basic path tracing

src/colors.rs

@@ -1,4 +1,4 @@
-use std::ops::{Mul, MulAssign};
+use std::ops::{MulAssign};
 use cgmath::{ElementWise, Vector4};
 use image::{DynamicImage, GenericImage, Rgba};
 
@@ -61,7 +61,7 @@ pub fn normalize_colors_global(radiosity_buffer: &mut Vec<Vec<Vector4<f32>>>) ->
     let range = maximum_colors - minimum_colors;
     //normalize to range
     for column in &mut *radiosity_buffer {
-        for mut radiosity_value in column {
+        for radiosity_value in column {
             //normalize to range
             radiosity_value.div_assign_element_wise(range);
             //map to [0.0..255]
@@ -77,12 +77,13 @@ pub fn map_radmap_to_colors(radiosity_buffer: &Vec<Vec<Vector4<f32>>>) -> Vec<Ve
     let mut color_buffer: Vec<Vec<Rgba<u8>>> = Vec::with_capacity(radiosity_buffer.len());
     radiosity_buffer.iter().enumerate().for_each(|(x, col)| {
         color_buffer.push(Vec::with_capacity(radiosity_buffer[0].len()));
-        col.iter().enumerate().for_each(|(y, color_value)| {
+        col.iter().enumerate().for_each(|(_y, color_value)| {
             //ceil and cast individual colors
             let casted = color_value.map(|comp| {
                 f32::ceil(comp) as u8
             });
-            color_buffer[x].push(Rgba::from([casted.x, casted.y, casted.z, casted.w]));
+            //TODO: no alpha rendering
+            color_buffer[x].push(Rgba::from([casted.x, casted.y, casted.z, 255]));
         });
     });
 

src/main.rs

@@ -7,11 +7,9 @@ mod scene_data;
 mod colors;
 
 use std::string::String;
-use std::sync::{Arc, LockResult, Mutex};
 use cgmath::Vector4;
 use clap::{Parser};
 use easy_gltf::Scene;
-use image::{DynamicImage};
 use crate::colors::{map_radmap_to_colors, normalize_colors_global, store_colors_to_image};
 use crate::renderer::render;
 

src/renderer.rs

@@ -1,15 +1,17 @@
+use std::f32::consts::PI;
 use std::ops::{Add, Mul};
-use std::sync::{Arc, LockResult, Mutex};
+use std::sync::{Arc, Mutex};
 use cgmath::{Angle, ElementWise, InnerSpace, Matrix4, Vector2, Vector3, Vector4};
 use rayon::iter::{IntoParallelIterator, ParallelIterator};
 use easy_gltf::model::{Mode};
-use easy_gltf::{Camera, Material, Projection, Scene};
+use easy_gltf::{Camera, Projection, Scene};
 use crate::Args;
 use crate::geometry::{Intersectable};
 use crate::ray::{construct_primary_rays, Ray};
 use crate::scene_data::IntersectionData;
 
 const RAY_EPSILON: f32 = 0.0007;
+const EMISSION_MULTIPLIER: f32 = 10.0;
 
 pub fn render(scenes: &Vec<Scene>,
               cl_args: &Args) -> Arc<Mutex<Vec<Vec<Vector4<f32>>>>> {
@@ -36,11 +38,11 @@ pub fn render(scenes: &Vec<Scene>,
     // the distance from the camera origin to the view plane
     let z: f32 = cl_args.height as f32 / (2.0 * fovy.mul(0.5).tan());
 
-    let mut radiosity_buffer: Arc<Mutex<Vec<Vec<Vector4<f32>>>>> =
+    let radiosity_buffer: Arc<Mutex<Vec<Vec<Vector4<f32>>>>> =
         Arc::new(Mutex::new(Vec::with_capacity(cl_args.width)));
 
     //prepare the radiosity buffer
-    (0..cl_args.width).into_iter().for_each(|px| {
+    (0..cl_args.width).into_iter().for_each(|_px| {
         let mut empty_vector = Vec::with_capacity(cl_args.height);
         for _ in 0..cl_args.height {
             empty_vector.push(Vector4::new(0.0, 0.0, 0.0, 0.0));
@@ -154,24 +156,50 @@ fn accumulate_colors(intersection_data: &IntersectionData,
                     .get_base_color_alpha(Vector2::new(0.0, 0.0))
             );
 
+    //TODO: hack, because light sources are always too dim
+    pixel_radiosity *= EMISSION_MULTIPLIER;
+
     //get the intersected triangle and calculate the face normals
     let intersected_triangle = intersection_data.intersected_triangle();
-    let face_normal: Vector3<f32> = (intersected_triangle[0].position - intersected_triangle[1].position)
-        .cross(intersected_triangle[0].position - intersected_triangle[2].position).normalize();
+    let tangent = (intersected_triangle[0].position -
+        intersected_triangle[1].position).normalize();
+    let face_normal: Vector3<f32> = tangent
+        .cross(intersected_triangle[0].position -
+            intersected_triangle[2].position).normalize();
+    let bitangent = tangent.cross(face_normal);
+
+    /**
+    generate random direction on hemisphere
+    **/
+    let phi = rand::random::<f32>() * 2.0 * PI;
+    //allow arbitrary angles
+    let theta = rand::random::<f32>() * 2.0 * PI;
+
+    let sin_theta = f32::sin(theta);
+    let direction = tangent * f32::cos(phi) * sin_theta +
+        bitangent * f32::sin(phi) * sin_theta +
+        face_normal * f32::cos(theta);
 
     let secondary_ray = Ray {
         //prevent self-intersection
         source: intersection_data.intersection_point() + RAY_EPSILON * face_normal,
-        direction: face_normal,
+        direction: direction.normalize(),
     };
 
-    let incoming_radiosity = raytrace(
+    //path trace recursively
+    let incoming_radiosity: Vector4<f32> = raytrace(
         &secondary_ray,
         global_scene,
         recursion_depth_left - 1);
 
+    let cos_weighting = direction.dot(face_normal);
+
+    let brdf = 0.5 * intersection_data.material().get_base_color_alpha(
+        Vector2::new(0.0,0.0)
+    );
+
     //reflected component
-    pixel_radiosity += incoming_radiosity * 0.2;
+    pixel_radiosity += (brdf.mul_element_wise(incoming_radiosity) * cos_weighting * 2.0 * PI) ;
 
     pixel_radiosity
 }

src/scene_data.rs

@@ -1,6 +1,6 @@
 use std::sync::Arc;
 use cgmath::Vector3;
-use easy_gltf::{Material, Scene};
+use easy_gltf::{Material};
 use easy_gltf::model::Triangle;
 
 pub(crate) struct IntersectionData {