object.h

一本关于OPenGL的很好的电子书

#ifndef __OBJECT_H
#define __OBJECT_H

#include "tree.h"
#include "vector.h"
#include "camera.h"

/*
	OBJECT.H

  	The CObject class

	OpenGL Game Programming
	Author: Kevin Hawkins
	Date: 3/29/2001
	Description: The CObject class is derived from CNode and
			   represents an object in the game world.

*/

class CObject : public CNode
{
protected:
	bool bDelete;

	// perform basic physics on the object
	virtual void OnAnimate(scalar_t deltaTime) 
	{
		position += velocity * deltaTime;
		velocity += acceleration * deltaTime;
	}

	// draw the object given the camera position
	virtual void OnDraw(CCamera *camera) {}	

	// collide with other objects
	virtual void OnCollision(CObject *collisionObject) {}

	// perform collision and other preparations for this object
	virtual void OnPrepare() 
	{
		ProcessCollisions(FindRoot());	// perform collisions starting with
									// root world object
	}

public:
	CVector position;		// object position
	CVector velocity;		// velocity of object
	CVector acceleration;	// acceleration
	scalar_t size;			// size of bounding sphere (radius)

	CObject() { bDelete = false; }
	~CObject() {}

	virtual void Load() {}
	virtual void Unload() {}

	// draw object
	void Draw(CCamera *camera) 
	{
		// push modelview matrix on stack
		glPushMatrix();
			OnDraw(camera);		// draw this object
			if (HasChild())		// draw children
				((CObject*)childNode)->Draw(camera);
		glPopMatrix();

		// draw siblings
		if (HasParent() && !IsLastChild())
			((CObject*)nextNode)->Draw(camera);
	}

	// animate object
	void Animate(scalar_t deltaTime) 
	{
		OnAnimate(deltaTime);		// animate this object
	
		// animate children
		if (HasChild())
			((CObject*)childNode)->Animate(deltaTime);

		// animate siblings
		if (HasParent() && !IsLastChild())
			((CObject*)nextNode)->Animate(deltaTime);

		if (bDelete)
			delete this;
	}

	// perform collision detection
	void ProcessCollisions(CObject *obj) 
	{
		// if this object's bounding sphere collides with obj's sphere
		// and obj is not this object
		if (((obj->position - position).Length() <= (obj->size + size)) &&
			(obj != ((CObject*)this)))
		{
			OnCollision(obj);		// perform this object's collision with obj

			// test child collisions with obj
			if (HasChild())
				((CObject*)childNode)->ProcessCollisions(obj);

			// test sibling collisions with obj
			if (HasParent() && !IsLastChild())
				((CObject*)nextNode)->ProcessCollisions(obj);
		}

		// if obj has children, check collisions with these children
		if (obj->HasChild())
			ProcessCollisions((CObject*)(obj->childNode));

		// if obj has siblings, check collisions with these siblings
		if (obj->HasParent() && !obj->IsLastChild())
			ProcessCollisions((CObject*)(obj->nextNode));
	}

	// prepare object
	void Prepare()
	{
		OnPrepare();						// prepare this object

		if (HasChild())					// prepare children
			((CObject*)childNode)->Prepare();

		if (HasParent() && !IsLastChild())		// prepare siblings
			((CObject*)nextNode)->Prepare();
	}

	// find root object of cyclic linked list tree
	CObject *FindRoot()
	{
		// if this object has a parent node, return the root of the parent node
		if (parentNode)
			return ((CObject*)parentNode)->FindRoot();

		return this;
	}
};


#endif