Basic raytracing
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1 changed files with 167 additions and 110 deletions
277
src/main.rs
277
src/main.rs
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@ -1,11 +1,11 @@
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use cgmath::prelude::*;
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use cgmath::{vec3, vec4, InnerSpace, Matrix4, Point3, Vector3};
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use cgmath::{vec3, vec4, InnerSpace, Matrix4, Point3, Vector3, Zero};
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use image::ImageBuffer;
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use utilities::prelude::*;
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use std::f32::{consts::PI as M_PI, MAX};
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use std::f32::{consts::PI as M_PI, MAX, MIN};
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struct Triangle {
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points: [Vector3<f32>; 3],
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@ -25,6 +25,92 @@ struct View {
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fov: f32,
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}
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struct Ray {
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origin: Vector3<f32>,
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direction: Vector3<f32>,
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inv_direction: Vector3<f32>,
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signs: Vector3<usize>,
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}
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impl Ray {
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pub fn new(origin: Vector3<f32>, direction: Vector3<f32>) -> Ray {
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let inv_direction = 1.0 / direction;
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let x = (inv_direction.x < 0.0) as usize;
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let y = (inv_direction.y < 0.0) as usize;
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let z = (inv_direction.z < 0.0) as usize;
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Ray {
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origin,
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direction,
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inv_direction,
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signs: Vector3::new(x, y, z),
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}
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}
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}
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struct AABB {
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bounds: [Vector3<f32>; 2],
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start_index: usize,
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end_index: usize,
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}
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impl AABB {
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fn new() -> AABB {
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AABB {
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bounds: [Vector3::zero(), Vector3::zero()],
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start_index: 0,
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end_index: 0,
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}
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}
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fn intersect(&self, ray: &Ray) -> bool {
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let mut tmin = (self.bounds[ray.signs.x].x - ray.origin.x) * ray.inv_direction.x;
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let mut tmax = (self.bounds[1 - ray.signs.x].x - ray.origin.x) * ray.inv_direction.x;
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let tymin = (self.bounds[ray.signs.y].y - ray.origin.y) * ray.inv_direction.y;
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let tymax = (self.bounds[1 - ray.signs.y].y - ray.origin.y) * ray.inv_direction.y;
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if tmin > tymax || tymin > tmax {
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return false;
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}
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if tymin > tmin {
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tmin = tymin;
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}
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if tymax < tmax {
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tmax = tymax;
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}
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let tzmin = (self.bounds[ray.signs.z].z - ray.origin.z) * ray.inv_direction.z;
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let tzmax = (self.bounds[1 - ray.signs.z].z - ray.origin.z) * ray.inv_direction.z;
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if tmin > tzmax || tzmin > tmax {
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return false;
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}
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if tzmin > tmin {
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tmin = tzmin;
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}
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if tzmax < tmax {
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tmax = tzmax;
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}
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let mut t = tmin;
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if t < 0.0 {
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t = tmax;
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if t < 0.0 {
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return false;
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}
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}
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true
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}
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}
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fn main() {
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let input_data = [Triangle::new(
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vec3(0.0, 0.0, 0.0),
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@ -38,53 +124,44 @@ fn main() {
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fov: 45.0,
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};
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let (origin, direction) = calculate_ray(640, 360, 1280, 720, &view);
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let color = pixel_color(origin, direction, &input_data);
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//debug_raytracer(1280, 720, &view, &input_data);
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debug_raytracer(1280, 720, &view, &input_data);
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}
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fn f_to_u(color: f32) -> u8 {
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((color * 255.0) / 1.0) as u8
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}
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fn calculate_ray(
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x: u32,
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y: u32,
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dim_x: u32,
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dim_y: u32,
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view: &View,
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) -> (Vector3<f32>, Vector3<f32>) {
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fn calculate_ray(x: u32, y: u32, dim_x: u32, dim_y: u32, view: &View) -> Ray {
