From 2e69164dde33fb177cf5092a20d2b24ca86a88ef Mon Sep 17 00:00:00 2001
From: STP <adam.a.french@outlook.com>
Date: Mon, 13 Nov 2023 01:26:59 -0500
Subject: [PATCH] Added phong shading

---
 src/primitive.rs |  3 ++-
 src/raytracer.rs | 60 +++++++++++++++++++++++++++++++++++++++++++-----
 src/scene.rs     |  4 ++--
 3 files changed, 58 insertions(+), 9 deletions(-)

diff --git a/src/primitive.rs b/src/primitive.rs
index 831790b..ef49b2f 100644
--- a/src/primitive.rs
+++ b/src/primitive.rs
@@ -1,12 +1,13 @@
 use crate::ray::Ray;
 use crate::{EPSILON, INFINITY};
-use lazy_static::lazy_static;
 use nalgebra::{distance, Matrix4, Point3, Vector3};
 use roots::{find_roots_quadratic, Roots};
 use std::fs::File;
 use std::io::{BufRead, BufReader};
 use std::path::Path;
 
+use lazy_static::lazy_static;
+
 lazy_static! {
     static ref MAGENTA_MATERIAL: Material = Material::magenta();
 }
diff --git a/src/raytracer.rs b/src/raytracer.rs
index 90ba6c1..8910049 100644
--- a/src/raytracer.rs
+++ b/src/raytracer.rs
@@ -1,9 +1,16 @@
 use crate::{
+    light::Light,
     primitive::{Intersection, Primitive},
     ray::Ray,
     scene::Scene,
     INFINITY,
 };
+use lazy_static::lazy_static;
+lazy_static! {
+    static ref VEC3_ONE: Vector3<f32> = Vector3::new(1.0, 1.0, 1.0);
+    static ref VEC3_ZERO: Vector3<f32> = Vector3::new(1.0, 1.0, 1.0);
+}
+
 use nalgebra::{distance, Matrix4, Point3, Vector3, Vector4};
 
 // Find the closest intersection, given a ray in world coordinates
@@ -30,23 +37,64 @@ fn get_closest_intersection<'a>(scene: &'a Scene, ray: &Ray) -> Option<Intersect
 }
 
 // We want to shade a point placed in our scene
-fn phong_shade_point(scene: &Scene, intersect: &Intersection) -> Option<Vector4<f32>> {
+fn phong_shade_point(scene: &Scene, intersect: &Intersection) -> Vector3<f32> {
+    //Useful vectors !!!! CHECK IF WE CAN OPTIMISE
+    let zero_vector = Vector3::new(0.0, 0.0, 0.0);
+    let one_vector = Vector3::new(1.0, 1.0, 1.0);
     //Unpack the intersection data
     let Intersection {
         primitive,
         point,
         normal,
         incidence,
-        distance,
+        ..
     } = intersect;
     let ambient_light = scene.ambient_light;
     let material = primitive.get_material();
     let kd = material.kd;
-    let ks = material.kd;
+    let ks = material.ks;
     let shininess = material.shininess;
     // We should now have all the information for our ray-tracer
 
-    // Let us first compute the ambient light component
-    let ambient = ambient_light * kd;
-    None
+    // Let us first compute the ambient light component and set it as out base colour
+    let mut colour = kd.component_mul(&ambient_light);
+
+    for light in &scene.lights {
+        let Light {
+            position: light_position,
+            colour: light_colour,
+            falloff: light_falloff,
+        } = light;
+
+        // Get light incidence vector
+        let to_light = light_position - point;
+        let light_distance = to_light.norm();
+        let light_incidence = to_light.normalize();
+
+        // Compute light falloff
+        let falloff = 1.0
+            / (light_falloff[0]
+                + light_falloff[1] * light_distance
+                + light_falloff[2] * light_distance * light_distance);
+
+        // Compute diffuse
+        let n_dot_l = normal.dot(&light_incidence);
+        let diffuse = if n_dot_l > 0.0 {
+            kd * n_dot_l
+        } else {
+            zero_vector
+        };
+
+        // Compute specular
+        let h = (light_incidence + incidence).normalize();
+        let n_dot_h = normal.dot(&h);
+        let specular = if n_dot_h > 0.0 {
+            ks * n_dot_h.powf(shininess)
+        } else {
+            zero_vector
+        };
+
+        colour += light_colour.component_mul(&((diffuse + specular) * falloff));
+    }
+    nalgebra::clamp(colour, zero_vector, one_vector)
 }
diff --git a/src/scene.rs b/src/scene.rs
index 8b0f373..492771c 100644
--- a/src/scene.rs
+++ b/src/scene.rs
@@ -5,8 +5,8 @@ use nalgebra::Vector3;
 
 pub struct Scene<'a> {
     pub primitives: Vec<Box<dyn Primitive<'a>>>,
-    lights: Vec<Light>,
-    camera: Camera,
+    pub lights: Vec<Light>,
+    pub cameras: Vec<Camera>,
     pub ambient_light: Vector3<f32>,
 }