@ -0,0 +1,48 @@
+use crate::ray::Ray;
+use crate::vec3::Vec3;
+
+pub struct LinearInterpolationY;
+
+impl crate::Demo for LinearInterpolationY {
+    fn name(&self) -> String {
+        "linear_interpolation_y".to_owned()
+    }
+
+    fn render(&self, buf: &mut Vec<u8>, w: usize, h: usize) {
+        let lower_left_corner = Vec3::new(-2.0, -1.0, -1.0);
+        let horizontal = Vec3::new(4.0, 0.0, 0.0);
+        let vertical = Vec3::new(0.0, 2.0, 0.0);
+        // Observer position
+        let origin = Vec3::new(0.0, 0.0, 0.0);
+
+        let mut offset = 0;
+        for j in (0..h) {
+            for i in 0..w {
+                // relative offsets
+                // current position to total width/length
+                let u = i as f32 / w as f32;
+                let v = j as f32 / h as f32;
+
+                let ray = Ray::new(origin, lower_left_corner + horizontal * u + vertical * v);
+                let color = calc_color(ray);
+                let ir = (255.99 * color[0]) as u8;
+                let ig = (255.99 * color[1]) as u8;
+                let ib = (255.99 * color[2]) as u8;
+
+                buf[offset] = ir;
+                buf[offset + 1] = ig;
+                buf[offset + 2] = ib;
+                buf[offset + 3] = 0;
+                offset += 4;
+            }
+        }
+    }
+}
+
+#[inline]
+fn calc_color(ray: Ray) -> Vec3 {
+    let unit_direction = ray.direction().unit_vector();
+    let t = 0.5 * (unit_direction.y() + 1.0);
+    // (1.0 - t) * start blend_color + t * end color
+    Vec3::new(1.0, 1.0, 1.0) * (1.0 - t) + Vec3::new(0.5, 0.7, 1.0) * t
+}

ria-weekend/src/main.rs

@@ -0,0 +1,105 @@
+mod demo;
+mod linear_interpolation_y;
+mod ppm_example;
+mod ray;
+mod simple_sphere;
+mod vec3;
+
+use demo::Demo;
+use linear_interpolation_y::LinearInterpolationY;
+use ppm_example::PpmExample;
+use sdl2::{
+    event::{Event, WindowEvent},
+    keyboard::Keycode,
+    pixels::PixelFormatEnum,
+    rect::Rect,
+    render::{Canvas, Texture, TextureValueError},
+    video::Window,
+    EventPump, Sdl,
+};
+use simple_sphere::SimpleSphere;
+use vec3::Vec3;
+
+fn main() -> Result<(), String> {
+    let sdl_ctx = sdl2::init()?;
+    let video_subsys = sdl_ctx.video()?;
+
+    let (mut width, mut height): (usize, usize) = (500, 500);
+
+    let mut window = video_subsys
+        .window("Ray tracing in a weekend", width as u32, height as u32)
+        .position_centered()
+        .build()
+        .map_err(|e| e.to_string())?;
+
+    let mut event_pump = sdl_ctx.event_pump()?;
+
+    let mut canvas = window
+        .into_canvas()
+        .target_texture()
+        .build()
+        .map_err(|e| e.to_string())?;
+
+    // Buffer to store a RGBA framebuffer
+    let mut buffer = vec![0; height * width * 4];
+
+    let texture_creator = canvas.texture_creator();
+    let mut texture = texture_creator
+        .create_texture_static(PixelFormatEnum::RGB888, width as u32, height as u32)
+        .map_err(|e| e.to_string())?;
+
+    let mut active_demo: Box<Demo> = Box::new(LinearInterpolationY);
+
+    loop {
+        for event in event_pump.poll_iter() {
+            match event {
+                Event::Quit { .. }
+                | Event::KeyDown {
+                    keycode: Some(Keycode::Escape),
+                    ..
+                } => return Ok(()),
+                Event::KeyUp {
+                    keycode: Some(Keycode::Num1),
+                    ..
+                } => {
+                    active_demo = Box::new(PpmExample);
+                }
+                Event::KeyUp {
+                    keycode: Some(Keycode::Num2),
+                    ..
+                } => {
+                    active_demo = Box::new(LinearInterpolationY);
+                }
+                Event::KeyUp {
+                    keycode: Some(Keycode::Num3),
+                    ..
+                } => {
+                    active_demo = Box::new(SimpleSphere);
+                }
+                Event::KeyUp {
+                    keycode: Some(Keycode::S),
+                    ..
+                } => {
+                    active_demo.save_as_ppm(&buffer, width, height);
+                }
+                Event::Window {
+                    win_event: WindowEvent::Resized(w, h),
+                    ..
+                } => {
+                    width = w as usize;
+                    height = h as usize;
+                    buffer.resize(width * height * 4, 0);
+                    texture = texture_creator
+                        .create_texture_static(PixelFormatEnum::RGB888, width as u32, height as u32)
+                        .expect("error in resizing texture");
+                }
+                _ => {}
+            };
+        }
+
+        active_demo.render(&mut buffer, width, height);
+        texture.update(None, &buffer, width * 4);
+        canvas.copy(&texture, None, None);
+        canvas.present();
+    }
+}

ria-weekend/src/ppm.rs

@@ -1,15 +0,0 @@
-use crate::vec3::Vec3;
-
-pub fn create_sample(buf: &mut String, dimensions: (u32, u32))  {
-    let (w, h ) = dimensions;
-    for j in (0..h).rev() {
-        for i in 0..w {
-            let color = Vec3::new((i as f32) / (w as f32), (j as f32) / (h as f32), 0.5_f32);
-
-            let ir = (255.99 * color[0]) as u8;
-            let ig = (255.99 * color[1]) as u8;
-            let ib = (255.99 * color[2]) as u8;
-            buf.push_str(&format!("{} {} {}\n", ir, ig, ib));
-        }
-    }
-}

