Oriented Bounding Box

From Ogre Wiki

This Class renders an Oriented Bounding Box using SimpleRenderable.

Example:

OBBoxRenderable* mOBBoxRenderable = new OBBoxRenderable();
...
mYourEntity = mSceneMgr->createEntity("test", "test.mesh");
mSceneMgr->getRootSceneNode()->createChildSceneNode("test")->attachObject(mYourEntity );
mSceneMgr->getSceneNode("test")->setPosition(25.0f, 0.0f, 25.0f);
mOBBoxRenderable->setupVertices(mYourEntity->getBoundingBox());
mSceneMgr->getSceneNode("test")->attachObject(mOBBoxRenderable);
...
delete mOBBoxRenderable; don't forget to delete it when you clean up your resources.

Oriented Bounding Box class:

OBBoxRenderable.h

#ifndef OBBOXRENDERABLE_H_
#define OBBOXRENDERABLE_H_

#include <OgreSimpleRenderable.h>
#include <OgreAxisAlignedBox.h>

private class OBBoxRenderable : public Ogre::SimpleRenderable
{
	Ogre::VertexData vertexes;
	public:
		OBBoxRenderable();
		void setupVertices(const Ogre::AxisAlignedBox& aab);
		virtual ~OBBoxRenderable();
		Ogre::Real getSquaredViewDepth(const Ogre::Camera*)const;
		Ogre::Real getBoundingRadius()const;
		virtual void getWorldTransforms (Ogre::Matrix4 *xform)const;
};

#endif /*OBBOXRENDERABLE_H_*/

OBBoxRenderable.cpp

#include "Ogre.h"

using namespace Ogre;

#include "OBBoxRenderable.h"

OBBoxRenderable::OBBoxRenderable()
{
	mRenderOp.vertexData = new Ogre::VertexData();
	mRenderOp.indexData = 0;
	mRenderOp.vertexData->vertexCount = 24;
	mRenderOp.vertexData->vertexStart = 0;
	mRenderOp.operationType = Ogre::RenderOperation::OT_LINE_LIST;
	mRenderOp.useIndexes = false;
	Ogre::VertexDeclaration* decl = mRenderOp.vertexData->vertexDeclaration;
	Ogre::VertexBufferBinding* bind = mRenderOp.vertexData->vertexBufferBinding;
	decl->addElement(0, 0, Ogre::VET_FLOAT3, Ogre::VES_POSITION);
	Ogre::HardwareVertexBufferSharedPtr vbuf = Ogre::HardwareBufferManager::getSingleton().createVertexBuffer(
		decl->getVertexSize(0), mRenderOp.vertexData->vertexCount, Ogre::HardwareBuffer::HBU_STATIC_WRITE_ONLY);
	// Bind buffer
	bind->setBinding(0, vbuf);
	// setup material
	Ogre::MaterialPtr matptrOBBoxManualMaterial = Ogre::MaterialManager::getSingleton().create("OBBoxManualMaterial", "General");
	matptrOBBoxManualMaterial->setReceiveShadows(false);
	matptrOBBoxManualMaterial->getTechnique(0)->setLightingEnabled(true);
	matptrOBBoxManualMaterial->getTechnique(0)->getPass(0)->setDiffuse(0, 1, 0, 0);
	matptrOBBoxManualMaterial->getTechnique(0)->getPass(0)->setAmbient(0, 1, 0);
	matptrOBBoxManualMaterial->getTechnique(0)->getPass(0)->setSelfIllumination(0, 1, 0);
	this->setCastShadows(false);
	//this->setQueryFlags(QF_UNKNOWN); // set a query flag to exlude from queries (if necessary).
	this->setMaterial("OBBoxManualMaterial");
}
	
