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ensoniq-buddy
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Merge pull request #1 from ksherlock/triangle 

use math for triangle/sawtooth algorithms.
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ksherlock 2021-10-12 17:07:59 -04:00 committed by GitHub
parent a012355b32 bbdbb42266
commit 3331a4ef45
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1 changed files with 22 additions and 7 deletions
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29
src/wave_data.jsx
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@ -1,12 +1,17 @@
function mod(a,b) {
return ((a % b) + b) % b;
}
function sine() {
const a = 127;
const p = 256;
var rv = [];
for (var n = 0; n < 256; ++n) {
var x = 128 + Math.round(127 * Math.sin(n * Math.PI / 128));
var x = 128 + Math.round(a * Math.sin(n * Math.PI / 128));
rv.push( x || 1 );
}
return rv;
@ -24,9 +29,14 @@ function square() {
function triangle() {
// 0x80 -> 0xff [25%] -> 0x80 [50%] -> 0x01 [75%] -> 0x80 [100%]
var rv = [];
for (var n = 0; n < 64; ++n) rv.push(0x80 + n * 2);
for (var n = 0; n < 128; ++n) rv.push(0xff - n * 2);
for (var n = 0; n < 64; ++n) rv.push(0x01 + n * 2);
const a = 127;
const p = 256;
for (var n = 0; n < 256; ++n) {
var x = 128 + Math.round(4*a/p * Math.abs(mod(n-p/4, p) - p/2)) - a;
rv.push(x || 1);
}
return rv;
}
@ -34,8 +44,13 @@ function triangle() {
function sawtooth() {
var rv = [];
for (var n = 0; n < 128; ++n) rv.push(0x80 + n);
for (var n = 0; n < 128; ++n) rv.push(0x01 + n);
const a = 127;
const p = 256;
for (var n = 0; n < 256; ++n) {
var x = 128 + Math.round(a * 2 * (n/p - Math.floor(.5 + n/p)));
rv.push(x || 1);
}
return rv;
}