50 lines
1.3 KiB
Markdown
50 lines
1.3 KiB
Markdown
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---
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title: Sutherland-Hodgman polygon clipping
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---
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# Sutherland-Hodgman polygon clipping
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---
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## Solutions
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<details><summary>Solution 1 (Click to Show/Hide)</summary>
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```javascript
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function clip(subjectPolygon, clipPolygon) {
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var cp1, cp2, s, e, i, j;
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var inside = function(p) {
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return (cp2[0] - cp1[0]) * (p[1] - cp1[1]) > (cp2[1] - cp1[1]) * (p[0] - cp1[0]);
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};
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var intersection = function() {
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var dc = [cp1[0] - cp2[0], cp1[1] - cp2[1]],
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dp = [s[0] - e[0], s[1] - e[1]],
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n1 = cp1[0] * cp2[1] - cp1[1] * cp2[0],
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n2 = s[0] * e[1] - s[1] * e[0],
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n3 = 1.0 / (dc[0] * dp[1] - dc[1] * dp[0]);
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return [(n1 * dp[0] - n2 * dc[0]) * n3, (n1 * dp[1] - n2 * dc[1]) * n3];
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};
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var outputList = subjectPolygon;
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cp1 = clipPolygon[clipPolygon.length - 1];
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for (j in clipPolygon) {
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var cp2 = clipPolygon[j];
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var inputList = outputList;
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outputList = [];
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s = inputList[inputList.length - 1]; //last on the input list
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for (i in inputList) {
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var e = inputList[i];
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if (inside(e)) {
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if (!inside(s)) {
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outputList.push(intersection());
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}
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outputList.push(e);
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} else if (inside(s)) {
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outputList.push(intersection());
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}
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s = e;
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}
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cp1 = cp2;
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}
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return outputList.map(e => e.map(f => Math.round(f * 1000) / 1000));
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}
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```
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</details>
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