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BLADERUNNER: Alternate fix method for rare path finding assert faults
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Disabled by default. This one allows polygons merged on a single point.
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@antoniou79
antoniou79 committed Mar 9, 2019
1 parent 05dcd7f commit c60c0c9
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Showing 2 changed files with 38 additions and 20 deletions.
54 changes: 36 additions & 18 deletions engines/bladerunner/obstacles.cpp
View file
Expand Up @@ -33,6 +33,7 @@
#include "common/debug.h"

#define DISABLE_PATHFINDING 0
#define USE_PATHFINDING_EXPERIMENTAL_FIX_2 0 // Alternate Fix: Allows polygons merged on one point

#define WITHIN_TOLERANCE(a, b) (((a) - 0.009) < (b) && ((a) + 0.009) > (b))

Expand Down Expand Up @@ -107,7 +108,7 @@ bool Obstacles::lineLineIntersection(LineSegment a, LineSegment b, Vector2 *inte
return false;
}

bool Obstacles::linePolygonIntersection(LineSegment lineA, VertexType lineAType, Polygon *polyB, Vector2 *intersectionPoint, int *intersectionIndex) {
bool Obstacles::linePolygonIntersection(LineSegment lineA, VertexType lineAType, Polygon *polyB, Vector2 *intersectionPoint, int *intersectionIndex, int pathLengthSinceLastIntersection) {
bool hasIntersection = false;
float nearestIntersectionDistance = 0.0f;

Expand All @@ -126,15 +127,15 @@ bool Obstacles::linePolygonIntersection(LineSegment lineA, VertexType lineAType,
|| (lineAType == BOTTOM_LEFT && lineBType == BOTTOM_RIGHT)
|| (lineAType == TOP_LEFT && lineBType == BOTTOM_LEFT)
) {
if (!(WITHIN_TOLERANCE(lineB.end.x, intersectionPoint->x) && WITHIN_TOLERANCE(lineB.end.y, intersectionPoint->y))) {
if (newIntersectionPoint != *intersectionPoint) {
float newIntersectionDistance = getLength(lineA.start.x, lineA.start.y, newIntersectionPoint.x, newIntersectionPoint.y);
if (!hasIntersection || newIntersectionDistance < nearestIntersectionDistance) {
hasIntersection = true;
nearestIntersectionDistance = newIntersectionDistance;
*intersectionPoint = newIntersectionPoint;
*intersectionIndex = i;
}
if ( (pathLengthSinceLastIntersection > 2)
|| ( (!(WITHIN_TOLERANCE(lineB.end.x, intersectionPoint->x) && WITHIN_TOLERANCE(lineB.end.y, intersectionPoint->y)))
&& (newIntersectionPoint != *intersectionPoint) )) {
float newIntersectionDistance = getLength(lineA.start.x, lineA.start.y, newIntersectionPoint.x, newIntersectionPoint.y);
if (!hasIntersection || newIntersectionDistance < nearestIntersectionDistance) {
hasIntersection = true;
nearestIntersectionDistance = newIntersectionDistance;
*intersectionPoint = newIntersectionPoint;
*intersectionIndex = i;
}
}
}
Expand Down Expand Up @@ -191,6 +192,7 @@ bool Obstacles::mergePolygons(Polygon &polyA, Polygon &polyB) {
bool flagAddVertexToVertexList = true;
bool flagDidFindIntersection = false;
int vertIndex = 0;
int pathLengthSinceLastIntersection = 0; // Part of pathfinding fix 2. It's only updated when enabling that fix, otherwise it is always zero (0).

Polygon *startingPolygon = polyPrimary;
int flagDone = false;
Expand All @@ -204,12 +206,16 @@ bool Obstacles::mergePolygons(Polygon &polyA, Polygon &polyB) {
polyPrimaryType = polyPrimary->vertexType[vertIndex];

if (flagAddVertexToVertexList) {
// In some cases polygons will have only one intersection (touching corners) and because of that second SWAP never occure,
#if USE_PATHFINDING_EXPERIMENTAL_FIX_2
assert(polyMerged.verticeCount < kPolygonVertexCount);
#else
// In some cases polygons will have only one intersection (touching corners) and because of that second SWAP never occurs,
// algorithm will stop only when the merged polygon is full.
if (polyMerged.verticeCount >= kPolygonVertexCount) {
flagDidMergePolygons = false;
break;
}
#endif
polyMerged.vertices[polyMerged.verticeCount] = polyLine.start;
polyMerged.vertexType[polyMerged.verticeCount] = polyPrimaryType;
polyMerged.verticeCount++;
Expand All @@ -218,7 +224,7 @@ bool Obstacles::mergePolygons(Polygon &polyA, Polygon &polyB) {
flagAddVertexToVertexList = true;
int polySecondaryIntersectionIndex = -1;

if (linePolygonIntersection(polyLine, polyPrimaryType, polySecondary, &intersectionPoint, &polySecondaryIntersectionIndex)) {
if (linePolygonIntersection(polyLine, polyPrimaryType, polySecondary, &intersectionPoint, &polySecondaryIntersectionIndex, pathLengthSinceLastIntersection)) {
if (WITHIN_TOLERANCE(intersectionPoint.x, polyLine.start.x) && WITHIN_TOLERANCE(intersectionPoint.y, polyLine.start.y)) {
flagAddVertexToVertexList = false;
polyMerged.verticeCount--; // TODO(madmoose): How would this work?
Expand All @@ -231,8 +237,14 @@ bool Obstacles::mergePolygons(Polygon &polyA, Polygon &polyB) {
SWAP(polyPrimary, polySecondary);

