main.cpp

This AI for Game Developers

#include "main.h"
#include "time.h"

//---------------------------------------------------------------------------
/*
Book:           AI for Game Developers
Authors:        David M. Bourg & Glenn Seemann
Example:        Potential function based movement, Chapter 5
*/
//---------------------------------------------------------------------------


#define		_TIMESTEP						0.0025
#define		_TOL							1e-10
#define		_FWDTIME						10
#define		_THRUSTFACTOR					1.0
#define     _CHASESETUP						true
#define		_SPAWN_AREA_R					100

#define		_MAX_NUM_UNITS					20

#define		_UNIT_LENGTH					4

#define		_OBSTACLE_RADIUS_FACTOR			4
#define		_OBSTACLE_RADIUS				_OBSTACLE_RADIUS_FACTOR * _UNIT_LENGTH
#define		_COLLISION_VISIBILITY_FACTOR	25

#define		_WIDEVIEW_RADIUS_FACTOR				200
#define		_NARROWVIEW_RADIUS_FACTOR			50
#define		_LIMITEDVIEW_RADIUS_FACTOR			30

#define		_SEPARATION_FACTOR				5
#define		_BACK_VIEW_ANGLE_FACTOR			1
#define		_FRONT_VIEW_ANGLE_FACTOR		1

#define		_NUM_OBSTACLES					1





// Global Variables:
int				FrameCounter = 0;
RigidBody2D		Units[_MAX_NUM_UNITS];
Vector			Target;
Vector			Obstacles[_NUM_OBSTACLES];

bool	Initialize(void)
{
	int i;

	GetRandomNumber(0, _WINWIDTH, true);
			
	for(i=0; i<_MAX_NUM_UNITS; i++)
	{	
		Units[i].fMass = 10;
		Units[i].fInertia = 10;
		Units[i].fInertiaInverse = 1/10;
		Units[i].vPosition.x = GetRandomNumber(_WINWIDTH/2-_SPAWN_AREA_R, _WINWIDTH/2+_SPAWN_AREA_R, false);
		Units[i].vPosition.y = GetRandomNumber(_WINHEIGHT/2-_SPAWN_AREA_R, _WINHEIGHT/2+_SPAWN_AREA_R, false);
		Units[i].fWidth = _UNIT_LENGTH/2;
		Units[i].fLength = _UNIT_LENGTH;
		Units[i].fHeight = _UNIT_LENGTH;
		Units[i].fOrientation = GetRandomNumber(0, 360, false);	
		Units[i].CD.y = -0.12*Units[i].fLength;		Units[i].CD.x = 0.0f;			// coordinates of the body center of drag
		Units[i].CT.y = -0.50*Units[i].fLength;		Units[i].CT.x = 0.0f;			// coordinates of the propeller thrust vector
		Units[i].CPT.y = 0.5*Units[i].fLength;		Units[i].CPT.x = -0.5*Units[i].fWidth;	// coordinates of the port bow thruster
		Units[i].CST.y = 0.5*Units[i].fLength;		Units[i].CST.x = 0.5*Units[i].fWidth;	// coordinates of the starboard bow thruster

		Units[i].ProjectedArea = (Units[i].fLength + Units[i].fWidth) * Units[i].fHeight;

		Units[i].ThrustForce = _THRUSTFORCE;
	

	}

	for(i=0; i<_NUM_OBSTACLES; i++)
	{
		Obstacles[i].x = /*400+_OBSTACLE_RADIUS*i;*/GetRandomNumber(_OBSTACLE_RADIUS*4, _WINWIDTH, false);
		Obstacles[i].y = /*380;*//*_WINHEIGHT/2;*/GetRandomNumber(_OBSTACLE_RADIUS*4, _WINHEIGHT, false);
	}

	return true;
}


void	DoUnitAI(int i)
{
		
		int		j;
		Vector	Fs;
		Vector	Pfs;
		Vector	r, u;
		double  U, A, B, n, m, d;

		// begin Flock AI
		Fs.x = Fs.y = Fs.z = 0;		
		Pfs.x = 0;
		Pfs.y = Units[i].fLength / 2.0f;
		
		
		if(Swarm)
		{
			for(j=1; j<_MAX_NUM_UNITS; j++)
			{
				if(i!=j)
				{
					r = Units[i].vPosition - Units[j].vPosition;
					u = r;
					u.Normalize();

