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581 lines
11 KiB
C
581 lines
11 KiB
C
// Emacs style mode select -*- C++ -*-
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//-----------------------------------------------------------------------------
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//
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// $Id:$
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//
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// Copyright (C) 1993-1996 by id Software, Inc.
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//
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// This source is available for distribution and/or modification
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// only under the terms of the DOOM Source Code License as
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// published by id Software. All rights reserved.
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//
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// The source is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// FITNESS FOR A PARTICULAR PURPOSE. See the DOOM Source Code License
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// for more details.
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//
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// $Log:$
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//
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// DESCRIPTION:
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// BSP traversal, handling of LineSegs for rendering.
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//
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//-----------------------------------------------------------------------------
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static const char
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rcsid[] = "$Id: r_bsp.c,v 1.4 1997/02/03 22:45:12 b1 Exp $";
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#include "doomdef.h"
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#include "m_bbox.h"
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#include "i_system.h"
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#include "r_main.h"
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#include "r_plane.h"
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#include "r_things.h"
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// State.
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#include "doomstat.h"
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#include "r_state.h"
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//#include "r_local.h"
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seg_t* curline;
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side_t* sidedef;
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line_t* linedef;
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sector_t* frontsector;
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sector_t* backsector;
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drawseg_t drawsegs[MAXDRAWSEGS];
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drawseg_t* ds_p;
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void
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R_StoreWallRange
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( int start,
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int stop );
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//
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// R_ClearDrawSegs
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//
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void R_ClearDrawSegs (void)
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{
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ds_p = drawsegs;
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}
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//
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// ClipWallSegment
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// Clips the given range of columns
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// and includes it in the new clip list.
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//
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typedef struct
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{
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int first;
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int last;
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} cliprange_t;
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#define MAXSEGS 32
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// newend is one past the last valid seg
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cliprange_t* newend;
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cliprange_t solidsegs[MAXSEGS];
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//
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// R_ClipSolidWallSegment
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// Does handle solid walls,
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// e.g. single sided LineDefs (middle texture)
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// that entirely block the view.
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//
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void
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R_ClipSolidWallSegment
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( int first,
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int last )
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{
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cliprange_t* next;
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cliprange_t* start;
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// Find the first range that touches the range
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// (adjacent pixels are touching).
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start = solidsegs;
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while (start->last < first-1)
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start++;
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if (first < start->first)
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{
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if (last < start->first-1)
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{
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// Post is entirely visible (above start),
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// so insert a new clippost.
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R_StoreWallRange (first, last);
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next = newend;
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newend++;
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while (next != start)
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{
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*next = *(next-1);
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next--;
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}
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next->first = first;
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next->last = last;
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return;
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}
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// There is a fragment above *start.
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R_StoreWallRange (first, start->first - 1);
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// Now adjust the clip size.
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start->first = first;
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}
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// Bottom contained in start?
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if (last <= start->last)
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return;
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next = start;
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while (last >= (next+1)->first-1)
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{
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// There is a fragment between two posts.
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R_StoreWallRange (next->last + 1, (next+1)->first - 1);
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next++;
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if (last <= next->last)
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{
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// Bottom is contained in next.
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// Adjust the clip size.
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start->last = next->last;
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goto crunch;
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}
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}
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// There is a fragment after *next.
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R_StoreWallRange (next->last + 1, last);
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// Adjust the clip size.
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start->last = last;
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// Remove start+1 to next from the clip list,
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// because start now covers their area.
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crunch:
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if (next == start)
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{
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// Post just extended past the bottom of one post.
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return;
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}
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while (next++ != newend)
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{
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// Remove a post.
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*++start = *next;
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}
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newend = start+1;
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}
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//
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// R_ClipPassWallSegment
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// Clips the given range of columns,
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// but does not includes it in the clip list.
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// Does handle windows,
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// e.g. LineDefs with upper and lower texture.
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//
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void
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R_ClipPassWallSegment
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( int first,
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int last )
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{
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cliprange_t* start;
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// Find the first range that touches the range
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// (adjacent pixels are touching).
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start = solidsegs;
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while (start->last < first-1)
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start++;
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if (first < start->first)
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{
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if (last < start->first-1)
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{
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// Post is entirely visible (above start).
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R_StoreWallRange (first, last);
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return;
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}
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// There is a fragment above *start.
