#ifndef lint
static char sccsid[] = "@(#)sphere.c	3.9 96/05/25 xlockmore";

#endif

/*-
 * sphere.c - Draw a bunch of shaded spheres for xlock,
 * the X Window System lockscreen.
 *
 * Copyright (c) 1988 by Sun Microsystems
 *
 * See xlock.c for copying information.
 *
 * Revision History:
 * 2-Sep-93: xlock version (David Bagley bagleyd@hertz.njit.edu)
 * 1988: Revised to use SunView canvas instead of gfxsw Sun Microsystems
 * 1982: Orignal Algorithm  Tom Duff  Lucasfilm Ltd.
 */


#include <math.h>
#include "xlock.h"

/* 
 * original copyright
 * **************************************************************************
 * Copyright 1988 by Sun Microsystems, Inc. Mountain View, CA.
 *
 * All Rights Reserved
 *
 * Permission to use, copy, modify, and distribute this software and its
 * documentation for any purpose and without fee is hereby granted, provided
 * that the above copyright notice appear in all copies and that both that
 * copyright notice and this permission notice appear in supporting
 * documentation, and that the names of Sun or MIT not be used in advertising
 * or publicity pertaining to distribution of the software without specific
 * prior written permission. Sun and M.I.T. make no representations about the
 * suitability of this software for any purpose. It is provided "as is"
 * without any express or implied warranty.
 *
 * SUN DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE, INCLUDING ALL
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
 * IN NO EVENT SHALL SUN BE LIABLE FOR ANY SPECIAL, INDIRECT OR CONSEQUENTIAL
 * DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR
 * PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS
 * ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS
 * SOFTWARE.
 * ***************************************************************************
 */

/* 
 * (NX, NY, NZ) is the light source vector -- length should be
 * 100
 */
#define NX 48
#define NY (-36)
#define NZ 80
#define NR 100
#define MIN(a,b) (((a)<(b))?(a):(b))
#define SQRT(a) ((int)sqrt((double)(a)))

ModeSpecOpt sphere_opts =
{0, NULL, NULL, NULL};

typedef struct {
	int         width, height;
	int         radius;
	int         x0;		/* x center */
	int         y0;		/* y center */
	int         color;
	int         x;
	int         maxy;
} spherestruct;

static spherestruct spheres[MAXSCREENS];

void
init_sphere(ModeInfo * mi)
{
	Window      win = MI_WINDOW(mi);
	spherestruct *ss = &spheres[screen];

	ss->width = MI_WIN_WIDTH(mi);
	ss->height = MI_WIN_HEIGHT(mi);

	XSetForeground(dsp, Scr[screen].gc, BlackPixel(dsp, screen));
	XFillRectangle(dsp, win, Scr[screen].gc, 0, 0, ss->width, ss->height);

	ss->x = ss->radius = 0;
}

void
draw_sphere(ModeInfo * mi)
{
	Window      win = MI_WINDOW(mi);
	spherestruct *ss = &spheres[screen];
	register    y;

	if (ss->x >= ss->radius) {
		ss->radius = LRAND() % (MIN(ss->width / 2, ss->height / 2) - 1) + 1;
		ss->x0 = LRAND() % ss->width;
		ss->y0 = LRAND() % ss->height;
		ss->x = -ss->radius;

		if (Scr[screen].npixels > 2)
			ss->color = LRAND() % Scr[screen].npixels;
	}
	ss->maxy = SQRT(ss->radius * ss->radius - ss->x * ss->x);
	XSetForeground(dsp, Scr[screen].gc, BlackPixel(dsp, screen));
	XDrawLine(dsp, win, Scr[screen].gc,
		  ss->x0 + ss->x, ss->y0 - ss->maxy,
		  ss->x0 + ss->x, ss->y0 + ss->maxy);
	if (!MI_WIN_IS_MONO(mi) && MI_NPIXELS(mi) > 2)
		XSetForeground(dsp, Scr[screen].gc, Scr[screen].pixels[ss->color]);
	else
		XSetForeground(dsp, Scr[screen].gc, WhitePixel(dsp, screen));
	for (y = -ss->maxy; y <= ss->maxy; y++)
		if ((LRAND() % (ss->radius * NR)) <=
		    (NX * ss->x + NY * y + NZ *
		     SQRT(ss->radius * ss->radius - ss->x * ss->x - y * y)))
			XDrawPoint(dsp, win, Scr[screen].gc,
				   ss->x + ss->x0, y + ss->y0);
	ss->x++;
}