mirror of
https://github.com/ZDoom/zdbsp.git
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330 lines
8.1 KiB
Text
330 lines
8.1 KiB
Text
// This is the same algorithm used by DoomBSP:
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//
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// Represent each sector by its bounding box. Then for each pair of
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// sectors, see if any chains of one-sided lines can walk from one
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// side of the convex hull for that pair to the other side.
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//
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// It works, but it's far from being perfect. It's quite easy for
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// this algorithm to consider two sectors as being visible from
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// each other when they are really not. But it won't erroneously
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// flag two sectors as obstructed when they're really not, and that's
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// the only thing that really matters when building a REJECT lump.
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#include <string.h>
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#include <stdio.h>
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#include "rejectbuilder.h"
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#include "templates.h"
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FRejectBuilder::FRejectBuilder (FLevel &level)
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: Level (level), BlockChains (NULL)
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{
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RejectSize = (Level.NumSectors*Level.NumSectors + 7) / 8;
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Reject = new BYTE[RejectSize];
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memset (Reject, 0, RejectSize);
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FindSectorBounds ();
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FindBlockChains ();
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BuildReject ();
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}
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FRejectBuilder::~FRejectBuilder ()
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{
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FBlockChain *chain, *next;
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chain = BlockChains;
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while (chain != NULL)
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{
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next = chain->Next;
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delete chain;
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chain = next;
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}
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}
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BYTE *FRejectBuilder::GetReject ()
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{
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return Reject;
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}
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void FRejectBuilder::FindSectorBounds ()
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{
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int i;
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SectorBounds = new BBox[Level.NumSectors];
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for (i = 0; i < Level.NumSectors; ++i)
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{
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SectorBounds[i].Bounds[LEFT] = SectorBounds[i].Bounds[BOTTOM] = INT_MAX;
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SectorBounds[i].Bounds[RIGHT] = SectorBounds[i].Bounds[TOP] = INT_MIN;
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}
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for (i = 0; i < Level.NumLines; ++i)
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{
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if (Level.Lines[i].sidenum[0] != NO_INDEX)
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{
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int secnum = Level.Sides[Level.Lines[i].sidenum[0]].sector;
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SectorBounds[secnum].AddPt (Level.Vertices[Level.Lines[i].v1]);
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SectorBounds[secnum].AddPt (Level.Vertices[Level.Lines[i].v2]);
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}
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if (Level.Lines[i].sidenum[1] != NO_INDEX)
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{
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int secnum = Level.Sides[Level.Lines[i].sidenum[1]].sector;
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SectorBounds[secnum].AddPt (Level.Vertices[Level.Lines[i].v1]);
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SectorBounds[secnum].AddPt (Level.Vertices[Level.Lines[i].v2]);
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}
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}
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}
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void FRejectBuilder::FindBlockChains ()
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{
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bool *marked = new bool[Level.NumLines];
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WORD *nextForVert = new WORD[Level.NumLines];
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WORD *firstLine = new WORD[Level.NumVertices];
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int i, j, k;
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FBlockChain *chain;
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FPoint pt;
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TArray<FPoint> pts;
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memset (nextForVert, 0xff, Level.NumLines*sizeof(*nextForVert));
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memset (firstLine, 0xff, Level.NumVertices*sizeof(*firstLine));
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memset (marked, 0, Level.NumLines*sizeof(*marked));
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for (i = 0; i < Level.NumLines; ++i)
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{
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if (Level.Lines[i].sidenum[0] == NO_INDEX || Level.Lines[i].sidenum[1] != NO_INDEX)
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{
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marked[i] = true;
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}
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else
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{
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nextForVert[Level.Lines[i].v1] = firstLine[Level.Lines[i].v1];
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firstLine[Level.Lines[i].v1] = i;
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}
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}
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for (i = 0; i < Level.NumLines; ++i)
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{
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if (marked[i])
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{
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continue;
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}
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pt.x = Level.Vertices[Level.Lines[i].v1].x >> FRACBITS;
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pt.y = Level.Vertices[Level.Lines[i].v1].y >> FRACBITS;
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pts.Clear ();
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pts.Push (pt);
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chain = new FBlockChain;
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chain->Bounds(LEFT) = chain->Bounds(RIGHT) = pt.x;
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chain->Bounds(TOP) = chain->Bounds(BOTTOM) = pt.y;
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for (j = i; j != NO_INDEX; )
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{
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marked[j] = true;
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pt.x = Level.Vertices[Level.Lines[j].v2].x >> FRACBITS;
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pt.y = Level.Vertices[Level.Lines[j].v2].y >> FRACBITS;
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pts.Push (pt);
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chain->Bounds.AddPt (pt);
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k = firstLine[Level.Lines[j].v2];
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if (k == NO_INDEX)
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{
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break;
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}
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if (nextForVert[k] == NO_INDEX)
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{
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j = marked[k] ? NO_INDEX : k;
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}
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else
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{
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int best = NO_INDEX;
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angle_t bestang = ANGLE_MAX;
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angle_t ang1 = PointToAngle (Level.Vertices[Level.Lines[j].v2].x - Level.Vertices[Level.Lines[j].v1].x,
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Level.Vertices[Level.Lines[j].v2].y - Level.Vertices[Level.Lines[j].v1].y) + (1 << 31);
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while (k != NO_INDEX)
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{
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if (!marked[k])
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{
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angle_t ang2 = PointToAngle (Level.Vertices[Level.Lines[k].v2].x - Level.Vertices[Level.Lines[k].v1].x,
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Level.Vertices[Level.Lines[k].v2].y - Level.Vertices[Level.Lines[k].v1].y) + (1 << 31);
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angle_t angdiff = ang2 - ang1;
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if (angdiff < bestang && angdiff > 0)
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{
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bestang = angdiff;
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best = k;
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}
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}
