add discharge collision detection

public/stylus/styles.styl

@@ -15,6 +15,14 @@ body
 	font-family FreePixel
 	font-size 16px
 
+canvas
+	-webkit-touch-callout none
+	-webkit-user-select none
+	-khtml-user-select none
+	-moz-user-select none
+	-ms-user-select none
+	user-select: none
+
 .small
 	font-family PixelArial
 	font-size 8px

server/game/room/world/body/turret/discharge/discharge.js

@@ -8,15 +8,21 @@ class Discharge {
 		this.yvel = data.yvel;
 		this.r = data.r;
 
-		this.lifetime = data.lifetime || 100;
+		this.lifetime = data.lifetime || 50;
 		this.fixture = fixture;
+		this.world = this.fixture.body.world;
 
-		// Might just make it this.world later if it turns out I need it more.
+		this.id = this.world.room.generateId();
-		this.id = this.fixture.body.world.room.generateId();
 	}
 
 	destroy() {
-		this.fixture.body.world.removeDischarge(this);
+		this.world.removeDischarge(this);
+	}
+
+	contact(body) {
+		if (body == this.body) return;
+
+		this.destroy();
 	}
 
 	packDelta() {
@@ -41,6 +47,25 @@ class Discharge {
 	}
 
 	tick() {
+		let start = {
+			x: this.x,
+			y: this.y
+		};
+
+		this.x += this.xvel;
+		this.y += this.yvel
+
+		let end = {
+			x: this.x,
+			y: this.y
+		};
+
+		let contact = this.world.physics.raycast(start, end);
+
+		if (contact) {
+			this.contact(contact.body);
+		}
+
 		if (this.lifetime-- <= 0)
 			this.destroy();
 	}

server/game/room/world/physics.js

@@ -4,6 +4,9 @@
 // so most changes done to it should be mirrored there to keep consistent
 // physics between client and server.
 
+// TODO: Put all physics constants into a JSON file that is sent to the client
+// as well so that the top paragraph no longer applies.
+
 // Note:
 // b2Body.GetWorldPoint is broken or something and to get it to work, you
 // must pass an object as the second argument. I don't think it matters what