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-rw-r--r--src/heretic/r_bsp.c484
1 files changed, 484 insertions, 0 deletions
diff --git a/src/heretic/r_bsp.c b/src/heretic/r_bsp.c
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+// Emacs style mode select -*- C++ -*-
+//-----------------------------------------------------------------------------
+//
+// Copyright(C) 1993-1996 Id Software, Inc.
+// Copyright(C) 1993-2008 Raven Software
+// Copyright(C) 2008 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.
+//
+// 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_bsp.c
+
+#include "doomdef.h"
+#include "m_bbox.h"
+#include "r_local.h"
+
+seg_t *curline;
+side_t *sidedef;
+line_t *linedef;
+sector_t *frontsector, *backsector;
+
+drawseg_t drawsegs[MAXDRAWSEGS], *ds_p;
+
+void R_StoreWallRange(int start, int stop);
+
+/*
+====================
+=
+= R_ClearDrawSegs
+=
+====================
+*/
+
+void R_ClearDrawSegs(void)
+{
+ ds_p = drawsegs;
+}
+
+//=============================================================================
+
+
+/*
+===============================================================================
+=
+= ClipWallSegment
+=
+= Clips the given range of columns and includes it in the new clip list
+===============================================================================
+*/
+
+typedef struct
+{
+ int first, last;
+} cliprange_t;
+
+#define MAXSEGS 32
+
+cliprange_t solidsegs[MAXSEGS], *newend; // newend is one past the last valid seg
+
+
+void R_ClipSolidWallSegment(int first, int last)
+{
+ cliprange_t *next, *start;
+
+// find the first range that touches the range (adjacent pixels are touching)
+ start = solidsegs;
+ while (start->last < first - 1)
+ start++;
+
+ if (first < start->first)
+ {
+ if (last < start->first - 1)
+ { // post is entirely visible (above start), so insert a new clippost
+ R_StoreWallRange(first, last);
+ next = newend;
+ newend++;
+ while (next != start)
+ {
+ *next = *(next - 1);
+ next--;
+ }
+ next->first = first;
+ next->last = last;
+ return;
+ }
+
+ // there is a fragment above *start
+ R_StoreWallRange(first, start->first - 1);
+ start->first = first; // adjust the clip size
+ }
+
+ if (last <= start->last)
+ return; // bottom contained in start
+
+ next = start;
+ while (last >= (next + 1)->first - 1)
+ {
+ // there is a fragment between two posts
+ R_StoreWallRange(next->last + 1, (next + 1)->first - 1);
+ next++;
+ if (last <= next->last)
+ { // bottom is contained in next
+ start->last = next->last; // adjust the clip size
+ goto crunch;
+ }
+ }
+
+ // there is a fragment after *next
+ R_StoreWallRange(next->last + 1, last);
+ start->last = last; // adjust the clip size
+
+
+// remove start+1 to next from the clip list,
+// because start now covers their area
+ crunch:
+ if (next == start)
+ return; // post just extended past the bottom of one post
+
+ while (next++ != newend) // remove a post
+ *++start = *next;
+ newend = start + 1;
+}
+
+/*
+===============================================================================
+=
+= R_ClipPassWallSegment
+=
+= Clips the given range of columns, but does not includes it in the clip list
+===============================================================================
+*/
+
+void R_ClipPassWallSegment(int first, int last)
+{
+ cliprange_t *start;
+
+// find the first range that touches the range (adjacent pixels are touching)
+ start = solidsegs;
+ while (start->last < first - 1)
+ start++;
+
+ if (first < start->first)
+ {
+ if (last < start->first - 1)
