[Csnd] UDO for morphing between arrays

The Csound Mailinglist
1

Hello everybody!

I don’t know if this already exists as an opcode (i couldn’t find it), so i tried to do it as an recursive UDO for an actual project.

I want to morph/interpolate between two arrays.
This should happen between the values of the same index.
For example:
Array-1[0] = 0
Array-2[0] = 10

ResultArray[0] gives the interpolate numbers between 0 and 10 via indexing.

I thought i found the solution,
but the value accumulation is not working as expected and i get strange results.

Here is my code:

opcode morf_arrays,k[],ki[]i[]o
  kIndex,iArray1[],iArray2[],iArrIndx xin
  kArray[] init lenarray(iArray1)
  
  iTable ftgen 0,0,0,-2,iArray1[iArrIndx],iArray2[iArrIndx]
  kRes tablei kIndex,iTable
  kArray[iArrIndx] = kRes
  if iArrIndx < lenarray(iArray1)-1 then
    kArray[] += morf_arrays(kIndex,iArray1,iArray2,iArrIndx+1)
  endif
  
  xout kArray
endop

instr 1
  iSpectrArr1[] fillarray 1,1.0, 3,0.33, 5,0.2, 7,0.8, 24,0.9, 12,0.1
  iSpectrArr2[] fillarray 2,1.0, 1,0.33, 50,0.2, 10,0.8, 24,0.9, 12,0.9

  kMorphIndex line 0,p3,1
  kSpectrArr[] morf_arrays kMorphIndex,iSpectrArr1,iSpectrArr2

  printk 0.1,kSpectrArr[2]
endin
Csound mailing list
Csound@listserv.heanet.ie
https://listserv.heanet.ie/cgi-bin/wa?A0=CSOUND
Send bugs reports to
        Issues · csound/csound · GitHub
Discussions of bugs and features can be posted here

2

Hi Philipp,
do you just want morphed values for every index or do you want to accumulate a value? If it's the former, you could do it in a loop:
kIndex = 0
while (kIndex < iArrayLen) do
   kResultArray[kIndex] = iArray1[kIndex] * kWeight + iArray2[kIndex}
     * (1 - kWeight)
   kIndex += 1
od
This would create a kResultArray every k-cycle, that morphs between iArray1 and iArray2 based on the kWeight parameter, i.e. how much of iArray1 and iArray2 will influence the output.

If ftables were a solution, you could try hvs1 (Hyper Vectorial Synthesis) or other table morphing opcodes, depending on your exact needs.

Best wishes,

Jeanette

3

linlin can do exactly that, see the following form, where kA and kB are two arrays of the same shape and kx is the interpolation index

kC[] **linlin** kx, kA[], kB[] [, kx0, kx1 ]
4

Thank you both!

linlin is perfect! I didn’t find it in the manual while searching for a fitting opcode, thanks!