Nandor Torai

I want to create a knob that works like a picctrl, but after a lot of researches I still cannot find a way to make it happen. 

My idea was to load a png with a knob with a few states/frames in it and manipulate it so only a portion (1 knob state) is visible at a time. So I would need to tell max to only show a partion of the picture from pixel 0 to 30 then for a secound frame 31 to 60 and so on. 

Hello, 

I want to create a knob that works like a picctrl, but after a lot of researches I still cannot find a way to make it happen. 

My idea was to load a png with a knob with a few states/frames in it and manipulate it so only a portion (1 knob state) is visible at a time. So I would need to tell max to only show a partion of the picture from pixel 0 to 30 then for a secound frame 31 to 60 and so on. 

Can anyone help me with that? 

Hello, 

I want to create a knob that works like a picctrl, but after a lot of researches I still cannot find a way to make it happen. 

creating-a-picctrl-in-jitter-with-a-"knob"-png

you could crop the matrix to a new, smaller matrix where the images are stored, then later you can just bang them to get a new frame with new content.

but if it is hundreds of pictures it is probably more clever to do the cropping live.

none-GL solutions could be built around jit.matrixset, -submatrix, -split or, because button content is uniform, -scissors.


you could crop the matrix to a new, smaller matrix where the images are stored, then later you can just bang them to get a new frame with new content.

but if it is hundreds of pictures it is probably more clever to do the cropping live.

none-GL solutions could be built around jit.matrixset, -submatrix, -split or, because button content is uniform, -scissors.




you just have to play around with the position of the picture. :) 

!AL Knob Blue 2S.png

Sorry ( I can't figure it out how to share a png without displaying it :( )

I found a way with jit.rota 

you just have to play around with the position of the picture. :) 



Sorry ( I can't figure it out how to share a png without displaying it :( ) 

but for this specific image i wouldnt even bother loading image files. :)

yep, rota can do it, too.
but for this specific image i wouldnt even bother loading image files. :)

Rendering a knob like that from scratch is out of my abilities right now. 

That's why I tried to do it with images in the first place. 

Can you point me in the right direction where should I start? :) 

Rendering a knob like that from scratch is out of my abilities right now. 

That's why I tried to do it with images in the first place. 
Can you point me in the right direction where should I start? :) 


if something looks like a simple vector image, there is a chance that you can draw it with a dozen messages right in max.

jit.lcd.help, jit.mgraphics.help ?

if something looks like a simple vector image, there is a chance that you can draw it with a dozen messages right in max.


I assume your final goal is to display the knob on the window (is that correct?)

The attached patch implements a possible approach. It generates the "live.dial" look procedurally on the GPU using jit.gl.pix, but it's quite a complex setup and maybe not worth it; it depends on what you need to do.

The best approach, IMO, is what Roman suggested: use jit.lcd to create the knob; it should require very few messages.

As an alternative, you could also consider loading the "snapshots" of the knob as different textures/matrices using jit.gl.textureset or jit.matrixset

I assume your final goal is to display the knob on the window (is that correct?)
The attached patch implements a possible approach. It generates the "live.dial" look procedurally on the GPU using jit.gl.pix, but it's quite a complex setup and maybe not worth it; it depends on what you need to do.

The best approach, IMO, is what Roman suggested: use jit.lcd to create the knob; it should require very few messages.
As an alternative, you could also consider loading the "snapshots" of the knob as different textures/matrices using jit.gl.textureset or jit.matrixset

i was missing approach #5, which is eventually the most simple one:

" messages to jit.matrix also can crop images. i have never tested it in practice though.

for it you just hook up another matrix object to the original matrix object.

i was missing approach #5, which is eventually the most simple one: 

the "srcdimstart" and "srcdimend" messages to jit.matrix also can crop images. i have never tested it in practice though.

Creating a picctrl in jitter with a "knob" png