Wednesday, January 11, 2012

CAOS Notes: Can I eat this?

Ever want to use CAOS to check if an object is edible? Invisible? Pickup-able by the hand?

Deciphering ATTR and BHVR values at a glace isn't the easiest thing in the world, and it's not exactly glaringly obvious how one would do so with CAOS, either. This is just a really simple script that teleports everything in the world that is edible by creatures to the hand, to demo how you might go about identifying BHVR or ATTR values in an agent.

enum 2 0 0
    setv va00 bhvr
    andv va00 16
    doif va00 = 16 and movs = 0
        mvsf mopx mopy

        velo 0 0

(Yes, this enums through everything in family 2. In big worlds, on slower machines, you might not want to run this script as it may lag you to oblivion and back. Try a clean DS-standalone world if you're having problems.)

It's really difficult to explain exactly how ANDV works if you have no background knowledge of bitwise operators. Heck, I confuse myself with it. But what you really need to know is this:

If you ANDV an agent's ATTR/BHVR value with the ATTR/BHVR value you're checking for, it will return that same value if it is valid.

Say you want to find out if an agent is set to Suffer Physics (ATTR number 128), you would set the ATTR in a variable and ANDV it 128. If it returns 128, the agent does indeed suffer physics. If it returns anything else, it does not.

So in this above example you can see that we've taken the BHVR number that declares the creature can eat said agent, 16, and ANDV'd it to the BHVR. If it returns 16 (and movs = 0, to stop it from trying to move items in vehicles and throwing errors), it is indeed edible, and thus is moved.

If you run this script, assuming your pointer is in a valid spot, all the edible objects in the world should come spewing forth from your fingertip. You'll notice this includes edible critters, including fish from your ponds and pests. Go on and try it!

You did try it, right?

You've probably noticed then, depending on what you've got in your world, that some of the agents weren't the sort of thing the game intended on having moved. Apples and blossoms may hang in midair, as well as other fruits that had been growing on plants. As an exercise, you might try altering the script to check for physics and collisions as well,

Here's a hint-- you can add the values together that you want to check for. For example, if you wanted to check if a creature could push (BHVR 1) and hit (BHVR 8) an agent, you can add those two and simply ANDV the BHVR 9. If it returns 9, both conditions are true.

I know this is supposed to be a tutorial, but I am having way too much fun spewing food and critters all over the place, so I will have to come back to this later. I am sure you more mature developers out there can actually find something useful to do with these commands.

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