Simplify collision triangle update function

html/images/space.svg

@@ -217,41 +217,20 @@
 
       triangles.forEach(t => {
         const attr = t.getAttribute('points').split(delim);
-        const [[xa, ya], [xb, yb], [xc, yc]] = attr.map(t => t.split(','));
-
-        // https://en.wikipedia.org/wiki/Curve_orientation#Practical_considerations
-        // Determinant for a convex polygon
-        const det = (+xb - +xa) * (+yc - +ya) - (+xc - +xa) * (+yb - +ya);
+        const [a, b,] = attr.map(t => t.split(','));
 
+        const cw = isClockwise(a, b, [positionX, positionY]);
+        const acute = isAcute(a, b, [positionX, positionY]);
         const pos = `${positionX},${positionY}`;
-        const isClockwise = det < 0;
-        let isAcute = false;
-
-        if (isClockwise) {
-          const [[ax, ay], [bx, by], [shipx, shipy]] =
-            t.getAttribute('points').split(' ').map(n => n.split(',').map(n => +n));
-
-          const da = distance(ax, ay, shipx, shipy);
-          const db = distance(bx, by, shipx, shipy);
-          const dc = distance(ax, ay, bx, by);
-
-          // https://en.wikipedia.org/wiki/Law_of_cosines
-          // Solve for angles alpha and beta with inverse cosine (arccosine)
-          const alpha = Math.acos((db ** 2 + dc ** 2 - da ** 2) / (2 * db * dc));
-          const beta = Math.acos((da ** 2 + dc ** 2 - db ** 2) / (2 * da * dc));
-          isAcute = alpha < halfPi && beta < halfPi;
-        }
 
         if (pos !== attr.pop()) {
           attr.push(pos);
           t.setAttribute('points', attr.join(delim));
         }
 
-        if (drawCollisionLines) {
-          t.classList[isClockwise && isAcute ? "add" : "remove"](className);
-          t.classList[isClockwise && !isAcute ? "add" : "remove"]("obtuse");
-          t.classList[!isClockwise ? "add" : "remove"]("anti-clockwise");
-        }
+        t.classList[cw && acute ? "add" : "remove"](className);
+        t.classList[cw && !acute ? "add" : "remove"]("obtuse");
+        t.classList[!cw ? "add" : "remove"]("anti-clockwise");
       });
     }