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Image Offset Convert
Matt DesLauriers edited this page Nov 23, 2016
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5 revisions
java
//offset to (x, y)
int y = i / width;
int x = i - width*y;
//(x, y) to offset
int i = x + (y * w);
js:
var x = i % width,
y = ~~( i / width );
int value = pixmap.getPixel(x, y);
int R = ((value & 0xff000000) >>> 24);
int G = ((value & 0x00ff0000) >>> 16);
int B = ((value & 0x0000ff00) >>> 8);
int A = ((value & 0x000000ff));
common stuff:
//remap [0.0 .. 1.0] to [-1.0 .. 1.0]
N * 2 - 1
//remap [-1.0 .. 1.0] to [0.0 .. 1.0]
N / 2 + 0.5
//remap [0.0 .. 1.0] to [1.0 .. 0.0 .. 1.0]
abs(N * 2 - 1)
// index to (x, y)
const x = Math.floor(index % columns);
const y = Math.floor(index / columns);
//(x, y) to offset
const index = x + (y * columns);