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#include "AABB.h"
#include "Plane3.h"
#include "Matrix4.h"
// Expand this AABB to include the given point.
void AABB::includePoint(const Vector3& point) {
// If not yet initialised, simply set the AABB to equal the point
if (!isValid())
{
origin = point;
extents = Vector3(0, 0, 0);
}
else
{
// Extend each axis separately
for (int i = 0; i < 3; ++i)
{
// Axis displacement from origin to point
double axisDisp = point[i] - origin[i];
// Half of extent increase needed (maybe negative if point inside)
double halfDif = 0.5f * (std::abs(axisDisp) - extents[i]);
if (halfDif > 0)
{
origin[i] += (axisDisp > 0) ? halfDif : -halfDif;
extents[i] += halfDif;
}
}
}
}
// Expand this AABB to include another AABB
void AABB::includeAABB(const AABB& other)
{
// Validity check. If both this and other are valid, use the extension
// algorithm. If only the other AABB is valid, set this AABB equal to it.
// If neither are valid we do nothing.
if (isValid() && other.isValid())
{
// Extend each axis separately
for (int i = 0; i < 3; ++i)
{
double displacement = other.origin[i] - origin[i];
double difference = other.extents[i] - extents[i];
if (fabs(displacement) > fabs(difference))
{
double half_difference = 0.5f * (fabs(displacement) + difference);
if (half_difference > 0.0f)
{
origin[i] += (displacement >= 0.0f) ? half_difference : -half_difference;
extents[i] += half_difference;
}
}
else if (difference > 0.0f)
{
origin[i] = other.origin[i];
extents[i] = other.extents[i];
}
}
}
else if (other.isValid())
{
origin = other.origin;
extents = other.extents;
}
}
VolumeIntersectionValue AABB::classifyPlane(const Plane3& plane) const
{
double originDot = plane.normal().dot(origin);
double extentsDot = fabs(plane.normal().x()) * extents.x() +
fabs(plane.normal().y()) * extents.y() +
fabs(plane.normal().z()) * extents.z();
if (originDot + extentsDot - plane.dist() < 0)
{
// largest dot product is still behind the plane
return VOLUME_OUTSIDE;
}
if (originDot - extentsDot - plane.dist() >= 0)
{
// smallest dot product still in front of the plane
return VOLUME_INSIDE;
}
return VOLUME_PARTIAL;
#if 0
// greebo: I've adjusted this code (as the old one was very likely wrong)
// following the explanations on AABB vs. Frustum intersection tests
// found here: http://fgiesen.wordpress.com/2010/10/17/view-frustum-culling/
double originDot = plane.normal().dot(origin);
double extendsDot = fabs(plane.normal().x()) * extents[0] +
fabs(plane.normal().y()) * extents[1] +
fabs(plane.normal().z()) * extents[2];
if (originDot + extendsDot > plane.dist())
{
// At least one point is on the positive side of the plane
return VOLUME_PARTIAL; // partially inside
}
else if (originDot - extendsDot >= plane.dist())
{
// Even the minimum point is on the positive side
return VOLUME_INSIDE; // totally inside
}
return VOLUME_OUTSIDE; // totally outside
#endif
}
unsigned int AABB::classifyOrientedPlane(const Matrix4& transform, const Plane3& plane) const
{
double distance_origin = plane.normal().dot(origin) + plane.dist();
if (fabs(distance_origin) < (fabs(extents[0] * plane.normal().dot(transform.xCol3())) +
fabs(extents[1] * plane.normal().dot(transform.yCol3())) +
fabs(extents[2] * plane.normal().dot(transform.zCol3()))))
{
return 1; // partially inside
}
else if (distance_origin < 0)
{
return 2; // totally inside
}
return 0; // totally outside
}
void AABB::getCorners(Vector3 corners[8], const Matrix4& rotation) const
{
Vector3 x = rotation.xCol3() * extents.x();
Vector3 y = rotation.yCol3() * extents.y();
Vector3 z = rotation.zCol3() * extents.z();
corners[0] = origin - x + y + z;
corners[1] = origin + x + y + z;
corners[2] = origin + x - y + z;
corners[3] = origin - x - y + z;
corners[4] = origin - x + y - z;
corners[5] = origin + x + y - z;
corners[6] = origin + x - y - z;
corners[7] = origin - x - y - z;
}
void AABB::getPlanes(Plane3 planes[6], const Matrix4& rotation) const
{
double x = rotation.xCol3().dot(origin);
double y = rotation.yCol3().dot(origin);
double z = rotation.zCol3().dot(origin);
planes[0] = Plane3( rotation.xCol3(), x + extents[0]);
planes[1] = Plane3(-rotation.xCol3(), -(x - extents[0]));
planes[2] = Plane3( rotation.yCol3(), y + extents[1]);
planes[3] = Plane3(-rotation.yCol3(), -(y - extents[1]));
planes[4] = Plane3( rotation.zCol3(), z + extents[2]);
planes[5] = Plane3(-rotation.zCol3(), -(z - extents[2]));
}
AABB AABB::createFromOrientedAABB(const AABB& aabb, const Matrix4& transform)
{
return AABB(
transform.transformPoint(aabb.origin),
Vector3(
fabs(transform[0] * aabb.extents[0]) +
fabs(transform[4] * aabb.extents[1]) +
fabs(transform[8] * aabb.extents[2]),
fabs(transform[1] * aabb.extents[0]) +
fabs(transform[5] * aabb.extents[1]) +
fabs(transform[9] * aabb.extents[2]),
fabs(transform[2] * aabb.extents[0]) +
fabs(transform[6] * aabb.extents[1]) +
fabs(transform[10] * aabb.extents[2])
)
);
}
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