/* navigate2.c
/*    An example of a navigation and interaction. Navigation is added
/*   to interact.c (without the joystick control of scaling). The positions
/*   and vectors used for interaction must be converted to world coordinates.
*/

#include <cave_ogl.h>
#include <GL/glu.h>

/* The data that will be shared between processes */
struct _balldata
	{
	float x,y,z;
	float radius;
	int grabbed;
	struct _balldata *next;
	};

void init_gl(void),draw_balls(struct _balldata **);
void check_add(struct _balldata **list);
struct _balldata * update_held(struct _balldata *ball);
struct _balldata * check_grab(struct _balldata **list);
void navigate(void);

main(int argc,char **argv)
{
 struct _balldata **ballList,*heldBall=NULL;
 CAVEConfigure(&argc,argv,NULL);
 ballList = (struct _balldata **) CAVEMalloc(sizeof(struct _balldata *));
 *ballList = NULL;
 CAVEInit();
 CAVEInitApplication(init_gl,0);
 CAVEDisplay(draw_balls,1,ballList);
 while (!CAVEgetbutton(CAVE_ESCKEY))
	{
	navigate();
	check_add(ballList);
	if (heldBall)
		heldBall = update_held(heldBall);
	else
		heldBall = check_grab(ballList);
	sginap(1);
	}
 CAVEExit();
}


#define SPEED 5.0f  /* Max navigation speed in feet per second */

/* navigate - perform the navigation calculations. */
void navigate(void)
{
 float jx=CAVE_JOYSTICK_X,jy=CAVE_JOYSTICK_Y,dt,t;
 static float prevtime = 0;
 t = CAVEGetTime();
 dt = t - prevtime;
 prevtime = t;
 if (fabs(jy)>0.2)
	{
	float wandFront[3];
	CAVEGetVector(CAVE_WAND_FRONT,wandFront);
	CAVENavTranslate(wandFront[0]*jy*SPEED*dt, wandFront[1]*jy*SPEED*dt,
			wandFront[2]*jy*SPEED*dt);
	}
 if (fabs(jx)>0.2)
	CAVENavRot(-jx*90.0f*dt,'y');
}


void check_add(struct _balldata **list)
{
 if (CAVEButtonChange(3) == -1)
	{
	struct _balldata *ball;
	float wandPos[3],wandFront[3];
	float wandWorldPos[3],wandWorldFront[3];
	ball = (struct _balldata *) CAVEMalloc(sizeof(struct _balldata));
	if (!ball)
		{
		fprintf(stderr,"OUT OF MEMORY!\n");
		return;
		}
	CAVEGetPosition(CAVE_WAND,wandPos);
	CAVENavConvertCAVEToWorld(wandPos,wandWorldPos);
	CAVEGetVector(CAVE_WAND_FRONT,wandFront);
	CAVENavConvertVectorCAVEToWorld(wandFront,wandWorldFront);
	ball->x = wandWorldPos[0] + wandWorldFront[0]*2;
	ball->y = wandWorldPos[1] + wandWorldFront[1]*2;
	ball->z = wandWorldPos[2] + wandWorldFront[2]*2;
	ball->radius = 1;
	ball->grabbed = 0;
	ball->next = *list;
	*list = ball;
	}
}


struct _balldata * update_held(struct _balldata *ball)
{
 if (!CAVEBUTTON1)
	{
	float wandPos[3],wandWorldPos[3];
	CAVEGetPosition(CAVE_WAND,wandPos);
	CAVENavConvertCAVEToWorld(wandPos,wandWorldPos);
	ball->x = wandWorldPos[0];
	ball->y = wandWorldPos[1];
	ball->z = wandWorldPos[2];
	ball->grabbed = 0;
	return NULL;
	}
 return ball;
}


struct _balldata * check_grab(struct _balldata **list)
{
 if (CAVEButtonChange(1) == 1)
	{
	struct _balldata *ball;
	float wandPos[3],wandWorldPos[3];
	CAVEGetPosition(CAVE_WAND,wandPos);
	CAVENavConvertCAVEToWorld(wandPos,wandWorldPos);
	for (ball = *list; ball; ball = ball->next)
		{
		float dist;
#define SQR(x) ((x)*(x))
		dist = SQR(ball->x - wandWorldPos[0]) +
			SQR(ball->y - wandWorldPos[1]) + 
			SQR(ball->z - wandWorldPos[2]);
		if (dist < SQR(ball->radius))
			{
			ball->grabbed = 1;
			return ball;
			}
		}
	}
 return NULL;
}




static GLUquadricObj *sphereObj;

/* init_gl - initialize GL lighting & materials */
void init_gl(void)
{
 float redMaterial[] = { .8, 0, .8, 1 };
 glEnable(GL_LIGHT0);
 glMaterialfv(GL_FRONT_AND_BACK, GL_AMBIENT_AND_DIFFUSE, redMaterial);
 sphereObj = gluNewQuadric();
}


/* draw_balls - draw the balls, using the shared data for their positions
  & sizes */
void draw_balls(struct _balldata **ballList)
{
 struct _balldata *ball;

 glClearColor(0., 0., 0., 0.);
 glClear(GL_DEPTH_BUFFER_BIT|GL_COLOR_BUFFER_BIT);
 glEnable(GL_LIGHTING);

 for (ball = *ballList; ball; ball = ball->next)
/* Draw the grabbed ball in CAVE coordinates */
	if (ball->grabbed)
		{
		glPushMatrix();
		 CAVEWandTransform();
		 gluSphere(sphereObj, ball->radius, 8, 8);
		glPopMatrix();
		}
/* Draw all the other balls in world coordinates */
	else
		{
		glPushMatrix();
		 CAVENavTransform();
		 glTranslatef(ball->x, ball->y, ball->z);
		 gluSphere(sphereObj, ball->radius, 4, 4);
		glPopMatrix();
		}

 glDisable(GL_LIGHTING);
}