Able to draw lines of ship between the three vertices.

src/lib.rs

@@ -41,8 +41,8 @@ const RADIUS: f64 = 250.;
 const BACKGROUND: &str = "#ffffff";
 const BLACK: &str      = "#000000";
 const RED: &str        = "#ff0000";
-const _GREEN: &str      = "#00ff00";
-const _BLUE: &str       = "#0000ff";
+const GREEN: &str      = "#00ff00";
+const BLUE: &str       = "#0000ff";
 
 const SCALAR: usize = 0; 
 const E1: usize = 1;
@@ -130,6 +130,15 @@ fn draw_point(context: &CanvasRenderingContext2d, point: &CGA) {
     context.set_fill_style_str(RED);
     context.arc(x, y, 2., 0., TWO_PI).unwrap();
     context.fill();
+
+    let (x,y) = get_point(point);
+    let (x,y) = point_to_screen_space(x,y);
+
+    context.begin_path();
+    context.set_fill_style_str(BLUE);
+    context.arc(x, y, 2., 0., TWO_PI).unwrap();
+    context.fill();
+
 }
 
 //TODO Integrate into get geometry
@@ -161,6 +170,14 @@ fn get_hyperbolic_point(point: &CGA) -> (f64, f64) {
     (r*x,r*y)
 }
 
+fn get_point(point: &CGA) -> (f64, f64) {
+    let x = point[E1];
+    let y = point[E2];
+    let n = CGA::e4()+CGA::e5();
+    let norm = -(point | &n)[SCALAR];
+    (x/norm, y/norm)
+}
+
 fn get_geometry(circle: &CGA) -> Geometry {
     //Naively assume we are given a valid line/circle
     let n_bar = CGA::e4() - CGA::e5();
@@ -193,7 +210,7 @@ fn get_geometry(circle: &CGA) -> Geometry {
 
 fn draw_line(context: &CanvasRenderingContext2d, line: &CGA) {
     context.begin_path();
-    context.set_stroke_style_str(_GREEN);
+    context.set_stroke_style_str(GREEN);
 
     let geometry = get_geometry(line);
     match geometry {
@@ -216,6 +233,52 @@ fn draw_line(context: &CanvasRenderingContext2d, line: &CGA) {
     context.stroke();
 }
 
+fn draw_line_between(context: &CanvasRenderingContext2d, a: &CGA, b: &CGA) {
+    let line = CGA::e4() ^ a ^ b ^ CGA::e3();
+    let geometry = get_geometry(&line);
+    context.begin_path();
+    context.set_stroke_style_str(GREEN);
+    match geometry {
+        Geometry::Circle(x,y,r) => {
+            let (a_x, a_y) = get_point(a);
+            let (b_x, b_y) = get_point(b);
+            let mut theta_a = (a_y-y).atan2(a_x-x);
+            let mut theta_b = (b_y-y).atan2(b_x-x);
+            if theta_a < 0. {
+                theta_a += TWO_PI;
+            }
+            if theta_b < 0. {
+                theta_b += TWO_PI;
+            }
+            let mut delta = theta_b - theta_a;
+            if delta < -PI {
+                delta += TWO_PI;
+            } else if delta > PI {
+                delta -= TWO_PI;
+            }
+            let (x,y) = point_to_screen_space(x,y);
+            let r = RADIUS*r;
+            if delta < 0. {
+                if theta_a + delta < 0. {
+                    context.arc(x, y, r, 0., theta_a).unwrap();
+                    context.arc(x, y, r, theta_a + delta + TWO_PI, TWO_PI).unwrap();
+                } else {
+                    context.arc(x, y, r, theta_a + delta, theta_a).unwrap();
+                }
+            } else {
+                if theta_a + delta > TWO_PI {
+                    context.arc(x, y, r, theta_a, TWO_PI).unwrap();
+                    context.arc(x, y, r, 0., theta_a + delta - TWO_PI).unwrap();
+                } else {
+                    context.arc(x, y, r, theta_a, theta_a + delta).unwrap();
+                }
+            }
+        },
+        _ => {},
+    }
+    context.stroke();
+}
+
 fn _get_hyperbolic_translation(vec: &CGA) -> CGA {
     let vec_sqr = (vec * vec)[SCALAR];
     if vec_sqr >= 1. {
@@ -332,6 +395,9 @@ impl Game {
         draw_point(&self.context, &p0);
         draw_point(&self.context, &p1);
         draw_point(&self.context, &p2);
+        draw_line_between(&self.context, &p0, &p1);
+        draw_line_between(&self.context, &p1, &p2);
+        draw_line_between(&self.context, &p2, &p0);
 
         //Construct and draw line pointing straight ahead, to help orient the player.
         let com_p = com * gen_hyperbolic_point(&CGA::zero()) * com.Reverse();