The APL Orchard

Fawn Locke

00:06

A fun way to express 2n+1 ⊢∘(1∘+)\

Adám

@FawnLocke Simpler: (1+⊢)\

Fawn Locke

Right, of course

Adám

Pro-tip: double your backticks to disable backslash escapes.

Fawn Locke

Thanks!

Brian BED

00:49

this changes the color of a displayed image, but when done inside a function it isn't done globally so i can't make a loop display an animation for example.

'BM'⎕WC'Bitmap'('Bits'(800 800⍴40⌿40/disp))('CMap'(4 3⍴255 0 0 0))

so how do i make it global?

Adám

Not sure what your overall code does, but every time you run that line, you re-create the bitmap. You might want to look at ⎕WS to set new values for the bitmap instead.

Btw, are you sure you want to use Bits and CMap instead of CBits?

Brian BED

i have no idea :D

i just searched in this chat for displaying an image and i copied

ill look on apl cart see what i find

Adám

OK, you probably want CBits which allows full colour images instead of a 256-colour palette.

Brian BED

huh wdym? i was able to use full range

hm i actually don't know whats the diffrence between full palet and 256 palet... i thought 256 was the max range

Adám

It isn't the range of the channels, it is the number of distinct colours at any given time.

Brian BED

00:55

ohhh i wasn't able to use more than 255 distinct colors?

Adám

Correct. Much simpler, imo, to use a single matrix to represent your bitmap directly, instead of indices into a colour palette.

You know about RGB, right?

Brian BED

@Adám o also, my code is a map explorer with structures and such

@Adám ye ye

Adám

A colour number is 256⊥R G B where each channel is in the range 0–255

And so you simply make the CBits property a matrix of such colour numbers.

Brian BED

@Adám yes definetly. it took me a bit to figure out how to use it the way i used it

Adám

'BM'⎕WC'Bitmap'('CBits' matrix_of_col_nums)

and then to update the bitmap:

'BM'⎕WS'CBits' matrix_of_col_nums

Alternatively, you can use the property via the namespace syntax: BM.CBits←matrix_of_col_nums

Brian BED

01:00

@Adám the format of "matrix_of_col_nums" is it "3 3⍴⊂3⍴0"(3x3 pixel image) ?

Adám

No, a 3-by-3 black image would be 3 3⍴0

Why 0? Because 0=256⊥0 0 0

Brian BED

wait let me get the hang of the ⊥ as i've never used it before

Adám

It is base decode. It converts from base-256 to a normal (base-10) number.

(255,127,0)₂₅₆ = 16744192

In APL: ⋄ 256⊥255 127 0

TryAPL

@Adám 16744192

Adám

Should give a nice orange.

Brian BED

01:07

'BM'⎕WC'Bitmap'('CBits'(3 3⍴256⊥255 127 0))
this should work right?

it doesn't for me and idk why

Adám

This works for me:

  'f'⎕WC'Form'
  'f.b'⎕WC'Bitmap'('CBits'(16 16⍴256⊥255 127 0))
  'f.i'⎕WC'Image'(0 0)('Picture' 'f.b')

Brian BED

awesome did for me too. perfect template

Adám

And then you can update (and even resize) the image on the fly like f.b.CBits←16/16⌿?16 16⍴256*3

Brian BED

ahhhhhhh was just about to ask

Adám

Also note that you can update just subsets of the entire image like with f.b.CBits[⍳16;⍳16]←256⊥255 127 0

Brian BED