/// <summary>
/// Raycasts a given <c>Ray</c> in this maze.
/// </summary>
/// <param name="ray">The <c>Ray</c> to cast.</param>
/// <param name="radius">The radius of the thing casting the ray.</param>
public void Raycast(ref Ray ray, double radius)
{
if (Math.Abs(ray.Magnitude) < Double.Epsilon)
{
ray.Velocity = 0;
return;
}
var gridCoords = new CoordI(ray.Origin);
double len = 0;
double ax;
double ay;
var walled = false;
var south = ray.GoingSouth();
var east = ray.GoingEast();
if ((south && !east) || (!south && east))
{
ax = 1.0 / Math.Cos(Consts.QuarterTurn - ray.Angle % Consts.QuarterTurn);
ay = 1.0 / Math.Cos(ray.Angle % Consts.QuarterTurn);
}
else
{
ax = 1.0 / Math.Cos(ray.Angle % Consts.QuarterTurn);
ay = 1.0 / Math.Cos(Consts.QuarterTurn - ray.Angle % Consts.QuarterTurn);
}
var testCoord = ray.Origin - gridCoords;
var testSpace = new CoordD(1,1) - testCoord;
if (_walls.test_wall(gridCoords, 2) && testSpace.X < radius)
ray.Origin.X -= radius - testSpace.X;
else if (_walls.test_wall(gridCoords, 3) && testSpace.Y < radius)
ray.Origin.Y -= radius - testSpace.Y;
else if (_walls.test_wall(gridCoords, 0) && testCoord.X < radius)
ray.Origin.X += radius - testCoord.X;
else if (_walls.test_wall(gridCoords, 1) && testCoord.Y < radius)
ray.Origin.Y += radius - testCoord.Y;
while (len < ray.Magnitude && !walled)
{
var gridSpace = ray.Origin.ByAngle(ray.Angle, len) - gridCoords;
var cellSpace = new CoordD(1,1) - gridSpace;
gridSpace.Abs();
cellSpace.Abs();
var hx = (east ? cellSpace.X : gridSpace.X) * ax;
var hy = (south ? cellSpace.Y : gridSpace.Y) * ay;
if (hx < hy)
len += (east ? Math.Max(0, cellSpace.X - radius) : Math.Max(0, gridSpace.X - radius)) * ax;
else
len += (south ? Math.Max(0, cellSpace.Y - radius) : Math.Max(0, gridSpace.Y - radius)) * ay;
var dir = hx < hy ? 0 : 1;
if ((hx < hy && east) || (hx >= hy && south)) dir += 2;
walled = !_walls.InBounds(gridCoords, dir) || _walls.test_wall(gridCoords, dir);
if (walled) continue;
switch (dir)
{
case 0:
gridCoords.X -= 1;
break;
case 1:
gridCoords.Y -= 1;
break;
case 2:
gridCoords.X += 1;
break;
case 3:
gridCoords.Y += 1;
break;
}
}
ray.Velocity = Math.Min(len, ray.Magnitude) / ray.Magnitude;
}
