r_aclip.c

/*
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_aclip.c: clip routines for drawing Alias models directly to the screen

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

static finalvert_t    fv[2][8];
static auxvert_t    av[8];

void R_AliasProjectFinalVert (finalvert_t *fv, auxvert_t *av);
void R_Alias_clip_top (finalvert_t *pfv0, finalvert_t *pfv1,
  finalvert_t *out);
void R_Alias_clip_bottom (finalvert_t *pfv0, finalvert_t *pfv1,
  finalvert_t *out);
void R_Alias_clip_left (finalvert_t *pfv0, finalvert_t *pfv1,
  finalvert_t *out);
void R_Alias_clip_right (finalvert_t *pfv0, finalvert_t *pfv1,
  finalvert_t *out);

#if defined(M68KASM) || defined(PPCASM)
extern int R_AliasClip (finalvert_t *in, finalvert_t *out, int flag,
                        int count, void(*clip)(finalvert_t *pfv0,
                        finalvert_t *pfv1, finalvert_t *out) );
#endif


/*
================
R_Alias_clip_z

pfv0 is the unclipped vertex, pfv1 is the z-clipped vertex
================
*/
void R_Alias_clip_z (finalvert_t *pfv0, finalvert_t *pfv1, finalvert_t *out)
{
  float   scale;
  auxvert_t *pav0, *pav1, avout;

  pav0 = &av[pfv0 - &fv[0][0]];
  pav1 = &av[pfv1 - &fv[0][0]];

  if (pfv0->v[1] >= pfv1->v[1])
  {
    scale = (ALIAS_Z_CLIP_PLANE - pav0->fv[2]) /
        (pav1->fv[2] - pav0->fv[2]);
  
    avout.fv[0] = pav0->fv[0] + (pav1->fv[0] - pav0->fv[0]) * scale;
    avout.fv[1] = pav0->fv[1] + (pav1->fv[1] - pav0->fv[1]) * scale;
    avout.fv[2] = ALIAS_Z_CLIP_PLANE;
  
    out->v[2] = pfv0->v[2] + (pfv1->v[2] - pfv0->v[2]) * scale;
    out->v[3] = pfv0->v[3] + (pfv1->v[3] - pfv0->v[3]) * scale;
    out->v[4] = pfv0->v[4] + (pfv1->v[4] - pfv0->v[4]) * scale;
  }
  else
  {
    scale = (ALIAS_Z_CLIP_PLANE - pav1->fv[2]) /
        (pav0->fv[2] - pav1->fv[2]);
  
    avout.fv[0] = pav1->fv[0] + (pav0->fv[0] - pav1->fv[0]) * scale;
    avout.fv[1] = pav1->fv[1] + (pav0->fv[1] - pav1->fv[1]) * scale;
    avout.fv[2] = ALIAS_Z_CLIP_PLANE;
  
    out->v[2] = pfv1->v[2] + (pfv0->v[2] - pfv1->v[2]) * scale;
    out->v[3] = pfv1->v[3] + (pfv0->v[3] - pfv1->v[3]) * scale;
    out->v[4] = pfv1->v[4] + (pfv0->v[4] - pfv1->v[4]) * scale;
  }

  R_AliasProjectFinalVert (out, &avout);

  if (out->v[0] < r_refdef.aliasvrect.x)
    out->flags |= ALIAS_LEFT_CLIP;
  if (out->v[1] < r_refdef.aliasvrect.y)
    out->flags |= ALIAS_TOP_CLIP;
  if (out->v[0] > r_refdef.aliasvrectright)
    out->flags |= ALIAS_RIGHT_CLIP;
  if (out->v[1] > r_refdef.aliasvrectbottom)
    out->flags |= ALIAS_BOTTOM_CLIP;  
}


