Adding the missing effects.

[luckcolors]

Hello. I really like this project :) and i hope in the future there will be support for all the xm effects.

[a1k0n]

Yep, I was looking at it this morning. The rest shouldn't be too difficult to add; some are fairly tricky like note delay (I am liable to break corner cases of portamento in the process) so I'd like to throw a bunch of tests in first.

I'll enumerate the currently missing effects here (using OpenMPT's guide):

Effect column:

• [ ] 7xy - Tremolo - easy
• [ ] E3x - Glissando control - unlikely to implement
• [x] E4x - Vibrato waveform - vibrato is hardcoded to sine; not too hard to support this
• [x] E5x - Set finetune - need to add per-channel finetune control and set it to sample finetune on trigger
• [x] E6x - Pattern loop - ugh.
• [ ] E7x - Tremolo waveform - same as E4x
• [ ] E9x - retrigger - should be easy since Rxy is already done
• [ ] EDx - Note delay - tricky, special case like portamento.
• [ ] EEx - Pattern delay - Have to think about this one. Requires player state cleanup.
• [x] Gxx - Global volume - Need to add a global volume control, currently hardcoded to -10dB.
• [x] Hxy - Global volume slide - same as above
• [ ] Kxx - Delayed key-off - should be easy
• [ ] Lxx - Envelope position - also easy
• [ ] Pxy - Panning slide - easy
• [ ] Txy - Tremor - Probably easy, depending on envelope behavior
• [ ] X1x / X2x - Extra Fine Portamento - easy, since we're in javascript and can modify period by 0.25.

Volume column:

• [x] gxx - tone portamento - medium effort since portamentos are all special cased
• [x] hxx / uxx - vibrato depth / speed - easy, aliased to 4xy
• [ ] lxx / rxx - panning slide - easy

The effects are implemented in a table in xmeffects.js and anything marked "easy" above can probably be implemented completely within that file. Pull requests appreciated.

[a1k0n]

Gxx done, thanks @hillerstorm!