//
// Copyright(C) 1993-1996 Id Software, Inc.
// Copyright(C) 2005-2014 Simon Howard
//
// 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.
//
// DESCRIPTION:
//	Rendering main loop and setup functions,
//	 utility functions (BSP, geometry, trigonometry).
//	See tables.c, too.
//

#include <stdio.h>
#include <stdlib.h>

#include "d_loop.h"
#include "d_player.h"
#include "doomdata.h"
#include "doomtype.h"
#include "i_video.h"
#include "m_bbox.h"
#include "m_fixed.h"
#include "m_menu.h"
#include "p_mobj.h"
#include "r_bsp.h"
#include "r_data.h"
#include "r_defs.h"
#include "r_draw.h"
#include "r_main.h"
#include "r_plane.h"
#include "r_sky.h"
#include "r_state.h"
#include "r_things.h"
#include "tables.h"

#include "ipu_host.h"
#include "doomstat.h" // TMP< REMOVEME

// Fineangles in the SCREENWIDTH wide window.
#define FIELDOFVIEW 2048

int viewangleoffset;

// increment every time a check is made
int validcount = 1;

lighttable_t *fixedcolormap;
extern lighttable_t **walllights;

int centerx;
int centery;

fixed_t centerxfrac;
fixed_t centeryfrac;
fixed_t projection;

// just for profiling purposes
int framecount;

int sscount;
int linecount;
int loopcount;

fixed_t viewx;
fixed_t viewy;
fixed_t viewz;

angle_t viewangle;

fixed_t viewcos;
fixed_t viewsin;

player_t *viewplayer;

// 0 = high, 1 = low
int detailshift;

//
// precalculated math tables
//
angle_t clipangle;

// The viewangletox[viewangle + FINEANGLES/4] lookup
// maps the visible view angles to screen X coordinates,
// flattening the arc to a flat projection plane.
// There will be many angles mapped to the same X.
int viewangletox[FINEANGLES / 2];

// The xtoviewangleangle[] table maps a screen pixel
// to the lowest viewangle that maps back to x ranges
// from clipangle to -clipangle.
angle_t xtoviewangle[SCREENWIDTH + 1];

lighttable_t *scalelight[LIGHTLEVELS][MAXLIGHTSCALE];
lighttable_t *scalelightfixed[MAXLIGHTSCALE];
lighttable_t *zlight[LIGHTLEVELS][MAXLIGHTZ];

// bumped light from gun blasts
int extralight;

int renderIPUonly; // JOSEF

void (*colfunc)(void);
void (*basecolfunc)(void);
void (*fuzzcolfunc)(void);
void (*transcolfunc)(void);
void (*spanfunc)(void);

//
// R_AddPointToBox
// Expand a given bbox
// so that it encloses a given point.
//
void R_AddPointToBox(int x, int y, fixed_t *box) {
  if (x < box[BOXLEFT])
    box[BOXLEFT] = x;
  if (x > box[BOXRIGHT])
    box[BOXRIGHT] = x;
  if (y < box[BOXBOTTOM])
    box[BOXBOTTOM] = y;
  if (y > box[BOXTOP])
    box[BOXTOP] = y;
}

//
// R_PointOnSide
// Traverse BSP (sub) tree,
//  check point against partition plane.
// Returns side 0 (front) or 1 (back).
//
int R_PointOnSide(fixed_t x, fixed_t y, node_t *node) {
  fixed_t dx;
  fixed_t dy;
  fixed_t left;
  fixed_t right;

  if (!node->dx) {
    if (x <= node->x)
      return node->dy > 0;

    return node->dy < 0;
  }
  if (!node->dy) {
    if (y <= node->y)
      return node->dx < 0;

    return node->dx > 0;
  }

  dx = (x - node->x);
  dy = (y - node->y);

