lesson3.txt

#color 0xffc3e1fe
#coord 305 17
#title The Subframe Lessons
#title 103: Permanent BRAY

#font 7px
#color 0xfffbfbbb
#coord 37 46
#section 3.1 ARAY

If activated with PSCN, ARAY shoots a special orange BRAY.
This mode is generally not useful in subframe,
but we'll use it here to illustrate some basic principles.

As a subframer, you should think in terms of update functions.

The relevant part of ARAY's update function is as follows.

For each adjacent SPRK(PSCN) of __life 3__:
Generate a BRAY in the direction opposite to the SPRK.

#section 3.2 Life 3? What's that?

SPRK has a property called "life". When created, it has a life of 4.

Every frame, the life of all SPRKs are decreased by one.
This happens __before any particle updates__.

#section 3.3 Permanent BRAY

Remember the CONV-BTRY combo in solid SPRK?
Together, they convert a SPRK of life 3 to a SPRK of life 4.

Since ARAY needs a SPRK of life 3, it needs to be placed
__before__ the CONV-BTRY.

The SPRK created by the BTRY will only "activate"* the ARAY
__the next frame__, after its life has decreased to 3!

* Always remember that SPRK never actually activates anything;
it's the ARAY looking for the SPRK, not the other way round!

#font 5px
#color 0xffbefcc4
#coord 410 48
#section Activity #3.1

Mouseover this SPRK.
You should see Life: 4 here,
since BTRY creates a SPRK of life 4.

Now, enable subframe debugging mode.

Shift-F this INSL, then check SPRK's life.
It should now be 3, since life is
decremented __before any particle updates__.

#section Activity #3.2

Make a permanent BRAY from scratch,
pointing diagonally left and down.

In other words, make this subframe!

Here are some hints:
- Set the ctype of CONV to PSCN by
selecting PSCN and clicking on the CONV.
This specifies what CONV converts SPRK into.
You should then see "PSCN" appear here
when you mouseover the CONV.
- BTRY SPRKs conductors further away
than you think.
- Don't forget to reload particle order!
- Use Shift-F to debug.

#answer 150 10

Extra credit: In the early days of subframe,
two of the eight cardinal directions were
thought to be especially difficult for
permanent BRAY. Which two are these and why?