+ { // post is entirely visible (above start)
+ R_StoreWallRange(first, last);
+ return;
+ }
+
+ // there is a fragment above *start
+ R_StoreWallRange(first, start->first - 1);
+ }
+
+ if (last <= start->last)
+ return; // bottom contained in start
+
+ while (last >= (start + 1)->first - 1)
+ {
+ // there is a fragment between two posts
+ R_StoreWallRange(start->last + 1, (start + 1)->first - 1);
+ start++;
+ if (last <= start->last)
+ return;
+ }
+
+ // there is a fragment after *next
+ R_StoreWallRange(start->last + 1, last);
+}
+
+
+
+/*
+====================
+=
+= R_ClearClipSegs
+=
+====================
+*/
+
+void R_ClearClipSegs(void)
+{
+ solidsegs[0].first = -0x7fffffff;
+ solidsegs[0].last = -1;
+ solidsegs[1].first = viewwidth;
+ solidsegs[1].last = 0x7fffffff;
+ newend = solidsegs + 2;
+}
+
+
+//=============================================================================
+
+/*
+======================
+=
+= R_AddLine
+=
+= Clips the given segment and adds any visible pieces to the line list
+=
+======================
+*/
+
+void R_AddLine(seg_t * line)
+{
+ int x1, x2;
+ angle_t angle1, angle2, span, tspan;
+
+ curline = line;
+
+// OPTIMIZE: quickly reject orthogonal back sides
+
+ angle1 = R_PointToAngle(line->v1->x, line->v1->y);
+ angle2 = R_PointToAngle(line->v2->x, line->v2->y);
+
+//
+// clip to view edges
+// OPTIMIZE: make constant out of 2*clipangle (FIELDOFVIEW)
+ span = angle1 - angle2;
+ if (span >= ANG180)
+ return; // back side
+
+ rw_angle1 = angle1; // global angle needed by segcalc
+ angle1 -= viewangle;
+ angle2 -= viewangle;
+
+ tspan = angle1 + clipangle;
+ if (tspan > 2 * clipangle)
+ {
+ tspan -= 2 * clipangle;
+ if (tspan >= span)
+ return; // totally off the left edge
+ angle1 = clipangle;
+ }
+ tspan = clipangle - angle2;
+ if (tspan > 2 * clipangle)
+ {
+ tspan -= 2 * clipangle;
+ if (tspan >= span)
+ return; // totally off the left edge
+ angle2 = -clipangle;
+ }
+
+//
+// the seg is in the view range, but not necessarily visible
+//
+ angle1 = (angle1 + ANG90) >> ANGLETOFINESHIFT;
+ angle2 = (angle2 + ANG90) >> ANGLETOFINESHIFT;
+ x1 = viewangletox[angle1];
+ x2 = viewangletox[angle2];
+ if (x1 == x2)
+ return; // does not cross a pixel
+
+ backsector = line->backsector;
+
+ if (!backsector)
+ goto clipsolid; // single sided line
+
+ if (backsector->ceilingheight <= frontsector->floorheight
+ || backsector->floorheight >= frontsector->ceilingheight)
+ goto clipsolid; // closed door
+
+ if (backsector->ceilingheight != frontsector->ceilingheight
+ || backsector->floorheight != frontsector->floorheight)
+ goto clippass; // window
+
+// reject empty lines used for triggers and special events
+ if (backsector->ceilingpic == frontsector->ceilingpic
+ && backsector->floorpic == frontsector->floorpic
+ && backsector->lightlevel == frontsector->lightlevel
+ && curline->sidedef->midtexture == 0)
+ return;
+
+ clippass:
+ R_ClipPassWallSegment(x1, x2 - 1);
+ return;
+
+ clipsolid:
+ R_ClipSolidWallSegment(x1, x2 - 1);
+}
+
+//============================================================================
+
+
+/*
+===============================================================================
+=
+= R_CheckBBox
+=
+= Returns true if some part of the bbox might be visible
+=
+===============================================================================
+*/
+
+int checkcoord[12][4] = {
+ {3, 0, 2, 1},
+ {3, 0, 2, 0},
+ {3, 1, 2, 0},
+ {0},
+ {2, 0, 2, 1},
+ {0, 0, 0, 0},
+ {3, 1, 3, 0},
+ {0},
+ {2, 0, 3, 1},
+ {2, 1, 3, 1},
+ {2, 1, 3, 0}
+};
