specular reflections appear to be working

src/colors.rs

@@ -25,6 +25,7 @@ pub fn normalize_colors_global(radiosity_buffer: &mut Vec<Vec<Vector4<f32>>>) ->
 
     //calculate difference between min and max pixel radiosity
     let range = maximum_radiosity - minimum_radiosity;
+
     //normalize to range
     for column in &mut *radiosity_buffer {
         for radiosity_value in column {
@@ -32,6 +33,7 @@ pub fn normalize_colors_global(radiosity_buffer: &mut Vec<Vec<Vector4<f32>>>) ->
             radiosity_value.map(|single_channel_radiosity|
                 f32::powf(single_channel_radiosity, 1.0 / GAMMA)
             );
+
             //normalize to range
             radiosity_value.div_assign_element_wise(range);
             //map to [0.0..255]

src/main.rs

@@ -38,7 +38,7 @@ pub struct Args {
     debug: bool,
     ///path tracing recursion depth
     #[arg(long)]
-    recurse: usize
+    recurse: usize,
 }
 
 fn main() {
@@ -66,6 +66,8 @@ fn main() {
     let output_image =
         store_colors_to_image(as_colors);
 
-    output_image.save("/home/clemens/repositorys/raytrace-rs/output_image.png").expect("Unable to save image!");
+    output_image
+        .save("/home/clemens/repositorys/raytrace-rs/output_image.png")
+        .expect("Unable to save image!");
 }
 

src/math_utils.rs

@@ -29,9 +29,28 @@ pub fn uniform_random_angle_triangle_hemisphere(intersected_triangle: Triangle,
 }
 
 /// Calculate a triangle from the three Vertices
-pub fn face_normal_for_triangle(triangle: &Triangle) -> Vector3<f32> {
+pub fn face_normal_for_triangle(triangle: &Triangle, raydir: Vector3<f32>) -> Vector3<f32> {
     let tangent = (triangle[0].position -
         triangle[1].position).normalize();
-    tangent.cross(triangle[0].position -
-        triangle[2].position).normalize()
+    let mut normal = tangent.cross(triangle[0].position -
+        triangle[2].position).normalize();
+
+    if normal.dot(-raydir) < 0.0 {
+        normal *= -1.0;
+    }
+
+    normal
+}
+
+/// mirrors the given ray direction vector
+/// (assuming to be pointing towards the camera) along the normal
+pub fn mirror_ray(ray_direction: Vector3<f32>, normal: Vector3<f32>) -> Vector3<f32> {
+    let mut new_normal = normal;
+    if normal.dot(-ray_direction) < 0.0 {
+        new_normal = normal * -1.0;
+    }
+
+    //mirror vector (specular sampling)
+    ray_direction -
+        2.0 * (ray_direction.dot(new_normal)) * new_normal
 }

src/renderer.rs

@@ -8,11 +8,12 @@ use easy_gltf::{Camera, Projection, Scene};
 use indicatif::ParallelProgressIterator;
 use crate::Args;
 use crate::geometry::{Intersectable};
-use crate::math_utils::{face_normal_for_triangle, uniform_random_angle_triangle_hemisphere};
+use crate::math_utils::{face_normal_for_triangle, mirror_ray, uniform_random_angle_triangle_hemisphere};
 use crate::ray::{construct_primary_rays, Ray};
 use crate::scene_data::IntersectionData;
 
 const RAY_EPSILON: f32 = 0.0007;
+const RAY_DECAY: f32 = 0.1;
 
 pub fn render(scenes: &Vec<Scene>,
               cl_args: &Args) -> Arc<Mutex<Vec<Vec<Vector4<f32>>>>> {
@@ -67,12 +68,13 @@ pub fn render(scenes: &Vec<Scene>,
 
                 //let the initial pixel color be black and opaque
                 let mut pixel_radiosity: Vector4<f32> = Vector4::new(0.0, 0.0, 0.0, 1.0);
-
                 //cast each ray and get the output luminosity and sum them up
                 rays.iter().for_each(|ray| {
                     pixel_radiosity = pixel_radiosity.add(
-                        raytrace(&ray, render_scene, cl_args.recurse)
-                    );
+                        raytrace(&ray,
+                                 render_scene,
+                                 cl_args.recurse,
+                        ));
                 });
 
                 //store radiosity into the buffer
@@ -87,12 +89,18 @@ pub fn render(scenes: &Vec<Scene>,
     radiosity_buffer
 }
 