  // Try to quickly decide by looking at sign bits.
  if ((node->dy ^ node->dx ^ dx ^ dy) & 0x80000000) {
    if ((node->dy ^ dx) & 0x80000000) {
      // (left is negative)
      return 1;
    }
    return 0;
  }

  left = FixedMul(node->dy >> FRACBITS, dx);
  right = FixedMul(dy, node->dx >> FRACBITS);

  if (right < left) {
    // front side
    return 0;
  }
  // back side
  return 1;
}

int R_PointOnSegSide(fixed_t x, fixed_t y, seg_t *line) {
  fixed_t lx;
  fixed_t ly;
  fixed_t ldx;
  fixed_t ldy;
  fixed_t dx;
  fixed_t dy;
  fixed_t left;
  fixed_t right;

  lx = line->v1->x;
  ly = line->v1->y;

  ldx = line->v2->x - lx;
  ldy = line->v2->y - ly;

  if (!ldx) {
    if (x <= lx)
      return ldy > 0;

    return ldy < 0;
  }
  if (!ldy) {
    if (y <= ly)
      return ldx < 0;

    return ldx > 0;
  }

  dx = (x - lx);
  dy = (y - ly);

  // Try to quickly decide by looking at sign bits.
  if ((ldy ^ ldx ^ dx ^ dy) & 0x80000000) {
    if ((ldy ^ dx) & 0x80000000) {
      // (left is negative)
      return 1;
    }
    return 0;
  }

  left = FixedMul(ldy >> FRACBITS, dx);
  right = FixedMul(dy, ldx >> FRACBITS);

  if (right < left) {
    // front side
    return 0;
  }
  // back side
  return 1;
}

//
// R_PointToAngle
// To get a global angle from cartesian coordinates,
//  the coordinates are flipped until they are in
//  the first octant of the coordinate system, then
//  the y (<=x) is scaled and divided by x to get a
//  tangent (slope) value which is looked up in the
//  tantoangle[] table.

//

angle_t R_PointToAngle(fixed_t x, fixed_t y) {
  x -= viewx;
  y -= viewy;

  if ((!x) && (!y))
    return 0;

  if (x >= 0) {
    // x >=0
    if (y >= 0) {
      // y>= 0

      if (x > y) {
        // octant 0
        return tantoangle[SlopeDiv(y, x)];
      } else {
        // octant 1
        return ANG90 - 1 - tantoangle[SlopeDiv(x, y)];
      }
    } else {
      // y<0
      y = -y;

      if (x > y) {
        // octant 8
        return -tantoangle[SlopeDiv(y, x)];
      } else {
        // octant 7
        return ANG270 + tantoangle[SlopeDiv(x, y)];
      }
    }
  } else {
    // x<0
    x = -x;

    if (y >= 0) {
      // y>= 0
      if (x > y) {
        // octant 3
        return ANG180 - 1 - tantoangle[SlopeDiv(y, x)];
      } else {
        // octant 2
        return ANG90 + tantoangle[SlopeDiv(x, y)];
      }
    } else {
      // y<0
      y = -y;

      if (x > y) {
        // octant 4
        return ANG180 + tantoangle[SlopeDiv(y, x)];
      } else {
        // octant 5
        return ANG270 - 1 - tantoangle[SlopeDiv(x, y)];
      }
    }
  }
  return 0;
}

angle_t R_PointToAngle2(fixed_t x1, fixed_t y1, fixed_t x2, fixed_t y2) {
  viewx = x1;
  viewy = y1;

  return R_PointToAngle(x2, y2);
}

fixed_t R_PointToDist(fixed_t x, fixed_t y) {
  int angle;
  fixed_t dx;
  fixed_t dy;
  fixed_t temp;
  fixed_t dist;
  fixed_t frac;

  dx = abs(x - viewx);
  dy = abs(y - viewy);

  if (dy > dx) {
    temp = dx;
    dx = dy;
    dy = temp;
  }

  // Fix crashes in udm1.wad

  if (dx != 0) {
    frac = FixedDiv(dy, dx);
  } else {
    frac = 0;
  }

  angle = (tantoangle[frac >> DBITS] + ANG90) >> ANGLETOFINESHIFT;

