Question

I have an algorithm which can find if a point is in a given polygon:

 int CGlEngineFunctions::PointInPoly(int npts, float *xp, float *yp, float x, float y)
 {
     int i, j, c = 0;
     for (i = 0, j = npts-1; i < npts; j = i++) {
         if ((((yp[i] <= y) && (y < yp[j])) ||
             ((yp[j] <= y) && (y < yp[i]))) &&
             (x < (xp[j] - xp[i]) * (y - yp[i]) / (yp[j] - yp[i]) + xp[i]))
             c = !c;
     }
     return c;
 }

given this, how could I make it check if its within a rectangle defind by Ptopleft and Pbottomright instead of a single point?

Thanks

Basically you know how in Adobe Illustrator you can drag to select all objects that fall within the selection rectangle? well I mean that. –

Answer 1

Can’t you just find the minimum and maximum x and y values among the points of the polygon and check to see if any of the values are outside the rectangle’s dimensions?