143 lines
3.6 KiB
Rust
143 lines
3.6 KiB
Rust
mod mesh_loader;
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use std::fs::File;
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use std::{env};
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use std::error::Error;
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use std::f32::consts::PI;
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use std::io::{BufReader};
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use glm::*;
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use show_image::{ImageInfo, ImageView, WindowOptions};
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use crate::mesh_loader::{Face, load_mesh};
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const W: i32 = 320;
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const H: i32 = 240;
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#[derive(Copy, Clone)]
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struct Color(u8, u8, u8);
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struct Image {
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w: i32,
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h: i32,
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data: Vec<u8>,
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}
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impl Image {
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fn data(&self) -> &[u8] {
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self.data.as_slice()
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}
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fn put_pixel(&mut self, x: i32, y: i32, color: Color) {
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if x < 0 || x >= self.w || y < 0 || y > self.h {
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return;
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}
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let index = 3 * (x + self.w * y) as usize;
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self.data[index] = color.0;
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self.data[index + 1] = color.1;
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self.data[index + 2] = color.2;
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}
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}
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fn ypr_to_mat(ypr: Vec3) -> Mat3 {
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let Vec3 { x: yaw, y: pitch, z: roll } = ypr;
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let m_roll = mat3(
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roll.cos(), roll.sin(), 0.0,
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-roll.sin(), roll.cos(), 0.0,
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0.0, 0.0, 1.0);
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let m_yaw = mat3(
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yaw.cos(), 0.0, yaw.sin(),
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0.0, 1.0, 0.0,
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-yaw.sin(), 0.0, yaw.cos());
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let m_pitch = mat3(
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1.0, 0.0, 0.0,
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0.0, pitch.cos(), -pitch.sin(),
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0.0, pitch.sin(), pitch.cos());
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m_roll * m_pitch * m_yaw
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}
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struct TraceResult {
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distance: f32,
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normal: Vec3,
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}
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fn trace_to_mesh(mesh: &[Face], base: Vec3, ray: Vec3) -> Option<TraceResult> {
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let mut ret: Option<TraceResult> = None;
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let mut dist = f32::INFINITY;
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for f in mesh {
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let fs = (0..3).map(|k| edge_dist(f.vertices[k], f.vertices[(k + 1) % 3], base, ray));
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if fs.into_iter().all(|f| f >= 0.0) {
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let m = Mat3 { c0: f.vertices[1] - f.vertices[0], c1: f.vertices[2] - f.vertices[0], c2: -ray };
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if let Some(m) = m.inverse() {
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let rel = m * (base - f.vertices[0]);
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if rel.z > dist {
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continue;
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}
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dist = rel.z;
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ret = Some(TraceResult {
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distance: rel.z,
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normal: f.normal,
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});
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} else {
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continue;
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}
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}
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}
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ret
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}
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fn render(mesh: &[Face], camera: impl Fn(Vec2) -> (Vec3, Vec3)) -> Image {
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let mut img = Image {
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w: W,
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h: H,
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data: vec![0; (3 * W * H) as usize],
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};
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let img_size = vec2(W as f32, H as f32);
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for y in 0..H {
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for x in 0..W {
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let img_coords = vec2(x as f32, y as f32);
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let off = (img_coords - img_size * 0.5) / img_size.y;
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let (base, ray) = camera(off);
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if let Some(r) = trace_to_mesh(mesh, base, ray) {
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let color = clamp(to_ivec3(r.normal * 120.0 + 128.0), ivec3(0, 0, 0), ivec3(255, 255, 255));
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img.put_pixel(x, y, Color(color.x as u8, color.y as u8, color.z as u8));
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}
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}
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}
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img
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}
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#[show_image::main]
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fn main() -> Result<(), Box<dyn Error>> {
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let args: Vec<String> = env::args().collect();
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let mesh = {
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let f = File::open(&args[1])?;
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let mut f = BufReader::new(f);
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load_mesh(&mut f)?
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};
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let window = show_image::create_window("Raytracing", WindowOptions::default())?;
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loop {
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for phi in 0..360 {
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let m_view = ypr_to_mat(vec3((135.0 + phi as f32) * PI / 180.0, -30.0 * PI / 180.0, 0.0f32));
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let m_camera = transpose(&m_view);
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let img = render(mesh.as_slice(), |off| {
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// perspective projection
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let base = vec3(0.0, 0.0, -40.0);
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let ray = vec3(off.x, off.y, 2.0);
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// orthographic projection
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// let base = vec3(off.x, off.y, -10.0);
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// let ray = vec3(0.0, 0.0, 1.0);
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(m_camera * base, m_camera * ray)
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});
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let image = ImageView::new(ImageInfo::rgb8(W as u32, H as u32), img.data());
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window.set_image("image", image)?;
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}
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}
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}
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fn edge_dist(a: Vec3, b: Vec3, base: Vec3, dir: Vec3) -> f32 {
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// Note: given that the input is not arbitrary but comes from a cartesian product of certain (a, b) pairs and certain (base, dir) pairs, this can be optimized from Cnm to an+bm+cnm with c<C.
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Mat3 { c0: b - a, c1: base - a, c2: -dir }.determinant()
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}
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