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WAVY -- dual-oscillator wavetable combination instrument
in RTcmix/insts/jg
## quick syntax:WAVY(outsk, dur, AMP, FREQA, FREQB, PHASEB, WAVETABLEA, WAVETABLEB, expr[, PAN])
CAPITALIZED parameters are pfield-enabled for table or dynamic control (see the maketable or makeconnection scorefile commands). Parameters after the [bracket] are optional and default to 0 unless otherwise noted. p0 = output start time (seconds) p1 = duration (seconds) p2 = amplitude (absolute, for 16-bit soundfiles: 0-32768) p3 = oscil A frequency (Hz or oct.pc) p4 = oscil B frequency (Hz or oct.pc; if zero, same as A) p5 = phase offset for second oscillator (0-1) p6 = oscil A wavetable reference p7 = oscil B wavetable reference (if zero, same as A) p8 = combination expression ("a + b", "a - b", "a * b", etc.; see the Usage Notes below) p9 = pan (0-1 stereo; 0.5 is middle) [optional; default is 0.5] p2 (amplitude), p3, (oscil A freq), p4 (oscil B freq) and p5 (phase oscil B), and p9 (pan) can receive dynamic updates from a table or real-time control source. p6 (oscil A wavetable) and p7 (oscil B wavetable) should be references to pfield table-handles. Author: John Gibson, 6/15/05 The WAVY instrument combines the outputs of two oscillators (both
accessing the same wavetable) according to a mathematical expression given
in the expr parameter.
## Usage NotesWAVY allows you to use most any mathematical expression to
combine the two oscillator streams. "a" represents the output of the
first oscillator, "b", the second one. Some general examples:
expr = "(a ^ 5) * .5" expr = "a - b" expr = "if (abs(a) < .5, a ^ .1, a * (b - 1))" (etc.) WAVY will not run very quickly.
Bear in mind, however, that sample values (i.e. the instantaneous sampled amplitude) of a signal are being used. For example, you may think this equation expr = "a * b" expr
would produce a frequency modulation kind of effect. Instead,
the above equation produces simple amplitude modulation
between the two oscillators.
The frequencies of the two oscillators can be set independently (
This is the listing (taken from the
fparser
library) of the kinds of expressions that can be used
by The function string understood by the class is very similar to the C-syntax. Arithmetic float expressions can be created from float literals, variables or functions using the following operators in this order of precedence: () expressions in parentheses first -A unary minus A^B exponentiation (A raised to the power B) A*B A/B A%B multiplication, division and modulo A+B A-B addition and subtraction A=B A<B A>B comparison between A and B (result is either 0 or 1) A&B result is 1 if int(A) and int(B) differ from 0, else 0. A|B result is 1 if int(A) or int(B) differ from 0, else 0. Since the unary minus has higher precedence than any other operator, for example the following expression is valid: x*-y Note that the '=' comparison can be inaccurate due to floating point precision problems (eg. "sqrt(100)=10" probably returns 0, not 1). The class supports these functions: abs(A) : Absolute value of A. If A is negative, returns -A otherwise returns A. acos(A) : Arc-cosine of A. Returns the angle, measured in radians, whose cosine is A. acosh(A) : Same as acos() but for hyperbolic cosine. asin(A) : Arc-sine of A. Returns the angle, measured in radians, whose sine is A. asinh(A) : Same as asin() but for hyperbolic sine. atan(A) : Arc-tangent of (A). Returns the angle, measured in radians, whose tangent is (A). atan2(A,B): Arc-tangent of A/B. The two main differences to atan() is that it will return the right angle depending on the signs of A and B (atan() can only return values betwen -pi/2 and pi/2), and that the return value of pi/2 and -pi/2 are possible. atanh(A) : Same as atan() but for hyperbolic tangent. ceil(A) : Ceiling of A. Returns the smallest integer greater than A. Rounds up to the next higher integer. cos(A) : Cosine of A. Returns the cosine of the angle A, where A is measured in radians. cosh(A) : Same as cos() but for hyperbolic cosine. cot(A) : Cotangent of A (equivalent to 1/tan(A)). csc(A) : Cosecant of A (equivalent to 1/sin(A)). eval(...) : This a recursive call to the function to be evaluated. The number of parameters must be the same as the number of parameters taken by the function. Usually called inside if() to avoid infinite recursion. exp(A) : Exponential of A. Returns the value of e raised to the power A where e is the base of the natural logarithm, i.e. the non-repeating value approximately equal to 2.71828182846. floor(A) : Floor of A. Returns the largest integer less than A. Rounds down to the next lower integer. if(A,B,C) : If int(A) differs from 0, the return value of this function is B, else C. Only the parameter which needs to be evaluated is evaluated, the other parameter is skipped; this makes it safe to use eval() in them. int(A) : Rounds A to the closest integer. 