Add Phong material

src/integrators.rs

@@ -1,5 +1,6 @@
 use nalgebra::{convert, RealField, Vector3};
 
+use super::algebra_utils::try_change_of_basis_matrix;
 use super::colour::ColourRgbF;
 use super::raycasting::{IntersectionInfo, Ray};
 use super::sampler::Sampler;
@@ -25,13 +26,19 @@ impl<T: RealField> Integrator<T> for WhittedIntegrator<T> {
         self.lights
             .iter()
             .map(|light| {
+                let basis_change =
+                    try_change_of_basis_matrix(&info.tangent, &info.cotangent, &info.normal)
+                        .expect("Normal, tangent and cotangent don't for a valid basis.");
                 match sampler
                     .sample(&Ray::new(info.location, light.direction).bias(convert(0.000000001)))
                 {
                     Some(_) => self.ambient_light,
                     None => {
-                        info.material.bsdf()(info.retro, light.direction, light.colour)
-                            * light.direction.dot(&info.normal)
+                        info.material.bsdf()(
+                            basis_change * info.retro,
+                            basis_change * light.direction,
+                            light.colour,
+                        ) * light.direction.dot(&info.normal).abs()
                     }
                 }
             })

src/lib.rs

@@ -1,3 +1,4 @@
+pub mod algebra_utils;
 pub mod camera;
 pub mod colour;
 pub mod image;

src/main.rs

@@ -13,7 +13,7 @@ use std::rc::Rc;
 use vanrijn::camera::partial_render_scene;
 use vanrijn::colour::{ColourRgbF, NamedColour};
 use vanrijn::image::{ClampingToneMapper, ImageRgbF, ImageRgbU8, ToneMapper};
-use vanrijn::materials::LambertianMaterial;
+use vanrijn::materials::{LambertianMaterial, PhongMaterial};
 use vanrijn::raycasting::{Plane, Sphere};
 use vanrijn::scene::Scene;
 
@@ -88,9 +88,11 @@ pub fn main() -> Result<(), Box<dyn std::error::Error>> {
             Box::new(Sphere::new(
                 Vector3::new(0.0, 1.5, 6.0),
                 1.0,
-                Rc::new(LambertianMaterial {
+                Rc::new(PhongMaterial {
                     colour: ColourRgbF::from_named(NamedColour::Red),
-                    diffuse_strength: 0.1,
+                    diffuse_strength: 0.05,
+                    smoothness: 20.0,
+                    specular_strength: 250.0,
                 }),
             )),
         ],

src/materials.rs

@@ -1,6 +1,6 @@
 use nalgebra::{RealField, Vector3};
 
-use super::colour::ColourRgbF;
+use super::colour::{ColourRgbF, NamedColour};
 
 use std::fmt::Debug;
 
@@ -36,3 +36,31 @@ impl<T: RealField> Material<T> for LambertianMaterial<T> {
         )
     }
 }
+
+#[derive(Debug)]
+pub struct PhongMaterial<T: RealField> {
+    pub colour: ColourRgbF<T>,
+    pub diffuse_strength: T,
+    pub specular_strength: T,
+    pub smoothness: T,
+}
+
+impl<T: RealField> Material<T> for PhongMaterial<T> {
+    fn bsdf<'a>(
+        &'a self,
+    ) -> Box<dyn Fn(Vector3<T>, Vector3<T>, ColourRgbF<T>) -> ColourRgbF<T> + 'a> {
+        Box::new(
+            move |w_o: Vector3<T>, w_i: Vector3<T>, colour_in: ColourRgbF<T>| {
+                if w_i.z < T::zero() || w_o.z < T::zero() {
+                    ColourRgbF::from_vector3(&Vector3::zeros())
+                } else {
+                    let reflection_vector = Vector3::new(-w_i.x, -w_i.y, w_i.z);
+                    self.colour * colour_in * self.diffuse_strength
+                        + ColourRgbF::from_named(NamedColour::White)
+                            * w_o.dot(&reflection_vector).abs().powf(self.smoothness)
+                            * (self.specular_strength / w_i.dot(&Vector3::z_axis()))
+                }
+            },
+        )
+    }
+}