  // use as cosine
  dist = FixedDiv(dx, finesine[angle]);

  return dist;
}

//
// R_InitPointToAngle
//
void R_InitPointToAngle(void) {
// UNUSED - now getting from tables.c
#if 0
    int	i;
    long	t;
    float	f;
//
// slope (tangent) to angle lookup
//
    for (i=0 ; i<=SLOPERANGE ; i++)
    {
	f = atan( (float)i/SLOPERANGE )/(3.141592657*2);
	t = 0xffffffff*f;
	tantoangle[i] = t;
    }
#endif
}

//
// R_ScaleFromGlobalAngle
// Returns the texture mapping scale
//  for the current line (horizontal span)
//  at the given angle.
// rw_distance must be calculated first.
//
fixed_t R_ScaleFromGlobalAngle(angle_t visangle) {
  fixed_t scale;
  angle_t anglea;
  angle_t angleb;
  int sinea;
  int sineb;
  fixed_t num;
  int den;

// UNUSED
#if 0
{
    fixed_t		dist;
    fixed_t		z;
    fixed_t		sinv;
    fixed_t		cosv;
	
    sinv = finesine[(visangle-rw_normalangle)>>ANGLETOFINESHIFT];	
    dist = FixedDiv (rw_distance, sinv);
    cosv = finecosine[(viewangle-visangle)>>ANGLETOFINESHIFT];
    z = abs(FixedMul (dist, cosv));
    scale = FixedDiv(projection, z);
    return scale;
}
#endif

  anglea = ANG90 + (visangle - viewangle);
  angleb = ANG90 + (visangle - rw_normalangle);

  // both sines are allways positive
  sinea = finesine[anglea >> ANGLETOFINESHIFT];
  sineb = finesine[angleb >> ANGLETOFINESHIFT];
  num = FixedMul(projection, sineb) << detailshift;
  den = FixedMul(rw_distance, sinea);

  if (den > num >> FRACBITS) {
    scale = FixedDiv(num, den);

    if (scale > 64 * FRACUNIT)
      scale = 64 * FRACUNIT;
    else if (scale < 256)
      scale = 256;
  } else
    scale = 64 * FRACUNIT;

  return scale;
}

//
// R_InitTables
//
void R_InitTables(void) {
// UNUSED: now getting from tables.c
#if 0
    int		i;
    float	a;
    float	fv;
    int		t;
    
    // viewangle tangent table
    for (i=0 ; i<FINEANGLES/2 ; i++)
    {
	a = (i-FINEANGLES/4+0.5)*PI*2/FINEANGLES;
	fv = FRACUNIT*tan (a);
	t = fv;
	finetangent[i] = t;
    }
    
    // finesine table
    for (i=0 ; i<5*FINEANGLES/4 ; i++)
    {
	// OPTIMIZE: mirror...
	a = (i+0.5)*PI*2/FINEANGLES;
	t = FRACUNIT*sin (a);
	finesine[i] = t;
    }
#endif
}

//
// R_InitTextureMapping
//
void R_InitTextureMapping(void) {
  int i;
  int x;
  int t;
  fixed_t focallength;

  // Use tangent table to generate viewangletox:
  //  viewangletox will give the next greatest x
  //  after the view angle.
  //
  // Calc focallength
  //  so FIELDOFVIEW angles covers SCREENWIDTH.
  focallength =
      FixedDiv(centerxfrac, finetangent[FINEANGLES / 4 + FIELDOFVIEW / 2]);

  for (i = 0; i < FINEANGLES / 2; i++) {
    if (finetangent[i] > FRACUNIT * 2)
      t = -1;
    else if (finetangent[i] < -FRACUNIT * 2)
      t = viewwidth + 1;
    else {
      t = FixedMul(finetangent[i], focallength);
      t = (centerxfrac - t + FRACUNIT - 1) >> FRACBITS;

      if (t < -1)
        t = -1;
      else if (t > viewwidth + 1)
        t = viewwidth + 1;
    }
    viewangletox[i] = t;
  }

