Scientist, Designer, and Teacher. Assoc Prof of CompSci in visualization at Mississippi State University. Believes information wants to be seen. Loves Python. @dr_tj
mutable dda_points = dda(mutable start, mutable end)
function dda([x0, y0], [x1, y1]) {
// Round to determine pixel location
const pixel = (x, y) => [Math.round(x), Math.round(y)];
// Differences and step value
let [dx, dy] = [x1 - x0, y1 - y0];
let step = 0;
if(Math.abs(dx) > Math.abs(dy))
step = Math.abs(dx);
else
step = Math.abs(dy);
// Find slope and stepping direction
dx /= step; dy /= step;
// Generate
let [x, y] = [x0, y0];
const pixels = [pixel(x, y)];
for(let i = 0; i < step; ++i)
{
x += dx; y += dy;
pixels.push(pixel(x,y));
}
return pixels;
}
function midpoint([x0, y0], [x1, y1])
{
// Round to determine pixel location
const pixel = (x,y) => [Math.round(x), Math.round(y)]
let [i0, j0] = pixel(x0,y0);
let [i1, j1] = pixel(x1,y1);
let [i,j] = [i0,j0];
// Steps
let stepi = i1 > i0 ? 1 : i1 < i0? -1 : 0;
let stepj = j1 > j0 ? 1 : j1 < j0? -1 : 0;
// Determine error
let di = Math.abs(i1 - i0);
let dj = Math.abs(j1 - j0);
// Find line orientation
let steep = false;
if(dj > di)
{
steep = true;
[i,j] = [j,i];
[di,dj] = [dj,di];
[stepi,stepj] = [stepj,stepi];
}
let d = di - (2 * dj);
// Rasterize
const pixels = [];
const push_pixel = (i,j,steep) => steep? pixels.push([j,i]) : pixels.push([i,j]);
push_pixel(i,j,steep);
for(let count = 1; count <= di; ++count)
{
// Update midpoint/error term
if(d <= 0)
{
j += stepj;
d += 2 * di;
}
i += stepi;
d -= 2 * dj;
push_pixel(i,j,steep);
}
return pixels;
}
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