Soft shadows

assignment-1b/Cargo.lock

@@ -22,11 +22,13 @@ name = "assignment-1b"
 version = "0.1.0"
 dependencies = [
  "anyhow",
+ "base64",
  "clap",
  "derivative",
  "nalgebra",
  "num",
  "ordered-float",
+ "rand",
  "rayon",
  "tracing",
 ]
@@ -37,6 +39,12 @@ version = "1.1.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "d468802bab17cbc0cc575e9b053f41e72aa36bfa6b7f55e3529ffa43161b97fa"
 
+[[package]]
+name = "base64"
+version = "0.21.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "a4a4ddaa51a5bc52a6948f74c06d20aaaddb71924eab79b8c97a8c556e942d6a"
+
 [[package]]
 name = "bitflags"
 version = "1.3.2"
@@ -179,6 +187,17 @@ dependencies = [
  "libc",
 ]
 
+[[package]]
+name = "getrandom"
+version = "0.2.8"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "c05aeb6a22b8f62540c194aac980f2115af067bfe15a0734d7277a768d396b31"
+dependencies = [
+ "cfg-if",
+ "libc",
+ "wasi",
+]
+
 [[package]]
 name = "heck"
 version = "0.4.1"
@@ -395,6 +414,12 @@ version = "0.2.9"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "e0a7ae3ac2f1173085d398531c705756c94a4c56843785df85a60c1a0afac116"
 
+[[package]]
+name = "ppv-lite86"
+version = "0.2.17"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "5b40af805b3121feab8a3c29f04d8ad262fa8e0561883e7653e024ae4479e6de"
+
 [[package]]
 name = "proc-macro-error"
 version = "1.0.4"
@@ -437,6 +462,36 @@ dependencies = [
  "proc-macro2",
 ]
 
+[[package]]
+name = "rand"
+version = "0.8.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "34af8d1a0e25924bc5b7c43c079c942339d8f0a8b57c39049bef581b46327404"
+dependencies = [
+ "libc",
+ "rand_chacha",
+ "rand_core",
+]
+
+[[package]]
+name = "rand_chacha"
+version = "0.3.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "e6c10a63a0fa32252be49d21e7709d4d4baf8d231c2dbce1eaa8141b9b127d88"
+dependencies = [
+ "ppv-lite86",
+ "rand_core",
+]
+
+[[package]]
+name = "rand_core"
+version = "0.6.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "ec0be4795e2f6a28069bec0b5ff3e2ac9bafc99e6a9a7dc3547996c5c816922c"
+dependencies = [
+ "getrandom",
+]
+
 [[package]]
 name = "rawpointer"
 version = "0.2.1"
@@ -589,6 +644,12 @@ version = "0.9.4"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "49874b5167b65d7193b8aba1567f5c7d93d001cafc34600cee003eda787e483f"
 
+[[package]]
+name = "wasi"
+version = "0.11.0+wasi-snapshot-preview1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "9c8d87e72b64a3b4db28d11ce29237c246188f4f51057d65a7eab63b7987e423"
+
 [[package]]
 name = "wide"
 version = "0.7.5"

assignment-1b/Cargo.toml

@@ -14,10 +14,12 @@ path = "src/main.rs"
 
 [dependencies]
 anyhow = "1.0.68"
+base64 = "0.21.0"
 clap = { version = "4.1.4", features = ["cargo", "derive"] }
 derivative = "2.2.0"
 nalgebra = "0.32.1"
 num = { version = "0.4.0", features = ["serde"] }
 ordered-float = "3.4.0"
+rand = "0.8.5"
 rayon = "1.6.1"
 tracing = "0.1.37"

assignment-1b/Makefile

@@ -19,12 +19,14 @@ EXAMPLES_PNG := $(patsubst %.txt,%.png,$(EXAMPLES))
 all: $(HANDIN)
 
