Fix corner collision detection

html/images/space.svg

@@ -73,13 +73,13 @@
     </g>
   </g>
 
-  <polygon class="wall" points="20,20 40,20 40,40 20,40" />
+  <!-- <polygon class="wall" points="20,20 40,20 40,40 20,40" /> -->
   <!-- <polygon class="wall" points="-10,-30 -10,-40 30,-50 60,-30 80,0 150,0 150,10 60,50 -10,40 -20,20 20,20 20,-20" /> -->
   <!-- <polygon class="wall" points="-130,-80 -40,-70 -70,-10 -100,40 -120,100" /> -->
-  <!-- <g> -->
-  <!--   <polygon class="wall" points="-130,-80 -40,-70 -70,-10" /> -->
-  <!--   <polygon class="wall" points="50,70 90,-10 130,70" /> -->
-  <!-- </g> -->
+  <g>
+    <polygon class="wall" points="-130,-80 -40,-70 -70,-10" />
+    <polygon class="wall" points="50,70 90,-10 130,70" />
+  </g>
 
   <g id="triangles"></g>
   <g id="edges"></g>
@@ -343,11 +343,27 @@
       });
     }
 
-    function detectCollision(corners, [xc, yc], edge) {
+    function detectEdgeCollision([xc, yc], edge) {
       const shipRadius = 5;
       const [[xa, ya], [xb, yb]] = edge.split(' ').map(n => n.split(',').map(n => +n));
 
-      const cornerCollision = corners.some(([[ax, ay], [bx, by]]) => {
+      const da = distance(xa, ya, xc, yc);
+      const db = distance(xb, yb, xc, yc);
+      // TODO: calculate this one ahead of time
+      const dc = distance(xa, ya, xb, yb);
+
+      // https://en.wikipedia.org/wiki/Altitude_(triangle)#Altitude_in_terms_of_the_sides
+      // Find altitude of side c (the base)
+      const s = (1 / 2) * (da + db + dc);
+      const hc = (2 / dc) * Math.sqrt(s * (s - da) * (s - db) * (s - dc));
+
+      const edgeCollision = hc <= shipRadius;
+
+      return edgeCollision;
+    }
+
+    function detectCornerCollision(corners, xc, yc) {
+      const collidesWithCorner = corners.some(([[ax, ay], [bx, by]]) => {
         cornerPt.x = ax - xc;
         cornerPt.y = ay - yc;
 
@@ -361,25 +377,13 @@
         return collideWithA || collideWithB;
       });
 
-      const da = distance(xa, ya, xc, yc);
-      const db = distance(xb, yb, xc, yc);
-      // TODO: calculate this one ahead of time
-      const dc = distance(xa, ya, xb, yb);
-
-      // https://en.wikipedia.org/wiki/Altitude_(triangle)#Altitude_in_terms_of_the_sides
-      // Find altitude of side c (the base)
-      const s = (1 / 2) * (da + db + dc);
-      const hc = (2 / dc) * Math.sqrt(s * (s - da) * (s - db) * (s - dc));
-
-      const sideCollision = hc <= shipRadius;
-
-      return cornerCollision || sideCollision;
+      return collidesWithCorner;
     }
 
-    function detectAllCollisions(corners, [xc, yc], edges) {
-      return edges.map(edge => {
-        return detectCollision(corners, [xc, yc], edge);
-      }).some(c => c);
+    function detectCollisions(corners, [xc, yc], edges) {
+      const edgeCollision = edges.map(edge => detectEdgeCollision([xc, yc], edge)).some(c => c);
+      const cornerCollision = detectCornerCollision(corners, xc, yc);
+      return cornerCollision || edgeCollision;
     }
 
     function updateShip(elapsed) {
@@ -474,13 +478,10 @@
       if (restart) {
         restart = false;
         [...edgeContainer.children].forEach(c => c.remove());;
-        // drawEdges(edgePts);
         drawAllEdges(allEdgePts);
       }
 
-      // const collision = detectCollision(wallCorners, position, findEdges(edgePts, position));
-      const collision = detectAllCollisions(allWallCorners, position, findAllEdges(allEdgePts, position));
-      // wall.setAttribute('fill', collision ? 'red' : 'black');
+      const collision = detectCollisions(allWallCorners, position, findAllEdges(allEdgePts, position));
       walls.forEach(w => w.setAttribute('fill', collision ? 'red' : 'black'));
 
       if (collision) {