feat: triangle

src/triangle.rs

@@ -0,0 +1,100 @@
+use crate::{hittable::Hittable, material::MaterialKind, math_utils::is_front_face, types_defined::{HitRecord, Point, Ray, Vec3}};
+
+pub struct Triangle {
+    pub points: Vec<Vec3>,
+    pub material: Option<MaterialKind>,
+}
+
+impl Triangle {
+    pub fn new(p1: Point, p2: Point, p3: Point, material: Option<MaterialKind>,) -> Self {
+        Triangle { 
+            points: vec![
+                p1, p2, p3
+            ],
+            material: material
+        }
+    }
+}
+
+impl Hittable for Triangle {
+
+    fn hit(&self, r: &Ray, t_min: f32, t_max: f32, hit_record: &mut HitRecord) -> bool {
+        let p0 = self.points[0];
+        let p1 = self.points[1];
+        let p2 = self.points[2];
+        let u = Vec3 {
+            x: p1.x - p0.x,
+            y: p1.y - p0.y,
+            z: p1.z - p0.z,
+        };
+        let v = Vec3 {
+            x: p2.x - p0.x,
+            y: p2.y - p0.y,
+            z: p2.z - p0.z,
+        };
+        let normal = Vec3 {
+            x: u.y * v.z - u.z * v.y,
+            y: u.z * v.x - u.x * v.z,
+            z: u.x * v.y - u.y * v.x,
+        };
+        let denominator = r.direction.x * normal.x + r.direction.y * normal.y + r.direction.z * normal.z;
+        if denominator.abs() < std::f32::EPSILON {
+            return false;
+        }
+        let w0 = Vec3 {
+            x: r.point.x - p0.x,
+            y: r.point.y - p0.y,
+            z: r.point.z - p0.z,
+        };
+        let t = -(w0.x * normal.x + w0.y * normal.y + w0.z * normal.z) / denominator;
+        if t < t_min || t > t_max {
+            return false;
+        }
+        let P = Vec3 {
+            x: r.point.x + t * r.direction.x,
+            y: r.point.y + t * r.direction.y,
+            z: r.point.z + t * r.direction.z,
+        };
+        let w = Vec3 {
+            x: P.x - p0.x,
+            y: P.y - p0.y,
+            z: P.z - p0.z,
+        };
+        let uv_cross = Vec3 {
+            x: u.y * v.z - u.z * v.y,
+            y: u.z * v.x - u.x * v.z,
+            z: u.x * v.y - u.y * v.x,
+        };
+        let wv_cross = Vec3 {
+            x: w.y * v.z - w.z * v.y,
+            y: w.z * v.x - w.x * v.z,
+            z: w.x * v.y - w.y * v.x,
+        };
+        let uw_cross = Vec3 {
+            x: u.y * w.z - u.z * w.y,
+            y: u.z * w.x - u.x * w.z,
+            z: u.x * w.y - u.y * w.x,
+        };
+        let alpha = (wv_cross.x * normal.x + wv_cross.y * normal.y + wv_cross.z * normal.z) / (uv_cross.x * normal.x + uv_cross.y * normal.y + uv_cross.z * normal.z);
+        let beta = (uw_cross.x * normal.x + uw_cross.y * normal.y + uw_cross.z * normal.z) / (uv_cross.x * normal.x + uv_cross.y * normal.y + uv_cross.z * normal.z);
+        if alpha >= 0.0 && beta >= 0.0 && alpha + beta <= 1.0 {
+        
+            hit_record.p = P;
+            hit_record.t = t;
+            hit_record.normal = normal;
+            hit_record.front_face = is_front_face(r, normal);
+            hit_record.material = if let Some(ref m) = self.material {
+                match m {
+                    MaterialKind::Lambertian(l) => Some(MaterialKind::Lambertian(l.clone())),
+                    MaterialKind::Metal(m) => Some(MaterialKind::Metal(m.clone())),
+                    MaterialKind::Dielectric(d) => Some(MaterialKind::Dielectric(d.clone())),
+                }
+            } else {
+                None
+            };
+
+            return true;
+        }
+        false
+    }
+}