Refactored everything again

ria-weekend/examples/ppm.rs

@@ -1,43 +1,13 @@
 extern crate ria_weekend;
 
-use ria_weekend::ppm;
-use std::error::Error;
-use std::fs::File;
-use std::{io, io::Write};
+use ria_weekend::{ppm, demo::Demo};
 
 fn main() {
-    let mut height = 1080;
-    let mut width = 1920;
+    let demo = Demo::new("ppm_sample");
+    let dimensions = demo.dimensions();
+    let mut buf = String::new();
 
-    println!("Enter width and height seperated by space");
+    ppm::create_sample(&mut buf, dimensions);
 
-    let mut input = String::new();
-    io::stdin()
-        .read_line(&mut input)
-        .expect("error in reading input");
-
-    let input = input
-        .trim()
-        .split(" ")
-        .map(|v| v.parse::<u32>().expect("error in parsing input"))
-        .collect::<Vec<u32>>();
-
-    if input.len() >= 2 {
-        height = input[1];
-        width = input[0];
-    }
-    let file_name = format!("ppm_sample{}x{}.ppm", width, height);
-    let mut buf = format!("P3\n{} {}\n255\n", width, height);
-
-    ppm::create_sample(&mut buf, height, width);
-
-    let mut file = match File::create(&file_name) {
-        Ok(file) => file,
-        Err(e) => panic!("couldn't create {}: {}", file_name, e.description()),
-    };
-
-    match file.write_all(buf.as_bytes()) {
-        Ok(_) => println!("Succesfully wrote to {}", file_name),
-        Err(e) => panic!("couldn't write to {}: {}", file_name, e.description()),
-    }
+    demo.save_as_ppm(buf);
 }

ria-weekend/examples/ray_demo.rs

@@ -1,41 +1,22 @@
 extern crate ria_weekend;
 
-use ria_weekend::ray;
-use std::error::Error;
-use std::fs::File;
-use std::{io, io::Write};
+use ria_weekend::{demo::Demo, ray, ray::Ray, vec3::Vec3};
 
 fn main() {
-    let mut height = 100;
-    let mut width = 200;
+    let demo = Demo::new("ray_demo");
+    let dimensions = demo.dimensions();
 
-    println!("Enter width and height seperated by space");
-
-    let mut input = String::new();
-    io::stdin()
-        .read_line(&mut input)
-        .expect("error in reading input");
-
-    let input = input
-        .trim()
-        .split(" ")
-        .map(|v| v.parse::<u32>().expect("error in parsing input"))
-        .collect::<Vec<u32>>();
-
-    if input.len() >= 2 {
-        height = input[1];
-        width = input[0];
-    }
-    let file_name = format!("ray_demo{}x{}.ppm", width, height);
-    let mut buf = format!("P3\n{} {}\n255\n", width, height);
-    let mut file = match File::create(&file_name) {
-        Ok(file) => file,
-        Err(e) => panic!("couldn't create {}: {}", file_name, e.description()),
+    let mut buf = String::new();
+    // 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
     };
-    ray::create_ray_demo(&mut buf, width, height);
 
-    match file.write_all(buf.as_bytes()) {
-        Ok(_) => println!("Succesfully wrote to {}", file_name),
-        Err(e) => panic!("couldn't write to {}: {}", file_name, e.description()),
-    }
+    ray::create_ray_demo(&mut buf, dimensions, linear_interpolate_y);
+
+    demo.save_as_ppm(buf);
 }

ria-weekend/src/demo.rs

@@ -0,0 +1,61 @@
+use std::error::Error;
+use std::fs::File;
+use std::{io, io::Write};
+
+#[derive(Debug)]
+pub struct Demo {
+    width: u32,
+    height: u32,
+    file_name: String,
+}
+
+impl Demo {
+    pub fn new(file_name: &str) -> Demo {
+        let mut height = 100;
+        let mut width = 200;
+
+        println!("Enter width and height seperated by space");
+
+        let mut input = String::new();
+        io::stdin()
+            .read_line(&mut input)
+            .expect("error in reading input");
+
+        let input = input
+            .trim()
+            .split(" ")
+            .map(|v| v.parse::<u32>().expect("error in parsing input"))
+            .collect::<Vec<u32>>();
+
+        if input.len() >= 2 {
+            height = input[1];
+            width = input[0];
+        }
+        let file_name = format!("{}-{}x{}.ppm", file_name, width, height);
+
+        Demo {
+            width,
+            height,
+            file_name,
+        }
+    }
+
+    pub fn save_as_ppm(&self, buf: String) {
+        let mut header = format!("P3\n{} {}\n255\n", self.width, self.height);
+
+        let mut file = match File::create(&self.file_name) {
+            Ok(file) => file,
+            Err(e) => panic!("couldn't create {}: {}", self.file_name, e.description()),
+        };
+        file.write(header.as_bytes())
+            .expect("error in writing file header");
+        match file.write_all(buf.as_bytes()) {
+            Ok(_) => println!("Succesfully wrote to {}", self.file_name),
+            Err(e) => panic!("couldn't write to {}: {}", self.file_name, e.description()),
+        }
+    }
+
+    pub fn dimensions(&self) -> (u32, u32) {
+        (self.width, self.height)
+    }
+}

ria-weekend/src/lib.rs

@@ -1,3 +1,5 @@
 pub mod ppm;
 pub mod vec3;
 pub mod ray;
+pub mod demo;
+

ria-weekend/src/ppm.rs

@@ -1,6 +1,7 @@
 use crate::vec3::Vec3;
 
-pub fn create_sample(buf: &mut String, h: u32, w: u32)  {
+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);

ria-weekend/src/ray.rs

@@ -20,16 +20,12 @@ impl Ray {
     }
 }
 
-// linear interpolation based on y coordinate
-// top to down
-fn 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
-}
+pub fn create_ray_demo<F>(buf: &mut String, dimensions: (u32, u32), op: F)
+where
+    F: Fn(Ray) -> Vec3,
+{
+    let (w, h) = dimensions;
 
-pub fn create_ray_demo(buf: &mut String, w: u32, h: u32) {
     // 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);
@@ -47,7 +43,7 @@ pub fn create_ray_demo(buf: &mut String, w: u32, h: u32) {
 
             let ray = Ray::new(origin, lower_left_corner + horizontal * u + vertical * v);
 
-            let color = linear_interpolate_y(ray);
+            let color = op(ray);
             let ir = (255.99 * color[0]) as u32;
             let ig = (255.99 * color[1]) as u32;
             let ib = (255.99 * color[2]) as u32;