static double Bisection(int n, double x1, double x2, double y1, double y2)
{
double x, y;
x = (x1+x2)/2;
if((x2 - x1) < TOLERANCE)
return x;
else
{
y = BessJn(n, x);
if(SameSign(y1, y))
return Bisection(n, x, x2, y, y2);
else
return Bisection(n, x1, x, y1, y);
}
}
void RayTracingEnvironment::Trace4Rays(const FourRays &rays, fltx4 TMin, fltx4 TMax,
RayTracingResult *rslt_out,
int32 skip_id, ITransparentTriangleCallback *pCallback)
{
int msk=rays.CalculateDirectionSignMask();
if (msk!=-1)
Trace4Rays(rays,TMin,TMax,msk,rslt_out,skip_id, pCallback);
else
{
// sucky case - can't trace 4 rays at once. in the worst case, need to trace all 4
// separately, but usually we will still get 2x, Since our tracer only does 4 at a
// time, we will have to cover up the undesired rays with the desired ray
//!! speed!! there is room for some sse-ization here
FourRays tmprays;
tmprays.origin=rays.origin;
uint8 need_trace[4]={1,1,1,1};
for(int try_trace=0;try_trace<4;try_trace++)
{
if (need_trace[try_trace])
{
need_trace[try_trace]=2; // going to trace it
// replicate the ray being traced into all 4 rays
tmprays.direction.x=ReplicateX4(rays.direction.X(try_trace));
tmprays.direction.y=ReplicateX4(rays.direction.Y(try_trace));
tmprays.direction.z=ReplicateX4(rays.direction.Z(try_trace));
// now, see if any of the other remaining rays can be handled at the same time.
for(int try2=try_trace+1;try2<4;try2++)
if (need_trace[try2])
{
if (
SameSign(rays.direction.X(try2),
rays.direction.X(try_trace)) &&
SameSign(rays.direction.Y(try2),
rays.direction.Y(try_trace)) &&
SameSign(rays.direction.Z(try2),
rays.direction.Z(try_trace)))
{
need_trace[try2]=2;
tmprays.direction.X(try2) = rays.direction.X(try2);
tmprays.direction.Y(try2) = rays.direction.Y(try2);
tmprays.direction.Z(try2) = rays.direction.Z(try2);
}
}
// ok, now trace between 1 and 3 rays, and output the results
RayTracingResult tmpresults;
msk=tmprays.CalculateDirectionSignMask();
assert(msk!=-1);
Trace4Rays(tmprays,TMin,TMax,msk,&tmpresults,skip_id, pCallback);
// now, move results to proper place
for(int i=0;i<4;i++)
if (need_trace[i]==2)
{
need_trace[i]=0;
rslt_out->HitIds[i]=tmpresults.HitIds[i];
SubFloat(rslt_out->HitDistance, i) = SubFloat(tmpresults.HitDistance, i);
rslt_out->surface_normal.X(i) = tmpresults.surface_normal.X(i);
rslt_out->surface_normal.Y(i) = tmpresults.surface_normal.Y(i);
rslt_out->surface_normal.Z(i) = tmpresults.surface_normal.Z(i);
}
}
}
}
}