flagDidMergePolygons = true;
#if USE_PATHFINDING_EXPERIMENTAL_FIX_2
pathLengthSinceLastIntersection = 0;
#endif
} else {
vertIndex = (vertIndex + 1) % polyPrimary->verticeCount;
#if USE_PATHFINDING_EXPERIMENTAL_FIX_2
pathLengthSinceLastIntersection++;
#endif
flagDidFindIntersection = false;
}
if (polyPrimary->vertices[vertIndex] == startingPolygon->vertices[0]) {
Expand Down Expand Up @@ -543,11 +555,13 @@ bool Obstacles::findPolygonVerticeByXZ(int *polygonIndex, int *verticeIndex, int
return false;
}

bool Obstacles::findPolygonVerticeByXZWithinTolerance(float x, float z, int *polygonIndex, int *verticeIndex) const {
bool Obstacles::findPolygonVerticeByXZWithinTolerance(float x, float z, int *polygonIndex, int *verticeIndex, int startSearchFromPolygonIdx) const {
*polygonIndex = -1;
*verticeIndex = -1;

for (int i = 0; i != kPolygonCount; ++i) {
// for (int i = 0; i != kPolygonCount; ++i) {
for (int countUp = 0, i = startSearchFromPolygonIdx; countUp != kPolygonCount; ++countUp, ++i) {
i = i % kPolygonCount; // we want to circle around to go through all polygons
if (!_polygons[i].isPresent || _polygons[i].verticeCount == 0) {
continue;
}
Expand Down Expand Up @@ -687,7 +701,7 @@ bool Obstacles::findFarthestAvailablePathVertex(Vector2 *path, int pathSize, Vec
int vertexTypeStartPrev = -1;
int polygonIndexStart = -1;
int vertexIndexStart = -1;
bool startOnPolygon = findPolygonVerticeByXZWithinTolerance(start.x, start.z, &polygonIndexStart, &vertexIndexStart);
bool startOnPolygon = findPolygonVerticeByXZWithinTolerance(start.x, start.z, &polygonIndexStart, &vertexIndexStart, 0);
if (startOnPolygon) {
int vertexIndexStartPrev = (vertexIndexStart - 1 + _polygons[polygonIndexStart].verticeCount) % _polygons[polygonIndexStart].verticeCount;

Expand All @@ -700,7 +714,7 @@ bool Obstacles::findFarthestAvailablePathVertex(Vector2 *path, int pathSize, Vec
bool foundVertexNeighbor = false;
int polygonIndexPath = -1;
int vertexIndexPath = -1;
bool pathVertexOnPolygon = findPolygonVerticeByXZWithinTolerance(path[pathVertexIdx].x, path[pathVertexIdx].y, &polygonIndexPath, &vertexIndexPath) == 1;
bool pathVertexOnPolygon = findPolygonVerticeByXZWithinTolerance(path[pathVertexIdx].x, path[pathVertexIdx].y, &polygonIndexPath, &vertexIndexPath, 0) == 1;

//start and current path vertices are on same polygon and are next to each other
if (pathVertexOnPolygon && polygonIndexStart == polygonIndexPath) {
Expand Down Expand Up @@ -748,8 +762,12 @@ bool Obstacles::findFarthestAvailablePathVertex(Vector2 *path, int pathSize, Vec

int polygonIndexIntersection = -1;
int vertexIndexIntersection = -1;
if (findPolygonVerticeByXZWithinTolerance(intersection.x, intersection.y, &polygonIndexIntersection, &vertexIndexIntersection)) {
// hntersection has to be vertex only on current polygon
if (findPolygonVerticeByXZWithinTolerance(intersection.x, intersection.y, &polygonIndexIntersection, &vertexIndexIntersection, currentPolygonIdx)) {
// Intersection has to be vertex only on current polygon
// Part of pathfinding fix 2 (dealing with merge on only one edge point)
// but also speeds up process:
// we start (a cyclical) searching in Polygons array
// beginning from the current polygon index
assert(polygonIndexIntersection == currentPolygonIdx);

if (verticesCanIntersect(vertexTypeStartPrev, vertexTypeStart, start.x, start.z, path[pathVertexIdx].x, path[pathVertexIdx].y)) {
Expand Down
4 changes: 2 additions & 2 deletions engines/bladerunner/obstacles.h
View file
Expand Up @@ -71,7 +71,7 @@ class Obstacles {
bool _backup;

static bool lineLineIntersection(LineSegment a, LineSegment b, Vector2 *intersectionPoint);
static bool linePolygonIntersection(LineSegment lineA, VertexType lineAType, Polygon *polyB, Vector2 *intersectionPoint, int *intersectionIndex);
static bool linePolygonIntersection(LineSegment lineA, VertexType lineAType, Polygon *polyB, Vector2 *intersectionPoint, int *intersectionIndex, int pathLengthSinceLastIntersection);

bool mergePolygons(Polygon &polyA, Polygon &PolyB);

Expand All @@ -93,7 +93,7 @@ class Obstacles {

float pathTotalDistance(const Vector2 *path, int pathSize, Vector2 from, Vector2 to) const;
bool findPolygonVerticeByXZ(int *polygonIndex, int *verticeIndex, int *verticeCount, float x, float z) const;
bool findPolygonVerticeByXZWithinTolerance(float x, float z, int *polygonIndex, int *verticeIndex) const;
bool findPolygonVerticeByXZWithinTolerance(float x, float z, int *polygonIndex, int *verticeIndex, int startSearchFromPolygonIdx) const;

void clearPath();
int buildNegativePath(int polyIndex, int vertStartIndex, Vector2 startPos, int vertEndIndex, Vector2 endPos, Vector2 *path, int pathCapacity, bool *pathBlocked);
Expand Down

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