// worldlight.cpp

#include "cube.h"

extern bool hasoverbright;

VAR(lightscale, 1, 4, 100);

void
lightray(float bx, float by,
    persistent_entity &light) // done in realtime, needs to be fast
{
	float lx = light.x + (rnd(21) - 10) * 0.1f;
	float ly = light.y + (rnd(21) - 10) * 0.1f;
	float dx = bx - lx;
	float dy = by - ly;
	float dist = (float)sqrt(dx * dx + dy * dy);
	if (dist < 1.0f)
		return;
	int reach = light.attr1;
	int steps = (int)(reach * reach * 1.6f /
	                  dist); // can change this for speedup/quality?
	const int PRECBITS = 12;
	const float PRECF = 4096.0f;
	int x = (int)(lx * PRECF);
	int y = (int)(ly * PRECF);
	int l = light.attr2 << PRECBITS;
	int stepx = (int)(dx / (float)steps * PRECF);
	int stepy = (int)(dy / (float)steps * PRECF);
	int stepl =
	    fast_f2nat(l / (float)steps); // incorrect: light will fade quicker
	                                  // if near edge of the world

	if (hasoverbright) {
		l /= lightscale;
		stepl /= lightscale;

		if (light.attr3 ||
		    light.attr4) // coloured light version, special case because
		                 // most lights are white
		{
			int dimness = rnd(
			    (255 -
			        (light.attr2 + light.attr3 + light.attr4) / 3) /
			        16 +
			    1);
			x += stepx * dimness;
			y += stepy * dimness;

			if (OUTBORD(x >> PRECBITS, y >> PRECBITS))
				return;

			int g = light.attr3 << PRECBITS;
			int stepg = fast_f2nat(g / (float)steps);
			int b = light.attr4 << PRECBITS;
			int stepb = fast_f2nat(b / (float)steps);
			g /= lightscale;
			stepg /= lightscale;
			b /= lightscale;
			stepb /= lightscale;
			loopi(steps)
			{
				sqr *s = S(x >> PRECBITS, y >> PRECBITS);
				int tl = (l >> PRECBITS) + s->r;
				s->r = tl > 255 ? 255 : tl;
				tl = (g >> PRECBITS) + s->g;
				s->g = tl > 255 ? 255 : tl;
				tl = (b >> PRECBITS) + s->b;
				s->b = tl > 255 ? 255 : tl;
				if (SOLID(s))
					return;
				x += stepx;
				y += stepy;
				l -= stepl;
				g -= stepg;
				b -= stepb;
				stepl -= 25;
				stepg -= 25;
				stepb -= 25;
			};
		} else // white light, special optimized version
		{
			int dimness = rnd((255 - light.attr2) / 16 + 1);
			x += stepx * dimness;
			y += stepy * dimness;

			if (OUTBORD(x >> PRECBITS, y >> PRECBITS))
				return;

			loopi(steps)
			{
				sqr *s = S(x >> PRECBITS, y >> PRECBITS);
				int tl = (l >> PRECBITS) + s->r;
				s->r = s->g = s->b = tl > 255 ? 255 : tl;
				if (SOLID(s))
					return;
				x += stepx;
				y += stepy;
				l -= stepl;
				stepl -= 25;
			};
		};
	} else // the old (white) light code, here for the few people with old
	       // video cards that don't support overbright
	{
		loopi(steps)
		{
			sqr *s = S(x >> PRECBITS, y >> PRECBITS);
			int light = l >> PRECBITS;
			if (light > s->r)
				s->r = s->g = s->b = (uchar)light;
			if (SOLID(s))
				return;
			x += stepx;
			y += stepy;
			l -= stepl;
		};
	};
};

void
calclightsource(persistent_entity &l)
{
	int reach = l.attr1;
	int sx = l.x - reach;
	int ex = l.x + reach;
	int sy = l.y - reach;
	int ey = l.y + reach;

	rndreset();

	const float s = 0.8f;

	for (float sx2 = (float)sx; sx2 <= ex; sx2 += s * 2) {
		lightray(sx2, (float)sy, l);
		lightray(sx2, (float)ey, l);
	};
	for (float sy2 = sy + s; sy2 <= ey - s; sy2 += s * 2) {
		lightray((float)sx, sy2, l);
		lightray((float)ex, sy2, l);
	};

	rndtime();
};

void
postlightarea(block &a) // median filter, smooths out random noise in light and
                        // makes it more mipable
{
	loop(x, a.xs) loop(y, a.ys) // assumes area not on edge of world
	{
		sqr *s = S(x + a.x, y + a.y);
#define median(m)                                                              \
	s->m =                                                                 \
	    (s->m * 2 + SW(s, 1, 0)->m * 2 + SW(s, 0, 1)->m * 2 +              \
	        SW(s, -1, 0)->m * 2 + SW(s, 0, -1)->m * 2 + SW(s, 1, 1)->m +   \
	        SW(s, 1, -1)->m + SW(s, -1, 1)->m + SW(s, -1, -1)->m) /        \
	    14; // median is 4/2/1 instead
		median(r);
		median(g);
		median(b);
	};

	remip(a);
};

void
calclight()
{
	loop(x, ssize) loop(y, ssize)
	{
		sqr *s = S(x, y);
		s->r = s->g = s->b = 10;
	}

	loopv(ents)
	{
		entity &e = ents[i];
		if (e.type == LIGHT)
			calclightsource(e);
	}

	block b = {1, 1, ssize - 2, ssize - 2};
	postlightarea(b);
	setvar(@"fullbright", 0);
}

VARP(dynlight, 0, 16, 32);

vector<block *> dlights;

void
cleardlights()
{
	while (!dlights.empty()) {
		block *backup = dlights.pop();
		blockpaste(*backup);
		free(backup);
	}
}

void
dodynlight(vec &vold, vec &v, int reach, int strength, dynent *owner)
{
	if (!reach)
		reach = dynlight;
	if (owner->monsterstate)
		reach = reach / 2;
	if (!reach)
		return;
	if (v.x < 0 || v.y < 0 || v.x > ssize || v.y > ssize)
		return;

	int creach = reach + 16; // dependant on lightray random offsets!
	block b = {(int)v.x - creach, (int)v.y - creach, creach * 2 + 1,
	    creach * 2 + 1};

	if (b.x < 1)
		b.x = 1;
	if (b.y < 1)
		b.y = 1;
	if (b.xs + b.x > ssize - 2)
		b.xs = ssize - 2 - b.x;
	if (b.ys + b.y > ssize - 2)
		b.ys = ssize - 2 - b.y;

	dlights.add(blockcopy(b)); // backup area before rendering in dynlight

	persistent_entity l = {(short)v.x, (short)v.y, (short)v.z, (short)reach,
	    LIGHT, (uchar)strength, 0, 0};
	calclightsource(l);
	postlightarea(b);
}

// utility functions also used by editing code

block *
blockcopy(block &s)
{
	block *b = (block *)alloc(sizeof(block) + s.xs * s.ys * sizeof(sqr));
	*b = s;
	sqr *q = (sqr *)(b + 1);
	for (int x = s.x; x < s.xs + s.x; x++)
		for (int y = s.y; y < s.ys + s.y; y++)
			*q++ = *S(x, y);
	return b;
}

void
blockpaste(block &b)
{
	sqr *q = (sqr *)((&b) + 1);
	for (int x = b.x; x < b.xs + b.x; x++)
		for (int y = b.y; y < b.ys + b.y; y++)
			*S(x, y) = *q++;
	remipmore(b);
}