Hi there,

I'm attempting to create a keyboard level scaling patch emulation, and to do that I need to control the ways in which curves interact with the volume levels of MIDI notes - the only problem is, I know nothing about curve synthesis. If someone could give me a tutorial or some advice on how to create a simple linear and exponential curve that would be great!

-James

[mapping/exponential_curve] have a look at the helpfile

I had a look, but this is using [gcanvas], whereas I want to use array. I also don't want to adjust the size or length of the curves, merely where they are placed on the grid (e.g. their position on the x axis) any ideas?

Could someone please help me make a linear curve from points x0 y-99 to x100 y99?

I'm including the patch I'm working on.

here's the patch.

http://www.pdpatchrepo.info/hurleur/arraycurve.pd

How about:

[bang]
|
[for++ 0 99]
|
[t f f]
| |
|
|
[expr -99 + 2 * $f1]
|
| [ r indx ]
| |
[tabwrite Levelscale]

The and [r] are just for ASCII convenience.

Awesome, thanks man! Do you have any more tutorials on doing this? I also need to set the limits of the graph (to stop it going out of bounds, e.g. more than 99)

There's some good info on expr and related objects at:
http://www.crca.ucsd.edu/~yadegari/expr.html

You could use [clip -99 99] after the [expr] to limit the output, or make sure the expression inside is scaled to keep the output within the bounds you want.

@Jamestocher said:

I had a look, but this is using [gcanvas]

I think you misunderstood the helpfile there. The array and [gcanvas] are overlapping. The points are plotted in the array, while the [gcanvas] object is just used for mouse interaction so that you can adjust the curve while dragging.

Also, the mapping objects don't draw to an array themselves, they just calculate the curves by taking a linear input range of 0-1 and remapping that to a curved output in the range of 0-1. The reason for this is to make your ranges easy to scale. For example:

[/ 100] <-- scale your 0-100 range to 0-1
|
[mapping/exponential_curve]
|

• <-- scale the output to 0-198
  |
  [- 99] <-- bring it down to -99 to 99

So all you really need to do is scale the x-axis range you need to plot to 0-1 and the output range up to what you need and plot it your array using a method similar to what emacpher posted.