/*
	vid.c

	general video driver functions

	Copyright (C) 1996-1997 Id Software, Inc.

	This program is free software; you can redistribute it and/or
	modify it under the terms of the GNU General Public License
	as published by the Free Software Foundation; either version 2
	of the License, or (at your option) any later version.

	This program is distributed in the hope that it will be useful,
	but WITHOUT ANY WARRANTY; without even the implied warranty of
	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

	See the GNU General Public License for more details.

	You should have received a copy of the GNU General Public License
	along with this program; if not, write to:

		Free Software Foundation, Inc.
		59 Temple Place - Suite 330
		Boston, MA  02111-1307, USA

	$Id$
*/

#ifdef HAVE_CONFIG_H
# include "config.h"
#endif
#include <math.h>

#include "compat.h"
#include "console.h"
#include "cvar.h"
#include "qargs.h"
#include "sys.h"
#include "va.h"
#include "vid.h"
#include "view.h"

extern viddef_t vid;					// global video state

/*
	Software and hardware gamma support
*/
byte		gammatable[256];
cvar_t		*vid_gamma;
cvar_t		*vid_system_gamma;
qboolean	vid_gamma_avail;		// hardware gamma availability

/*
	Screen size
*/
int 		scr_width, scr_height;
cvar_t		*vid_width;
cvar_t		*vid_height;

void
VID_GetWindowSize (int def_w, int def_h)
{
	int pnum;

	vid_width = Cvar_Get ("vid_width", va ("%d", def_w), CVAR_NONE, NULL, "screen width");
	vid_height = Cvar_Get ("vid_height", va ("%d", def_h), CVAR_NONE, NULL, "screen height");

	if ((pnum = COM_CheckParm ("-width"))) {
		if (pnum >= com_argc - 1)
			Sys_Error ("VID: -width <width>\n");

		Cvar_Set (vid_width, com_argv[pnum + 1]);

		if (!vid_width->int_val)
			Sys_Error ("VID: Bad window width\n");
	}

	if ((pnum = COM_CheckParm ("-height"))) {
		if (pnum >= com_argc - 1)
			Sys_Error ("VID: -height <height>\n");

		Cvar_Set (vid_height, com_argv[pnum + 1]);

		if (!vid_height->int_val)
			Sys_Error ("VID: Bad window height\n");
	}

	if ((pnum = COM_CheckParm ("-winsize"))) {
		if (pnum >= com_argc - 2)
			Sys_Error ("VID: -winsize <width> <height>\n");

		Cvar_Set (vid_width, com_argv[pnum + 1]);
		Cvar_Set (vid_height, com_argv[pnum + 2]);

		if (!vid_width->int_val || !vid_height->int_val)
			Sys_Error ("VID: Bad window width/height\n");
	}

	Cvar_SetFlags (vid_width, vid_width->flags | CVAR_ROM);
	Cvar_SetFlags (vid_height, vid_height->flags | CVAR_ROM);

	scr_width = vid.width = vid_width->int_val;
	scr_height = vid.height = vid_height->int_val;
}

/****************************************************************************
 *								GAMMA FUNCTIONS 							*
 ****************************************************************************/

void
VID_BuildGammaTable (double gamma)
{
	int 	i;

	if (gamma == 1.0) { // linear, don't bother with the math
		for (i = 0; i < 256; i++) {
			gammatable[i] = i;
		}
	} else {
		double	g = 1.0 / gamma;
		int 	v;

		for (i = 0; i < 256; i++) { // Build/update gamma lookup table
			v = (int) ((255.0 * pow ((double) i / 255.0, g)) + 0.5);
			gammatable[i] = bound (0, v, 255);
		}
	}
}

/*
	VID_UpdateGamma

	This is a callback to update the palette or system gamma whenever the
	vid_gamma Cvar is changed.
*/
void
VID_UpdateGamma (cvar_t *vid_gamma)
{
	double gamma = bound (0.1, vid_gamma->value, 9.9);

	if (vid_gamma_avail && vid_system_gamma->int_val) {	// Have system, use it
		Con_DPrintf ("Setting hardware gamma to %g\n", gamma);
		VID_BuildGammaTable (1.0);	// hardware gamma wants a linear palette
		VID_SetGamma (gamma);
	} else {	// We have to hack the palette
		Con_DPrintf ("Setting software gamma to %g\n", gamma);
		VID_BuildGammaTable (gamma);
		V_UpdatePalette (); // update with the new palette
	}
}

/*
	VID_InitGamma

	Initialize the vid_gamma Cvar, and set up the palette
*/
void
VID_InitGamma (unsigned char *pal)
{
	int 	i;
	double	gamma = 1.45;

	if ((i = COM_CheckParm ("-gamma"))) {
		gamma = atof (com_argv[i + 1]);
	}
	gamma = bound (0.1, gamma, 9.9);

	vid_gamma = Cvar_Get ("vid_gamma", va ("%f", gamma), CVAR_ARCHIVE,
						  VID_UpdateGamma, "Gamma correction");

	VID_UpdateGamma (vid_gamma);

	for (i = 0; i < 768; i++) {
		pal[i] = gammatable[pal[i]];
	}
}