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Forums > C64 Composing > Drawing wavforms on screen via the oscillator/envelope generator
2007-04-02 17:19
Conrad

Registered: Nov 2006
Posts: 856
Drawing wavforms on screen via the oscillator/envelope generator

Hi there.

I'm just curious if reading the current value from $d41b/d41c would allow you to draw real-time waveforms on a bitmap screen. I would think this could be done by applying the current value of the oscillator/envelop to the Y position of the pixel to be drawn on screen, and so on until you could get a nice output waveform on the screen (like you do in many .wav editors.) Is it possible? It would be a very nice effect for a music demo (only if it can be done in real time of course :-)

Thanks.
 
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2007-04-02 19:28
Bamu®
Account closed

Registered: May 2005
Posts: 1332
Quote: and what's the use of it when filter is nonlinear? you would have a lookup table , additionally different for 6581 and 8580


www.vulture.c64.org


Nah, I'm only interested in the 8580 SID. You can easily read what the module is writing to the SID.

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My heroes: Huelsbeck, Cane, Dos, Cadaver, Oakvalley
2007-04-02 19:32
yago

Registered: May 2002
Posts: 333
Not realtime, but useful nevertheless:

Sidoszi

2007-04-02 19:35
Bamu®
Account closed

Registered: May 2005
Posts: 1332
Quote: Not realtime, but useful nevertheless:

Sidoszi



Nice Yago!!!!

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My heroes: Huelsbeck, Cane, Dos, Cadaver, Oakvalley
2007-04-02 19:40
yago

Registered: May 2002
Posts: 333
whatever
2007-04-02 19:44
Conrad

Registered: Nov 2006
Posts: 856
Okay, I believe I have my answer... thanks everyone.


and btw, /me prefers the good old fashioned lot:

:-) :-D :-/ :-( =-) :-P :) :( :O 8-|

¬_¬ ^_^

screw all that hyper-link shite.
2007-04-02 19:52
null
Account closed

Registered: Jun 2006
Posts: 645
^_^ ^_^ ^_^ ^_^ ^_^ ^_^ ^_^ ^_^ ^_^ ^_^ ^_^
>_> >_> >_> >_> >_> >_> >_> >_> >_> >_> >_>
<_< <_< <_< <_< <_< <_< <_< <_< <_< <_< <_<
>_< >_< >_< >_< >_< >_< >_< >_< >_< >_< >_<
o_O o_O o_O o_O o_O o_O o_O o_O o_O o_O o_O
O_o O_o O_o O_o O_o O_o O_o O_o O_o O_o O_o
*_* *_* *_* *_* *_* *_* *_* *_* *_* *_* *_*
@_@ @_@ @_@ @_@ @_@ @_@ @_@ @_@ @_@ @_@ @_@
V_V V_V V_V V_V V_V V_V V_V V_V V_V V_V V_V
T_T T_T T_T T_T T_T T_T T_T T_T T_T T_T T_T
¬_¬ ¬_¬ ¬_¬ ¬_¬ ¬_¬ ¬_¬ ¬_¬ ¬_¬ ¬_¬ ¬_¬ ¬_¬
-_- -_- -_- -_- -_- -_- -_- -_- -_- -_- -_-
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Knoeki/DigitalSoundsSystem/SwappersWithAttitude
2007-04-02 19:56
Bamu®
Account closed

Registered: May 2005
Posts: 1332
Quote:
screw all that hyper-link shite.

Nope, I'm already in love with it.

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My heroes: Huelsbeck, Cane, Dos, Cadaver, Oakvalley
2007-04-03 14:24
Oswald

Registered: Apr 2002
Posts: 5127
Nostalgia

on the d64 you can find "funplayer" which allows you to load a music in binary form, and then set init/jsr stuff, then when you go to play mode it will display the 3rd channel on a char screen, adsr envelope included. :) oh and 50 fps :)

there must be a roy/replay musicdisk out there aswell, which does this vertically with changing the X coord of a sprite.
2007-04-03 14:51
Conrad

Registered: Nov 2006
Posts: 856
@Oswald: Wow, that's a neat routine :) (and is also exactly what I am asking about.) Although you say it is 50hz (which i believe you as i have tried it out :) does it use a lot of raster time?
2007-04-03 16:01
Oswald

Registered: Apr 2002
Posts: 5127
crd, yes. but it depends on the waveform a lot, as drawing the vertical lines to connect the points takes a lot of time. so the most cpu eater stuff is high frequency triangle or high freq combined waveforms where there is the most hassle with the vertical lines. the fastest is to do low freq squares. its not impossible to slow it down to 25fps, but when testing I did not found a tune which achieved that.
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