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Fix the CheckLineMovement algorithm. Added some comments and a test to avoid problems.

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This addresses some "stuck units" cases.

This was SVN commit r16918.
This commit is contained in:
Nicolas Auvray 2015-08-13 16:21:39 +00:00
parent 01de76f4be
commit 1c9ea56800
1 changed files with 15 additions and 4 deletions
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19
source/simulation2/helpers/Pathfinding.h
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@ -171,8 +171,8 @@ namespace Pathfinding
// vice versa).
u16 i0, j0, i1, j1;
Pathfinding::NearestNavcell(x0, z0, i0, j0, grid.m_W, grid.m_H);
Pathfinding::NearestNavcell(x1, z1, i1, j1, grid.m_W, grid.m_H);
NearestNavcell(x0, z0, i0, j0, grid.m_W, grid.m_H);
NearestNavcell(x1, z1, i1, j1, grid.m_W, grid.m_H);
// Find which direction the line heads in
int di = (i0 < i1 ? +1 : i1 < i0 ? -1 : 0);
@ -185,6 +185,11 @@ namespace Pathfinding
while (true)
{
// Make sure we are still in the limits
ENSURE(
((di > 0 && i0 <= i && i <= i1) || (di < 0 && i1 <= i && i <= i0) || (di == 0 && i == i0)) &&
((dj > 0 && j0 <= j && j <= j1) || (dj < 0 && j1 <= j && j <= j0) || (dj == 0 && j == j0)));
// Fail if we're moving onto an impassable navcell
bool passable = IS_PASSABLE(grid.get(i, j), passClass);
if (passable)
@ -197,12 +202,13 @@ namespace Pathfinding
return true;
// If we can only move horizontally/vertically, then just move in that direction
if (di == 0)
// If we are reaching the limits, we can go straight to the end
if (di == 0 || i == i1)
{
j += dj;
continue;
}
else if (dj == 0)
else if (dj == 0 || j == j1)
{
i += di;
continue;
@ -217,6 +223,11 @@ namespace Pathfinding
// navcell, we simply need to test that the edge's endpoints are not both on the
// same side of the line.
// If we are crossing exactly a vertex of the grid, we will get dota or dotb equal
// to 0. In that case we arbitrarily choose to move of dj.
// This only works because we handle the case (i == i1 || j == j1) beforehand.
// Otherwise we could go outside the j limits and never reach the final navcell.
entity_pos_t xia = entity_pos_t::FromInt(i).Multiply(Pathfinding::NAVCELL_SIZE);
entity_pos_t xib = entity_pos_t::FromInt(i+1).Multiply(Pathfinding::NAVCELL_SIZE);
entity_pos_t zj = entity_pos_t::FromInt(j + (dj+1)/2).Multiply(Pathfinding::NAVCELL_SIZE);