Draw first real image

ray-tracing-scene/src/basic_scene.rs

@@ -0,0 +1,49 @@
+use rand::Rng;
+use ray_tracing_core::material::DefaultMaterial;
+use ray_tracing_core::prelude::*;
+use ray_tracing_core::scene::{Intersection, Scene};
+
+pub struct BasicScene {
+    pub(crate) spheres: Vec<(Pos3, Float)>,
+}
+
+impl BasicScene {
+    pub fn new() -> Self {
+        Self {
+            spheres: vec![(Pos3::zero(), 1.0), (Pos3::new(0.0, 0.0, 2.5), 2.0)],
+        }
+    }
+}
+
+impl<R: Rng> Scene<R> for BasicScene {
+    fn intersect(&self, ray: Ray, min: Float, max: Float) -> Option<Intersection<'_, R>> {
+        let mut intersection: Option<Intersection<'_, R>> = None;
+
+        for &(c, r) in &self.spheres {
+            let offset = ray.start() - c;
+            let p = Dir3::dot(ray.dir(), offset);
+            let delta = p * p - (offset.length_squared() - r * r);
+
+            if delta >= 0.0 {
+                let d = -p - Float::sqrt(delta);
+
+                let int = Intersection::new(
+                    d,
+                    ((ray.start() + d * ray.dir()) - c).normalize(),
+                    &DefaultMaterial {},
+                );
+                if d >= min && d <= max {
+                    if let Some(i) = intersection.as_ref() {
+                        if i.t() > d {
+                            intersection.replace(int);
+                        }
+                    } else {
+                        intersection = Some(int)
+                    }
+                }
+            }
+        }
+
+        intersection
+    }
+}