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R_StoreWallRange (first, start->first - 1);
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}
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// Bottom contained in start?
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if (last <= start->last)
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return;
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while (last >= (start+1)->first-1)
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{
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// There is a fragment between two posts.
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R_StoreWallRange (start->last + 1, (start+1)->first - 1);
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start++;
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if (last <= start->last)
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return;
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}
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// There is a fragment after *next.
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R_StoreWallRange (start->last + 1, last);
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}
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//
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// R_ClearClipSegs
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//
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void R_ClearClipSegs (void)
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{
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solidsegs[0].first = -0x7fffffff;
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solidsegs[0].last = -1;
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solidsegs[1].first = viewwidth;
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solidsegs[1].last = 0x7fffffff;
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newend = solidsegs+2;
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}
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//
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// R_AddLine
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// Clips the given segment
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// and adds any visible pieces to the line list.
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//
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void R_AddLine (seg_t* line)
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{
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int x1;
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int x2;
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angle_t angle1;
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angle_t angle2;
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angle_t span;
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angle_t tspan;
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curline = line;
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// OPTIMIZE: quickly reject orthogonal back sides.
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angle1 = R_PointToAngle (line->v1->x, line->v1->y);
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angle2 = R_PointToAngle (line->v2->x, line->v2->y);
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// Clip to view edges.
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// OPTIMIZE: make constant out of 2*clipangle (FIELDOFVIEW).
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span = angle1 - angle2;
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// Back side? I.e. backface culling?
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if (span >= ANG180)
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return;
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// Global angle needed by segcalc.
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rw_angle1 = angle1;
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angle1 -= viewangle;
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angle2 -= viewangle;
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tspan = angle1 + clipangle;
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if (tspan > 2*clipangle)
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{
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tspan -= 2*clipangle;
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// Totally off the left edge?
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if (tspan >= span)
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return;
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angle1 = clipangle;
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}
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tspan = clipangle - angle2;
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if (tspan > 2*clipangle)
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{
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tspan -= 2*clipangle;
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// Totally off the left edge?
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if (tspan >= span)
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return;
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angle2 = -clipangle;
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}
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// The seg is in the view range,
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// but not necessarily visible.
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angle1 = (angle1+ANG90)>>ANGLETOFINESHIFT;
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angle2 = (angle2+ANG90)>>ANGLETOFINESHIFT;
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x1 = viewangletox[angle1];
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x2 = viewangletox[angle2];
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// Does not cross a pixel?
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if (x1 == x2)
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return;
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backsector = line->backsector;
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// Single sided line?
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if (!backsector)
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goto clipsolid;
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// Closed door.
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if (backsector->ceilingheight <= frontsector->floorheight
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|| backsector->floorheight >= frontsector->ceilingheight)
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goto clipsolid;
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// Window.
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if (backsector->ceilingheight != frontsector->ceilingheight
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|| backsector->floorheight != frontsector->floorheight)
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goto clippass;
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// Reject empty lines used for triggers
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// and special events.
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// Identical floor and ceiling on both sides,
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// identical light levels on both sides,
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// and no middle texture.
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if (backsector->ceilingpic == frontsector->ceilingpic
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&& backsector->floorpic == frontsector->floorpic
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&& backsector->lightlevel == frontsector->lightlevel
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&& curline->sidedef->midtexture == 0)
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{
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return;
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}
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clippass:
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R_ClipPassWallSegment (x1, x2-1);
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return;
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clipsolid:
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R_ClipSolidWallSegment (x1, x2-1);
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}
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//
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// R_CheckBBox
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// Checks BSP node/subtree bounding box.
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// Returns true
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// if some part of the bbox might be visible.
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//
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int checkcoord[12][4] =
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{
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{3,0,2,1},
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{3,0,2,0},
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{3,1,2,0},
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{0},
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{2,0,2,1},
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{0,0,0,0},
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{3,1,3,0},
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{0},
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{2,0,3,1},
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{2,1,3,1},
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{2,1,3,0}
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};
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boolean R_CheckBBox (fixed_t* bspcoord)
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{
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int boxx;
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int boxy;
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int boxpos;
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fixed_t x1;
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fixed_t y1;
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fixed_t x2;
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fixed_t y2;
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angle_t angle1;
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angle_t angle2;
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angle_t span;
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angle_t tspan;
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cliprange_t* start;
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int sx1;
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int sx2;
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// Find the corners of the box
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// that define the edges from current viewpoint.
