From c5505ab84820248c6dba35fc06aef9e0ced183de Mon Sep 17 00:00:00 2001
From: Julian T <julian@jtle.dk>
Date: Thu, 5 Aug 2021 15:42:43 +0200
Subject: Add XY rectangle

---
 src/world/shapes/rectangle.rs | 105 ++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 105 insertions(+)
 create mode 100644 src/world/shapes/rectangle.rs

(limited to 'src/world/shapes/rectangle.rs')

diff --git a/src/world/shapes/rectangle.rs b/src/world/shapes/rectangle.rs
new file mode 100644
index 0000000..313ebb8
--- /dev/null
+++ b/src/world/shapes/rectangle.rs
@@ -0,0 +1,105 @@
+use crate::{NEAR_ZERO, Float};
+use crate::core::{Ray, Vector3f, Bound3f};
+use crate::world::{Hittable, DynHittable, Intersection, Instancable};
+
+const OUT_XY: Vector3f = Vector3f { x: 0.0, y: 0.0, z: 1.0 };
+
+pub enum Plane {
+    XY,
+}
+
+pub struct Rect {
+    // Size of rectangle in first dimension
+    d1: Float,
+    // Size in second
+    d2: Float,
+    // Offset of plane plane. Should only be used when composing other types
+    offset: Float,
+
+    plane: Plane,
+}
+
+impl Rect {
+    pub fn new(width: Float, height: Float, plane: Plane) -> Self {
+        Rect {d1: width, d2: height, offset: 0.0, plane}
+    }
+
+    pub fn new_with_offset(d1: Float, d2: Float, offset: Float, plane: Plane) -> Self {
+        Rect {
+            d1, d2,
+            offset,
+            plane
+        }
+    }
+}
+
+impl Hittable for Rect {
+    fn intersect(&self, ray: &Ray) -> Option<Intersection> {
+        let t = (self.offset-ray.origin.z) / ray.direction.z;
+        if t <= NEAR_ZERO {
+            return None;
+        }
+
+        let poi = ray.at(t);
+        // Check if at is inside rectangle on plane
+        if poi.x.abs() > (self.d1/2.0) || poi.y.abs() > (self.d2/2.0) {
+            // No collision
+            return None;
+        }
+
+        Some(Intersection::new(OUT_XY, poi, ray, t))
+    }
+
+    fn bounding_box(&self) -> Bound3f {
+        // A rectangle has no area, but we will give it some for its bounding box
+        Bound3f::new(
+            Vector3f::new_xyz(-self.d1, -self.d2, self.offset - 0.0001),
+            Vector3f::new_xyz(self.d1, self.d2, self.offset + 0.0001)
+            )
+    }
+}
+
+impl Into<DynHittable> for Rect {
+    fn into(self) -> DynHittable {
+        DynHittable::new(Box::new(self))
+    }
+}
+
+impl Instancable for Rect {}
+
+impl Plane {
+    pub fn switch(&self, v: Vector3f) -> Vector3f {
+        match self {
+            Plane::XY => v,
+        }
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn xy_rect() {
+        let rect = Rect::new_xy(5.0, 5.0);
+        let ray = Ray {
+            origin: Vector3f::new_xyz(0.0, 1.0, 1.5),
+            direction: Vector3f::new_xyz(0.0, 0.0, -1.0),
+        };
+
+        let t = rect.intersect(&ray).unwrap().t;
+        assert!((t - 1.5).abs() < 0.01);
+    }
+
+    #[test]
+    fn xy_rect_offset() {
+        let rect = Rect::new_with_offset(5.0, 5.0, -1.0, Plane::XY);
+        let ray = Ray {
+            origin: Vector3f::new_xyz(0.0, 1.0, 1.5),
+            direction: Vector3f::new_xyz(0.0, 0.0, -1.0),
+        };
+
+        let t = rect.intersect(&ray).unwrap().t;
+        assert!((t - 2.5).abs() < 0.01);
+    }
+}
-- 
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