///////////////////////////////////////////////////////////////////////////////
// Intersect with frustum by repeated slicing
void CBrush::Intersect(const CFrustum& frustum, CBrush& result) const
{
ENSURE(&result != this);
if (!frustum.GetNumPlanes())
{
result = *this;
return;
}
CBrush buf;
const CBrush* prev = this;
CBrush* next;
if (frustum.GetNumPlanes() & 1)
next = &result;
else
next = &buf;
for(size_t i = 0; i < frustum.GetNumPlanes(); ++i)
{
prev->Slice(frustum[i], *next);
prev = next;
if (prev == &buf)
next = &result;
else
next = &buf;
}
ENSURE(prev == &result);
}
///////////////////////////////////////////////////////////////////////////////
// Intersect with frustum by repeated slicing
void CBrush::Intersect(const CFrustum& frustum, CBrush& result) const
{
ENSURE(&result != this);
if (!frustum.GetNumPlanes())
{
result = *this;
return;
}
CBrush buf;
const CBrush* prev = this;
CBrush* next;
// Repeatedly slice this brush with each plane of the frustum, alternating between 'result' and 'buf' to
// save intermediate results. Set up the starting brush so that the final version always ends up in 'result'.
if (frustum.GetNumPlanes() & 1)
next = &result;
else
next = &buf;
for(size_t i = 0; i < frustum.GetNumPlanes(); ++i)
{
prev->Slice(frustum[i], *next);
prev = next;
if (prev == &buf)
next = &result;
else
next = &buf;
}
ENSURE(prev == &result);
}
