/*
	gl_rlight.c

	(description)

	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
#ifdef HAVE_STRING_H
# include <string.h>
#endif
#ifdef HAVE_STRINGS_H
# include <strings.h>
#endif

#include <math.h>
#include <stdio.h>

#include "glquake.h"

int         r_dlightframecount;
extern qboolean lighthalf;


/*
==================
R_AnimateLight
==================
*/
void
R_AnimateLight (void)
{
	int         i, j, k;

//
// light animations
// 'm' is normal light, 'a' is no light, 'z' is double bright
	i = (int) (cl.time * 10);
	for (j = 0; j < MAX_LIGHTSTYLES; j++) {
		if (!cl_lightstyle[j].length) {
			d_lightstylevalue[j] = 256;
			continue;
		}
		k = i % cl_lightstyle[j].length;
		k = cl_lightstyle[j].map[k] - 'a';
		k = k * 22;
		d_lightstylevalue[j] = k;
	}
}

/*
=============================================================================

DYNAMIC LIGHTS BLEND RENDERING

=============================================================================
*/

void
AddLightBlend (float r, float g, float b, float a2)
{
	float       a;

	v_blend[3] = a = v_blend[3] + a2 * (1 - v_blend[3]);

	a2 = a2 / a;

	v_blend[0] = v_blend[0] * (1 - a2) + r * a2;
	v_blend[1] = v_blend[1] * (1 - a2) + g * a2;
	v_blend[2] = v_blend[2] * (1 - a2) + b * a2;
//Con_Printf("AddLightBlend(): %4.2f %4.2f %4.2f %4.6f\n", v_blend[0], v_blend[1], v_blend[2], v_blend[3]);
}

float       bubble_sintable[33], bubble_costable[33];

void
R_InitBubble ()
{
	float       a;
	int         i;
	float      *bub_sin, *bub_cos;

	bub_sin = bubble_sintable;
	bub_cos = bubble_costable;

	for (i = 32; i >= 0; i--) {
		a = i / 32.0 * M_PI * 2;
		*bub_sin++ = sin (a);
		*bub_cos++ = cos (a);
	}
}

void
R_RenderDlight (dlight_t *light)
{
	int         i, j;

	vec3_t      v;
	float       rad;
	float      *bub_sin, *bub_cos;

	bub_sin = bubble_sintable;
	bub_cos = bubble_costable;
	rad = light->radius * 0.35;

	VectorSubtract (light->origin, r_origin, v);
	if (Length (v) < rad) {				// view is inside the dlight
		AddLightBlend (light->color[0], light->color[1], light->color[2], light->radius * 0.0003);
		return;
	}

	glBegin (GL_TRIANGLE_FAN);
	if (lighthalf)
		glColor3f (light->color[0] * 0.5, light->color[1] * 0.5,
				   light->color[2] * 0.5);
	else
		glColor3fv (light->color);
	for (i = 0; i < 3; i++)
		v[i] = light->origin[i] - vpn[i] * rad;
	glVertex3fv (v);
	glColor3f (0, 0, 0);
	for (i = 16; i >= 0; i--) {
		for (j = 0; j < 3; j++)
			v[j] = light->origin[j] + (vright[j] * (*bub_cos) +
									   +vup[j] * (*bub_sin)) * rad;
		bub_sin += 2;
		bub_cos += 2;
		glVertex3fv (v);
	}
	glEnd ();
	// No, we don't reset here, we reset in the function which calls this
	// one.
	// Largely because this is called in a big loop.
	// glColor3ubv(lighthalf_v);
}

/*
=============
R_RenderDlights
=============
*/
void
R_RenderDlights (void)
{
	int         i;
	dlight_t   *l;

	if (!gl_flashblend->int_val)
		return;

	r_dlightframecount = r_framecount + 1;	// because the count hasn't
	// advanced yet for this frame
	glDepthMask (GL_FALSE);
	glDisable (GL_TEXTURE_2D);
	glBlendFunc (GL_ONE, GL_ONE);
	if (gl_smoothdlights->int_val)
		glShadeModel (GL_SMOOTH);

	l = cl_dlights;
	for (i = 0; i < MAX_DLIGHTS; i++, l++) {
		if (l->die < cl.time || !l->radius)
			continue;
		R_RenderDlight (l);
	}

	if (!gl_smooth->int_val)
		glShadeModel (GL_FLAT);
	glColor3ubv (lighthalf_v);
	glEnable (GL_TEXTURE_2D);
	glBlendFunc (GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
	glDepthMask (GL_TRUE);
}


/*
=============================================================================

DYNAMIC LIGHTS

=============================================================================
*/

/*
=============
R_MarkLights
=============
*/
// LordHavoc: heavily modified, to eliminate unnecessary texture uploads,
//            and support bmodel lighting better
void
R_MarkLights (vec3_t lightorigin, dlight_t *light, int bit, mnode_t *node)
{
	mplane_t   *splitplane;
	float       dist, l, maxdist;
	msurface_t *surf;
	int         i, j, s, t;
	vec3_t      impact;

	if (node->contents < 0)
		return;

	splitplane = node->plane;
	dist = DotProduct (lightorigin, splitplane->normal) - splitplane->dist;

	if (dist > light->radius) {
		if (node->children[0]->contents >= 0)	// save some time by not
												// pushing another stack
												// frame
			R_MarkLights (lightorigin, light, bit, node->children[0]);
		return;
	}
	if (dist < -light->radius) {
		if (node->children[1]->contents >= 0)	// save some time by not
												// pushing another stack
												// frame
			R_MarkLights (lightorigin, light, bit, node->children[1]);
		return;
	}

	maxdist = light->radius * light->radius;

