public static void Solve()
{
for (double aimedAtX = pointL.X + inc; aimedAtX < pointR.X; aimedAtX += inc)
{
LineD firstShot = new LineD(Origin, new PointD(aimedAtX, (triangleHeight + 1)));
long numBounces = CountBounces(firstShot);
}
//PointD hit = firstShot.GetIntersection(B);
}
private static long CountBounces(LineD shot)
{
long numBounces = 0;
LineD reflectedFrom = null;
LineD lastReflectedFrom = null;
PointD p = null;
LineDIntersection intersect;
do
{
// find intersection (try each of three lines)
p = null; // reset
reflectedFrom = null;
if (p == null && lastReflectedFrom != TopLine)
{
intersect = shot.GetIntersection(TopLine);
if (intersect.LinesIntersect)
{
p = intersect.Intersection;
reflectedFrom = TopLine;
}
}
if (p == null && lastReflectedFrom != LefLine)
{
intersect = shot.GetIntersection(LefLine);
if (intersect.LinesIntersect)
{
p = intersect.Intersection;
reflectedFrom = LefLine;
}
}
if (p == null && lastReflectedFrom != RigLine)
{
intersect = shot.GetIntersection(RigLine);
if (intersect.LinesIntersect)
{
p = intersect.Intersection;
reflectedFrom = RigLine;
}
}
// compute attack deltas. Reverse the "horizontal" determined by orientation!!!
// negate the "horizontal" element
// compute the new line
// increaseshot count
numBounces++;
lastReflectedFrom = reflectedFrom;
} while (p != Origin);
return numBounces;
}
public LineDIntersection GetIntersection(LineD b)
{
// http://local.wasp.uwa.edu.au/~pbourke/geometry/lineline2d/
double x1 = A.X;
double x2 = B.X;
double x3 = b.A.X;
double x4 = b.B.X;
double y1 = A.Y;
double y2 = B.Y;
double y3 = b.A.Y;
double y4 = b.B.Y;
double numua = (x4 - x3)*(y1 - y3) - (y4 - y3)*(x1 - x3);
double numub = (x2 - x1) * (y1 - y3) - (y2 - y1) * (x1 - x3);
double denom = (y4 - y3) * (x2 - x1) - (x4 - x3) * (y2 - y1);
//double denom = (b.B.Y - b.A.Y) * (B.X - A.X) - (b.B.X - b.A.X) * (B.Y - A.Y);
//double uanum = (b.B.X - b.A.X) * (A.Y - b.A.Y) - (b.B.Y - b.A.Y) * (A.X - b.A.X);
//double ubnum = (B.X - A.X) * (A.Y - b.A.Y) - (B.Y - A.Y) * (B.Y - A.Y);
LineDIntersection intersection = new LineDIntersection();
if (denom == 0)
{
if (numua == 0 && numub == 0)
{
// lines are coincident!
intersection.LinesIntersect = false;
intersection.LinesAreCoincident = true;
return intersection;
}
// lines are parallel!
intersection.LinesIntersect = false;
intersection.LinesAreParallel = true;
return intersection;
}
else
{
double ua = (numua / denom);
double ub = (numub / denom);
intersection.ua = ua;
intersection.ub = ub;
if (ua >= 0.0d && ua <= 1.0d && ub >= 0.0d && ub <= 1.0d)
{
double x = x1 + ua*(x2 - x1);
double y = y1 + ua*(y2 - y1);
intersection.LinesIntersect = true;
intersection.Intersection = new PointD(x, y);
}
else
{
intersection.LinesIntersect = false;
}
return intersection;
}
}
private static void TestAndReportOnIntersection(LineD Line1, LineD Line2)
{
LineDIntersection hit = Line1.GetIntersection(Line2);
Console.WriteLine();
Console.WriteLine("Line1 {0}", Line1);
Console.WriteLine("Line2 {0}", Line2);
if (hit.LinesIntersect)
{
Console.WriteLine("Found Point {0}", hit.Intersection);
Console.WriteLine("ua {0} ub {1}", hit.ua, hit.ub);
}
else
{
if (hit.LinesAreParallel)
Console.WriteLine("Parallel");
else if (hit.LinesAreCoincident)
Console.WriteLine("Coincident");
else
{
Console.WriteLine("ua {0} ub {1}", hit.ua, hit.ub);
Console.WriteLine("May have hit, but not long enough!");
}
}
}
