Time for action - setting a range of bits with BitMask.range

Let's fix our BitMasks to work better for our purpose.

  1. In the setupCollisions method of our Cycle class, change the line where we set the Into collide mask for self.shieldCN to this:
    self.shieldCN.setIntoCollideMask(BitMask32.range(2,3))
  2. Save the file as CycleClass_03.py.
  3. Modify WorldClass_02.py to import CycleClass_03.py instead of CycleClass_02.py. Then, save it as WorldClass_03.py and run it from the command prompt. Attempt to collide the cycles together and we'll see that the collision is detected again, like in the following image:
Time for action - setting a range of bits with BitMask.range

Now our cycles can collide with each other again because they share bits on their BitMasks.

BitMasks are often misunderstood because they are both an esoteric concept and also largely invisible when being used. We never really see the BitMasks themselves, just the result of their use. For that reason, we should make certain of our understanding before we move on.

  1. What is a BitMask?
  2. To what purpose do we employ BitMasks?
  3. How do we apply BitMasks?
  4. What is the difference between a From mask and an Into mask?
  5. Will these two BitMasks allow a collision to occur?
    0000 0000 0000 0000 0000 0000 0110 0000
0000 0000 0000 0000 0000 0000 0010 1010