  // Scan viewangletox[] to generate xtoviewangle[]:
  //  xtoviewangle will give the smallest view angle
  //  that maps to x.
  for (x = 0; x <= viewwidth; x++) {
    i = 0;
    while (viewangletox[i] > x)
      i++;
    xtoviewangle[x] = (i << ANGLETOFINESHIFT) - ANG90;
  }

  // Take out the fencepost cases from viewangletox.
  for (i = 0; i < FINEANGLES / 2; i++) {
    t = FixedMul(finetangent[i], focallength);
    t = centerx - t;

    if (viewangletox[i] == -1)
      viewangletox[i] = 0;
    else if (viewangletox[i] == viewwidth + 1)
      viewangletox[i] = viewwidth;
  }

  clipangle = xtoviewangle[0];
}

//
// R_InitLightTables
// Only inits the zlight table,
//  because the scalelight table changes with view size.
//
#define DISTMAP 2

void R_InitLightTables(void) {
  int i;
  int j;
  int level;
  int startmap;
  int scale;

  // Calculate the light levels to use
  //  for each level / distance combination.
  for (i = 0; i < LIGHTLEVELS; i++) {
    startmap = ((LIGHTLEVELS - 1 - i) * 2) * NUMCOLORMAPS / LIGHTLEVELS;
    for (j = 0; j < MAXLIGHTZ; j++) {
      scale = FixedDiv((SCREENWIDTH / 2 * FRACUNIT), (j + 1) << LIGHTZSHIFT);
      scale >>= LIGHTSCALESHIFT;
      level = startmap - scale / DISTMAP;

      if (level < 0)
        level = 0;

      if (level >= NUMCOLORMAPS)
        level = NUMCOLORMAPS - 1;

      zlight[i][j] = colormaps + level * 256;
    }
  }
}

//
// R_SetViewSize
// Do not really change anything here,
//  because it might be in the middle of a refresh.
// The change will take effect next refresh.
//
boolean setsizeneeded;
int setblocks;
int setdetail;

void R_SetViewSize(int blocks, int detail) {
  setsizeneeded = true;
  setblocks = blocks;
  setdetail = detail;
}

//
// R_ExecuteSetViewSize
//
void R_ExecuteSetViewSize(void) {
  
  IPU_R_ExecuteSetViewSize();

  fixed_t cosadj;
  fixed_t dy;
  int i;
  int j;
  int level;
  int startmap;

  setsizeneeded = false;

  if (setblocks == 11) {
    scaledviewwidth = SCREENWIDTH;
    viewheight = SCREENHEIGHT;
  } else {
    scaledviewwidth = setblocks * 32;
    viewheight = (setblocks * 168 / 10) & ~7;
  }

  detailshift = setdetail;
  viewwidth = scaledviewwidth >> detailshift;

  centery = viewheight / 2;
  centerx = viewwidth / 2;
  centerxfrac = centerx << FRACBITS;
  centeryfrac = centery << FRACBITS;
  projection = centerxfrac;

  if (!detailshift) {
    colfunc = basecolfunc = R_DrawColumn;
    fuzzcolfunc = R_DrawFuzzColumn;
    transcolfunc = R_DrawTranslatedColumn;
    spanfunc = R_DrawSpan;
  } else {
    colfunc = basecolfunc = R_DrawColumnLow;
    fuzzcolfunc = R_DrawFuzzColumnLow;
    transcolfunc = R_DrawTranslatedColumnLow;
    spanfunc = R_DrawSpanLow;
  }

  R_InitBuffer(scaledviewwidth, viewheight);

  R_InitTextureMapping();

  // psprite scales
  pspritescale = FRACUNIT * viewwidth / SCREENWIDTH;
  pspriteiscale = FRACUNIT * SCREENWIDTH / viewwidth;

