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Code cleanup and small optimizations in RecastFilter.cpp rcFilterLedgeSpans (https://github.com/recastnavigation/recastnavigation/pull/672) 

- 3e94c3b6fc

* Code cleanup and minor refactor in RecastFilter.cpp rcFilterLedgeSpans

Because span.smax is always > 0, bot > 0 as well, and (-walkableClimb - bot) is always < -walkableClimb. Furthermore, as long as minNeighborHeight < -walkableClimb' at least once, there is no need to continue the traversal.

* Code cleanup and minor refactor in RecastFilter.cpp rcFilterLedgeSpans

Because span.smax is always > 0, bot > 0 as well, and (-walkableClimb - bot) is always < -walkableClimb. Furthermore, as long as minNeighborHeight < -walkableClimb' at least once, there is no need to continue the traversal.

* Update RecastFilter.cpp

Revise Comment
This commit is contained in:
ikpil 2024-01-01 14:10:57 +09:00 committed by Ikpil
parent 2d36b5f639
commit 9d01b5243f
1 changed files with 49 additions and 38 deletions
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101
src/DotRecast.Recast/RcFilters.cs
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@ -84,70 +84,79 @@ namespace DotRecast.Recast
/// A span is a ledge if: <tt>RcAbs(currentSpan.smax - neighborSpan.smax) > walkableClimb</tt>
///
/// @see rcHeightfield, rcConfig
public static void FilterLedgeSpans(RcTelemetry ctx, int walkableHeight, int walkableClimb, RcHeightfield solid)
public static void FilterLedgeSpans(RcTelemetry ctx, int walkableHeight, int walkableClimb, RcHeightfield heightfield)
{
using var timer = ctx.ScopedTimer(RcTimerLabel.RC_TIMER_FILTER_BORDER);
int w = solid.width;
int h = solid.height;
int xSize = heightfield.width;
int zSize = heightfield.height;
// Mark border spans.
for (int y = 0; y < h; ++y)
for (int z = 0; z < zSize; ++z)
{
for (int x = 0; x < w; ++x)
for (int x = 0; x < xSize; ++x)
{
for (RcSpan s = solid.spans[x + y * w]; s != null; s = s.next)
for (RcSpan span = heightfield.spans[x + z * xSize]; span != null; span = span.next)
{
// Skip non walkable spans.
if (s.area == RC_NULL_AREA)
continue;
int bot = (s.smax);
int top = s.next != null ? s.next.smin : SPAN_MAX_HEIGHT;
// Find neighbours minimum height.
int minh = SPAN_MAX_HEIGHT;
// Min and max height of accessible neighbours.
int asmin = s.smax;
int asmax = s.smax;
for (int dir = 0; dir < 4; ++dir)
if (span.area == RC_NULL_AREA)
{
int dx = x + GetDirOffsetX(dir);
int dy = y + GetDirOffsetY(dir);
// Skip neighbours which are out of bounds.
if (dx < 0 || dy < 0 || dx >= w || dy >= h)
{
minh = Math.Min(minh, -walkableClimb - bot);
continue;
}
int bot = (span.smax);
int top = span.next != null ? span.next.smin : SPAN_MAX_HEIGHT;
// Find neighbours minimum height.
int minNeighborHeight = SPAN_MAX_HEIGHT;
// Min and max height of accessible neighbours.
int accessibleNeighborMinHeight = span.smax;
int accessibleNeighborMaxHeight = span.smax;
for (int direction = 0; direction < 4; ++direction)
{
int dx = x + GetDirOffsetX(direction);
int dz = z + GetDirOffsetY(direction);
// Skip neighbours which are out of bounds.
if (dx < 0 || dz < 0 || dx >= xSize || dz >= zSize)
{
minNeighborHeight = (-walkableClimb - 1);
break;
}
// From minus infinity to the first span.
RcSpan ns = solid.spans[dx + dy * w];
int nbot = -walkableClimb;
int ntop = ns != null ? ns.smin : SPAN_MAX_HEIGHT;
RcSpan neighborSpan = heightfield.spans[dx + dz * xSize];
int neighborTop = neighborSpan != null ? neighborSpan.smin : SPAN_MAX_HEIGHT;
// Skip neightbour if the gap between the spans is too small.
if (Math.Min(top, ntop) - Math.Max(bot, nbot) > walkableHeight)
minh = Math.Min(minh, nbot - bot);
if (Math.Min(top, neighborTop) - bot >= walkableHeight)
{
minNeighborHeight = (-walkableClimb - 1);
break;
}
// Rest of the spans.
for (ns = solid.spans[dx + dy * w]; ns != null; ns = ns.next)
for (neighborSpan = heightfield.spans[dx + dz * xSize]; neighborSpan != null; neighborSpan = neighborSpan.next)
{
nbot = ns.smax;
ntop = ns.next != null ? ns.next.smin : SPAN_MAX_HEIGHT;
int neighborBot = neighborSpan.smax;
neighborTop = neighborSpan.next != null ? neighborSpan.next.smin : SPAN_MAX_HEIGHT;
// Skip neightbour if the gap between the spans is too small.
if (Math.Min(top, ntop) - Math.Max(bot, nbot) > walkableHeight)
if (Math.Min(top, neighborTop) - Math.Max(bot, neighborBot) >= walkableHeight)
{
minh = Math.Min(minh, nbot - bot);
int accessibleNeighbourHeight = neighborBot - bot;
minNeighborHeight = Math.Min(minNeighborHeight, accessibleNeighbourHeight);
// Find min/max accessible neighbour height.
if (MathF.Abs(nbot - bot) <= walkableClimb)
if (MathF.Abs(accessibleNeighbourHeight) <= walkableClimb)
{
if (nbot < asmin)
asmin = nbot;
if (nbot > asmax)
asmax = nbot;
if (neighborBot < accessibleNeighborMinHeight) accessibleNeighborMinHeight = neighborBot;
if (neighborBot > accessibleNeighborMaxHeight) accessibleNeighborMaxHeight = neighborBot;
}
else if (accessibleNeighbourHeight < -walkableClimb)
{
break;
}
}
}
@ -155,14 +164,16 @@ namespace DotRecast.Recast
// The current span is close to a ledge if the drop to any
// neighbour span is less than the walkableClimb.
if (minh < -walkableClimb)
s.area = RC_NULL_AREA;
if (minNeighborHeight < -walkableClimb)
{
span.area = RC_NULL_AREA;
}
// If the difference between all neighbours is too large,
// we are at steep slope, mark the span as ledge.
if ((asmax - asmin) > walkableClimb)
if ((accessibleNeighborMaxHeight - accessibleNeighborMinHeight) > walkableClimb)
{
s.area = RC_NULL_AREA;
span.area = RC_NULL_AREA;
}
}
}