working filled triangles

src/main.rs

@@ -133,7 +133,6 @@ fn line_verts(mut a: Point2i, mut b: Point2i) -> Vec<Point2i> {
     let mut verts: Vec<Point2i> = Vec::new();
 
     let step = (b.y - a.y) as f32 / (b.x - a.x) as f32;
-    let sign = step.signum() as i32;
     let mut y = a.y as f32;
     for x in (a.x)..b.x {
         let p = if is_steep {
@@ -155,38 +154,24 @@ fn triangle_lines(a: Point2i, b: Point2i, c: Point2i, color: TGAColor, fb: &mut
 }
 
 fn triangle_filled(a: Point2i, b: Point2i, c: Point2i, color: TGAColor, fb: &mut TGAImage) {
-    let mut verts = line_verts(a, b);
+    let mut sorted = [a, b, c];
-    verts.extend(line_verts(b, c));
+    sorted.sort_unstable_by(|a, b| a.y.cmp(&b.y));
-    verts.extend(line_verts(c, a));
+    let [a, b, c] = sorted;
 
-    let mut lines: BTreeMap<i32, Vec<i32>> = BTreeMap::new();
+    let total_height = c.y - a.y;
-    for vert in verts.into_iter() {
+
-        lines
+    let segment_height = b.y - a.y;
-            .entry(vert.y)
+    for y in a.y..=b.y {
-            .and_modify(|e| {
+        let dy = y - a.y;
-                e.push(vert.x);
+        let x1 = a.x + ((c.x - a.x) * dy) / total_height;
-                e.sort_unstable();
+        let x2 = a.x + ((b.x - a.x) * dy) / segment_height;
-            })
+        line(Point2i::new(x1, y), Point2i::new(x2, y), color, fb);
-            .or_insert(vec![vert.x]);
     }
 
-    let mut prev_y: Option<i32> = None;
+    let segment_height = c.y - b.y;
-    for (y, xs) in lines.iter_mut() {
+    for y in b.y..=c.y {
-        let len = xs.len();
+        let x1 = a.x + ((c.x - a.x) * (y - a.y)) / total_height;
-        match len {
+        let x2 = b.x + ((c.x - b.x) * (y - b.y)) / segment_height;
-            0 => {}
+        line(Point2i::new(x1, y), Point2i::new(x2, y), color, fb);
-            1 => fb.set(xs[0] as u32, *y as u32, color),
-            _ => {
-                let start = xs[0];
-                let end = xs[len - 1];
-                line(Point2i::new(start, *y), Point2i::new(end, *y), color, fb);
-            }
-        }
-        if let Some(prev) = prev_y {
-            if (y - prev).abs() > 1 {
-                dbg!(y);
-            }
-        }
-        prev_y = Some(*y)
     }
 }