/*
 * OpenGL rendering in its own window
 *
 *  T.C. Zhao and M. Overmars
 *
 */

#include "GL/glx.h"
#include "GL/gl.h"
#include "forms.h"
#include <stdlib.h>

extern Window fl_glwincreate(int *, GLXContext *, int, int);

/**** Forms and Objects ****/
typedef struct {
	FL_FORM *glcontrol;
	void *vdata;
	char *cdata;
	long ldata;
	FL_OBJECT *polybutt;
} FD_glcontrol;

extern FD_glcontrol * create_form_glcontrol(void);

extern int handle_expose(XEvent *, void *);

int prim = GL_POLYGON;     /* GL primitive to draw */
Window glwin;

int main(int argc, char *argv[])
{
   FD_glcontrol *fd_glcontrol;
   GLXContext context;
   int config[] = {GLX_RGBA, GLX_DEPTH_SIZE, 16, GLX_DOUBLEBUFFER, None};

   fl_initialize(&argc, argv, "FormDemo", 0, 0);
   fd_glcontrol = create_form_glcontrol();

   if(!(glwin = fl_glwincreate(config, &context, 250, 250)))
   {
      fprintf(stderr,"GLWin: Can't create OpenGL window\n"); 
      exit(0);
   }

   fl_add_event_callback(glwin, Expose, handle_expose, 0);

   fl_winshow(glwin);

   /* show the first form */
   fl_set_button(fd_glcontrol->polybutt, 1);
   fl_show_form(fd_glcontrol->glcontrol,FL_PLACE_CENTER,
                FL_FULLBORDER,"glcontrol");

   fl_do_forms();
   return 0;
}

static void draw_cube( void )
{
   glColor3f( 1.0, 0.0, 0.0 );
   glBegin( prim );
   glVertex3f( 1.0, 1.0, 1.0 );
   glVertex3f( 1.0, -1.0, 1.0 );
   glVertex3f( 1.0, -1.0, -1.0 );
   glVertex3f( 1.0, 1.0, -1.0 );
   glEnd();

   glBegin( prim );
   glVertex3f( -1.0, 1.0, 1.0 );
   glVertex3f( -1.0, 1.0, -1.0 );
   glVertex3f( -1.0, -1.0, -1.0 );
   glVertex3f( -1.0, -1.0, 1.0 );
   glEnd();

   /* Y faces */
   glColor3f( 0.0, 1.0, 0.0 );
   glBegin( prim );
   glVertex3f(  1.0, 1.0,  1.0 );
   glVertex3f(  1.0, 1.0, -1.0 );
   glVertex3f( -1.0, 1.0, -1.0 );
   glVertex3f( -1.0, 1.0,  1.0 );
   glEnd();

   glBegin( prim );
   glVertex3f(  1.0, -1.0,  1.0 );
   glVertex3f( -1.0, -1.0,  1.0 );
   glVertex3f( -1.0, -1.0, -1.0 );
   glVertex3f(  1.0, -1.0, -1.0 );
   glEnd();

   /* Z faces */
   glColor3f( 0.0, 0.0, 1.0 );
   glBegin( prim );
   glVertex3f(  1.0,  1.0,  1.0 );
   glVertex3f( -1.0,  1.0,  1.0 );
   glVertex3f( -1.0, -1.0,  1.0 );
   glVertex3f(  1.0, -1.0,  1.0 );
   glEnd();

   glBegin( prim );
   glVertex3f(  1.0, 1.0, -1.0 );
   glVertex3f(  1.0,-1.0, -1.0 );
   glVertex3f( -1.0,-1.0, -1.0 );
   glVertex3f( -1.0, 1.0, -1.0 );
   glEnd();
}

int animate(XEvent *ev, void *data)
{
    static GLfloat xrot, yrot, zrot;

    glClear( GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
    glPushMatrix();
    glRotatef( xrot, 1.0, 0.0, 0.0 );
    glRotatef( yrot, 0.0, 1.0, 0.0 );
    glRotatef( zrot, 0.0, 0.0, 1.0 );
    glTranslatef(-1.0,1.2,-0.5); 
    draw_cube();
    glPopMatrix();
    glFinish();

    if(ev->type != Expose)
    {
      xrot += 10.0;
      yrot += 7.0;
      zrot -= 3.0;
    }

    glXSwapBuffers(fl_display, glwin);
    return 0;
}

/* Initialization and expose handler */
int
handle_expose(XEvent *xev, void *data)
{
    FL_Coord w ,h ;

    fl_get_winsize(glwin, &w, &h); 
    glViewport(0,0, w, h); 

    glClearColor(0.0,0.0,0.0,0.0);

    glMatrixMode( GL_PROJECTION );
    glLoadIdentity();
    glFrustum( -1.0, 1.0,  -1.0, 1.0,  1.0, 10.0 ); 
    glTranslatef( 0.0, 0.0, -5.0 );  

    glMatrixMode( GL_MODELVIEW ); 
    glLoadIdentity();
    glCullFace( GL_BACK );
    glEnable( GL_CULL_FACE ); 
    glShadeModel( GL_FLAT );
    animate(xev, 0);
    return 0;
}

/* Form definition generated by fdesign */

/* callback functions */
void change_primitive(FL_OBJECT *ob, long data)
{
    prim = data;
}

void animate_callback(FL_OBJECT *ob, long data)
{
    fl_set_idle_callback(fl_get_button(ob) ? animate:0, 0);
}

FD_glcontrol *create_form_glcontrol(void)
{
  FL_OBJECT *obj;
  FD_glcontrol *fdui = (FD_glcontrol *) fl_calloc(1, sizeof(FD_glcontrol));

  fdui->glcontrol = fl_bgn_form(FL_NO_BOX, 241, 121);
  obj = fl_add_box(FL_UP_BOX,0,0,241,121,"");
  obj = fl_add_frame(FL_ENGRAVED_FRAME,20,26,90,70,"");
  fdui->polybutt = obj = fl_add_checkbutton(FL_RADIO_BUTTON,30,61,70,30,"Polygon");
    fl_set_object_callback(obj,change_primitive,GL_POLYGON);
  obj = fl_add_checkbutton(FL_RADIO_BUTTON,30,31,70,30,"Line");
    fl_set_object_callback(obj,change_primitive,GL_LINE_LOOP);
  obj = fl_add_button(FL_NORMAL_BUTTON,150,21,80,30,"Done");
    fl_set_button_shortcut(obj,"Dd",1);
  obj = fl_add_roundbutton(FL_PUSH_BUTTON,150,71,80,30,"Animate");
    fl_set_object_callback(obj,animate_callback,0);
  fl_end_form();

  return fdui;
}
/*---------------------------------------*/

