From f7bb59cfeded24dc58359243b29978b5810ab341 Mon Sep 17 00:00:00 2001
From: gbrochar <gaetanbrochard@protonmail.com>
Date: Fri, 11 Dec 2020 21:05:34 +0100
Subject: [PATCH] shading

---
 src/main.rs   |  5 +----
 src/object.rs |  2 +-
 src/render.rs | 34 ++++++++++++++++++++--------------
 src/sphere.rs |  5 +++--
 4 files changed, 25 insertions(+), 21 deletions(-)

diff --git a/src/main.rs b/src/main.rs
index 9da117c..e20a28c 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -10,7 +10,6 @@ use sdl2::event::Event;
 use sdl2::keyboard::Keycode;
 use sdl2::pixels::PixelFormatEnum;
 use sdl2::surface::Surface;
-use std::time::Duration;
 
 fn main() {
     let sdl_context = sdl2::init().unwrap();
@@ -31,7 +30,7 @@ fn main() {
     // let surface = Surface::from_data(&mut data, 800, 600, 3, PixelFormatEnum::RGB24).unwrap();
     let texture_creator = canvas.texture_creator();
     let mut event_pump = sdl_context.event_pump().unwrap();
-    let mut i = 0;
+    // let mut i = 0;
     'running: loop {
         render(&mut *data);
         // put_pixel(
@@ -67,7 +66,5 @@ fn main() {
                 _ => {}
             }
         }
-        // The rest of the game loop goes here...
-        // ::std::thread::sleep(Duration::new(0, 1_000_000_000u32 / 60));
     }
 }
diff --git a/src/object.rs b/src/object.rs
index c9b41e6..cec659c 100644
--- a/src/object.rs
+++ b/src/object.rs
@@ -2,5 +2,5 @@ use super::ray::Ray;
 
 pub trait Object {
     fn get_intersection(&self, ray: Ray) -> Option<f64>;
-    fn get_normal(&self) -> [f64; 3];
+    fn get_normal(&self, n: [f64; 3]) -> [f64; 3];
 }
diff --git a/src/render.rs b/src/render.rs
index 278bc45..40f2f41 100644
--- a/src/render.rs
+++ b/src/render.rs
@@ -6,11 +6,6 @@ use crate::ray::Ray;
 use crate::sphere::Sphere;
 use sdl2::pixels::Color;
 
-struct Camera {
-    rv: [f64; 3],
-    uv: [f64; 3],
-}
-
 fn put_pixel(data: &mut [u8], x: usize, y: usize, color: Color) {
     data[y * 3 * 800 + x * 3] = color.r;
     data[y * 3 * 800 + x * 3 + 1] = color.g;
@@ -36,10 +31,6 @@ pub fn render(data: &mut [u8]) {
         &mat4::new_identity(),
         &vec3::new(1., 1., 0.),
     );
-    let camera = Camera {
-        rv: [1., 0., 0.],
-        uv: [0., 1., 0.],
-    };
     for x in 0..800 {
         for y in 0..600 {
             let mut ray = Ray {
@@ -54,21 +45,36 @@ pub fn render(data: &mut [u8]) {
             ray.direction[0] /= n;
             ray.direction[1] /= n;
             ray.direction[2] /= n;
-            let ray2 = Box::clone(&Box::new(ray));
+            // let ray2 = Box::clone(&Box::new(ray));
             // vec3::transform_mat4(&mut ray.direction, &ray2.direction, &projection_matrix);
+            let ray2 = Box::clone(&Box::new(ray));
             vec3::transform_mat4(&mut ray.origin, &ray2.origin, &view_matrix);
             let ray2 = Box::clone(&Box::new(ray));
             vec3::transform_mat4(&mut ray.origin, &ray2.origin, &model_matrix);
             match sphere.get_intersection(ray) {
-                Some(v) => {
+                Some(dist) => {
+                    let n = [
+                        ray.origin[0] + ray.direction[0] * dist,
+                        ray.origin[1] + ray.direction[1] * dist,
+                        ray.origin[2] + ray.direction[2] * dist,
+                    ];
+                    let normal = sphere.get_normal(n);
+                    let light = [n[0] - 10., n[1] - 10., n[2] - 10.];
+                    let scalar = (light[0].powi(2) + light[1].powi(2) + light[2].powi(2)).sqrt();
+                    let light_d = [light[0] / scalar, light[1] / scalar, light[2] / scalar];
+                    let mut diffuse =
+                        normal[0] * light_d[0] + normal[1] * light_d[1] + normal[2] * light_d[2];
+                    if diffuse < 0. {
+                        diffuse = 0.;
+                    }
                     put_pixel(
                         &mut *data,
                         x,
                         y,
                         Color {
-                            r: 255,
-                            g: 0,
-                            b: 0,
+                            r: (diffuse * 255.) as u8,
+                            g: (diffuse * 255.) as u8,
+                            b: (diffuse * 255.) as u8,
                             a: 0,
                         },
                     );
diff --git a/src/sphere.rs b/src/sphere.rs
index 11a560f..ab78bde 100644
--- a/src/sphere.rs
+++ b/src/sphere.rs
@@ -31,7 +31,8 @@ impl Object for Sphere {
             None
         }
     }
-    fn get_normal(&self) -> [f64; 3] {
-        vec3::new_zero()
+    fn get_normal(&self, n: [f64; 3]) -> [f64; 3] {
+        let scalar = (n[0].powi(2) + n[1].powi(2) + n[2].powi(2)).sqrt();
+        [n[0] / scalar, n[1] / scalar, n[2] / scalar]
     }
 }