0.5 is rounded to 1. log(A) : Natural (base e) logarithm of A. log10(A) : Base 10 logarithm of A. max(A,B) : If A>B, the result is A, else B. min(A,B) : If A<B, the result is A, else B. sec(A) : Secant of A (equivalent to 1/cos(A)). sin(A) : Sine of A. Returns the sine of the angle A, where A is measured in radians. sinh(A) : Same as sin() but for hyperbolic sine. sqrt(A) : Square root of A. Returns the value whose square is A. tan(A) : Tangent of A. Returns the tangent of the angle A, where A is measured in radians. tanh(A) : Same as tan() but for hyperbolic tangent. Examples of function string understood by the class: "1+2" "x-1" "-sin(sqrt(x^2+y^2))" "sqrt(XCoord*XCoord + YCoord*YCoord)" An example of a recursive function is the factorial function: "if(n>1, n*eval(n-1), 1)" Note that a recursive call has some overhead, which makes it a bit slower than any other operation. It may be a good idea to avoid recursive functions in very time-critical applications. Recursion also takes some memory, so extremely deep recursions should be avoided (eg. millions of nested recursive calls). Also note that the if() function is the only place where making a recursive call is safe. In any other place it will cause an infinite recursion (which will make the program eventually run out of memory). Note that WAVY scorefiles use small letters a and b
for the expression.
## Sample Scoresvery basic:rtsetparams(44100, 2, 256) load("WAVY") dur = 60 amp = 20000 env = maketable("line", 1000, 0,0, .1,1, dur-.1,1, dur,0) expr = "a - b" wavetA = maketable("wave", 5000, "sine") wavetB = maketable("wave", 5000, "tri") freqA = cpspch(8.00) freqB = makeconnection("mouse", "y", min=100, max=2000, dflt=freqA, lag=80, "freqB") phase_offset = makeconnection("mouse", "x", min=0, max=1, dflt=0, lag=80, "phase offset") WAVY(0, dur, amp * env, freqA, freqB, phase_offset, wavetA, wavetB, expr) slightly more advanced: rtsetparams(44100, 2, 256) load("WAVY") dur = 30 amp = 20000 env = maketable("line", 1000, 0,0, .1,1, dur-.1,1, dur,0) freqA = cpspch(6.00) expr = "a * b" // try one of these wavet = maketable("random", 100, "even", min=-1, max=1, seed=1) //wavet = maketable("wave", 5000, "saw") //wavet = maketable("wave", 1000, "sine") freqB1 = makeconnection("mouse", "x", min=100, max=1000, default=149.0, lag=70, "freqB1") freqB2 = makeconnection("mouse", "y", min=100, max=1000, default=149.0, lag=70, "freqB2") WAVY(start=0, dur, amp * env, freqA, freqB1, 0, wavet, 0, expr, pan=.6) WAVY(start=0, dur, amp * env, freqA * 1.01, freqB2, 0, wavet, 0, expr, pan=.4) fun stuff! rtsetparams(44100, 2, 256) load("WAVY") // set to true (or 1) to let you muck around (blindly) with the waveform wavedraw = false dur = 60 amp = 15000 env = maketable("line", 1000, 0,0, .1,1, dur-.1,1, dur,0) pitch = 6.00 low = 0.01 high = 0.99 lfreq = 0.1 phase_offset1 = makeLFO("tri", lfreq, min=low, max=high) // try one of these //expr = "(a ^ 5) * .5" //expr = "a - b" expr = "if (abs(a) < .5, a ^ .1, a * (b - 1))" // try one of these //wavet = maketable("random", 100, "even", min=-1, max=1, seed=1) wavet = maketable("wave", 5000, "saw") if (wavedraw) { index = makeconnection("mouse", "x", min=0, max=1, dflt=0, lag=80, "index") value = makeconnection("mouse", "y", min=-1, max=1, dflt=0, lag=80, "value") wavet = modtable(wavet, "draw", index, value, .1) } WAVY(start=0, dur, amp * env, pitch, 0, phase_offset1, wavet, 0, expr, pan=.6) // need a separate LFO instance for this phase_offset2 = makeLFO("tri", lfreq + 0.02, min=low, max=high) pitch += 0.001 WAVY(start=0, dur, amp * env, pitch, 0, phase_offset2, wavet, 0, expr, pan=.4) ## See AlsoAMINST, FMINST, HALFWAVE, MULTIWAVE, SYNC, VWAVE, WAVESHAPE, WAVETABLE |