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if (viewx <= bspcoord[BOXLEFT])
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boxx = 0;
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else if (viewx < bspcoord[BOXRIGHT])
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boxx = 1;
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else
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boxx = 2;
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if (viewy >= bspcoord[BOXTOP])
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boxy = 0;
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else if (viewy > bspcoord[BOXBOTTOM])
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boxy = 1;
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else
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boxy = 2;
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boxpos = (boxy<<2)+boxx;
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if (boxpos == 5)
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return true;
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x1 = bspcoord[checkcoord[boxpos][0]];
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y1 = bspcoord[checkcoord[boxpos][1]];
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x2 = bspcoord[checkcoord[boxpos][2]];
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y2 = bspcoord[checkcoord[boxpos][3]];
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// check clip list for an open space
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angle1 = R_PointToAngle (x1, y1) - viewangle;
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angle2 = R_PointToAngle (x2, y2) - viewangle;
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span = angle1 - angle2;
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// Sitting on a line?
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if (span >= ANG180)
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return true;
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tspan = angle1 + clipangle;
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if (tspan > 2*clipangle)
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{
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tspan -= 2*clipangle;
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// Totally off the left edge?
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if (tspan >= span)
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return false;
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angle1 = clipangle;
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}
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tspan = clipangle - angle2;
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if (tspan > 2*clipangle)
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{
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tspan -= 2*clipangle;
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// Totally off the left edge?
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if (tspan >= span)
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return false;
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angle2 = -clipangle;
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}
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// Find the first clippost
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// that touches the source post
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// (adjacent pixels are touching).
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angle1 = (angle1+ANG90)>>ANGLETOFINESHIFT;
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angle2 = (angle2+ANG90)>>ANGLETOFINESHIFT;
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sx1 = viewangletox[angle1];
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sx2 = viewangletox[angle2];
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// Does not cross a pixel.
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if (sx1 == sx2)
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return false;
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sx2--;
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start = solidsegs;
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while (start->last < sx2)
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start++;
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if (sx1 >= start->first
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&& sx2 <= start->last)
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{
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// The clippost contains the new span.
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return false;
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}
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return true;
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}
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//
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// R_Subsector
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// Determine floor/ceiling planes.
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// Add sprites of things in sector.
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// Draw one or more line segments.
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//
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void R_Subsector (int num)
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{
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int count;
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seg_t* line;
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subsector_t* sub;
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#ifdef RANGECHECK
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if (num>=numsubsectors)
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I_Error ("R_Subsector: ss %i with numss = %i",
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num,
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numsubsectors);
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#endif
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sscount++;
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sub = &subsectors[num];
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frontsector = sub->sector;
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count = sub->numlines;
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line = &segs[sub->firstline];
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if (frontsector->floorheight < viewz)
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{
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floorplane = R_FindPlane (frontsector->floorheight,
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frontsector->floorpic,
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frontsector->lightlevel);
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}
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else
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floorplane = NULL;
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if (frontsector->ceilingheight > viewz
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|| frontsector->ceilingpic == skyflatnum)
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{
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ceilingplane = R_FindPlane (frontsector->ceilingheight,
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frontsector->ceilingpic,
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frontsector->lightlevel);
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}
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else
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ceilingplane = NULL;
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R_AddSprites (frontsector);
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while (count--)
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{
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R_AddLine (line);
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line++;
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}
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}
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//
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// RenderBSPNode
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// Renders all subsectors below a given node,
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// traversing subtree recursively.
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// Just call with BSP root.
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void R_RenderBSPNode (int bspnum)
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{
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node_t* bsp;
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int side;
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// Found a subsector?
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if (bspnum & NF_SUBSECTOR)
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{
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if (bspnum == -1)
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R_Subsector (0);
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else
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R_Subsector (bspnum&(~NF_SUBSECTOR));
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return;
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}
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bsp = &nodes[bspnum];
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// Decide which side the view point is on.
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side = R_PointOnSide (viewx, viewy, bsp);
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// Recursively divide front space.
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R_RenderBSPNode (bsp->children[side]);
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// Possibly divide back space.
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if (R_CheckBBox (bsp->bbox[side^1]))
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R_RenderBSPNode (bsp->children[side^1]);
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}
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