ria-weekend/src/ppm_example.rs

@@ -0,0 +1,28 @@
+use crate::vec3::Vec3;
+pub struct PpmExample;
+
+impl crate::Demo for PpmExample {
+    fn name(&self) -> String {
+        "ppm_example".to_owned()
+    }
+
+    fn render(&self, buf: &mut Vec<u8>, w: usize, h: usize) {
+        let mut offset = 0;
+        for j in (0..h) {
+            for i in 0..w {
+                let color = Vec3::new((i as f32) / (w as f32), (j as f32) / (h as f32), 0.2);
+
+                let ir = (255.99 * color[0]) as u8;
+                let ig = (255.99 * color[1]) as u8;
+                let ib = (255.99 * color[2]) as u8;
+
+                buf[offset] = ir;
+                buf[offset + 1] = ig;
+                buf[offset + 2] = ib;
+                buf[offset + 3] = 255;
+
+                offset += 4;
+            }
+        }
+    }
+}

ria-weekend/src/ray.rs

@@ -19,35 +19,3 @@ impl Ray {
         return self.a + self.b * t;
     }
 }
-
-pub fn create_ray_demo<F>(buf: &mut Vec<u8>, dimensions: (u32, u32), op: F)
-where
-    F: Fn(Ray) -> Vec3,
-{
-    let (w, h) = dimensions;
-
-    // uses standard cg RHS notation
-    // y up, z pointing outwards and x to right
-    let lower_left_corner = Vec3::new(-1.0, -1.0, -1.0);
-    let horizontal = Vec3::new(2.0, 0.0, 0.0);
-    let vertical = Vec3::new(0.0, 2.0, 0.0);
-    // observer
-    let origin = Vec3::new(0.0, 0.0, 0.0);
-
-    for j in (0..h).rev() {
-        for i in 0..w {
-            // relative offsets
-            // current position to total width/length
-            let u = i as f32 / w as f32;
-            let v = j as f32 / h as f32;
-
-            let ray = Ray::new(origin, lower_left_corner + horizontal * u + vertical * v);
-
-            let color = op(ray);
-            let ir = (255.99 * color[0]) as u8;
-            let ig = (255.99 * color[1]) as u8;
-            let ib = (255.99 * color[2]) as u8;
-            buf.extend([ir, ig, ib].iter());
-        }
-    }
-}

ria-weekend/src/simple_sphere.rs

@@ -0,0 +1,72 @@
+use crate::{ray::Ray, vec3::Vec3};
+
+pub struct SimpleSphere;
+
+impl crate::Demo for SimpleSphere {
+    fn name(&self) -> String {
+        "simple_sphere".to_owned()
+    }
+
+    fn render(&self, buf: &mut Vec<u8>, w: usize, h: usize) {
+        let lower_left_corner = Vec3::new(-2.0, -1.0, -1.0);
+        let horizontal = Vec3::new(4.0, 0.0, 0.0);
+        let vertical = Vec3::new(0.0, 2.0, 0.0);
+        // Observer position
+        let origin = Vec3::new(0.0, 0.0, 0.0);
+
+        let mut offset = 0;
+        for j in 0..h {
+            for i in 0..w {
+                // relative offsets
+                // current position to total width/length
+                let u = i as f32 / w as f32;
+                let v = j as f32 / h as f32;
+
+                let ray = Ray::new(origin, lower_left_corner + horizontal * u + vertical * v);
+                let color = calc_color(ray);
+                let ir = (255.99 * color[0]) as u8;
+                let ig = (255.99 * color[1]) as u8;
+                let ib = (255.99 * color[2]) as u8;
+
+                buf[offset] = ir;
+                buf[offset + 1] = ig;
+                buf[offset + 2] = ib;
+                buf[offset + 3] = 0;
+                offset += 4;
+            }
+        }
+    }
+}
+
+fn ray_hit_sphere(center: Vec3, radius: f32, ray: &Ray) -> bool {
+    // dot(A + t*B - C, A + t*B - C) =  R*R
+    // when expanded we get
+    // t * t * dot(B, B) + 2 * t * dot(B, A-C) + dot(A-C, A-C) - R*R = 0
+
+    // A-C
+    let ac = ray.origin() - center;
+    let a = ray.direction().dot(&ray.direction());
+    let b = 2.0 * ac.dot(&ray.direction());
+    let c = ac.dot(&ac) - radius * radius;
+    let discriminant = b * b - 4.0 * a * c;
+
+    discriminant > 0.0
+}
+
+fn calc_color(ray: Ray) -> Vec3 {
+    // linear interpolation based on y coordinate
+    // top to down
+    // center at z=-1. xy axis cuts sphere in half
+    if ray_hit_sphere(Vec3::new(0.0, 0.0, 1.0), 0.5, &ray) {
+        // For all rays that hit sphere, return red color
+        // This will result in a sphere that is red in color
+        return Vec3::new(1.0, 0.0, 0.0);
+    }
+    let unit_direction = ray.direction().unit_vector();
+    // For rays that don't hit sphere, It'll paint the gradient as the background
+    // Linear gradient depends on y
+    let t = 0.5 * (unit_direction.y() + 1.0);
+
+    // start color + end color
+    Vec3::new(1.0, 1.0, 1.0) * (1.0 - t) + Vec3::new(0.5, 0.7, 1.0) * t
+}