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r_plane.c
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r_plane.c
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//
// Copyright (C) 1993-1996 Id Software, Inc.
// Copyright (C) 2023 Frenkel Smeijers
//
// 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, see <https://www.gnu.org/licenses/>.
//
// R_planes.c
#include "doomdef.h"
#include "r_local.h"
//
// sky mapping
//
int32_t skyflatnum;
int32_t skytexture;
static int32_t skytexturemid;
//
// opening
//
static visplane_t visplanes[MAXVISPLANES], *lastvisplane;
visplane_t *floorplane, *ceilingplane;
static int16_t openings[MAXOPENINGS];
int16_t *lastopening;
//
// clip values are the solid pixel bounding the range
// floorclip starts out SCREENHEIGHT
// ceilingclip starts out -1
//
int16_t floorclip[SCREENWIDTH];
int16_t ceilingclip[SCREENWIDTH];
//
// spanstart holds the start of a plane span
// initialized to 0 at start
//
static int32_t spanstart[SCREENHEIGHT];
//
// texture mapping
//
static lighttable_t **planezlight;
static fixed_t planeheight;
fixed_t yslope[SCREENHEIGHT];
fixed_t distscale[SCREENWIDTH];
static fixed_t basexscale, baseyscale;
static fixed_t cachedheight[SCREENHEIGHT];
static fixed_t cacheddistance[SCREENHEIGHT];
static fixed_t cachedxstep[SCREENHEIGHT];
static fixed_t cachedystep[SCREENHEIGHT];
/*
================
=
= R_InitSkyMap
=
= Called whenever the view size changes
=
================
*/
void R_InitSkyMap (void)
{
skyflatnum = R_FlatNumForName ("F_SKY1");
skytexturemid = 100*FRACUNIT;
}
/*
================
=
= R_MapPlane
=
global vars:
planeheight
ds_source
basexscale
baseyscale
viewx
viewy
BASIC PRIMITIVE
================
*/
static void R_MapPlane (int32_t y, int32_t x1, int32_t x2)
{
angle_t angle;
fixed_t distance, length;
uint32_t index;
#ifdef RANGECHECK
if (x2 < x1 || x1<0 || x2>=viewwidth || (uint32_t)y>viewheight)
I_Error ("R_MapPlane: %i, %i at %i",x1,x2,y);
#endif
if (planeheight != cachedheight[y])
{
cachedheight[y] = planeheight;
distance = cacheddistance[y] = FixedMul (planeheight, yslope[y]);
ds_xstep = cachedxstep[y] = FixedMul (distance,basexscale);
ds_ystep = cachedystep[y] = FixedMul (distance,baseyscale);
}
else
{
distance = cacheddistance[y];
ds_xstep = cachedxstep[y];
ds_ystep = cachedystep[y];
}
length = FixedMul (distance,distscale[x1]);
angle = (viewangle + xtoviewangle[x1])>>ANGLETOFINESHIFT;
ds_xfrac = viewx + FixedMul(finecosine[angle], length);
ds_yfrac = -viewy - FixedMul(finesine[angle], length);
if (fixedcolormap)
ds_colormap = fixedcolormap;
else
{
index = distance >> LIGHTZSHIFT;
if (index >= MAXLIGHTZ )
index = MAXLIGHTZ-1;
ds_colormap = planezlight[index];
}
ds_y = y;
ds_x1 = x1;
ds_x2 = x2;
spanfunc (); // high or low detail
}
//=============================================================================
/*
====================
=
= R_ClearPlanes
=
= At begining of frame
====================
*/
void R_ClearPlanes (void)
{
int32_t i;
angle_t angle;
//
// opening / clipping determination
//
for (i=0 ; i<viewwidth ; i++)
{
floorclip[i] = viewheight;
ceilingclip[i] = -1;
}
lastvisplane = visplanes;
lastopening = openings;
//
// texture calculation
//
memset (cachedheight, 0, sizeof(cachedheight));
angle = (viewangle-ANG90)>>ANGLETOFINESHIFT; // left to right mapping
// scale will be unit scale at SCREENWIDTH/2 distance
basexscale = FixedDiv (finecosine[angle],centerxfrac);
baseyscale = -FixedDiv (finesine[angle],centerxfrac);
}
/*
===============
=
= R_FindPlane
=
