dynamic multidimensional array help

pizza · Joined: Jun 30, 2012 Posts: 2 Location: moon

my first post, but i've had a ton of questions answered by this forum's archives. thanks everyone.

i'd like to make a dynamic, 3d array for an animation application. something like

Antimon · Posted: Sun Jul 01, 2012 5:03 am Post subject:

I'll start from the bottom, skip ahead until you reach the part that's causing you problems. :)

Coming from a more low-level programming background, I find it sometimes helps to think of these things as arrays containing arrays containing arrays, rather than something that has multiple dimensions.

So, a two dimensional array of integers can be thought of as an array where each element of the array is an array containing integers. So this:

int a[2][3];

is one array (a) containing two arrays (a[0] and a[1]) who, in turn, contain three integers each. All integers in a[0] and a[1] are initialized to zero by ChucK.

If we want to add another integer array so that the size becomes a[3][3], we can do that like this, using ChucK's push operator for adding elements at the end of an array:

a << [4,5,6];

Now there's a third array a[2], which contains the numbers 4, 5 and 6. a[0] and a[1] still both contain 0, 0, 0.

If we now want to add a third dimension, we'll be dealing with an array that contains arrays that in turn contain arrays of integers:

int q[0][3][3];

This new array is as of yet empty, since it was initialized with zero in the first size placeholder. We can make that size 1 by running this (using our previous array a):

q << a;

The size of q is now as if we had initialized it like this:

int q[1][3][3];

...though if we had initialized it like that it would be all zeroes, now it contains one "frame" (from your example) with the numbers that we put in a before.

I made some code to test that what I said above checked out, including it below. Hope this helps!

Antimon · Posted: Sun Jul 01, 2012 5:06 am Post subject:

Oh and

pizza!

pizza · Joined: Jun 30, 2012 Posts: 2 Location: moon

i got it!

and i get it!

antimon, thank you so much for your help. i learned a lot.

for posterity, this is how i expanded the array in my app (only two lines!):

Antimon · Posted: Mon Jul 02, 2012 9:56 am Post subject:

Glad that I could help. Smile

Btw, judging from what you say happens, writing this:

int cel[1][16][8];

inside a block (i.e. some code that is enclosed within curly brackets, like the contents of your if statement or a function) will cause a new array to be created each time you enter that block, which is also inaccessible outside the block. If you write the same thing at root level - i.e. not enclosed by any curly brackets at all - it becomes a global variable that is initialized when the program starts, and stays the same throughout the program's life length.

This is different from, say, javascript (if you've hacked some of that), where a variable declared anywhere (with "var" in front of it) is available to either the whole function it was declared in, or if was declared outside a function, the whole program.