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Bresenham's Line Algorithm canvas api
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| // code taken from | |
| // https://stackoverflow.com/a/50625904 | |
| var canvas = document.getElementById('canvas'); | |
| var ctx = canvas.getContext('2d'); | |
| function BMFastPixelArtLine(ctx, x1, y1, x2, y2) { | |
| x1 = Math.round(x1); | |
| y1 = Math.round(y1); | |
| x2 = Math.round(x2); | |
| y2 = Math.round(y2); | |
| const dx = Math.abs(x2 - x1); | |
| const sx = x1 < x2 ? 1 : -1; | |
| const dy = Math.abs(y2 - y1); | |
| const sy = y1 < y2 ? 1 : -1; | |
| var error, len, rev, count = dx; | |
| ctx.beginPath(); | |
| if (dx > dy) { | |
| error = dx / 2; | |
| rev = x1 > x2 ? 1 : 0; | |
| if (dy > 1) { | |
| error = 0; | |
| count = dy - 1; | |
| do { | |
| len = error / dy + 2 | 0; | |
| ctx.rect(x1 - len * rev, y1, len, 1); | |
| x1 += len * sx; | |
| y1 += sy; | |
| error -= len * dy - dx; | |
| } while (count--); | |
| } | |
| if (error > 0) { ctx.rect(x1, y2, x2 - x1, 1) } | |
| } else if (dx < dy) { | |
| error = dy / 2; | |
| rev = y1 > y2 ? 1 : 0; | |
| if (dx > 1) { | |
| error = 0; | |
| count--; | |
| do { | |
| len = error / dx + 2 | 0; | |
| ctx.rect(x1, y1 - len * rev, 1, len); | |
| y1 += len * sy; | |
| x1 += sx; | |
| error -= len * dx - dy; | |
| } while (count--); | |
| } | |
| if (error > 0) { ctx.rect(x2, y1, 1, y2 - y1) } | |
| } else { | |
| do { | |
| ctx.rect(x1, y1, 1, 1); | |
| x1 += sx; | |
| y1 += sy; | |
| } while (count--); | |
| } | |
| ctx.fill(); | |
| } | |
| BMFastPixelArtLine(ctx, 50, 50, 150, 150) |
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