private bool AddLineIntercepts(LineDef line)
{
int s1;
int s2;
// Avoid precision problems with two routines.
if (trace.Dx > Fixed.FromInt(16) ||
trace.Dy > Fixed.FromInt(16) ||
trace.Dx < -Fixed.FromInt(16) ||
trace.Dy < -Fixed.FromInt(16))
{
s1 = Geometry.PointOnDivLineSide(line.Vertex1.X, line.Vertex1.Y, trace);
s2 = Geometry.PointOnDivLineSide(line.Vertex2.X, line.Vertex2.Y, trace);
}
else
{
s1 = Geometry.PointOnLineSide(trace.X, trace.Y, line);
s2 = Geometry.PointOnLineSide(trace.X + trace.Dx, trace.Y + trace.Dy, line);
}
if (s1 == s2)
{
// Line isn't crossed.
return(true);
}
// Hit the line.
target.MakeFrom(line);
var frac = InterceptVector(trace, target);
if (frac < Fixed.Zero)
{
// Behind source.
return(true);
}
// Try to early out the check.
if (earlyOut && frac < Fixed.One && line.BackSector == null)
{
// Stop checking.
return(false);
}
intercepts[interceptCount].Frac = frac;
intercepts[interceptCount].Line = line;
intercepts[interceptCount].Thing = null;
interceptCount++;
// Continue.
return(true);
}
/// <summary>
/// Returns true if strace crosses the given subsector successfully.
/// </summary>
private bool CrossSubsector(int subsectorNumber, int validCount)
{
var map = world.Map;
var subsector = map.Subsectors[subsectorNumber];
var count = subsector.SegCount;
// Check lines.
for (var i = 0; i < count; i++)
{
var seg = map.Segs[subsector.FirstSeg + i];
var line = seg.LineDef;
// Allready checked other side?
if (line.ValidCount == validCount)
{
continue;
}
line.ValidCount = validCount;
var v1 = line.Vertex1;
var v2 = line.Vertex2;
var s1 = Geometry.DivLineSide(v1.X, v1.Y, trace);
var s2 = Geometry.DivLineSide(v2.X, v2.Y, trace);
// Line isn't crossed?
if (s1 == s2)
{
continue;
}
occluder.MakeFrom(line);
s1 = Geometry.DivLineSide(trace.X, trace.Y, occluder);
s2 = Geometry.DivLineSide(targetX, targetY, occluder);
// Line isn't crossed?
if (s1 == s2)
{
continue;
}
// The check below is imported from Chocolate Doom to
// avoid crash due to two-sided lines with no backsector.
if (line.BackSector == null)
{
return(false);
}
// Stop because it is not two sided anyway.
// Might do this after updating validcount?
if ((line.Flags & LineFlags.TwoSided) == 0)
{
return(false);
}
// Crosses a two sided line.
var front = seg.FrontSector;
var back = seg.BackSector;
// No wall to block sight with?
if (front.FloorHeight == back.FloorHeight &&
front.CeilingHeight == back.CeilingHeight)
{
continue;
}
// Possible occluder because of ceiling height differences.
Fixed openTop;
if (front.CeilingHeight < back.CeilingHeight)
{
openTop = front.CeilingHeight;
}
else
{
openTop = back.CeilingHeight;
}
// Because of ceiling height differences.
Fixed openBottom;
if (front.FloorHeight > back.FloorHeight)
{
openBottom = front.FloorHeight;
}
else
{
openBottom = back.FloorHeight;
}
// Quick test for totally closed doors.
if (openBottom >= openTop)
{
// Stop.
return(false);
}
var frac = InterceptVector(trace, occluder);
if (front.FloorHeight != back.FloorHeight)
{
var slope = (openBottom - sightZStart) / frac;
if (slope > bottomSlope)
{
bottomSlope = slope;
}
}
if (front.CeilingHeight != back.CeilingHeight)
{
var slope = (openTop - sightZStart) / frac;
if (slope < topSlope)
{
topSlope = slope;
}
}
if (topSlope <= bottomSlope)
{
// Stop.
return(false);
}
}
// Passed the subsector ok.
return(true);
}