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k = nextForVert[k];
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}
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j = best;
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}
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}
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chain->NumPoints = pts.Size();
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chain->Points = new FPoint[chain->NumPoints];
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memcpy (chain->Points, &pts[0], chain->NumPoints*sizeof(*chain->Points));
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chain->Next = BlockChains;
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BlockChains = chain;
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}
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}
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void FRejectBuilder::HullSides (const BBox &box1, const BBox &box2, FPoint sides[4])
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{
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static const int vertSides[4][2] = {
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{ LEFT, BOTTOM },
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{ LEFT, TOP },
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{ RIGHT, TOP },
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{ RIGHT, BOTTOM }
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};
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static const int stuffSpots[4] = { 0, 3, 2, 1 };
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const int *boxp1, *boxp2;
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boxp1 = box2.Bounds;
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boxp2 = box1.Bounds;
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for (int mainBox = 2; mainBox != 0; )
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{
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const int *stuffs = stuffSpots + (--mainBox)*2;
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int outerEdges[4];
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outerEdges[LEFT] = boxp1[LEFT] <= boxp2[LEFT];
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outerEdges[TOP] = boxp1[TOP] >= boxp2[TOP];
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outerEdges[RIGHT] = boxp1[RIGHT] >= boxp2[RIGHT];
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outerEdges[BOTTOM] = boxp1[BOTTOM] <= boxp2[BOTTOM];
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for (int vertex = 0; vertex < 4; ++vertex)
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{
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if (outerEdges[(vertex-1)&3] != outerEdges[vertex])
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{
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FPoint *pt = &sides[stuffs[outerEdges[vertex]]];
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pt->x = boxp1[vertSides[vertex][0]];
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pt->y = boxp1[vertSides[vertex][1]];
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}
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}
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boxp1 = box1.Bounds;
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boxp2 = box2.Bounds;
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}
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}
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int FRejectBuilder::PointOnSide (const FPoint *pt, const FPoint &lpt1, const FPoint &lpt2)
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{
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return (pt->y - lpt1.y) * (lpt2.x - lpt1.x) >= (pt->x - lpt1.x) * (lpt2.y - lpt1.y);
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}
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bool FRejectBuilder::ChainBlocks (const FBlockChain *chain,
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const BBox *hullBounds, const FPoint *hullPts)
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{
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int startSide, side, i;
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if (chain->Bounds[LEFT] > hullBounds->Bounds[RIGHT] ||
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chain->Bounds[RIGHT] < hullBounds->Bounds[LEFT] ||
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chain->Bounds[TOP] < hullBounds->Bounds[BOTTOM] ||
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chain->Bounds[BOTTOM] > hullBounds->Bounds[TOP])
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{
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return false;
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}
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startSide = -1;
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for (i = 0; i < chain->NumPoints; ++i)
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{
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const FPoint *pt = &chain->Points[i];
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if (PointOnSide (pt, hullPts[1], hullPts[2]))
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{
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startSide = -1;
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continue;
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}
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if (PointOnSide (pt, hullPts[3], hullPts[0]))
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{
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startSide = -1;
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continue;
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}
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if (PointOnSide (pt, hullPts[0], hullPts[1]))
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{
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side = 0;
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}
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else if (PointOnSide (pt, hullPts[2], hullPts[3]))
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{
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side = 1;
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}
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else
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{
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continue;
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}
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if (startSide == -1 || startSide == side)
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{
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startSide = side;
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}
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else
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{
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return true;
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}
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}
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return false;
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}
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void FRejectBuilder::BuildReject ()
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{
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int s1, s2;
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for (s1 = 0; s1 < Level.NumSectors-1; ++s1)
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{
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printf (" Reject: %3d%%\r", s1*100/Level.NumSectors);
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for (s2 = s1 + 1; s2 < Level.NumSectors; ++s2)
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{
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BBox HullBounds;
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FPoint HullPts[4];
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const BBox *sb1, *sb2;
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sb1 = &SectorBounds[s1];
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sb2 = &SectorBounds[s2];
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int pos = s1*Level.NumSectors + s2;
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if (Reject[pos>>3] & (1<<(pos&7)))
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{
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continue;
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}
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// Overlapping and touching sectors are considered to always
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// see each other.
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if (sb1->Bounds[LEFT] <= sb2->Bounds[RIGHT] &&
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sb1->Bounds[RIGHT] >= sb2->Bounds[LEFT] &&
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sb1->Bounds[TOP] >= sb2->Bounds[BOTTOM] &&
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sb1->Bounds[BOTTOM] <= sb2->Bounds[TOP])
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{
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continue;
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}
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HullBounds(LEFT) = MIN (sb1->Bounds[LEFT], sb2->Bounds[LEFT]);
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HullBounds(RIGHT) = MAX (sb1->Bounds[RIGHT], sb2->Bounds[RIGHT]);
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HullBounds(BOTTOM) = MIN (sb1->Bounds[BOTTOM], sb2->Bounds[BOTTOM]);
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HullBounds(TOP) = MAX (sb1->Bounds[TOP], sb2->Bounds[TOP]);
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HullSides (*sb1, *sb2, HullPts);
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for (FBlockChain *chain = BlockChains; chain != NULL; chain = chain->Next)
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{
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if (ChainBlocks (chain, &HullBounds, HullPts))
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{
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break;
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}
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}
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if (chain == NULL)
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{
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continue;
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}
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Reject[pos>>3] |= 1 << (pos & 7);
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pos = s2*Level.NumSectors + s1;
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Reject[pos>>3] |= 1 << (pos & 7);
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}
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}
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printf (" Reject: 100%%\n");
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}
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