Bug in rcFilterLedgeSpans causing voxels along walls to be filtered too?

[charlesj...@gmail.com]

Line 144 checks the abs of the span differences and compares it to walkableClimb.  This will cause it to filter ledges as well as up against a wall.  This seems like a bug as the point of this function is to erode away from ledges and prevent AI from going off of them.

I have locally edited this code to the below and have found the results to be quite good:
if ((nbot - bot) <= -walkableClimb)

This ensures that we only track asmin and asmax when there is a dropoff, not the edge of a wall.

Has anyone else ran into this?

[Evgeny Adamenkov]

> Line 144 checks the abs of the span differences and compares it to walkableClimb.  This will cause it to filter ledges as well as up against a wall.

As far as I can see, this is not what is happening there, and also the comment in line 79 is not correct (/// A span is a ledge if: <tt>rcAbs(currentSpan.smax - neighborSpan.smax) > walkableClimb</tt>).

Only ledges are filtered, in lines 154-159, just like what you want:

// 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;
}

Remember that minh is updated in line 141 (minh = rcMin(minh, nbot - bot);)

So basically the code is already doing what you want, despite the misleading comment in line 79.

The lines 144-148 are not about ledge voxels, they are about too much difference in (the level of) accessible neighbours, for a situation like this:

--

  |

  |

  -X-

      |

      L

where the voxel X is in the middle of a steep slope.  With your proposed change, only dropoffs will be considered, so the code will only be able to catch sharp peaks, like this:

  X

 | |

 | |

|   |

(as far as I can tell).

Evgeny

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