float-y line function

src/main.rs

@@ -33,13 +33,36 @@ fn main() {
     let h = 64;
     let mut framebuffer = TGAImage::new(w, h, TGAFormat::RGB);
 
-    bench(&mut framebuffer);
+    //bench(&mut framebuffer);
+    baseline(&mut framebuffer);
 
     framebuffer
         .write_file("framebuffer.tga", true, true)
         .unwrap();
 }
 
+fn baseline(framebuffer: &mut TGAImage) {
+    let ax = 7;
+    let ay = 3;
+    let bx = 12;
+    let by = 37;
+    let cx = 62;
+    let cy = 53;
+
+    framebuffer.set(ax, ay, WHITE);
+    framebuffer.set(bx, by, WHITE);
+    framebuffer.set(cx, cy, WHITE);
+
+    let a = Point::new(ax, ay);
+    let b = Point::new(bx, by);
+    let c = Point::new(cx, cy);
+
+    line(a, b, framebuffer, BLUE);
+    line(c, b, framebuffer, GREEN);
+    line(c, a, framebuffer, YELLOW);
+    line(a, c, framebuffer, RED);
+}
+
 fn bench(fb: &mut TGAImage) {
     let mut rng = rand::rng();
 
@@ -72,13 +95,14 @@ fn line(mut a: Point, mut b: Point, fb: &mut TGAImage, color: TGAColor) {
         std::mem::swap(&mut a.y, &mut b.y);
     }
 
+    let mut y = a.y as f32;
+    let step = (b.y - a.y) as f32 / (b.x - a.x) as f32;
     for x in (a.x)..b.x {
-        let t = (x - a.x) as f32 / (b.x - a.x) as f32;
-        let y = (a.y as f32 + (b.y - a.y) as f32 * t).round_ties_even() as u32;
         if is_steep {
-            fb.set(y, x as u32, color);
+            fb.set(y as u32, x as u32, color);
         } else {
-            fb.set(x as u32, y, color);
+            fb.set(x as u32, y as u32, color);
         }
+        y += step;
     }
 }