					A = 2000;
					B = 20000;
					n = 1;
					m = 2;
					d = r.Magnitude()/Units[i].fLength;
					U = -A/pow(d, n) + B/pow(d, m);
	
					Fs += VRotate2D( -Units[i].fOrientation, U * u);	
				}
			}
		}

		if(Chase)
		{
			r = Units[i].vPosition - Units[0].vPosition;
			u = r;
			u.Normalize();

			A = 10000;
			B = 10000;
			n = 1;
			m = 2;
			d = r.Magnitude()/Units[i].fLength;
			U = -A/pow(d, n) + B/pow(d, m);
	
			Fs += VRotate2D( -Units[i].fOrientation, U * u);	
		}

		if(Avoid)
		{
			for(j=0; j<_NUM_OBSTACLES; j++)
			{
				r = Units[i].vPosition - Obstacles[j];
				u = r;
				u.Normalize();

				A = 0;
				B = 13000;
				n = 1;
				m = 2.5;
				d = r.Magnitude()/Units[i].fLength;
				U = -A/pow(d, n) + B/pow(d, m);
	
				Fs += VRotate2D( -Units[i].fOrientation, U * u);				
			}
		}
				
		Units[i].Fa = Fs;
		Units[i].Pa = Pfs;
		// end Flock AI

}

void	UpdateSimulation(void)
{
	double	dt = _TIMESTEP;
	int		i;
	
	// initialize the back buffer
	if(FrameCounter >= _RENDER_FRAME_COUNT)
	{
		if(!ShowTrails)
			ClearBackBuffer();
		DrawObstacles();
	}
	
	// Update player controlled unit:	
	Units[0].SetThrusters(false, false, 1);
	Units[0].SetThrusters(false, false, 1);

	if (IsKeyDown(VK_RIGHT))
		Units[0].SetThrusters(true, false, 0.5);

	if (IsKeyDown(VK_LEFT))
		Units[0].SetThrusters(false, true, 0.5);

	Units[0].UpdateBodyEuler(dt);
	if(FrameCounter >= _RENDER_FRAME_COUNT)
		DrawCraft(Units[0], RGB(0, 255, 0));

	if(Units[0].vPosition.x > _WINWIDTH) Units[0].vPosition.x = 0;
	if(Units[0].vPosition.x < 0) Units[0].vPosition.x = _WINWIDTH;
	if(Units[0].vPosition.y > _WINHEIGHT) Units[0].vPosition.y = 0;
	if(Units[0].vPosition.y < 0) Units[0].vPosition.y = _WINHEIGHT;
	
	// update computer controlled units:	
	for(i=1; i<_MAX_NUM_UNITS; i++)
	{		
		DoUnitAI(i);
		
		Units[i].UpdateBodyEuler(dt);

		if(FrameCounter >= _RENDER_FRAME_COUNT)
		{
			if(Units[i].Leader)
				DrawCraft(Units[i], RGB(255,0,0));
			else {
				if(Units[i].Interceptor)
					DrawCraft(Units[i], RGB(255,0,255));		
				else
					DrawCraft(Units[i], RGB(0,0,255));
			}
		}

		if(Units[i].vPosition.x > _WINWIDTH) Units[i].vPosition.x = 0;
		if(Units[i].vPosition.x < 0) Units[i].vPosition.x = _WINWIDTH;
		if(Units[i].vPosition.y > _WINHEIGHT) Units[i].vPosition.y = 0;
		if(Units[i].vPosition.y < 0) Units[i].vPosition.y = _WINHEIGHT;		
	} // end i-loop	

	if(FrameCounter >= _RENDER_FRAME_COUNT) {
		CopyBackBufferToWindow();
		FrameCounter = 0;
	}  else
		FrameCounter++;
}

void	DrawCraft(RigidBody2D	craft, COLORREF clr)
{
	Vector	vList[5];
	double	wd, lg;
	int		i;
	Vector	v1;

	wd = craft.fWidth;
	lg = craft.fLength;
	vList[0].y = lg/2;	vList[0].x = wd/2;
	vList[1].y = -lg/2;	vList[1].x = wd/2;
	vList[2].y = -lg/2;	vList[2].x = -wd/2;
	vList[3].y = lg/2;	vList[3].x = -wd/2;
	vList[4].y = lg/2*1.5; vList[4].x = 0;
	for(i=0; i<5; i++)
	{
		v1 = VRotate2D(craft.fOrientation, vList[i]);
		vList[i] = v1 + craft.vPosition;			
	}

