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docs/lib-in_shape.md

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+# in_shape
+
+Checks wether a point is inside a shape.
+
+## Parameters
+
+- `shapt_pts` : The shape points.
+- `pt` : The point to be checked.
+- `include_edge` : If a point is on the edge of the shape, the function is default to return `false`. If `include_edge` is `true`, the function returns `true`.
+- `epsilon` : An upper bound on the relative error due to rounding in floating point arithmetic. Default to 0.0001.
+
+## Examples
+
+    include <shape_taiwan.scad>;
+    include <in_shape.scad>;
+
+    points = shape_taiwan(30);
+
+    %polygon(points);
+
+    n = 200;
+    xs = rands(-9, 9, n);
+    ys = rands(-16, 16, n);
+
+    pts = [
+        for(i = [0:n]) 
+            let(p = [xs[i], ys[i]]) 
+            if(in_shape(points, p, true))
+            p
+        ]; 
+
+    for(p = pts) {
+        translate(p) 
+            circle(.2); 
+    }
+
+![in_shape](images/lib-in_shape-1.JPG)