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

*/
// r_light.c

#include "quakedef.h"
#include "r_local.h"

int	r_dlightframecount;


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

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

/*
=============
R_MarkLights
=============
*/
void R_MarkLights(dlight_t *light, int bit, mnode_t *node)
{
    mplane_t	*splitplane;
    float		dist;
    msurface_t	*surf;
    int			i;

    if (node->contents < 0) {
        return;
    }

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

    if (dist > light->radius) {
        R_MarkLights(light, bit, node->children[0]);
        return;
    }
    if (dist < -light->radius) {
        R_MarkLights(light, bit, node->children[1]);
        return;
    }

// mark the polygons
    surf = cl.worldmodel->surfaces + node->firstsurface;
    for (i=0 ; i<node->numsurfaces ; i++, surf++) {
        if (surf->dlightframe != r_dlightframecount) {
            surf->dlightbits = 0;
            surf->dlightframe = r_dlightframecount;
        }
        surf->dlightbits |= bit;
    }

    R_MarkLights(light, bit, node->children[0]);
    R_MarkLights(light, bit, node->children[1]);
}


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

    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;
        }
        R_MarkLights(l, 1<<i, cl.worldmodel->nodes);
    }
}


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

LIGHT SAMPLING

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

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	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

    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;
    }

    if (r < r_refdef.ambientlight) {
        r = r_refdef.ambientlight;
    }

    return r;
}

