# Sutherland-Hodgman polygon clipping

## Solutions

Solution 1 (Click to Show/Hide)
``````function clip(subjectPolygon, clipPolygon) {
var cp1, cp2, s, e, i, j;
var inside = function(p) {
return (cp2[0] - cp1[0]) * (p[1] - cp1[1]) > (cp2[1] - cp1[1]) * (p[0] - cp1[0]);
};
var intersection = function() {
var dc = [cp1[0] - cp2[0], cp1[1] - cp2[1]],
dp = [s[0] - e[0], s[1] - e[1]],
n1 = cp1[0] * cp2[1] - cp1[1] * cp2[0],
n2 = s[0] * e[1] - s[1] * e[0],
n3 = 1.0 / (dc[0] * dp[1] - dc[1] * dp[0]);
return [(n1 * dp[0] - n2 * dc[0]) * n3, (n1 * dp[1] - n2 * dc[1]) * n3];
};
var outputList = subjectPolygon;
cp1 = clipPolygon[clipPolygon.length - 1];
for (j in clipPolygon) {
var cp2 = clipPolygon[j];
var inputList = outputList;
outputList = [];
s = inputList[inputList.length - 1]; //last on the input list
for (i in inputList) {
var e = inputList[i];
if (inside(e)) {
if (!inside(s)) {
outputList.push(intersection());
}
outputList.push(e);
} else if (inside(s)) {
outputList.push(intersection());
}
s = e;
}
cp1 = cp2;
}
return outputList.map(e => e.map(f => Math.round(f * 1000) / 1000));
}
``````