/*
  Copyright (C) 2010-2011  Charles Pence <charles@charlespence.net>
  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 3 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, see <http://www.gnu.org/licenses/>.
*/
#include "pch.h"
#include "quakedef.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 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[1]*(1-a2) + r*a2;
    v_blend[1] = v_blend[1]*(1-a2) + g*a2;
    v_blend[2] = v_blend[2]*(1-a2) + b*a2;
}

void R_RenderDlight (dlight_t *light)
{
    int        i, j;
    float    a;
    vec3_t    v;
    float    rad;

    rad = light->radius * 0.35;

    VectorSubtract (light->origin, r_refdef.origin, v);
    if (Length (v) < rad)
    {    // view is inside the dlight
        AddLightBlend (1, 0.5, 0, light->radius * 0.0003);
        return;
    }

    glBegin (GL_TRIANGLE_FAN);
    glColor3f (0.2,0.1,0.0);
    for (i=0 ; i<3 ; i++)
        v[i] = light->origin[i] - r_refdef.forward[i]*rad;
    glVertex3fv (v);
    glColor3f (0,0,0);
    for (i=16 ; i>=0 ; i--)
    {
        a = i/16.0 * M_PI*2;
        for (j=0 ; j<3 ; j++)
            v[j] = light->origin[j] + r_refdef.right[j]*cos(a)*rad
                + r_refdef.up[j]*sin(a)*rad;
        glVertex3fv (v);
    }
    glEnd ();
}


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

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;
    float        l, maxdist;
    int            j, s, t;
    vec3_t        impact;

loc0:
    // LordHavoc: .lit support end
    if (node->contents < 0)
        return;

    splitplane = node->plane; // LordHavoc: original code

    if (splitplane->type < 3)
        dist = light->origin[splitplane->type] - splitplane->dist;
    else
        dist = DotProduct (light->origin, splitplane->normal) - splitplane->dist; // LordHavoc: original code

    if (dist > light->radius)
    {
        node = node->children[0];
        goto loc0;
    }

    if (dist < -light->radius)
    {
        node = node->children[1];
        goto loc0;
    }

    maxdist = light->radius*light->radius; // LordHavoc: .lit support (actually this is just a major lighting speedup, no relation to color :)

// 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] = light->origin[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)
        R_MarkLights (light, bit, node->children[0]); // LordHavoc: original code
    if (node->children[1]->contents >= 0)
        R_MarkLights (light, bit, node->children[1]); // LordHavoc: original code
}


/*
=============
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 (vec3_t color, mnode_t *node, vec3_t start, vec3_t end)
{
    float        front, back, frac;
    vec3_t        mid;

loc0:
    if (node->contents < 0)
        return false;        // didn't hit anything

// calculate mid point
    if (node->plane->type < 3)
    {
        front = start[node->plane->type] - node->plane->dist;
        back = end[node->plane->type] - node->plane->dist;
    }
    else
    {
        front = DotProduct(start, node->plane->normal) - node->plane->dist;
        back = DotProduct(end, node->plane->normal) - node->plane->dist;
    }
    // LordHavoc: optimized recursion
    if ((back < 0) == (front < 0))
    {
        node = node->children[front < 0];
        goto loc0;
    }

    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
    if (RecursiveLightPoint (color, node->children[front < 0], start, mid))
        return true;    // hit something
    else
    {
        int i, ds, dt;
        msurface_t *surf;

        // check for impact on this node
        surf = cl.worldmodel->surfaces + node->firstsurface;
        for (i = 0;i < node->numsurfaces;i++, surf++)
        {
            if (surf->flags & SURF_NOLIGHTMAPS)
                continue;

            ds = (int) ((float) DotProduct (mid, surf->texinfo->vecs[0]) + surf->texinfo->vecs[0][3]);
            dt = (int) ((float) DotProduct (mid, surf->texinfo->vecs[1]) + surf->texinfo->vecs[1][3]);
            if (ds < surf->texturemins[0] || dt < surf->texturemins[1])
                continue;

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

            if (ds > surf->extents[0] || dt > surf->extents[1])
                continue;
            if (surf->samples)
            {
                // LordHavoc: enhanced to interpolate lighting
                byte *lightmap;
                int maps, line3, dsfrac = ds & 15, dtfrac = dt & 15, r00 = 0, g00 = 0, b00 = 0, r01 = 0, g01 = 0, b01 = 0, r10 = 0, g10 = 0, b10 = 0, r11 = 0, g11 = 0, b11 = 0;
                float scale;
                line3 = ((surf->extents[0]>>4)+1)*3;
                lightmap = surf->samples + ((dt>>4) * ((surf->extents[0]>>4)+1) + (ds>>4))*3; // LordHavoc: *3 for color
                for (maps = 0;maps < MAXLIGHTMAPS && surf->styles[maps] != 255;maps++)
                {
                    scale = (float) d_lightstylevalue[surf->styles[maps]] * 1.0 / 256.0;
                    r00 += (float) lightmap[      0] * scale;g00 += (float) lightmap[      1] * scale;b00 += (float) lightmap[2] * scale;
                    r01 += (float) lightmap[      3] * scale;g01 += (float) lightmap[      4] * scale;b01 += (float) lightmap[5] * scale;
                    r10 += (float) lightmap[line3+0] * scale;g10 += (float) lightmap[line3+1] * scale;b10 += (float) lightmap[line3+2] * scale;
                    r11 += (float) lightmap[line3+3] * scale;g11 += (float) lightmap[line3+4] * scale;b11 += (float) lightmap[line3+5] * scale;
                    lightmap += ((surf->extents[0]>>4)+1) * ((surf->extents[1]>>4)+1)*3; // LordHavoc: *3 for colored lighting
                }
                color[0] += (float) ((int) ((((((((r11-r10) * dsfrac) >> 4) + r10)-((((r01-r00) * dsfrac) >> 4) + r00)) * dtfrac) >> 4) + ((((r01-r00) * dsfrac) >> 4) + r00)));
                color[1] += (float) ((int) ((((((((g11-g10) * dsfrac) >> 4) + g10)-((((g01-g00) * dsfrac) >> 4) + g00)) * dtfrac) >> 4) + ((((g01-g00) * dsfrac) >> 4) + g00)));
                color[2] += (float) ((int) ((((((((b11-b10) * dsfrac) >> 4) + b10)-((((b01-b00) * dsfrac) >> 4) + b00)) * dtfrac) >> 4) + ((((b01-b00) * dsfrac) >> 4) + b00)));
            }
            return true; // success
        }
    // go down back side
        return RecursiveLightPoint (color, node->children[front >= 0], mid, end);
    }
}

vec3_t lightcolor; // LordHavoc: used by model rendering

int R_LightPoint (vec3_t p)
{
    vec3_t        end;

    if (Cvar_VariableValue("r_fullbright") || !cl.worldmodel->lightdata)
    {
        lightcolor[0] = lightcolor[1] = lightcolor[2] = 255;
        return 255;
    }

    end[0] = p[0];
    end[1] = p[1];
    end[2] = p[2] - 2048;
    lightcolor[0] = lightcolor[1] = lightcolor[2] = 0;
    RecursiveLightPoint (lightcolor, cl.worldmodel->nodes, p, end);
    return ((lightcolor[0] + lightcolor[1] + lightcolor[2]) * (1.0f / 3.0f));
}


