static MyPoint[] CalculateConvexPolygon(MyPoint[] points)
{
Array.Sort(points);
int numPoints = points.Length;
MyPoint[] result = new MyPoint[numPoints * 2];
int currentIndex = 0;
int minIndex = 2;
for (int i = 0; i < numPoints; i++)
{
while (currentIndex >= minIndex)
{
MyPoint p1 = MyPoint.Sub(result[currentIndex - 1], result[currentIndex - 2]);
MyPoint p2 = MyPoint.Sub(points[i], result[currentIndex - 2]);
if (MyPoint.Cross(p1, p2) <= 0)
{
currentIndex--;
}
else
{
break;
}
}
result[currentIndex++] = points[i];
}
minIndex = currentIndex + 1;
for (int i = numPoints - 2; i >= 0; i--)
{
while (currentIndex >= minIndex)
{
MyPoint p1 = MyPoint.Sub(result[currentIndex - 1], result[currentIndex - 2]);
MyPoint p2 = MyPoint.Sub(points[i], result[currentIndex - 2]);
if (MyPoint.Cross(p1, p2) <= 0)
{
currentIndex--;
}
else
{
break;
}
}
result[currentIndex++] = points[i];
}
Array.Resize <MyPoint>(ref result, currentIndex - 1);
return(result);
}
private void UpdateRectangles(bool createNewRectangles)
{
if (fRectangles == null || createNewRectangles)
{
fRectangles = MyFactory.GetRandomRectangles();
fAngle = 0;
}
else
{
foreach (var rectangle in fRectangles)
{
rectangle.Angle = fAngle;
}
}
int numberOfPoints = 4 * fRectangles.Count;
MyPoint[] points = new MyPoint[numberOfPoints];
int pointIndex = 0;
foreach (var rectangle in fRectangles)
{
var corners = rectangle.CalculateCorners();
points[pointIndex++] = corners[0];
points[pointIndex++] = corners[1];
points[pointIndex++] = corners[2];
points[pointIndex++] = corners[3];
}
var polygon = CalculateConvexPolygon(points);
if (fLines == null)
{
fLines = new DynamicPrimitiveLine(fSpriteBatch.GraphicsDevice);
fLines.UseVertexBuffer = false;
}
else
{
fLines.Clear();
}
double boardArea = 0;
foreach (var rectangle in fRectangles)
{
var corners = rectangle.CalculateCorners();
fLines.AddLine(ToVertexPositionColor(corners[0], Color.White), ToVertexPositionColor(corners[1], Color.White));
fLines.AddLine(ToVertexPositionColor(corners[1], Color.White), ToVertexPositionColor(corners[2], Color.White));
fLines.AddLine(ToVertexPositionColor(corners[2], Color.White), ToVertexPositionColor(corners[3], Color.White));
fLines.AddLine(ToVertexPositionColor(corners[3], Color.White), ToVertexPositionColor(corners[0], Color.White));
boardArea += rectangle.Width * rectangle.Height;
}
double polyArea = 0;
int numberOfPolyLines = polygon.Length;
for (int i = 0; i < numberOfPolyLines; i++)
{
int j = (i + 1) % numberOfPolyLines;
MyPoint p1 = polygon[i];
MyPoint p2 = polygon[j];
polyArea += MyPoint.Cross(p1, p2);
fLines.AddLine(ToVertexPositionColor(p1, Color.Red), ToVertexPositionColor(p2, Color.Red));
}
polyArea = polyArea / 2;
double ratio = 100.0 * boardArea / polyArea;
//System.Console.WriteLine($"Area: {polyArea} PolyPoints: {numberOfPolyLines}, Ratio: {ratio:F1} %");
}
