int BasicPrimitiveTests::IntersectingSegmentAgainstSphere(const LineSegment & segment, const BoundingSphere & sphere, float & rtn_t1, float & rtn_t2)
{
Eigen::Vector3f m = segment.GetPointA() - sphere.GetCenter();
float b = (m).dot(segment.GetPointB() - segment.GetPointA());
float c = m.dot(m);
float discriminant = b * b - c;
int intersection_count = 0;
float t1 = -b - sqrt(discriminant);
float t2 = -b + sqrt(discriminant);
if (t1 >= 0.0f && t1 <= 1.0f && t2 >= 0.0f && t2 <= 1.0f)
{
rtn_t1 = t1;
rtn_t2 = t2;
return 2;
}
else if (t1 >= 0.0f && t1 <= 1.0f)
{
rtn_t1 = t1;
return 1;
}
else if (t2 >= 0.0f && t2 <= 1.0f)
{
rtn_t1 = t2;
return 1;
}
return 0;
}
int BasicPrimitiveTests::IntersectingSegmentAgainstAABB(const LineSegment & segment, const AABB & aabb, float & rtn_t1, float & rtn_t2)
{
rtn_t1 = 0.0f;
rtn_t2 = FLT_MAX;
Eigen::Vector3f aabb_min = aabb.GetCenter() - aabb.GetExtents();
Eigen::Vector3f aabb_max = aabb.GetCenter() + aabb.GetExtents();
Eigen::Vector3f segment_direction = segment.GetPointB() - segment.GetPointA();
for (int i = 0; i < 3; ++i)
{
if (abs(segment_direction[i]) < EPSILON)
{
//Ray is parallel to slab. Not hit if origin not within slab.
if (segment.GetPointA()[i] < aabb_min[i] || segment.GetPointA()[i] > aabb_max[i])
{
return 0;
}
}
else
{
float one_over_direction = 1.0f / segment_direction[i];
float t1 = (aabb_min[i] - segment.GetPointA()[i]) * one_over_direction;
float t2 = (aabb_max[i] - segment.GetPointA()[i]) * one_over_direction;
if (t1 > 1.0f && t2 > 1.0f)
{
return 0;
}
if (t1 > t2) Swap(t1, t2);
if (t1 > rtn_t1) rtn_t1 = t1;
if (t2 > rtn_t2) rtn_t2 = t2;
if (rtn_t1 > rtn_t2) return 0;
}
}
if (rtn_t1 >= 0.0f && rtn_t1 <= 1.0f)
{
if (rtn_t2 >= 0.0f && rtn_t2 <= 1.0f)
{
return 2;
}
else
{
return 1;
}
}
else
{
Swap(rtn_t1, rtn_t2);
if (rtn_t1 >= 0.0f && rtn_t1 <= 1.0f)
{
return 1;
}
return 0;
}
}
bool BasicPrimitiveTests::IntersectingSegmentAgainstPlane(const LineSegment & segment, const Plane & plane, float & rtn_t)
{
/*
Main Idea:
-> Subsitutes line equation into plane to find intersection
-> Tests if intersection is within segment endpoints
Let:
-> Line Segment S:
-> S(t) = A + t * (B-A)
-> for 0 <= t <= 1
-> Plane P:
-> dot(n, X) = d
Solve for "t" of intersection:
-> t = ( d - dot(n, A) / dot(n, B-A) )
-> Return intersection only if:
-> 0 <= t <= 1
*/
rtn_t = ( plane.GetD() - plane.GetNormal().dot(segment.GetPointA()) ) / plane.GetNormal().dot(segment.GetPointB() - segment.GetPointA());
return (rtn_t <= 1.0f && rtn_t >= 0.0f);
}
int BasicPrimitiveTests::IntersectingSegmentAgainstAABB(const LineSegment & segment, const AABB & aabb)
{
Eigen::Vector3f segment_a_aabb = segment.GetPointA() - aabb.GetCenter();
Eigen::Vector3f segment_b_aabb = segment.GetPointB() - aabb.GetCenter();
Eigen::Vector3f segment_m_aabb = (segment_a_aabb + segment_b_aabb) * 0.5f;
return 0;
}
int BasicPrimitiveTests::IntersectingSegmentAgainstOBB(const LineSegment & segment, const OBB & obb)
{
Eigen::Matrix3f obb_rotation;
obb.GetRotationMatrix(obb_rotation);
Eigen::Vector3f segment_A_obb = obb_rotation * (segment.GetPointA() - obb.GetCenter());
Eigen::Vector3f segment_B_obb = obb_rotation * (segment.GetPointB() - obb.GetCenter());
return 0;
}