70 lines
2.2 KiB
Rust
70 lines
2.2 KiB
Rust
use crate::{light::Light, primitive::Intersection, scene::*};
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use nalgebra::{Unit, Vector3};
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static ZERO_VECTOR: Vector3<f32> = Vector3::new(0.0, 0.0, 0.0);
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// Function to shade a point in the scene using Phong shading model
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pub fn phong_shade_point(scene: &Scene, intersect: &Intersection) -> Vector3<u8> {
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let Intersection {
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point,
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normal,
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incidence,
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material,
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..
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} = intersect;
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let ambient_light = &scene.ambient_light;
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let kd = material.kd;
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let ks = material.ks;
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let shininess = material.shininess;
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// Compute the ambient light component and set it as base colour
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let mut colour = kd.component_mul(ambient_light);
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for light in &scene.lights {
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let Light {
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position: light_position,
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colour: light_colour,
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falloff: light_falloff,
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} = light;
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// Compute light incidence vector and its distance
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let to_light = light_position - point;
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let light_distance = to_light.norm();
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let light_incidence = Unit::new_normalize(to_light);
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// Compute light falloff
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let falloff = 1.0
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/ (light_falloff[0]
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+ light_falloff[1] * light_distance
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+ light_falloff[2] * light_distance * light_distance);
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// Compute diffuse
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let n_dot_l = normal.dot(&light_incidence);
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let diffuse = if n_dot_l > 0.0 {
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kd * n_dot_l
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} else {
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ZERO_VECTOR
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};
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// Compute specular
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let h = (&light_incidence.into_inner() + incidence.into_inner()).normalize();
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let n_dot_h = normal.dot(&h);
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let specular = if n_dot_h > 0.0 {
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ks * n_dot_h.powf(shininess)
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} else {
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ZERO_VECTOR
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};
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// Update colour with diffuse and specular components
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colour += light_colour.component_mul(&((diffuse + specular) * falloff));
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}
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// Clamp colour values to [0, 255] and convert to u8
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let r = nalgebra::clamp(colour.x * 255.0, 0.0, 255.0) as u8;
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let g = nalgebra::clamp(colour.y * 255.0, 0.0, 255.0) as u8;
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let b = nalgebra::clamp(colour.z * 255.0, 0.0, 255.0) as u8;
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Vector3::new(r, g, b)
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}
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