;s bitmask and the other entity&apos;s category.
If the resulting number isn&apos;t 0000 then we have a collision.
Take the player and enemy for instance:</p>
<pre><code>0001   player&apos;s category
1001   enemy&apos;s bitmask
----
0001   we have a collision
</code></pre><p>And how about the enemy and the powerup:</p>
<pre><code>0100   enemy&apos;s category
1001   powerup&apos;s bitmask
----
0000   we have NO collision
</code></pre><p>Armed with this knowledge, we can assert the following information from 