;Written by Iain McCurdy, 2006 -odevaudio -b400 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) 0dbfs = 1 ;MAXIMUM SOUND INTENSITY LEVEL REGARDLESS OF BIT DEPTH ;FLTK INTERFACE CODE;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; FLcolor 255, 255, 255, 0, 0, 0 ; LABEL | WIDTH | HEIGHT | X | Y FLpanel "lpf18", 500, 300, 0, 0 ;SWITCHES ON | OFF | TYPE | WIDTH | HEIGHT | X | Y | OPCODE | INS | STARTTIM | IDUR gkOnOff,ihOnOff FLbutton "On/Off", 1, 0, 22, 140, 25, 5, 5, 0, 1, 0, -1 FLsetColor2 255, 255, 50, ihOnOff ;SET SECONDARY COLOUR TO YELLOW ;VALUE DISPLAY BOXES LABEL | WIDTH | HEIGHT | X | Y idfco FLvalue " ", 70, 20, 5, 75 idres FLvalue " ", 70, 20, 5, 125 iddist FLvalue " ", 70, 20, 5, 175 idfrq FLvalue " ", 70, 20, 5, 225 idgain FLvalue " ", 70, 20, 5, 275 ;SLIDERS MIN | MAX | EXP | TYPE | DISP | WIDTH | HEIGHT | X | Y gkfco,ihfco FLslider "Filter Cutoff", 20, 19000, -1, 23, idfco, 490, 25, 5, 50 gkres,ihres FLslider "Resonance", 0, 1, 0, 23, idres, 490, 25, 5, 100 gkdist,ihdist FLslider "Distortion", 0, 11, 0, 23, iddist, 490, 25, 5, 150 gkfrq,ihfrq FLslider "Oscillator Frequency", 20, 20000, -1, 23, idfrq, 490, 25, 5, 200 gkgain,ihgain FLslider "Output Amplitude Scaling", 0, 1, 0, 23, idgain, 490, 25, 5, 250 ;SET INITIAL VALUES OF FLTK VALUATORS VALUE | HANDLE FLsetVal_i 19000, ihfco FLsetVal_i 100, ihfrq FLsetVal_i 0.5, ihgain FLsetVal_i 0, ihres FLsetVal_i 0, ihdist 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 sawtooth 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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; gisine ftgen 0, 0, 131072, 10, 1 ;SINE WAVE FUNCTION TABLE instr 1 if gkOnOff=0 then ;IF On/Off SWITCH IS SET TO 'OFF'... turnoff ;TURN THIS INSTRUMENT OFF endif ;END OF CONDITIONAL BRANCHING kporttime linseg 0,0.001,0.005,1,0.005 ;CREATE A VARIABLE FUNCTION THAT RAPIDLY RAMPS UP TO A SET VALUE kfrq portk gkfrq, kporttime ;SMOOTH MOVEMENT OF SLIDER VARIABLE kfco portk gkfco, kporttime ;SMOOTH MOVEMENT OF SLIDER VARIABLE asig vco 1, kfrq, 1, 0, gisine ;GENERATE A TRIANGLE WAVE AUDIO SIGNAL (NOTE THAT lpf18 EXPECTS A SIGNAL WITHIN THE RANGE -1 TO 1) ares lpf18 asig, kfco, gkres, gkdist outs ares * gkgain, ares * gkgain ;FILTER OUTPUT IS SENT TO THE AUDIO OUTPUTS AND RESCALED USING gkgain SLIDER VARIABLE endin f 0 3600 ;'DUMMY' SCORE EVENT - KEEPS REALTIME PERFORMANCE GOING FOR 1 HOUR