gpu-style filled triangles

src/main.rs

@@ -156,10 +156,16 @@ struct Triangle {
 
 impl Triangle {
     pub fn new(a: Point2i, b: Point2i, c: Point2i) -> Self {
-        let mut sorted = [a, b, c];
+        Self { a, b, c }
+    }
+
+    pub fn sort(&mut self) {
+        let mut sorted = [self.a, self.b, self.c];
         sorted.sort_unstable_by(|a, b| a.y.cmp(&b.y));
         let [a, b, c] = sorted;
-        Self { a, b, c }
+        self.a = a;
+        self.b = b;
+        self.c = c;
     }
 
     pub fn signed_area(&self) -> f32 {
@@ -179,13 +185,27 @@ impl Triangle {
             upper_right: Point2i::new(xmax, ymax),
         }
     }
+
     pub fn render_filled(&self, color: TGAColor, fb: &mut TGAImage) {
+        let fb = Arc::new(Mutex::new(fb));
         let bb = self.bb();
-        for y in bb.ymin()..=bb.ymax() {
+        let total_area = self.signed_area();
-            let a = Point2i::new(bb.xmin(), y);
+        (bb.ymin()..=bb.ymax()).into_par_iter().for_each(|y| {
-            let b = Point2i::new(bb.xmax(), y);
+            (bb.xmin()..bb.xmax()).into_par_iter().for_each(|x| {
-            line(a, b, color, fb);
+                let p = Point2i::new(x, y);
-        }
+                let a = Triangle::new(p, self.a, self.b).signed_area() / total_area;
+                let b = Triangle::new(p, self.b, self.c).signed_area() / total_area;
+                let c = Triangle::new(p, self.c, self.a).signed_area() / total_area;
+
+                if a.is_sign_positive()
+                    && b.is_sign_positive()
+                    && c.is_sign_positive()
+                    && let Ok(mut fb) = fb.lock()
+                {
+                    fb.set(x as u32, y as u32, color);
+                }
+            });
+        });
     }
 
     pub fn render_lines(&self, color: TGAColor, fb: &mut TGAImage) {