// mark the polygons
	surf = cl.worldmodel->surfaces + node->firstsurface;
	for (i = 0; i < node->numsurfaces; i++, surf++) {
		// LordHavoc: MAJOR dynamic light speedup here, eliminates marking of 
		// surfaces that are too far away from light, thus preventing
		// unnecessary renders and uploads
		for (j = 0; j < 3; j++)
			impact[j] = lightorigin[j] - surf->plane->normal[j] * dist;

		// clamp center of light to corner and check brightness
		l =
			DotProduct (impact,
						surf->texinfo->vecs[0]) + surf->texinfo->vecs[0][3] -
			surf->texturemins[0];
		s = l + 0.5;
		if (s < 0)
			s = 0;
		else if (s > surf->extents[0])
			s = surf->extents[0];
		s = l - s;
		l =
			DotProduct (impact,
						surf->texinfo->vecs[1]) + surf->texinfo->vecs[1][3] -
			surf->texturemins[1];
		t = l + 0.5;
		if (t < 0)
			t = 0;
		else if (t > surf->extents[1])
			t = surf->extents[1];
		t = l - t;
		// compare to minimum light
		if ((s * s + t * t + dist * dist) < maxdist) {
			if (surf->dlightframe != r_dlightframecount)	// not dynamic
															// until now
			{
				surf->dlightbits = bit;
				surf->dlightframe = r_dlightframecount;
			} else						// already dynamic
				surf->dlightbits |= bit;
		}
	}

	if (node->children[0]->contents >= 0)	// save some time by not pushing
											// another stack frame
		R_MarkLights (lightorigin, light, bit, node->children[0]);
	if (node->children[1]->contents >= 0)	// save some time by not pushing
											// another stack frame
		R_MarkLights (lightorigin, light, bit, node->children[1]);
}


/*
=============
R_PushDlights
=============
*/
void
R_PushDlights (vec3_t entorigin)
{
	int         i;
	dlight_t   *l;
	vec3_t      lightorigin;

	if (gl_flashblend->int_val)
		return;

	r_dlightframecount = r_framecount + 1;	// because the count hasn't
	// advanced yet for this frame
	l = cl_dlights;

	for (i = 0; i < MAX_DLIGHTS; i++, l++) {
		if (l->die < cl.time || !l->radius)
			continue;
		VectorSubtract (l->origin, entorigin, lightorigin);
		R_MarkLights (lightorigin, l, 1 << i, cl.worldmodel->nodes);
	}
}


/*
=============================================================================

LIGHT SAMPLING

=============================================================================
*/

mplane_t   *lightplane;
vec3_t      lightspot;

int
RecursiveLightPoint (mnode_t *node, vec3_t start, vec3_t end)
{
	int         r;
	float       front, back, frac;
	int         side;
	mplane_t   *plane;
	vec3_t      mid;
	msurface_t *surf;
	int         s, t, ds, dt;
	int         i;
	mtexinfo_t *tex;
	byte       *lightmap;
	unsigned int scale;
	int         maps;

	if (node->contents < 0)
		return -1;						// didn't hit anything

// calculate mid point

// FIXME: optimize for axial
	plane = node->plane;
	front = DotProduct (start, plane->normal) - plane->dist;
	back = DotProduct (end, plane->normal) - plane->dist;
	side = front < 0;

	if ((back < 0) == side)
		return RecursiveLightPoint (node->children[side], start, end);

	frac = front / (front - back);
	mid[0] = start[0] + (end[0] - start[0]) * frac;
	mid[1] = start[1] + (end[1] - start[1]) * frac;
	mid[2] = start[2] + (end[2] - start[2]) * frac;

// go down front side   
	r = RecursiveLightPoint (node->children[side], start, mid);
	if (r >= 0)
		return r;						// hit something

	if ((back < 0) == side)
		return -1;						// didn't hit anuthing

// check for impact on this node
	VectorCopy (mid, lightspot);
	lightplane = plane;

	surf = cl.worldmodel->surfaces + node->firstsurface;
	for (i = 0; i < node->numsurfaces; i++, surf++) {
		if (surf->flags & SURF_DRAWTILED)
			continue;					// no lightmaps

		tex = surf->texinfo;

		s = DotProduct (mid, tex->vecs[0]) + tex->vecs[0][3];
		t = DotProduct (mid, tex->vecs[1]) + tex->vecs[1][3];;

		if (s < surf->texturemins[0] || t < surf->texturemins[1])
			continue;

		ds = s - surf->texturemins[0];
		dt = t - surf->texturemins[1];

		if (ds > surf->extents[0] || dt > surf->extents[1])
			continue;

		if (!surf->samples)
			return 0;

		ds >>= 4;
		dt >>= 4;

		lightmap = surf->samples;
		r = 0;
		if (lightmap) {

			lightmap += dt * ((surf->extents[0] >> 4) + 1) + ds;

			for (maps = 0; maps < MAXLIGHTMAPS && surf->styles[maps] != 255;
				 maps++) {
				scale = d_lightstylevalue[surf->styles[maps]];
				r += *lightmap * scale;
				lightmap += ((surf->extents[0] >> 4) + 1) *
					((surf->extents[1] >> 4) + 1);
			}

			r >>= 8;
		}

		return r;
	}

// go down back side
	return RecursiveLightPoint (node->children[!side], mid, end);
}

int
R_LightPoint (vec3_t p)
{
	vec3_t      end;
	int         r;

	if (!cl.worldmodel->lightdata)
		return 255;

	end[0] = p[0];
	end[1] = p[1];
	end[2] = p[2] - 2048;

	r = RecursiveLightPoint (cl.worldmodel->nodes, p, end);

	if (r == -1)
		r = 0;

	return r;
}