  // thing clipping
  for (i = 0; i < viewwidth; i++)
    screenheightarray[i] = viewheight;

  // planes
  for (i = 0; i < viewheight; i++) {
    dy = ((i - viewheight / 2) << FRACBITS) + FRACUNIT / 2;
    dy = abs(dy);
    yslope[i] = FixedDiv((viewwidth << detailshift) / 2 * FRACUNIT, dy);
  }

  for (i = 0; i < viewwidth; i++) {
    cosadj = abs(finecosine[xtoviewangle[i] >> ANGLETOFINESHIFT]);
    distscale[i] = FixedDiv(FRACUNIT, cosadj);
  }

  // Calculate the light levels to use
  //  for each level / scale combination.
  for (i = 0; i < LIGHTLEVELS; i++) {
    startmap = ((LIGHTLEVELS - 1 - i) * 2) * NUMCOLORMAPS / LIGHTLEVELS;
    for (j = 0; j < MAXLIGHTSCALE; j++) {
      level = startmap - j * SCREENWIDTH / (viewwidth << detailshift) / DISTMAP;

      if (level < 0)
        level = 0;

      if (level >= NUMCOLORMAPS)
        level = NUMCOLORMAPS - 1;

      scalelight[i][j] = colormaps + level * 256;
    }
  }
}

//
// R_Init
//

void R_Init(void) {

  R_InitData();
  printf(".");
  R_InitPointToAngle();
  printf(".");
  R_InitTables();
  // viewwidth / viewheight / detailLevel are set by the defaults
  printf(".");

  R_SetViewSize(screenblocks, detailLevel);
  R_InitPlanes();
  printf(".");
  R_InitLightTables();
  printf(".");
  R_InitSkyMap();
  R_InitTranslationTables();
  printf(".");

  framecount = 0;
  
  IPU_R_Init();
}

//
// R_PointInSubsector
//
subsector_t *R_PointInSubsector(fixed_t x, fixed_t y) {
  node_t *node;
  int side;
  int nodenum;

  // single subsector is a special case
  if (!numnodes)
    return subsectors;

  nodenum = numnodes - 1;

  while (!(nodenum & NF_SUBSECTOR)) {
    node = &nodes[nodenum];
    side = R_PointOnSide(x, y, node);
    nodenum = node->children[side];
  }

  return &subsectors[nodenum & ~NF_SUBSECTOR];
}

//
// R_SetupFrame
//
void R_SetupFrame(player_t *player) {
  int i;

  viewplayer = player;
  viewx = player->mo->x;
  viewy = player->mo->y;
  viewangle = player->mo->angle + viewangleoffset;
  extralight = player->extralight;

  viewz = player->viewz;

  viewsin = finesine[viewangle >> ANGLETOFINESHIFT];
  viewcos = finecosine[viewangle >> ANGLETOFINESHIFT];

  sscount = 0;

  if (player->fixedcolormap) {
    fixedcolormap = colormaps + player->fixedcolormap * 256;

    walllights = scalelightfixed;

    for (i = 0; i < MAXLIGHTSCALE; i++)
      scalelightfixed[i] = fixedcolormap;
  } else
    fixedcolormap = 0;

  framecount++;
  validcount++;
}

//
// R_RenderView
//
void R_RenderPlayerView(player_t *player) {
  R_SetupFrame(player);

  // Clear buffers.
  R_ClearClipSegs();
  R_ClearDrawSegs();
  R_ClearPlanes();
  R_ClearSprites();

  // check for new console commands.
  NetUpdate();

  // The head node is the last node output.
  R_RenderBSPNode(numnodes - 1);

  // Check for new console commands.
  NetUpdate();

  // R_DrawPlanes();

  // Check for new console commands.
  // NetUpdate();

  IPU_R_RenderPlayerView();

  if (!renderIPUonly) R_DrawMasked();

  // Check for new console commands.
  NetUpdate();
}