	DrawLine(vList[0].x, vList[0].y, vList[1].x, vList[1].y, 2, clr);
	DrawLine(vList[1].x, vList[1].y, vList[2].x, vList[2].y, 2, clr);
	DrawLine(vList[2].x, vList[2].y, vList[3].x, vList[3].y, 2, clr);
	DrawLine(vList[3].x, vList[3].y, vList[4].x, vList[4].y, 2, clr);
	DrawLine(vList[4].x, vList[4].y, vList[0].x, vList[0].y, 2, clr);

	if(ShowVectors)
	{
		Vector	v, u;
		double	f = 0.025;

		// Show velocity vectors in green
		DrawLine(craft.vPosition.x, craft.vPosition.y, craft.vPosition.x+craft.vVelocity.x, craft.vPosition.y+craft.vVelocity.y, 3, RGB(0,255,0));
		
		// Show force vectors in black
		// thrust vector
		v.x = 0;
		v.y = craft.ThrustForce*f;
		v = VRotate2D(craft.fOrientation, v);
		u.x = craft.CT.x;
		u.y = craft.CT.y;
		u = VRotate2D(craft.fOrientation, u);
		DrawLine(craft.vPosition.x+u.x, craft.vPosition.y+u.y, craft.vPosition.x + u.x + v.x, craft.vPosition.y + u.y + v.y, 1, RGB(0,0,0));

		// port steering force
		v.x = craft.PThrust.x*f;
		v.y = craft.PThrust.y*f;
		v = VRotate2D(craft.fOrientation, v);
		u.x = craft.CPT.x;
		u.y = craft.CPT.y;
		u = VRotate2D(craft.fOrientation, u);
		DrawLine(craft.vPosition.x+u.x, craft.vPosition.y+u.y, craft.vPosition.x + u.x + v.x, craft.vPosition.y + u.y + v.y, 1, RGB(0,0,0));

		// stbd steering force
		v.x = craft.SThrust.x*f;
		v.y = craft.SThrust.y*f;
		v = VRotate2D(craft.fOrientation, v);
		u.x = craft.CST.x;
		u.y = craft.CST.y;
		u = VRotate2D(craft.fOrientation, u);
		DrawLine(craft.vPosition.x+u.x, craft.vPosition.y+u.y, craft.vPosition.x + u.x + v.x, craft.vPosition.y + u.y + v.y, 1, RGB(0,0,0));

		// applied force
		v.x = craft.Fa.x*f;
		v.y = craft.Fa.y*f;
		v = VRotate2D(craft.fOrientation, v);
		u.x = craft.Pa.x;
		u.y = craft.Pa.y;
		u = VRotate2D(craft.fOrientation, u);
		DrawLine(craft.vPosition.x+u.x, craft.vPosition.y+u.y, craft.vPosition.x + u.x + v.x, craft.vPosition.y + u.y + v.y, 1, RGB(0,0,0));

	}

}

void DrawObstacles(void)
{
	int		i;
	RECT	r;
	int		radius = _OBSTACLE_RADIUS/2;

	for(i=0; i<_NUM_OBSTACLES; i++)
	{
		SetRect(&r, Obstacles[i].x - radius, Obstacles[i].y - radius, Obstacles[i].x + radius, Obstacles[i].y + radius);
		DrawEllipse(&r, 2, RGB(255,0,0));

	}

}


int GetRandomNumber(int min, int max, bool seed)
{
	int	number;	

	if(seed)
		srand( (unsigned)time( NULL ) );
		
    number = (((abs(rand())%(max-min+1))+min));    
    
    if(number>max)
		number = max;

    if(number<min)
    	number = min;
		
	return number;
}


/*
void	DoAttractCraft2(void)
{
	// Apply Lenard-Jones potential force to Craft2
	Vector	r = Craft2.vPosition - Craft1.vPosition;
	Vector  u = r;

	u.Normalize();

	double  U, A, B, n, m, d;

	A = 1000;
	B = 31000;
	n = 2;
	m = 4;
	d = r.Magnitude()/Craft2.fLength;
	U = -A/pow(d, n) + B/pow(d, m);
	
	Craft2.Fa = VRotate2D( -Craft2.fOrientation, U * u);	
	
	Craft2.Pa.x = 0;
	Craft2.Pa.y = Craft2.fLength / 2;

	Target = Craft1.vPosition;
	
}
*/