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let aspect_ratio = dim_x as f32 / dim_y as f32;
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let p_x = (2.0 * ((x as f32 + 0.5) / dim_x as f32) - 1.0)
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* (view.fov / 2.0 * M_PI / 180.0).tan()
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* aspect_ratio;
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let p_y = (1.0 - 2.0 * (((dim_y - y) as f32 + 0.5) / dim_y as f32))
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* (view.fov / 2.0 * M_PI / 180.0).tan();
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let fov = view.fov / 180.0 * M_PI * 2.0;
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let p_x = (1.0 - 2.0 * ((x as f32 + 0.5) / dim_x as f32)) * fov * aspect_ratio;
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let p_y = (2.0 * (((y) as f32 + 0.5) / dim_y as f32) - 1.0) * fov;
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let camera_to_world = Matrix4::look_at(
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Point3::from_vec(view.position),
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Point3::from_vec(view.look_at),
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vec3(0.0, 0.0, 1.0),
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)
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.inverse_transform()
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.invert()
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.unwrap();
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let origin = camera_to_world * vec4(0.0, 0.0, 0.0, 1.0);
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let direction = camera_to_world * vec4(p_x, p_y, -1.0, 1.0);
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(origin.truncate(), direction.truncate().normalize())
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Ray::new(origin.truncate(), -direction.truncate().normalize())
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}
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fn debug_raytracer(dim_x: u32, dim_y: u32, view: &View, data: &[Triangle]) {
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let mut imgbuf = ImageBuffer::new(dim_x, dim_y);
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for (x, y, pixel) in imgbuf.enumerate_pixels_mut() {
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let (origin, direction) = calculate_ray(x, y, dim_x, dim_y, view);
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let ray = calculate_ray(x, y, dim_x, dim_y, view);
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let color = pixel_color(origin, direction, data);
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let acceleration_data = create_acceleration_data(data);
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let color = pixel_color(&ray, data, acceleration_data);
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*pixel = image::Rgb([f_to_u(color.x), f_to_u(color.y), f_to_u(color.z)]);
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}
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@ -92,21 +169,74 @@ fn debug_raytracer(dim_x: u32, dim_y: u32, view: &View, data: &[Triangle]) {
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imgbuf.save("raytrace.png").unwrap();
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}
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fn pixel_color(orig: Vector3<f32>, dir: Vector3<f32>, data: &[Triangle]) -> Vector3<f32> {
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fn create_acceleration_data(input_data: &[Triangle]) -> Vec<AABB> {
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let mut acceleration_data = Vec::new();
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let accel_count = (input_data.len() as f32 / 24.0).ceil() as usize;
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for i in 0..accel_count {
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let mut accel = AABB::new();
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let mut bbmin = vec3(MAX, MAX, MAX);
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let mut bbmax = vec3(MIN, MIN, MIN);
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// 3 vertices per triangles
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// 8 triangles per acceleration structure
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let start_index = 8 * i;
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let mut end_index = 8 * (i + 1);
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// check if end_index exceeds input data length
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if end_index > input_data.len() {
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end_index = input_data.len();
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}
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// set index information
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accel.start_index = start_index;
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accel.end_index = end_index;
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// create bounding box
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for k in start_index..end_index {
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for vertex in input_data[k].points.iter() {
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// check minimum values
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bbmin.x = bbmin.x.min(vertex.x);
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bbmin.y = bbmin.y.min(vertex.y);
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bbmin.z = bbmin.z.min(vertex.z);
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// check maximum values
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bbmax.x = bbmax.x.max(vertex.x);
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bbmax.y = bbmax.y.max(vertex.y);
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bbmax.z = bbmax.z.max(vertex.z);
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}
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}
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accel.bounds[0] = bbmin;
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accel.bounds[1] = bbmax;
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acceleration_data.push(accel);
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}
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acceleration_data
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}
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fn pixel_color(ray: &Ray, data: &[Triangle], acceleration_data: Vec<AABB>) -> Vector3<f32> {
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let mut final_color = vec3(0.0, 1.0, 0.0);
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let mut closest_value = MAX;
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let mut closest_index = -1;
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for i in 0..data.len() {
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let v0 = data[i].points[0];
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let v1 = data[i].points[1];
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let v2 = data[i].points[2];
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let mut t = 0.0;
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for accel in acceleration_data.iter() {
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if accel.intersect(ray) {
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for i in accel.start_index..accel.end_index {
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let v0 = data[i].points[0];
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let v1 = data[i].points[1];
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let v2 = data[i].points[2];
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let mut t = 0.0;
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if ray_triangle_intersect_naive(orig, dir, v0, v1, v2, &mut t) {
