bool Line::intersect( float angle, const Box3f& box ) const
{
if (box.isEmpty()) return false;
const Vec3f &max = box.getMax(), &min = box.getMin();
float fuzz = 0.0;
int i;
if (angle < 0.0)
{
fuzz = - angle;
}
else
{
// Find the farthest point on the bounding box (where the pick
// cone will be largest). The amount of fuzz at this point will
// be the minimum we can use. Expand the box by that amount and
// do an intersection.
double tanA = tan(angle);
for(i = 0; i < 8; i++)
{
Vec3f point(i & 01 ? min[0] : max[0],
i & 02 ? min[1] : max[1],
i & 04 ? min[2] : max[2]);
// how far is point from line origin??
Vec3f diff(point - getPosition());
double thisFuzz = sqrt(diff.dot(diff)) * tanA;
if (thisFuzz > fuzz)
fuzz = float(thisFuzz);
}
}
Box3f fuzzBox = box;
fuzzBox.extendBy(Vec3f(min[0] - fuzz, min[1] - fuzz, min[2] - fuzz));
fuzzBox.extendBy(Vec3f(max[0] + fuzz, max[1] + fuzz, max[2] + fuzz));
Vec3f scratch1, scratch2;
return intersect(fuzzBox, scratch1, scratch2);
}
void Sphere::circumscribe( const Box3f& box )
{
m_center = 0.5f * (box.getMin() + box.getMax());
m_radius = (box.getMax() - m_center).getLength();
}
bool Line::intersect( const Box3f& box, Vec3f& enter, Vec3f& exit ) const
{
if (box.isEmpty())
{
return false;
}
const Vec3f &pos = getPosition(), &dir = getDirection();
const Vec3f &max = box.getMax(), &min = box.getMin();
Vec3f points[8], inter, bary;
Plane plane;
int i, v0, v1, v2;
bool front = false, valid, validIntersection = false;
//
// First, check the distance from the ray to the center
// of the box. If that distance is greater than 1/2
// the diagonal distance, there is no intersection
// diff is the vector from the closest point on the ray to the center
// dist2 is the square of the distance from the ray to the center
// radi2 is the square of 1/2 the diagonal length of the bounding box
//
float t = (box.getCenter() - pos).dot(dir);
Vec3f diff(pos + dir * t - box.getCenter());
float dist2 = diff.dot(diff);
float radi2 = (max - min).dot(max - min) * 0.25f;
if (dist2 > radi2)
{
return false;
}
// set up the eight coords of the corners of the box
for(i = 0; i < 8; i++)
{
points[i].setValue(i & 01 ? min[0] : max[0],
i & 02 ? min[1] : max[1],
i & 04 ? min[2] : max[2]);
}
// intersect the 12 triangles.
for(i = 0; i < 12; i++)
{
switch(i)
{
case 0: v0 = 2; v1 = 1; v2 = 0; break; // +z
case 1: v0 = 2; v1 = 3; v2 = 1; break;
case 2: v0 = 4; v1 = 5; v2 = 6; break; // -z
case 3: v0 = 6; v1 = 5; v2 = 7; break;
case 4: v0 = 0; v1 = 6; v2 = 2; break; // -x
case 5: v0 = 0; v1 = 4; v2 = 6; break;
case 6: v0 = 1; v1 = 3; v2 = 7; break; // +x
case 7: v0 = 1; v1 = 7; v2 = 5; break;
case 8: v0 = 1; v1 = 4; v2 = 0; break; // -y
case 9: v0 = 1; v1 = 5; v2 = 4; break;
case 10: v0 = 2; v1 = 7; v2 = 3; break; // +y
case 11: v0 = 2; v1 = 6; v2 = 7; break;
default:
assert(false && "Must never happened");
v0 = v1 = v2 = 0; // to remove a warning.
}
valid = intersect( points[v0], points[v1], points[v2],
inter, bary, front);
if ( valid )
{
if (front)
{
enter = inter;
validIntersection = valid;
}
else
{
exit = inter;
validIntersection = valid;
}
}
}
return validIntersection;
}
bool Box3f::operator ==( const Box3f& b2 ) const
{
return ( (getMin() == b2.getMin()) && (getMax() == b2.getMax()) );
}