/* bounce.c
/*    An example of a dynamic CAVE environment. Two bouncing balls are
/*   drawn. The calculations for their movements are performed in the
/*   main process, and communicated to the drawing processes through
/*   shared memory.
*/

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


/* The data that will be shared between processes */
struct _balldata
	{
	float y;
	};

void init_gl(void),draw_balls(struct _balldata *);
struct _balldata *init_shmem(void);
void compute(struct _balldata *);

main(int argc,char **argv)
{
 struct _balldata *ball;
 CAVEConfigure(&argc,argv,NULL);
/* Initialize shared memory */
 ball = init_shmem();
 CAVEInit();
 CAVEInitApplication(init_gl,0);
/* Give the library a pointer to the drawing function, plus one argument */
 CAVEDisplay(draw_balls,1,ball);
 while (!CAVEgetbutton(CAVE_ESCKEY))
	{
/* Update the balls' positions */
	compute(ball);
	sginap(1);
	}
 CAVEExit();
}


/* init_shmem - initializes shared memory. The data is allocated from a
  shared memory arena, and so will be common to all processes forked after
  this is called. */
struct _balldata *init_shmem(void)
{
 struct _balldata *ball;
 ball = CAVEMalloc(2*sizeof(struct _balldata));
 bzero(ball,2*sizeof(struct _balldata));
 return ball;
}


/* compute - compute new positions for the balls. The height of the balls
  is a function of the current CAVE time. */
void compute(struct _balldata *ball)
{
 float t = CAVEGetTime();
 ball[0].y = fabs(sin(t)) * 6 + 1;
 ball[1].y = fabs(sin(t*1.2)) * 4 + 1;
}



static GLuint redMat, blueMat; 
static GLUquadricObj *sphereObj;

/* init_gl - initialize GL lighting & materials */
void init_gl(void)
{
 float redMaterial[] = { 1, 0, 0, 1 };
 float blueMaterial[] = { 0, 0, 1, 1 };
 glEnable(GL_LIGHT0);
 redMat = glGenLists(1);
 glNewList(redMat, GL_COMPILE);
 glMaterialfv(GL_FRONT_AND_BACK, GL_AMBIENT_AND_DIFFUSE, redMaterial);
 glEndList();
 blueMat = glGenLists(1);
 glNewList(blueMat, GL_COMPILE);
 glMaterialfv(GL_FRONT_AND_BACK, GL_AMBIENT_AND_DIFFUSE, blueMaterial);
 glEndList();
 sphereObj = gluNewQuadric();
}


/* draw_balls - draw the two balls, using the shared data for their
  y coordinates */
void draw_balls(struct _balldata *ball)
{
 glClearColor(0., 0., 0., 0.);
 glClear(GL_DEPTH_BUFFER_BIT|GL_COLOR_BUFFER_BIT);
 glEnable(GL_LIGHTING);

 glCallList(redMat);
 glPushMatrix();
 glTranslatef(2.0, ball[0].y, -5.0);
 gluSphere(sphereObj, 1.0, 8, 8);
 glPopMatrix();

 glCallList(blueMat);
 glPushMatrix();
 glTranslatef(-2.0, ball[1].y, -5.0);
 gluSphere(sphereObj, 1.0, 8, 8);
 glPopMatrix();

 glDisable(GL_LIGHTING);
}