+
+
+boolean R_CheckBBox(fixed_t * bspcoord)
+{
+ int boxx, boxy, boxpos;
+ fixed_t x1, y1, x2, y2;
+ angle_t angle1, angle2, span, tspan;
+ cliprange_t *start;
+ int sx1, sx2;
+
+// find the corners of the box that define the edges from current viewpoint
+ if (viewx <= bspcoord[BOXLEFT])
+ boxx = 0;
+ else if (viewx < bspcoord[BOXRIGHT])
+ boxx = 1;
+ else
+ boxx = 2;
+
+ if (viewy >= bspcoord[BOXTOP])
+ boxy = 0;
+ else if (viewy > bspcoord[BOXBOTTOM])
+ boxy = 1;
+ else
+ boxy = 2;
+
+ boxpos = (boxy << 2) + boxx;
+ if (boxpos == 5)
+ return true;
+
+ x1 = bspcoord[checkcoord[boxpos][0]];
+ y1 = bspcoord[checkcoord[boxpos][1]];
+ x2 = bspcoord[checkcoord[boxpos][2]];
+ y2 = bspcoord[checkcoord[boxpos][3]];
+
+
+//
+// check clip list for an open space
+//
+ angle1 = R_PointToAngle(x1, y1) - viewangle;
+ angle2 = R_PointToAngle(x2, y2) - viewangle;
+
+ span = angle1 - angle2;
+ if (span >= ANG180)
+ return true; // sitting on a line
+ tspan = angle1 + clipangle;
+ if (tspan > 2 * clipangle)
+ {
+ tspan -= 2 * clipangle;
+ if (tspan >= span)
+ return false; // totally off the left edge
+ angle1 = clipangle;
+ }
+ tspan = clipangle - angle2;
+ if (tspan > 2 * clipangle)
+ {
+ tspan -= 2 * clipangle;
+ if (tspan >= span)
+ return false; // totally off the left edge
+ angle2 = -clipangle;
+ }
+
+
+// find the first clippost that touches the source post (adjacent pixels are touching)
+ angle1 = (angle1 + ANG90) >> ANGLETOFINESHIFT;
+ angle2 = (angle2 + ANG90) >> ANGLETOFINESHIFT;
+ sx1 = viewangletox[angle1];
+ sx2 = viewangletox[angle2];
+ if (sx1 == sx2)
+ return false; // does not cross a pixel
+ sx2--;
+
+ start = solidsegs;
+ while (start->last < sx2)
+ start++;
+ if (sx1 >= start->first && sx2 <= start->last)
+ return false; // the clippost contains the new span
+
+ return true;
+}
+
+
+/*
+================
+=
+= R_Subsector
+=
+= Draw one or more segments
+================
+*/
+
+void R_Subsector(int num)
+{
+ int count;
+ seg_t *line;
+ subsector_t *sub;
+
+#ifdef RANGECHECK
+ if (num >= numsubsectors)
+ I_Error("R_Subsector: ss %i with numss = %i", num, numsubsectors);
+#endif
+
+ sscount++;
+ sub = &subsectors[num];
+ frontsector = sub->sector;
+ count = sub->numlines;
+ line = &segs[sub->firstline];
+
+ if (frontsector->floorheight < viewz)
+ floorplane = R_FindPlane(frontsector->floorheight,
+ frontsector->floorpic,
+ frontsector->lightlevel,
+ frontsector->special);
+ else
+ floorplane = NULL;
+ if (frontsector->ceilingheight > viewz
+ || frontsector->ceilingpic == skyflatnum)
+ ceilingplane = R_FindPlane(frontsector->ceilingheight,
+ frontsector->ceilingpic,
+ frontsector->lightlevel, 0);
+ else
+ ceilingplane = NULL;
+
+ R_AddSprites(frontsector);
+
+ while (count--)
+ {
+ R_AddLine(line);
+ line++;
+ }
+}
+
+
+/*
+===============================================================================
+=
+= RenderBSPNode
+=
+===============================================================================
+*/
+
+void R_RenderBSPNode(int bspnum)
+{
+ node_t *bsp;
+ int side;
+
+ if (bspnum & NF_SUBSECTOR)
+ {
+ if (bspnum == -1)
+ R_Subsector(0);
+ else
+ R_Subsector(bspnum & (~NF_SUBSECTOR));
+ return;
+ }
+
+ bsp = &nodes[bspnum];
+
+//
+// decide which side the view point is on
+//
+ side = R_PointOnSide(viewx, viewy, bsp);
+
+ R_RenderBSPNode(bsp->children[side]); // recursively divide front space
+
+ if (R_CheckBBox(bsp->bbox[side ^ 1])) // possibly divide back space
+ R_RenderBSPNode(bsp->children[side ^ 1]);
+}
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