void Intersector::trace_back_sides(
ShadingRay ray,
ShadingPoint& shading_point) const
{
while (trace(ray, shading_point))
{
if (dot(ray.m_dir, shading_point.get_original_shading_normal()) > 0.0)
break;
shading_point.refine_and_offset();
ray.m_org = shading_point.get_offset_point(ray.m_dir);
shading_point.clear();
}
}
bool Intersector::do_trace_same_material(
const ShadingRay& ray,
const ShadingPoint& parent_shading_point,
const bool offset_origin,
ShadingPoint& shading_point) const
{
ShadingRay up_ray(ray);
ShadingRay down_ray(ray);
down_ray.m_dir = -down_ray.m_dir;
if (offset_origin)
{
parent_shading_point.refine_and_offset();
const Vector3d offset =
parent_shading_point.get_offset_point(down_ray.m_dir) - parent_shading_point.get_point();
up_ray.m_org += offset;
}
const Material* parent_material = parent_shading_point.get_material();
// Trace the ray.
ShadingPoint up_shading_point;
trace_back_sides(
up_ray,
up_shading_point);
// Discard objects with different materials.
if (up_shading_point.hit())
{
if (up_shading_point.get_opposite_material() != parent_material)
up_shading_point.clear();
}
// Trace the opposite ray.
ShadingPoint down_shading_point;
trace_back_sides(
down_ray,
down_shading_point);
// Discard objects with different materials.
if (down_shading_point.hit())
{
if (down_shading_point.get_opposite_material() != parent_material)
down_shading_point.clear();
}
// Keep the nearest hit, if any.
if (up_shading_point.hit() && down_shading_point.hit())
{
shading_point =
up_shading_point.get_distance() < down_shading_point.get_distance() ? up_shading_point : down_shading_point;
return true;
}
else if (up_shading_point.hit())
{
shading_point = up_shading_point;
return true;
}
else if (down_shading_point.hit())
{
shading_point = down_shading_point;
return true;
}
return false;
}