OBBoxRenderable::~OBBoxRenderable()
{
	delete mRenderOp.vertexData;
}
	
void OBBoxRenderable::setupVertices(const Ogre::AxisAlignedBox& aab)
{
	Ogre::Vector3 vmax = aab.getMaximum();
	Ogre::Vector3 vmin = aab.getMinimum();
	Ogre::Real maxdistground = vmax.y;
	Ogre::Real mindistground = vmin.y;
	Ogre::Real maxx = vmax.x;
	Ogre::Real maxy = vmax.y;
	Ogre::Real maxz = vmax.z;
	Ogre::Real minx = vmin.x;
	Ogre::Real miny = vmin.y;
	Ogre::Real minz = vmin.z;
	// fill in the Vertex buffer: 12 lines with 2 endpoints each make up a box
	Ogre::HardwareVertexBufferSharedPtr vbuf = mRenderOp.vertexData->vertexBufferBinding->getBuffer(0);
	float* pPos = static_cast<float*>(vbuf->lock(Ogre::HardwareBuffer::HBL_DISCARD));
	// line 0
	*pPos++ = minx;
	*pPos++ = miny;
	*pPos++ = minz;
	*pPos++ = maxx;
	*pPos++ = miny;
	*pPos++ = minz;
	// line 1
	*pPos++ = minx;
	*pPos++ = miny;
	*pPos++ = minz;
	*pPos++ = minx;
	*pPos++ = miny;
	*pPos++ = maxz;
	// line 2
	*pPos++ = minx;
	*pPos++ = miny;
	*pPos++ = minz;
	*pPos++ = minx;
	*pPos++ = maxy;
	*pPos++ = minz;
	// line 3
	*pPos++ = minx;
	*pPos++ = maxy;
	*pPos++ = minz;
	*pPos++ = minx;
	*pPos++ = maxy;
	*pPos++ = maxz;
	// line 4
	*pPos++ = minx;
	*pPos++ = maxy;
	*pPos++ = minz;
	*pPos++ = maxx;
	*pPos++ = maxy;
	*pPos++ = minz;
	// line 5
	*pPos++ = maxx;
	*pPos++ = miny;
	*pPos++ = minz;
	*pPos++ = maxx;
	*pPos++ = miny;
	*pPos++ = maxz;
	// line 6
	*pPos++ = maxx;
	*pPos++ = miny;
	*pPos++ = minz;
	*pPos++ = maxx;
	*pPos++ = maxy;
	*pPos++ = minz;
	// line 7
	*pPos++ = minx;
	*pPos++ = maxy;
	*pPos++ = maxz;
	*pPos++ = maxx;
	*pPos++ = maxy;
	*pPos++ = maxz;
	// line 8
	*pPos++ = minx;
	*pPos++ = maxy;
	*pPos++ = maxz;
	*pPos++ = minx;
	*pPos++ = miny;
	*pPos++ = maxz;
	// line 9
	*pPos++ = maxx;
	*pPos++ = maxy;
	*pPos++ = minz;
	*pPos++ = maxx;
	*pPos++ = maxy;
	*pPos++ = maxz;
	// line 10
	*pPos++ = maxx;
	*pPos++ = miny;
	*pPos++ = maxz;
	*pPos++ = maxx;
	*pPos++ = maxy;
	*pPos++ = maxz;
	// line 11
	*pPos++ = minx;
	*pPos++ = miny;
	*pPos++ = maxz;
	*pPos++ = maxx;
	*pPos++ = miny;
	*pPos++ = maxz;
	vbuf->unlock();
	// setup the bounding box of this SimpleRenderable
	setBoundingBox(aab);
}
	
Ogre::Real OBBoxRenderable::getSquaredViewDepth(const Ogre::Camera* cam)const
{
	Ogre::Vector3 min, max, mid, dist;
	min = mBox.getMinimum();
	max = mBox.getMaximum();
	mid = ((max - min) * 0.5) + min;
	dist = cam->getDerivedPosition() - mid;
	return dist.squaredLength();
}
	
Ogre::Real OBBoxRenderable::getBoundingRadius()const
{
	return 0;
}
	
void OBBoxRenderable::getWorldTransforms (Ogre::Matrix4 *xform)const
{
	SimpleRenderable::getWorldTransforms (xform);
}