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if t < closest_value {
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closest_index = i as i32;
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closest_value = t;
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if ray_triangle_intersect_mt(ray, v0, v1, v2, &mut t) {
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if t < closest_value {
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closest_index = i as i32;
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closest_value = t;
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}
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}
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}
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}
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}
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@ -120,8 +250,7 @@ fn pixel_color(orig: Vector3<f32>, dir: Vector3<f32>, data: &[Triangle]) -> Vect
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// source: https://www.scratchapixel.com/lessons/3d-basic-rendering/ray-tracing-rendering-a-triangle/moller-trumbore-ray-triangle-intersection
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fn ray_triangle_intersect_mt(
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orig: Vector3<f32>,
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dir: Vector3<f32>,
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ray: &Ray,
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v0: Vector3<f32>,
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v1: Vector3<f32>,
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v2: Vector3<f32>,
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@ -129,7 +258,7 @@ fn ray_triangle_intersect_mt(
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) -> bool {
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let v0v1 = v1 - v0;
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let v0v2 = v2 - v0;
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let pvec = dir.cross(v0v2);
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let pvec = ray.direction.cross(v0v2);
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let det = v0v1.dot(pvec);
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// ray and triangle are parallel if det is close to 0
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@ -139,7 +268,7 @@ fn ray_triangle_intersect_mt(
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let inv_det = 1.0 / det;
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let tvec = orig - v0;
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let tvec = ray.origin - v0;
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let u = tvec.dot(pvec) * inv_det;
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if u < 0.0 || u > 1.0 {
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@ -147,7 +276,7 @@ fn ray_triangle_intersect_mt(
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}
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let qvec = tvec.cross(v0v1);
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let v = dir.dot(qvec) * inv_det;
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let v = ray.direction.dot(qvec) * inv_det;
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if v < 0.0 || u + v > 1.0 {
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return false;
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@ -157,75 +286,3 @@ fn ray_triangle_intersect_mt(
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true
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}
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fn ray_triangle_intersect_naive(
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orig: Vector3<f32>,
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dir: Vector3<f32>,
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v0: Vector3<f32>,
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v1: Vector3<f32>,
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v2: Vector3<f32>,
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t: &mut f32,
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) -> bool {
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// compute plane's normal
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let v0v1 = v1 - v0;
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let v0v2 = v2 - v0;
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// no need to normalize
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let N = v0v1.cross(v0v2);
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let area2 = N.magnitude();
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// Step 1: finding P
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// check if ray and plane are parallel ?
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let NdotRayDirection = N.dot(dir);
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if NdotRayDirection.abs() < 0.001
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// almost 0
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{
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return false;
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} // they are parallel so they don't intersect !
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// compute d parameter using equation 2
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let d = N.dot(v0);
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// compute t (equation 3)
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*t = (N.dot(orig) + d) / NdotRayDirection;
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// check if the triangle is in behind the ray
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if *t < 0.0 {
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return false;
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} // the triangle is behind
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// compute the intersection point using equation 1
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let P = orig + *t * dir;
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// Step 2: inside-outside test
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let mut C; // vector perpendicular to triangle's plane
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// edge 0
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let edge0 = v1 - v0;
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let vp0 = P - v0;
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C = edge0.cross(vp0);
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if N.dot(C) < 0.0 {
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return false;
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} // P is on the right side
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// edge 1
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let edge1 = v2 - v1;
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let vp1 = P - v1;
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C = edge1.cross(vp1);
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if N.dot(C) < 0.0 {
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return false;
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} // P is on the right side
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// edge 2
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let edge2 = v0 - v2;
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let vp2 = P - v2;
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C = edge2.cross(vp2);
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if N.dot(C) < 0.0 {
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return false;
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} // P is on the right side;
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true // this ray hits the triangle
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}
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