 $(BINARY): $(SOURCES)
+	mkdir -p target/docker
 	$(DOCKER) run \
 		--rm \
 		-v "$(shell pwd)":/usr/src/myapp \
 		-v cargo-registry:/usr/local/cargo \
 		--user "$(shell id -u)":"$(shell id -g)" \
 		-w /usr/src/myapp \
+		-e CARGO_TARGET_DIR=/usr/src/myapp/target/docker \
 		rust \
 		cargo build --release
 	mv target/release/raytracer1b $@

assignment-1b/examples/soft-shadow-demo.txt

@@ -0,0 +1,44 @@
+imsize 640 480
+eye 0 0 15
+viewdir 0 0 -1
+hfov 60
+updir 0 1 0
+bkgcolor 0.5 0.5 0.5
+depthcueing 0.5 0.5 0.5 1 0.4 40 20
+
+light 10 10 -10 1 1 1 1
+
+mtlcolor 0.5 1 0.5 1 1 1 0.2 0.4 0 10
+sphere 5 5 -20 5
+sphere -5 -5 -20 5
+
+mtlcolor 1 0.5 0.5 1 1 1 0.2 0.4 0 10
+sphere -10 0 -30 4
+sphere -20 0 -30 4
+sphere -30 0 -30 4
+sphere -40 0 -30 4
+sphere 0 0 -30 4
+sphere 10 0 -30 4
+sphere 20 0 -30 4
+sphere 30 0 -30 4
+sphere 40 0 -30 4
+
+sphere -10 -10 -30 4
+sphere -20 -10 -30 4
+sphere -30 -10 -30 4
+sphere -40 -10 -30 4
+sphere 0 -10 -30 4
+sphere 10 -10 -30 4
+sphere 20 -10 -30 4
+sphere 30 -10 -30 4
+sphere 40 -10 -30 4
+
+sphere -10 10 -30 4
+sphere -20 10 -30 4
+sphere -30 10 -30 4
+sphere -40 10 -30 4
+sphere 0 10 -30 4
+sphere 10 10 -30 4
+sphere 20 10 -30 4
+sphere 30 10 -30 4
+sphere 40 10 -30 4

assignment-1b/src/main.rs

@@ -1,11 +1,16 @@
 use std::fs::File;
 use std::path::PathBuf;
 
-use anyhow::Result;
+use anyhow::{ensure, Result};
 use assignment_1b::image::Image;
 use assignment_1b::ray::Ray;
 use assignment_1b::scene::Scene;
+use base64::{engine::general_purpose::STANDARD as BASE64, Engine};
 use clap::Parser;
+use rand::{
+  rngs::{StdRng, ThreadRng},
+  thread_rng, Rng, RngCore, SeedableRng,
+};
 use rayon::prelude::{IntoParallelIterator, ParallelIterator};
 
 /// Simple raycaster.

assignment-1b/src/scene/illumination.rs

@@ -1,14 +1,17 @@
-use anyhow::Result;
+use std::iter;
+
 use nalgebra::Vector3;
 use ordered_float::NotNan;
+use rand::Rng;
 use rayon::prelude::{
-  IndexedParallelIterator, IntoParallelRefIterator, ParallelIterator,
+  IndexedParallelIterator, IntoParallelIterator, IntoParallelRefIterator,
+  ParallelIterator,
 };
 
 use crate::{image::Color, ray::Ray};
 
 use super::{
-  data::{DepthCueing, Light, LightKind},
+  data::{DepthCueing, Light, LightKind, Object},
   Scene,
 };
 
@@ -59,14 +62,14 @@ impl Scene {
             .max(0.0)
             .powf(material.exponent);
 
-        let shadow_flag =
-          match self.in_shadow_of(obj_idx, intersection_context.point, light) {
-            true => 0.0,
-            false => 1.0,
-          };
+        let shadow_coefficient = self.compute_shadow_coefficient(
+          obj_idx,
+          intersection_context.point,
+          light,
+        );
 
         let diffuse_and_specular = diffuse_component + specular_component;
-        shadow_flag * light.color.component_mul(&diffuse_and_specular)
+        shadow_coefficient * light.color.component_mul(&diffuse_and_specular)
       })
       .sum();
 