#if !defined(M68KASM) && !defined(PPCASM)
void R_Alias_clip_left (finalvert_t *pfv0, finalvert_t *pfv1, finalvert_t *out)
{
  float   scale;
  int     i;

  if (pfv0->v[1] >= pfv1->v[1])
  {
    scale = (float)(r_refdef.aliasvrect.x - pfv0->v[0]) /
        (pfv1->v[0] - pfv0->v[0]);
    for (i=0 ; i<6 ; i++)
      out->v[i] = pfv0->v[i] + (pfv1->v[i] - pfv0->v[i])*scale + 0.5;
  }
  else
  {
    scale = (float)(r_refdef.aliasvrect.x - pfv1->v[0]) /
        (pfv0->v[0] - pfv1->v[0]);
    for (i=0 ; i<6 ; i++)
      out->v[i] = pfv1->v[i] + (pfv0->v[i] - pfv1->v[i])*scale + 0.5;
  }
}


void R_Alias_clip_right (finalvert_t *pfv0, finalvert_t *pfv1,
  finalvert_t *out)
{
  float   scale;
  int     i;

  if (pfv0->v[1] >= pfv1->v[1])
  {
    scale = (float)(r_refdef.aliasvrectright - pfv0->v[0]) /
        (pfv1->v[0] - pfv0->v[0]);
    for (i=0 ; i<6 ; i++)
      out->v[i] = pfv0->v[i] + (pfv1->v[i] - pfv0->v[i])*scale + 0.5;
  }
  else
  {
    scale = (float)(r_refdef.aliasvrectright - pfv1->v[0]) /
        (pfv0->v[0] - pfv1->v[0]);
    for (i=0 ; i<6 ; i++)
      out->v[i] = pfv1->v[i] + (pfv0->v[i] - pfv1->v[i])*scale + 0.5;
  }
}


void R_Alias_clip_top (finalvert_t *pfv0, finalvert_t *pfv1, finalvert_t *out)
{
  float   scale;
  int     i;

  if (pfv0->v[1] >= pfv1->v[1])
  {
    scale = (float)(r_refdef.aliasvrect.y - pfv0->v[1]) /
        (pfv1->v[1] - pfv0->v[1]);
    for (i=0 ; i<6 ; i++)
      out->v[i] = pfv0->v[i] + (pfv1->v[i] - pfv0->v[i])*scale + 0.5;
  }
  else
  {
    scale = (float)(r_refdef.aliasvrect.y - pfv1->v[1]) /
        (pfv0->v[1] - pfv1->v[1]);
    for (i=0 ; i<6 ; i++)
      out->v[i] = pfv1->v[i] + (pfv0->v[i] - pfv1->v[i])*scale + 0.5;
  }
}


void R_Alias_clip_bottom (finalvert_t *pfv0, finalvert_t *pfv1,
  finalvert_t *out)
{
  float   scale;
  int     i;

  if (pfv0->v[1] >= pfv1->v[1])
  {
    scale = (float)(r_refdef.aliasvrectbottom - pfv0->v[1]) /
        (pfv1->v[1] - pfv0->v[1]);

    for (i=0 ; i<6 ; i++)
      out->v[i] = pfv0->v[i] + (pfv1->v[i] - pfv0->v[i])*scale + 0.5;
  }
  else
  {
    scale = (float)(r_refdef.aliasvrectbottom - pfv1->v[1]) /
        (pfv0->v[1] - pfv1->v[1]);

    for (i=0 ; i<6 ; i++)
      out->v[i] = pfv1->v[i] + (pfv0->v[i] - pfv1->v[i])*scale + 0.5;
  }
}
#endif


#if !defined(M68KASM) && !defined(PPCASM)
int R_AliasClip (finalvert_t *in, finalvert_t *out, int flag, int count,
  void(*clip)(finalvert_t *pfv0, finalvert_t *pfv1, finalvert_t *out) )
{
  int     i,j,k;
  int     flags, oldflags;
  
  j = count-1;
  k = 0;
  for (i=0 ; i<count ; j = i, i++)
  {
    oldflags = in[j].flags & flag;
    flags = in[i].flags & flag;

    if (flags && oldflags)
      continue;
    if (oldflags ^ flags)
    {
      clip (&in[j], &in[i], &out[k]);
      out[k].flags = 0;
      if (out[k].v[0] < r_refdef.aliasvrect.x)
        out[k].flags |= ALIAS_LEFT_CLIP;
      if (out[k].v[1] < r_refdef.aliasvrect.y)
        out[k].flags |= ALIAS_TOP_CLIP;
      if (out[k].v[0] > r_refdef.aliasvrectright)
        out[k].flags |= ALIAS_RIGHT_CLIP;
      if (out[k].v[1] > r_refdef.aliasvrectbottom)
        out[k].flags |= ALIAS_BOTTOM_CLIP;  
      k++;
    }
    if (!flags)
    {
      out[k] = in[i];
      k++;
    }
  }
  
  return k;
}
#endif


/*
================
R_AliasClipTriangle
================
*/
void R_AliasClipTriangle (mtriangle_t *ptri)
{
  int       i, k, pingpong;
  mtriangle_t   mtri;
  unsigned    clipflags;