-
-fn raytrace(ray: &Ray, scene: &Scene, recursion_depth_left: usize) -> Vector4<f32> {
+/// raytrace recursively
+/// returns a Color Vector
+fn raytrace(ray: &Ray, scene: &Scene,
+            recursion_depth_left: usize,
+)
+            -> Vector4<f32> {
     let mut pixel_radiosity: Vector4<f32> = Vector4::new(0.0, 0.0, 0.0, 1.0);
 
     //abort if no recursion steps are left
-    if recursion_depth_left == 0 { return pixel_radiosity; }
+    if recursion_depth_left == 0 {
+        return pixel_radiosity;
+    }
 
     let mut smallest_t: f32 = f32::MAX;
     let mut intersection_data: Option<IntersectionData> = None;
@@ -148,7 +156,8 @@ fn raytrace(ray: &Ray, scene: &Scene, recursion_depth_left: usize) -> Vector4<f3
 /// called iff an intersection is detected to (recursively) accumulate radiosity at intersection
 fn accumulate_colors(intersection_data: &IntersectionData,
                      global_scene: &Scene,
-                     recursion_depth_left: usize) -> Vector4<f32> {
+                     recursion_depth_left: usize,
+) -> Vector4<f32> {
     let mut pixel_radiosity: Vector4<f32>
         = Vector4::new(0.0, 0.0, 0.0, 1.0);
 
@@ -162,6 +171,10 @@ fn accumulate_colors(intersection_data: &IntersectionData,
                     .get_base_color_alpha(Vector2::new(0.0, 0.0))
             );
 
+    //make shorter rays contribute more towards the total radiosity
+    //TODO: (probably) broken
+    let ray_decay_factor = f32::powf(recursion_depth_left as f32 + 1.0, RAY_DECAY);
+    pixel_radiosity *= ray_decay_factor;
 
     //get the intersected triangle and calculate the face normals
     let intersected_triangle = intersection_data.intersected_triangle();
@@ -169,8 +182,10 @@ fn accumulate_colors(intersection_data: &IntersectionData,
     let decision_factor = rand::random::<f32>();
     let mut direction: Vector3<f32>;
 
-    let face_normal =
-        face_normal_for_triangle(&intersection_data.intersected_triangle());
+    let face_normal = face_normal_for_triangle(
+        &intersection_data.intersected_triangle(),
+        intersection_data.ray().direction,
+    );
 
     let rough_sampling: bool = decision_factor <= intersection_data.material().pbr.roughness_factor;
 
@@ -182,9 +197,7 @@ fn accumulate_colors(intersection_data: &IntersectionData,
             intersection_data.ray(),
         );
     } else {
-        //mirror vector (specular sampling)
-        direction = intersection_data.ray().direction -
-            2.0 * (intersection_data.ray().direction.dot(face_normal)) * face_normal;
+        direction = mirror_ray(intersection_data.ray().direction, face_normal);
     }
 
     direction = direction.normalize();
@@ -196,10 +209,12 @@ fn accumulate_colors(intersection_data: &IntersectionData,
     };
 
     //path trace recursively
-    let incoming_radiosity: Vector4<f32> = raytrace(
+    let incoming_radiosity: Vector4<f32> =
+        raytrace(
             &secondary_ray,
             global_scene,
-        recursion_depth_left - 1);
+            recursion_depth_left - 1,
+        );
 
     //weigh by cosine term depending on view angel
     let cos_weighting = direction.dot(
@@ -212,12 +227,18 @@ fn accumulate_colors(intersection_data: &IntersectionData,
         brdf = intersection_data.material()
             //TODO: texture sampling!
             .get_base_color_alpha(Vector2::new(0.0, 0.0));
-        pixel_radiosity += brdf.mul_element_wise(incoming_radiosity) * cos_weighting * 2.0 * PI;
+
+        //weigh incoming radiosity more than own color so object won't look emissive
+        pixel_radiosity += 1.5 * incoming_radiosity;
+        pixel_radiosity += 1.2 * brdf.mul_element_wise(incoming_radiosity);
+        pixel_radiosity *= cos_weighting * 2.0 * PI * ray_decay_factor;
     } else {
+        //specular sampling
         pixel_radiosity += incoming_radiosity * cos_weighting * 2.0 * PI +
             intersection_data.material()
                 //TODO: texture sampling!
-                .get_base_color_alpha(Vector2::new(0.0, 0.0));
+                .get_base_color_alpha(Vector2::new(0.0, 0.0))
+                * ray_decay_factor;
     }
 
     pixel_radiosity