In § 17.10 we demonstrated continuous changes of pitchbend and volume ranging over several sound-objects and simple notes. Changes were simple in that their variations could be described as two straight lines. Therefore the only useful information required by the Csound instruments were the start and end values of each parameter.

The situation is often more complex. Parameters may change following arbitrary definitions between the on-setting and the off-setting of a Csound event (a line of the score). BP2 handles this case automatically and builds a function table tied to the event which it inserts before the score line.

In "-da.tryCsound", try for instance:

_ins(1) _pitchrange(200) _pitchbend(0) _pitchcont C4 _ _pitchbend(20)_ _ _pitchbend(165) _ _ D4 _ _ _ _pitchbend(150)

which yields the Csound score:

t 0.000 60.000

f101 0.000 256 -7 0.000 85 20.000 85 165.000 171 160.000

i1 0.000 6.000 8.00 90.000 90.000 0.000 0.000 160.000 101.000 ; C4

i1 6.000 4.000 8.02 90.000 90.000 0.000 160.000 150.000 0.000 ; D4

s

Here the variation of pitchbend on 'D4' is simple and requires only the start/end values (bold on the score). However, the pitchbend variation on 'C4' requires four values: 0, 20, 165 and 160, which BP2 stores in the 'f101' function table linked to 'C4'. The table index '101' appears as the last argument in event 'C4'. When it is 0 (the case with 'D4') no function table is attached.

In "-da.tryCsoundInstruments" a few examples demonstrate BP2's ability to combine calculated parameter values with predefined ones contained in the Csound score of a sound-object. See for instance a complex variation of 'blurb' on sound-object 'e' which contains 4 lines of Csound score.

_cont(blurb) _value(blurb,12) e _value(blurb,110) _ _value(blurb,130) _ _ _value(blurb,80) _ _ _value(blurb,-20) _ _value(blurb,-10) _ _ _ _value(blurb,40)

t 0.000 60.000

f101 0.000 256 -7 12.000 76 110.000 76 130.000 180 96.750

i2 0.000 3.330 7.04 8191.500 8191.500 64.000 64.000 12.000 96.750 101.000 ; E3

f102 0.000 256 -7 12.000 51 110.000 51 130.000 102 80.000 154 30.000

i2 0.000 5.000 7.00 8191.500 8191.500 64.000 64.000 12.000 30.000 102.000 ; C3

f103 5.000 256 -7 40.000 51 -6.000 51 8.000 205 70.000 ; table shifted

i2 5.000 5.000 7.02 8191.500 8191.500 64.000 64.000 40.000 70.000 103.000 ; D3

f104 6.660 256 -7 -13.400 26 -10.000 230 39.917

i2 6.660 3.335 7.07 8191.500 8191.500 64.000 64.000 -13.400 39.917 104.000 ; G3

s

BP2 created function tables attached to each event. But there is more than that. In the Csound score of 'e', event 'D3' had non-zero initial values on arguments 9 and 10. These values have been added to the ones determined by variations of the 'blurb' parameter, thus yielding 40 for argument 9 (the start value of 'blurb') and 70 for argument 10 (the end value). The same modification is reported in table 'f103', and all values in the table changed accordingly.

The first and last values of a function table always reflect the start and end values of the parameter it describes variations of. This allows Csound instruments to operate consistently, either interpolating start and end values, or looking at the attached function table.