#include <stdio.h>
#include "vogl.h"

static	Vstack	*vsfree =  (Vstack *) NULL;


/*
 * pushviewport
 *
 * pushes the current viewport on the viewport stack
 *
 */
void pushviewport(void)
{
Vstack	*nvport;
Token	*tok;

if (!vdevice.initialised)
verror("pushviewport: vogl not initialised");

if (vdevice.inobject) {
	tok = newtokens(1);

	tok->i = PUSHVIEWPORT;

	return;
	}

if (vsfree != (Vstack *)NULL) {
	nvport = vdevice.viewport;
	vdevice.viewport = vsfree;
	vsfree = vsfree->back;
	vdevice.viewport->back = nvport;
	vdevice.viewport->v.left = nvport->v.left;
	vdevice.viewport->v.right = nvport->v.right;
	vdevice.viewport->v.bottom = nvport->v.bottom;
	vdevice.viewport->v.top = nvport->v.top;
	}
else {
	nvport = (Vstack *)vallocate(sizeof(Vstack));
	nvport->back = vdevice.viewport;
	nvport->v.left = vdevice.viewport->v.left;
	nvport->v.right = vdevice.viewport->v.right;
	nvport->v.bottom = vdevice.viewport->v.bottom;
	nvport->v.top = vdevice.viewport->v.top;
	vdevice.viewport = nvport;
	}
}

/* ------------------------------------------------------------------------ */

/*
 * popviewport
 *
 * pops the top viewport off the viewport stack.
 *
 */
void popviewport(void)
{
Token	*tok;
Vstack	*nvport;

if (!vdevice.initialised)
verror("popviewport: vogl not initialised");

if (vdevice.inobject) {
	tok = newtokens(1);

	tok->i = POPVIEWPORT;

	return;
	}

if (vdevice.viewport->back == (Vstack *)NULL)
verror("popviewport: viewport stack underflow");
else {
	nvport = vdevice.viewport;
	vdevice.viewport = vdevice.viewport->back;
	nvport->back = vsfree;
	vsfree = nvport;
	}

vdevice.maxVx = (int)(vdevice.viewport->v.right * vdevice.sizeSx);
vdevice.maxVy = (int)(vdevice.viewport->v.top * vdevice.sizeSy);
vdevice.minVx = (int)(vdevice.viewport->v.left * vdevice.sizeSx);
vdevice.minVy = (int)(vdevice.viewport->v.bottom * vdevice.sizeSy);

CalcW2Vcoeffs();
}

/* ------------------------------------------------------------------------ */

/*
 * viewport
 *
 * Define a Viewport in Normalized Device Coordinates
 *
 * The viewport defines that fraction of the screen that the window will
 * be mapped onto. Unlike in VOGLE  the screen dimension is from 0 to sizeX
 * and 0 to sizeY.
 */
void viewport(
  Screencoord xlow,
  Screencoord xhigh,
  Screencoord ylow,
  Screencoord yhigh)
{
Token	*tok;
char	buf[35];

if (!vdevice.initialised) 
verror("viewport: vogl not initialised");

/*
 *	A few preliminary checks ....
 */

if (xlow < 0 || xhigh < 0) {
	sprintf(buf,"viewport: x dimension value is invalid");
	verror(buf);
	} 

if (ylow < 0 || yhigh < 0) {
	sprintf(buf,"viewport: y dimension value is invalid");
	verror(buf);
	} 

if (xlow >= xhigh) {
	sprintf(buf,"viewport: xleft(%d) >= xright(%d)", xlow, xhigh);
	verror(buf);
	} 
if (ylow >= yhigh) {
	sprintf(buf,"viewport: ybottom(%d) >= ytop(%d)", ylow, yhigh);
	verror(buf);
	} 

if (vdevice.inobject) {
	tok = newtokens(5);

	tok[0].i = VIEWPORT;
	tok[1].i = xlow;
	tok[2].i = xhigh;
	tok[3].i = ylow;
	tok[4].i = yhigh;

	return;
	}

if (xhigh >= vdevice.sizeSx)
xhigh = vdevice.sizeSx;

if (yhigh >= vdevice.sizeSy)
yhigh = vdevice.sizeSy;

/*
 * Make sure the viewport stack knows about us.....
 */
vdevice.viewport->v.left = xlow / (float)vdevice.sizeSx;
vdevice.viewport->v.right = xhigh / (float)vdevice.sizeSx;
vdevice.viewport->v.bottom = ylow / (float)vdevice.sizeSy;
vdevice.viewport->v.top = yhigh / (float)vdevice.sizeSy;

vdevice.minVx = xlow;
vdevice.minVy = ylow;
vdevice.maxVx = xhigh;
vdevice.maxVy = yhigh;

CalcW2Vcoeffs();
}

/* ------------------------------------------------------------------------ */

/*
 * getviewport
 *
 *	Returns the left, right, bottom and top limits of the current
 *	viewport.
 */
void getviewport(
  Screencoord *left,
  Screencoord *right,
  Screencoord *bottom,
  Screencoord *top)
{
*right = vdevice.maxVx;
*top = vdevice.maxVy;
*left = vdevice.minVx;
*bottom = vdevice.minVy;
}

/* ------------------------------------------------------------------------ */