//
// Hits the ray against the mesh
//
internal override void RayHitTestCore(
RayHitTestParameters rayParams,
FaceType hitTestableFaces)
{
Debug.Assert(hitTestableFaces != FaceType.None,
"Caller should make sure we're trying to hit something");
Point3DCollection positions = Positions;
if (positions == null)
{
return;
}
Point3D origin;
Vector3D direction;
rayParams.GetLocalLine(out origin, out direction);
Int32Collection indices = TriangleIndices;
// In the line case, we want to hit test all faces because we don't
// have a direction. This may differ from what faces we want to
// accept.
FaceType facesToHit;
if (rayParams.IsRay)
{
facesToHit = hitTestableFaces;
}
else
{
facesToHit = FaceType.Front | FaceType.Back;
}
//
// This code duplication is unfortunate but necessary. Breaking it down into methods
// further significantly impacts performance. About 5% improvement could be made
// by unrolling this code below even more.
//
// If futher perf investigation is done with this code, be sure to test NGEN assemblies only
// as JIT produces different, faster code than NGEN.
//
if (indices == null || indices.Count == 0)
{
FrugalStructList <Point3D> ps = positions._collection;
int count = ps.Count - (ps.Count % 3);
for (int i = count - 1; i >= 2; i -= 3)
{
int i0 = i - 2;
int i1 = i - 1;
int i2 = i;
Point3D v0 = ps[i0];
Point3D v1 = ps[i1];
Point3D v2 = ps[i2];
double hitTime;
Point barycentric;
// The line hit test is equivalent to a double sided
// triangle hit because it doesn't cull triangles based
// on winding
if (LineUtil.ComputeLineTriangleIntersection(
facesToHit,
ref origin,
ref direction,
ref v0,
ref v1,
ref v2,
out barycentric,
out hitTime
)
)
{
if (rayParams.IsRay)
{
ValidateRayHit(
rayParams,
ref origin,
ref direction,
hitTime,
i0,
i1,
i2,
ref barycentric
);
}
else
{
ValidateLineHit(
rayParams,
hitTestableFaces,
i0,
i1,
i2,
ref v0,
ref v1,
ref v2,
ref barycentric
);
}
}
}
}
else // indexed mesh
{
FrugalStructList <Point3D> ps = positions._collection;
FrugalStructList <int> idcs = indices._collection;
int count = idcs.Count;
int limit = ps.Count;
for (int i = 2; i < count; i += 3)
{
int i0 = idcs[i - 2];
int i1 = idcs[i - 1];
int i2 = idcs[i];
// Quit if we encounter an index out of range.
// This is okay because the triangles we ignore are not rendered.
// (see: CMilMeshGeometry3DDuce::Realize)
if ((0 > i0 || i0 >= limit) ||
(0 > i1 || i1 >= limit) ||
(0 > i2 || i2 >= limit))
{
break;
}
Point3D v0 = ps[i0];
Point3D v1 = ps[i1];
Point3D v2 = ps[i2];
double hitTime;
Point barycentric;
if (LineUtil.ComputeLineTriangleIntersection(
facesToHit,
ref origin,
ref direction,
ref v0,
ref v1,
ref v2,
out barycentric,
out hitTime
)
)
{
if (rayParams.IsRay)
{
ValidateRayHit(
rayParams,
ref origin,
ref direction,
hitTime,
i0,
i1,
i2,
ref barycentric
);
}
else
{
ValidateLineHit(
rayParams,
hitTestableFaces,
i0,
i1,
i2,
ref v0,
ref v1,
ref v2,
ref barycentric
);
}
}
}
}
}