/*
-----------------------------------------------------------------------------
This source file is part of the GameTools Project
http://www.gametools.org

Author: Martin Szydlowski
-----------------------------------------------------------------------------
*/

#include "OgreBvHierarchyCamera.h"

namespace Ogre
{

BvHierarchyCamera::BvHierarchyCamera(const String& name, SceneManager *sm):
Camera(name, sm)
{

}

BvHierarchyCamera::~BvHierarchyCamera()
{

}

//-----------------------------------------------------------------------
// enhanced vis calculation - borrowed from OctreeCamera - indicate when entire box inside the frustum
BvHierarchyCamera::NodeVisibility BvHierarchyCamera::getVisibilityEnhanced(const AxisAlignedBox& box) const
{
	++ mNumVisQueries;
	
	// Null boxes always invisible
	if ( box.isNull() )
		return BVHNV_NONE;

	// Make any pending updates to the calculated frustum planes
	updateFrustumPlanes();

	// Get corners of the box
	const Vector3* pCorners = box.getAllCorners();

	// For each plane, see if all points are on the negative side
	// If so, object is not visible.
	// If one or more are, it's partial.
	// If all aren't, full

	int corners[ 8 ] = {0, 4, 3, 5, 2, 6, 1, 7};

	int planes[ 6 ] = {FRUSTUM_PLANE_TOP, FRUSTUM_PLANE_BOTTOM,
		FRUSTUM_PLANE_LEFT, FRUSTUM_PLANE_RIGHT,
		FRUSTUM_PLANE_FAR, FRUSTUM_PLANE_NEAR };

	bool all_inside = true;

	for ( int plane = 0; plane < 6; ++plane )
	{

		// Skip far plane if infinite view frustum
		if (mFarDist == 0 && planes[ plane ] == FRUSTUM_PLANE_FAR)
			continue;

		bool all_outside = true;

		float distance = 0;

		for ( int corner = 0; corner < 8; ++corner )
		{
			distance = mFrustumPlanes[ planes[ plane ] ].getDistance( pCorners[ corners[ corner ] ] );
			all_outside = all_outside && ( distance < 0 );
			all_inside = all_inside && ( distance >= 0 );

			if ( !all_outside && !all_inside )
				break;
		}

		if ( all_outside )
			return BVHNV_NONE;
	}

	if ( all_inside )
		return BVHNV_FULL;
	else
		return BVHNV_PART;
}

//-----------------------------------------------------------------------
// simple vis calculation - does the same as isVisible, only different return type
BvHierarchyCamera::NodeVisibility BvHierarchyCamera::getVisibilitySimple(const AxisAlignedBox& box) const
{
	++ mNumVisQueries;

	// dummy
	FrustumPlane* culledBy = 0;
	if (mCullFrustum)
	{
		return mCullFrustum->isVisible(box, culledBy) ? BVHNV_PART : BVHNV_NONE;
	}
	else
	{
		return Frustum::isVisible(box, culledBy) ? BVHNV_PART : BVHNV_NONE;
	}
}

} // namespace Ogre