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Fix a very rare crash with complex Polyobjects
If all of the worst stars align when compiling Polyobject BSP and splitting a seg into two sets: - The very first seg in the current set fails all of the metrics for determining which side of a split it is on, and doesn't know which side it should go to. Since there are 0 are in front, it goes to front by default. - Every other seg in the same set don't fail their metrics, and they all decide they are meant to go to the front side. - Oops! Now there's nothing in the back side! I've fixed this by collecting all of the undecided segs in a split, and setting the new side after the other segs. Doing it in the normal loop means there's a non-zero chance the crash prevention will fail depending on how the segs are in memory. This can technically happen with even the most simplistic Polyobjects, but it becomes more common the more complex it is (add tons of lines, move and rotate it at the same time, so on). Quite an annoying crash since it doesn't always replicate consistently.
This commit is contained in:
Sally Coolatta
Christoph Oelckers
parent
23b489960e
commit
15521e5181
2 changed files with 100 additions and 59 deletions
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@ -496,8 +496,9 @@ int FNodeBuilder::SelectSplitter (uint32_t set, node_t &node, uint32_t &splitseg
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}
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if (bestseg == UINT_MAX)
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{ // No lines split any others into two sets, so this is a convex region.
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D(Printf (PRINT_LOG, "set %d, step %d, nosplit %d has no good splitter (%d)\n", set, step, nosplit, nosplitters));
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{
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// No lines split any others into two sets, so this is a convex region.
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D(Printf (PRINT_LOG, "set %d, step %d, nosplit %d has no good splitter (%d)\n", set, step, nosplit, nosplitters));
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return nosplitters ? -1 : 0;
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}
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@ -752,6 +753,54 @@ int FNodeBuilder::Heuristic (node_t &node, uint32_t set, bool honorNoSplit)
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return score;
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}
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void FNodeBuilder::DoGLSegSplit (uint32_t set, node_t &node, uint32_t splitseg, uint32_t &outset0, uint32_t &outset1, int side, int sidev0, int sidev1, bool hack)
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{
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FPrivSeg *seg = &Segs[set];
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if (side >= 0 && GLNodes)
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{
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if (sidev0 == 0)
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{
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double dist1 = AddIntersection (node, seg->v1);
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if (sidev1 == 0)
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{
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double dist2 = AddIntersection (node, seg->v2);
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FSplitSharer share = { dist1, set, dist2 > dist1 };
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SplitSharers.Push (share);
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}
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}
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else if (sidev1 == 0)
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{
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AddIntersection (node, seg->v2);
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}
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}
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if (hack && GLNodes)
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{
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uint32_t newback, newfront;
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newback = AddMiniseg (seg->v2, seg->v1, UINT_MAX, set, splitseg);
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if (HackMate == UINT_MAX)
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{
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newfront = AddMiniseg (Segs[set].v1, Segs[set].v2, newback, set, splitseg);
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Segs[newfront].next = outset0;
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outset0 = newfront;
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}
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else
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{
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newfront = HackMate;
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Segs[newfront].partner = newback;
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Segs[newback].partner = newfront;
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}
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Segs[newback].frontsector = Segs[newback].backsector =
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Segs[newfront].frontsector = Segs[newfront].backsector =
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Segs[set].frontsector;
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Segs[newback].next = outset1;
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outset1 = newback;
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}
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}
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void FNodeBuilder::SplitSegs (uint32_t set, node_t &node, uint32_t splitseg, uint32_t &outset0, uint32_t &outset1, unsigned int &count0, unsigned int &count1)
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{
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unsigned int _count0 = 0;
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@ -760,14 +809,15 @@ void FNodeBuilder::SplitSegs (uint32_t set, node_t &node, uint32_t splitseg, uin
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outset1 = UINT_MAX;
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Events.DeleteAll ();
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UnsetSegs.Clear ();
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SplitSharers.Clear ();
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while (set != UINT_MAX)
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{
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bool unset = false;
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bool hack;
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FPrivSeg *seg = &Segs[set];
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int next = seg->next;
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int sidev[2], side;
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if (HackSeg == set)
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@ -844,73 +894,61 @@ void FNodeBuilder::SplitSegs (uint32_t set, node_t &node, uint32_t splitseg, uin
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}
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else
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{
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// all that matters here is to prevent a crash so we must make sure that we do not end up with all segs being sorted to the same side - even if this may not be correct.
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// But if we do not do that this code would not be able to move on. Just discarding the seg is also not an option because it won't guarantee that we achieve an actual split.
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if (_count0 == 0)
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{
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side = 0;
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seg->next = outset0;
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outset0 = set;
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_count0++;
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}
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else
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{
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side = 1;
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seg->next = outset1;
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outset1 = set;
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_count1++;
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}
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// Sal May 28 2023
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// If all of the worst stars align:
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// - The very first seg in the list doesn't know which side it should go to and makes it here. 0 are in front, so it goes to front.
