Implement pathtracing

1 files changed, 41 insertions, 0 deletions

diff --git a/src/trace/pathtrace.rs b/src/trace/pathtrace.rs
new file mode 100644
index 0000000..32a8e15
--- /dev/null
+++ b/src/trace/pathtrace.rs
@@ -0,0 +1,41 @@
+use crate::scene::Scene;
+use crate::core::{Ray, Spectrum};
+use crate::sample::Sampler;
+use super::Tracer;
+
+pub struct PathTracer<'a> {
+    depth: i32,
+    scn: &'a Scene,
+}
+
+impl PathTracer<'_> {
+    pub fn new(scn: &Scene, depth: Option<i32>) -> PathTracer {
+        let depth = depth.unwrap_or(-1);
+
+        PathTracer {
+            depth,
+            scn,
+        }
+    }
+
+    pub fn trace_recur(&self, sampler: &mut dyn Sampler, ray: &Ray) -> Spectrum {
+
+        if let Some(i) = self.scn.intersect(ray) {
+            // Get a random direction in the hemisphere a i.p
+            // This is Lambertian reflection
+            let target = i.p + i.n + sampler.get_unit_vector();
+            return self.trace_recur(sampler, &Ray::new_to(i.p, target)) * 0.5;
+        }
+
+        // Simulates a sky
+        let t = (ray.direction.norm().y + 1.0) * 0.5;
+        Spectrum::new_rgb(1.0, 1.0, 1.0) * (1.0-t) + Spectrum::new_rgb(0.5, 0.7, 1.0) * t
+
+    }
+}
+
+impl Tracer for PathTracer<'_> {
+    fn trace(&self, sampler: &mut dyn Sampler, ray: &Ray) -> Spectrum {
+        self.trace_recur(sampler, ray)
+    }
+}