;Written by Iain McCurdy, 2006 -+rtaudio=PortAudio -b4096 sr = 44100 ;SAMPLE RATE kr = 441 ;CONTROL RATE ksmps = 100 ;NUMBER OF AUDIO SAMPLES IN EACH CONTROL CYCLE nchnls = 2 ;NUMBER OF CHANNELS (2=STEREO) ;FLTK INTERFACE CODE;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; ; LABEL | WIDTH | HEIGHT | X | Y FLpanel "lpf18", 500, 250, 0, 0 ;SWITCHES ON | OFF | TYPE | WIDTH | HEIGHT | X | Y | OPCODE | INS | STARTTIM | DUR gkOnOff,ihOnOff FLbutton "On/Off", 1, -1, 2, 150, 30, 0, 0, 0, 1, 0, -1 ;VALUE DISPLAY BOXES LABEL | WIDTH | HEIGHT | X | Y idfco FLvalue " ", 100, 20, 0, 80 idres FLvalue " ", 100, 20, 0,130 iddist FLvalue " ", 100, 20, 0,180 idfrq FLvalue " ", 100, 20, 0,230 ;SLIDERS MIN | MAX | EXP | TYPE | DISP | WIDTH | HEIGHT | X | Y gkfco,ihfco FLslider "Filter Cutoff", 20, 19000, -1, 5, idfco, 500, 30, 0, 50 gkres,ihres FLslider "Resonance", 0, 1, 0, 5, idres, 500, 30, 0, 100 gkdist,ihdist FLslider "Distortion", 0, 11, 0, 5, iddist, 500, 30, 0, 150 gkfrq,ihfrq FLslider "Oscillator Frequency", 20, 20000, -1, 5, idfrq, 500, 30, 0, 200 ;SET INITIAL VALUES OF FLTK VALUATORS ; VALUE | HANDLE FLsetVal_i 19000, ihfco FLsetVal_i 0, ihres FLsetVal_i -1, ihOnOff FLsetVal_i 0, ihdist FLsetVal_i 100, ihfrq FLpanel_end ;INSTRUCTIONS AND INFO PANEL FLpanel " ", 500, 320, 512, 0 ;TEXT BOXES TYPE | FONT | SIZE | WIDTH | HEIGHT | X | Y ih FLbox " lpf18 ", 1, 5, 14, 490, 15, 5, 0 ih FLbox "-------------------------------------------------------------", 1, 5, 14, 490, 15, 5, 20 ih FLbox "Lpf18 is a implementation of a 3-pole resonant low-pass ", 1, 5, 14, 490, 15, 5, 40 ih FLbox "filter. The '18' refers to the statistic that states that ", 1, 5, 14, 490, 15, 5, 60 ih FLbox "amplitude drops off at 18 decibels per octave beyond the ", 1, 5, 14, 490, 15, 5, 80 ih FLbox "cutoff frequency. ", 1, 5, 14, 490, 15, 5, 100 ih FLbox "The opcode's input arguments include cutoff frequency, ", 1, 5, 14, 490, 15, 5, 120 ih FLbox "resonance and distortion. ", 1, 5, 14, 490, 15, 5, 140 ih FLbox "Use of resonance and distortion can cause an increase in ", 1, 5, 14, 490, 15, 5, 160 ih FLbox "amplitude. To accomodate this phenomenon this example ", 1, 5, 14, 490, 15, 5, 180 ih FLbox "includes a control to scale down the output amplitude. ", 1, 5, 14, 490, 15, 5, 200 ih FLbox "An alternative approach would be to make use of the balance ", 1, 5, 14, 490, 15, 5, 220 ih FLbox "opcode to dynamically control the output signal. ", 1, 5, 14, 490, 15, 5, 240 ih FLbox "The input signal used in this example is a triangle waveform,", 1, 5, 14, 490, 15, 5, 260 ih FLbox "the frequency of which is adjustable using an on-screen ", 1, 5, 14, 490, 15, 5, 280 ih FLbox "slider. ", 1, 5, 14, 490, 15, 5, 300 FLpanel_end FLrun ;RUN THE FLTK WIDGET THREAD ;END OF FLTK INTERFACE CODE;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; gir ftgen 1, 0, 131072, 10, 1 ;SINE WAVE FUNCTION TABLE instr 1 if gkOnOff!=-1 goto CONTINUE ;SENSE FLTK ON/OFF SWITCH turnoff ;TURN THIS INSTRUMENT OFF IMMEDIATELY CONTINUE: asig vco 1, gkfrq, 1, 0 ;GENERATE A TRIANGLE WAVE AUDIO SIGNAL (NOTE THAT lpf18 EXPECTS A SIGNAL WITHIN THE RANGE -1 TO 1) kporttime linseg 0,.01,.01,1,.01 ;kporttime ramps up to a held value of .01 in .01 of a second kfco portk gkfco, kporttime ;PORTAMENTO IS APPLIED TO THE SLIDER VARIABLE gkfco IN ORDER TO SMOOTH ITS MOVEMENT SLIGHTLY ares lpf18 asig, kfco, gkres, gkdist outs ares * 32768, ares * 32768 ;FILTER OUTPUT IS SENT TO THE AUDIO OUTPUTS AND SCALED UP IN ORDER TO BE AUDIBLE endin f 0 3600 ;'DUMMY' SCORE EVENT - KEEPS REALTIME PERFORMANCE GOING FOR 1 HOUR