===============
*/
visplane_t *R_FindPlane (fixed_t height, int32_t picnum, int32_t lightlevel)
{
visplane_t *check;
if(picnum == skyflatnum)
{
// all skies map together
height = 0;
lightlevel = 0;
}
for(check = visplanes; check < lastvisplane; check++)
{
if(height == check->height
&& picnum == check->picnum
&& lightlevel == check->lightlevel)
break;
}
if(check < lastvisplane)
{
return(check);
}
if(lastvisplane-visplanes == MAXVISPLANES)
{
I_Error("R_FindPlane: no more visplanes");
}
lastvisplane++;
check->height = height;
check->picnum = picnum;
check->lightlevel = lightlevel;
check->minx = SCREENWIDTH;
check->maxx = -1;
memset(check->top,0xff,sizeof(check->top));
return(check);
}
/*
===============
=
= R_CheckPlane
=
===============
*/
visplane_t *R_CheckPlane (visplane_t *pl, int32_t start, int32_t stop)
{
int32_t intrl, intrh;
int32_t unionl, unionh;
int32_t x;
if (start < pl->minx)
{
intrl = pl->minx;
unionl = start;
}
else
{
unionl = pl->minx;
intrl = start;
}
if (stop > pl->maxx)
{
intrh = pl->maxx;
unionh = stop;
}
else
{
unionh = pl->maxx;
intrh = stop;
}
for (x=intrl ; x<= intrh ; x++)
if (pl->top[x] != 0xff)
break;
if (x > intrh)
{
pl->minx = unionl;
pl->maxx = unionh;
return pl; // use the same one
}
// make a new visplane
lastvisplane->height = pl->height;
lastvisplane->picnum = pl->picnum;
lastvisplane->lightlevel = pl->lightlevel;
pl = lastvisplane++;
pl->minx = start;
pl->maxx = stop;
memset (pl->top,0xff,sizeof(pl->top));
return pl;
}
//=============================================================================
/*
================
=
= R_MakeSpans
=
================
*/
static void R_MakeSpans (int32_t x, int32_t t1, int32_t b1, int32_t t2, int32_t b2)
{
while (t1 < t2 && t1<=b1)
{
R_MapPlane (t1,spanstart[t1],x-1);
t1++;
}
while (b1 > b2 && b1>=t1)
{
R_MapPlane (b1,spanstart[b1],x-1);
b1--;
}
while (t2 < t1 && t2<=b2)
{
spanstart[t2] = x;
t2++;
}
while (b2 > b1 && b2>=t2)
{
spanstart[b2] = x;
b2--;
}
}
/*
================
=
= R_DrawPlanes
=
= At the end of each frame
================
*/
void R_DrawPlanes (void)
{
visplane_t *pl;
int32_t light;
int32_t x, stop;
int32_t angle;
#ifdef RANGECHECK
if (ds_p - drawsegs > MAXDRAWSEGS)
I_Error ("R_DrawPlanes: drawsegs overflow (%i)", ds_p - drawsegs);
if (lastvisplane - visplanes > MAXVISPLANES)
I_Error ("R_DrawPlanes: visplane overflow (%i)", lastvisplane - visplanes);
if (lastopening - openings > MAXOPENINGS)
I_Error ("R_DrawPlanes: opening overflow (%i)", lastopening - openings);
#endif
for (pl = visplanes ; pl < lastvisplane ; pl++)
{
if (pl->minx > pl->maxx)
continue;
//
// sky flat
//
if (pl->picnum == skyflatnum)
{
dc_iscale = pspriteiscale>>detailshift;
dc_colormap = colormaps;// sky is allways drawn full bright
dc_texturemid = skytexturemid;
for (x=pl->minx ; x <= pl->maxx ; x++)
{
dc_yl = pl->top[x];
dc_yh = pl->bottom[x];
if (dc_yl <= dc_yh)
{
angle = (viewangle + xtoviewangle[x])>>ANGLETOSKYSHIFT;
dc_x = x;
dc_source = R_GetColumn(skytexture, angle);
colfunc ();
}
}
continue;
}
//
// regular flat
//
ds_source = W_CacheLumpNum(firstflat +
flattranslation[pl->picnum], PU_STATIC);
planeheight = abs(pl->height-viewz);
light = (pl->lightlevel >> LIGHTSEGSHIFT)+extralight;
if (light >= LIGHTLEVELS)
light = LIGHTLEVELS-1;
if (light < 0)
light = 0;
planezlight = zlight[light];
pl->top[pl->maxx+1] = 0xff;
pl->top[pl->minx-1] = 0xff;
stop = pl->maxx + 1;
for (x=pl->minx ; x<= stop ; x++)
R_MakeSpans (x,pl->top[x-1],pl->bottom[x-1]
,pl->top[x],pl->bottom[x]);
Z_ChangeTag (ds_source, PU_CACHE);
}
}