@@ -103,12 +106,12 @@ impl Scene {
 
   /// Perform another ray casting to see if there are any objects obstructing
   /// the light source to this particular point
-  pub fn in_shadow_of(
+  pub fn compute_shadow_coefficient(
     &self,
     obj_idx: usize,
     point: Vector3<f64>,
     light: &Light,
-  ) -> bool {
+  ) -> f64 {
     let light_direction = light.direction_from(point);
     let ray = Ray {
       origin: point,
@@ -124,6 +127,7 @@ impl Scene {
       .filter(|(i, _)| *i != obj_idx);
 
     // Get the list of intersections with all the other objects in the scene
+    // This list will be a set of opacities
     let intersections = other_objects
       .filter_map(|(_, object)| {
         let intersection_context = match object.kind.intersects_ray_at(&ray) {
@@ -133,35 +137,93 @@ impl Scene {
             None
           }
         }?;
+        let intersection_time = *intersection_context.time;
 
         match light.kind {
           // In the case of point lights, we must check to see if both t > 0 and
           // t is less than the time it took to even get to the light.
           LightKind::Point { location } => {
             let light_time = (location - ray.origin).norm();
-            let intersection_time = *intersection_context.time;
 
             if intersection_time <= 0.0 || intersection_time >= light_time {
               None
             } else {
-              Some(intersection_context)
+              let soft_shadow_coefficient =
+                self.compute_soft_shadow_coefficient(location, point, object);
+              Some(soft_shadow_coefficient)
             }
           }
 
           // In the case of directional lights, only t > 0 needs to be checked,
           // otherwise
           LightKind::Directional { .. } => {
-            if *intersection_context.time <= 0.0 {
+            if intersection_time <= 0.0 {
               None
             } else {
-              Some(intersection_context)
+              Some(0.0) // complete obstruction
             }
           }
         }
       })
       .collect::<Vec<_>>();
 
-    !intersections.is_empty()
+    let average =
+      intersections.iter().cloned().sum::<f64>() / intersections.len() as f64;
+
+    match intersections.is_empty() {
+      true => 1.0,
+      false => average,
+    }
+  }
+
+  fn compute_soft_shadow_coefficient(
+    &self,
+    light_location: Vector3<f64>,
+    original_intersection_point: Vector3<f64>,
+    object: &Object,
+  ) -> f64 {
+    // Soft shadows: jitter some rays here to somewhere close to the
+    // actual location as well, and measure the proportion
+    // of them that intersect any objects
+    const JITTER_RADIUS: f64 = 1.0;
+    const JITTER_RAYS: usize = 75;
+
+    let mut rng = rand::thread_rng();
+    let locations = iter::repeat_with(|| {
+      let x = rng.gen_range(0.0..JITTER_RADIUS);
+      let y = rng.gen_range(0.0..JITTER_RADIUS);
+      let z = rng.gen_range(0.0..JITTER_RADIUS);
+      let delta = Vector3::new(x, y, z);
+      light_location + delta
+    })
+    .take(JITTER_RAYS)
+    .collect::<Vec<_>>();
+    let num_obstructed_rays = locations
+      .into_par_iter()
+      .filter(|location| {
+        let direction = (location - original_intersection_point).normalize();
+        let ray = Ray {
+          origin: original_intersection_point,
+          direction,
+        };
+
+        let intersection_context = match object.kind.intersects_ray_at(&ray) {
+          Ok(Some(v)) => v,
+          Ok(None) => return false,
+          Err(err) => {
+            error!("Error while performing shadow casting: {err}");
+            return false;
+          }
+        };
+
+        let light_time = (location - ray.origin).norm();
+        let intersection_time = *intersection_context.time;
+
+        0.0 < intersection_time && intersection_time < light_time
+      })
+      .count();
+
+    (JITTER_RAYS - num_obstructed_rays) as f64 / JITTER_RAYS as f64
   }
 }