/*
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"

int r_dlightframecount;

#ifdef GLPPCASM
extern int RecursiveLightPoint (mnode_t *node, vec3_t start, vec3_t end);
#endif

/*
==================
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_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);
  glColor4f (0.8,0.0,0.0,0.2); // glColor3f (0.2,0.1,0.0); 30/01/2000 changed: M.Tretene
  for (i=0 ; i<3 ; i++)
    v[i] = light->origin[i] - vpn[i]*rad;
  glVertex3fv (v);
  glColor4f (0.8,0.4,0,0.2);  //glColor3f (0,0,0);  30/01/2000 changed: M.Tretene
  for (i=16 ; i>=0 ; i--)
  {
    a = i/16.0 * M_PI*2;
    for (j=0 ; j<3 ; j++)
      v[j] = light->origin[j] + vright[j]*cos(a)*rad
        + vup[j]*sin(a)*rad;
    glVertex3fv (v);
  }
  glEnd ();
}

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

  if (!gl_flashblend.value)
    return;

  r_dlightframecount = r_framecount + 1;  // because the count hasn't
                      //  advanced yet for this frame
  glDepthMask (0);
  glDisable (GL_TEXTURE_2D);
  glShadeModel (GL_SMOOTH);
  glEnable (GL_BLEND);
  //glBlendFunc (GL_ONE, GL_ONE);    // 30/01/2000 removed: M.Tretene

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

  glColor3f (1,1,1);
  glDisable (GL_BLEND);
  glEnable (GL_TEXTURE_2D);
  //glBlendFunc (GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);     // 30/01/2000 removed: M.Tretene
  glDepthMask (1);
}


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

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;

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


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

LIGHT SAMPLING

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

mplane_t    *lightplane;
vec3_t      lightspot;
 
#ifndef GLPPCASM
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
  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);
}
#endif

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;
}