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// - Literally every other seg in the list all want to go to the front side from the other metrics
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// - Oops! Now there's nothing in the back side!
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// So we need to collect these now and do them later, otherwise the crash prevention fails.
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UnsetSegs.Push(set);
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unset = true;
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}
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break;
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}
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if (side >= 0 && GLNodes)
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if (unset == false)
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{
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if (sidev[0] == 0)
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{
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double dist1 = AddIntersection (node, seg->v1);
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if (sidev[1] == 0)
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{
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double dist2 = AddIntersection (node, seg->v2);
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FSplitSharer share = { dist1, set, dist2 > dist1 };
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SplitSharers.Push (share);
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}
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}
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else if (sidev[1] == 0)
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{
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AddIntersection (node, seg->v2);
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}
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}
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if (hack && GLNodes)
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{
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uint32_t newback, newfront;
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newback = AddMiniseg (seg->v2, seg->v1, UINT_MAX, set, splitseg);
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if (HackMate == UINT_MAX)
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{
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newfront = AddMiniseg (Segs[set].v1, Segs[set].v2, newback, set, splitseg);
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Segs[newfront].next = outset0;
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outset0 = newfront;
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}
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else
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{
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newfront = HackMate;
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Segs[newfront].partner = newback;
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Segs[newback].partner = newfront;
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}
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Segs[newback].frontsector = Segs[newback].backsector =
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Segs[newfront].frontsector = Segs[newfront].backsector =
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Segs[set].frontsector;
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Segs[newback].next = outset1;
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outset1 = newback;
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DoGLSegSplit (set, node, splitseg, outset0, outset1, side, sidev[0], sidev[1], hack);
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}
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set = next;
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}
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for (unsigned int i = 0; i < UnsetSegs.Size(); ++i)
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{
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uint32_t unsetID = UnsetSegs[i];
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FPrivSeg *seg = &Segs[unsetID];
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int sidev[2], side;
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side = ClassifyLine (node, &Vertices[seg->v1], &Vertices[seg->v2], sidev);
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// all that matters here is to prevent a crash so we must make sure that we do not end up with all segs being sorted to the same side - even if this may not be correct.
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// But if we do not do that this code would not be able to move on. Just discarding the seg is also not an option because it won't guarantee that we achieve an actual split.
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if (_count0 == 0)
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{
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side = 0;
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seg->next = outset0;
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outset0 = unsetID;
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_count0++;
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}
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else
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{
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side = 1;
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seg->next = outset1;
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outset1 = unsetID;
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_count1++;
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}
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DoGLSegSplit (unsetID, node, splitseg, outset0, outset1, side, sidev[0], sidev[1], false);
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}
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FixSplitSharers (node);
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if (GLNodes)
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{
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AddMinisegs (node, splitseg, outset0, outset1);
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}
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assert(_count0 != 0 && _count1 != 0);
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count0 = _count0;
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count1 = _count1;
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}
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@ -269,6 +269,7 @@ private:
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TArray<int> Colinear; // Loops with edges colinear to a splitter
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FEventTree Events; // Vertices intersected by the current splitter
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TArray<uint32_t> UnsetSegs; // Segs with no definitive side in current splitter
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TArray<FSplitSharer> SplitSharers; // Segs colinear with the current splitter
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uint32_t HackSeg; // Seg to force to back of splitter
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@ -294,7 +295,9 @@ private:
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void CreateSubsectorsForReal ();
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bool CheckSubsector (uint32_t set, node_t &node, uint32_t &splitseg);
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bool CheckSubsectorOverlappingSegs (uint32_t set, node_t &node, uint32_t &splitseg);
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bool ShoveSegBehind (uint32_t set, node_t &node, uint32_t seg, uint32_t mate); int SelectSplitter (uint32_t set, node_t &node, uint32_t &splitseg, int step, bool nosplit);
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bool ShoveSegBehind (uint32_t set, node_t &node, uint32_t seg, uint32_t mate);
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int SelectSplitter (uint32_t set, node_t &node, uint32_t &splitseg, int step, bool nosplit);
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void DoGLSegSplit (uint32_t set, node_t &node, uint32_t splitseg, uint32_t &outset0, uint32_t &outset1, int side, int sidev0, int sidev1, bool hack);
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void SplitSegs (uint32_t set, node_t &node, uint32_t splitseg, uint32_t &outset0, uint32_t &outset1, unsigned int &count0, unsigned int &count1);
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uint32_t SplitSeg (uint32_t segnum, int splitvert, int v1InFront);
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int Heuristic (node_t &node, uint32_t set, bool honorNoSplit);
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