// copy vertexes and fix seam texture coordinates
  if (ptri->facesfront)
  {
    fv[0][0] = pfinalverts[ptri->vertindex[0]];
    fv[0][1] = pfinalverts[ptri->vertindex[1]];
    fv[0][2] = pfinalverts[ptri->vertindex[2]];
  }
  else
  {
    for (i=0 ; i<3 ; i++)
    {
      fv[0][i] = pfinalverts[ptri->vertindex[i]];
  
      if (!ptri->facesfront && (fv[0][i].flags & ALIAS_ONSEAM) )
        fv[0][i].v[2] += r_affinetridesc.seamfixupX16;
    }
  }

// clip
  clipflags = fv[0][0].flags | fv[0][1].flags | fv[0][2].flags;

  if (clipflags & ALIAS_Z_CLIP)
  {
    for (i=0 ; i<3 ; i++)
      av[i] = pauxverts[ptri->vertindex[i]];

    k = R_AliasClip (fv[0], fv[1], ALIAS_Z_CLIP, 3, R_Alias_clip_z);
    if (k == 0)
      return;

    pingpong = 1;
    clipflags = fv[1][0].flags | fv[1][1].flags | fv[1][2].flags;
  }
  else
  {
    pingpong = 0;
    k = 3;
  }

  if (clipflags & ALIAS_LEFT_CLIP)
  {
    k = R_AliasClip (fv[pingpong], fv[pingpong ^ 1],
              ALIAS_LEFT_CLIP, k, R_Alias_clip_left);
    if (k == 0)
      return;

    pingpong ^= 1;
  }

  if (clipflags & ALIAS_RIGHT_CLIP)
  {
    k = R_AliasClip (fv[pingpong], fv[pingpong ^ 1],
              ALIAS_RIGHT_CLIP, k, R_Alias_clip_right);
    if (k == 0)
      return;

    pingpong ^= 1;
  }

  if (clipflags & ALIAS_BOTTOM_CLIP)
  {
    k = R_AliasClip (fv[pingpong], fv[pingpong ^ 1],
              ALIAS_BOTTOM_CLIP, k, R_Alias_clip_bottom);
    if (k == 0)
      return;

    pingpong ^= 1;
  }

  if (clipflags & ALIAS_TOP_CLIP)
  {
    k = R_AliasClip (fv[pingpong], fv[pingpong ^ 1],
              ALIAS_TOP_CLIP, k, R_Alias_clip_top);
    if (k == 0)
      return;

    pingpong ^= 1;
  }

  for (i=0 ; i<k ; i++)
  {
    if (fv[pingpong][i].v[0] < r_refdef.aliasvrect.x)
      fv[pingpong][i].v[0] = r_refdef.aliasvrect.x;
    else if (fv[pingpong][i].v[0] > r_refdef.aliasvrectright)
      fv[pingpong][i].v[0] = r_refdef.aliasvrectright;

    if (fv[pingpong][i].v[1] < r_refdef.aliasvrect.y)
      fv[pingpong][i].v[1] = r_refdef.aliasvrect.y;
    else if (fv[pingpong][i].v[1] > r_refdef.aliasvrectbottom)
      fv[pingpong][i].v[1] = r_refdef.aliasvrectbottom;

    fv[pingpong][i].flags = 0;
  }

// draw triangles
  mtri.facesfront = ptri->facesfront;
  r_affinetridesc.ptriangles = &mtri;
  r_affinetridesc.pfinalverts = fv[pingpong];

// FIXME: do all at once as trifan?
  mtri.vertindex[0] = 0;
  for (i=1 ; i<k-1 ; i++)
  {
    mtri.vertindex[1] = i;
    mtri.vertindex[2] = i+1;
    D_PolysetDraw ();
  }
}