add wavetables

.gitignore

@@ -1,2 +1,4 @@
 
-build/*
+build/*
+
+*/__pycache__/*

scripts/wavetables/example_wavetable.py

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+
+import math
+from generate_wavetable import generateWavetable
+
+WAVETABLE_FILE_NAME = "config/wavetables/shark_fin.wt"
+
+# process expects a waveform from x=[0, 2pi) centered around f(x)=0
+# normalization is handled by the wavetable generator
+
+def sine(phase):
+    return math.sin(phase)
+
+def square(phase):
+    sample = 1.0
+    if(phase <= math.pi):
+        sample = -1
+    return sample
+
+def saw(phase):
+    return (phase / math.pi) - 1.0
+
+def triangle(phase):
+    sample = 0.0
+    if(phase <= math.pi/2.0):
+        sample = phase * 2.0/math.pi
+    elif(phase <= 3.0*math.pi/2.0):
+        sample = phase * (-2.0/math.pi) + 2.0
+    else:
+        sample = phase * 2.0/math.pi - 4.0
+    return sample
+
+def sharkFin(phase):
+    k = 10.0
+    sample = 0.0
+    if(phase <= math.pi):
+        sample = 2.0 * (phase/math.pi) ** k - 1.0
+    else:
+        sample = -2.0 * (phase/math.pi - 1) ** k + 1.0
+    return sample
+
+def sigmoid(phase):
+    k = 4.0
+    a = -k * (phase - math.pi)
+    sample = 2.0 / (1.0 + math.exp(a)) - 1.0
+    return sample
+
+# pass in the name of your wavetable file and the process function
+def main():
+    generateWavetable(WAVETABLE_FILE_NAME, sharkFin)
+
+if __name__ == "__main__":
+    main()

scripts/wavetables/generate_wavetable.py

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+
+# this is a script for generating a wavetable file
+# a wavetable file consists of a one-dimensional array of samples representing one period of a waveform
+# metadata includes:
+#   - file version (for program compatibilty)
+#   - binary format (float, double, int32, etc.)
+#   - domain (eg phase is represented from [0, 2pi) )
+#   - range (determined by datatype, e.g. float=[-1,1], int32=[-2^15, 2^15-1])
+#   - waveform RMS (for loudness normalization)
+#   - sample count
+# the synth program uses the filename, not any metadata
+
+# this script uses the input function to calculate samples
+# if you want a custom wavetable, copt/edit/modify the example function (i used desmos for brainstorming)
+# import this script and call generateWavetable(processFunction) to generate a custom wavetable
+
+from array import array
+import math
+
+wavetableLength = 2048
+
+def createFile(name):
+    filename = name
+    print("Creating file " + filename)
+    file = open(filename, "wb")
+    return file
+
+def writeMetadata(file):
+    print(">> im writing metadata")
+    
+def writeData(file, processFunction):
+    print(">> im generating the wavetable")
+
+    # init variables
+    data_list = [None] * wavetableLength
+    phaseInc = 2*math.pi / wavetableLength
+    x = 0
+    accumulator = 0
+
+    # generate each discrete sample
+    for i in range(wavetableLength):
+        sample = processFunction(x)
+        accumulator += sample * sample
+        x += phaseInc
+        data_list[i] = sample
+
+    # normalize by rms
+    rms = math.sqrt(accumulator/wavetableLength)
+    print(">> wavetable RMS: ", rms)
+    for i in range(wavetableLength):
+        data_list[i] /= rms
+
+    # write to file
+    binary_data = array("f", data_list)
+    file.write(binary_data)
+
+def closeFile(file):
+    print(">> finishing up")
+    file.close()
+
+def generateWavetable(name, processFunction):
+    print("Hello main")
+    file = createFile(name)
+    writeMetadata(file)
+    writeData(file, processFunction)
+    closeFile(file)
+    print("Done")