not sure I understand your answer, even though I must have read it more than 5 times
What do you mean by “agent never moves over the nodes that have a penalty if it moves diagonally like that.”?
The agent does move over nodes with penalties diagonally, but it should not, correct? It should behave like in any other scenario it is not suppose to move over the nodes (e.g. they are not traversable).
How to make so the agent cannot move diagonally as shown in the picture?
Unwanted behaviour
Expected behaviour:
when using only penalties on blue nodes in the picture
So if I understand correctly, the grid graph is just unusable when using penalties? Since if agents cross diagonally, it defeats the entire purpose of grid tiles.
I’ve been thinking about this.
So the main issue is that by going diagonally, the agent never actually moves over the nodes you have added penalties to. Currently, there’s no out of the box way to change this behavior.
However, I did come up with a solution, but it requires a minor change to the code.
If you open the GridNode.cs script, there should be a comment saying:
// Check if the other node has not yet been visited by this path
Right before that comment, add this snippet of code:
if (dir >= 4) {
// Get the two axis aligned neighbours that we are moving between
var d1 = dir - 4;
var d2 = (dir - 4 + 1) % 4;
var n1 = this.GetNeighbourAlongDirection(d1);
var n2 = this.GetNeighbourAlongDirection(d2);
// Theroretically reasonable scaling factor.
// This will make moving diagonally across a grid of nodes with penalties
// equally costly per unit of distance as moving in an axis aligned direction.
const float SQRT2_MINUS_1 = 0.414213f;
if (n1 != null) tmpCost += (uint)(path.GetTraversalCost(n1) * (SQRT2_MINUS_1 * 0.5f));
if (n2 != null) tmpCost += (uint)(path.GetTraversalCost(n2) * (SQRT2_MINUS_1 * 0.5f));
}
Thank you @aron_granberg very much! I cannot test this, as we are using the beta of the pathfinding and have your asset only as a manifest package, thus the code cannot be edited. Not sure how hard it is, but would you be able to deploy this addition to the beta? Maybe adding some optional flag into the grid graph?
Such a functionality seems like a common usage for many devs using grids.
What you can do is just copy and paste the package into your project for testing. Take a look at this page: Unity - Manual: Embedded dependencies under the Copying a Unity package from the cache section. Move it to Assets/AstarPathfindingProject.
Let me know how it works for you and maybe I’ll include it in the main package.
@aron_granberg big thanks for all your help! The provided solution works like a charm.
Would it be possible now to add it into an official beta release? Maybe like an option somwehere? Since the code is changed just manually, updating the package any time in the future would always just rewrite this fix.
Helo @aron_granberg, not sure if you remember this issue, but the fix code provided by you no longer works with the newest BETA version.
Is there any way how to fix this issue again? Or has it been maybe implemented as some flag?
uint cost = neighbourCosts[dir];
if (dir >= 4) {
// Get the two axis aligned neighbours that we are moving between
var d1 = dir - 4;
var d2 = (dir - 4 + 1) % 4;
var n1 = this.GetNeighbourAlongDirection(d1);
var n2 = this.GetNeighbourAlongDirection(d2);
// Theroretically reasonable scaling factor.
// This will make moving diagonally across a grid of nodes with penalties
// equally costly per unit of distance as moving in an axis aligned direction.
const float SQRT2_MINUS_1 = 0.414213f;
if (n1 != null) cost += (uint)(path.GetTraversalCost(n1) * (SQRT2_MINUS_1 * 0.5f));
if (n2 != null) cost += (uint)(path.GetTraversalCost(n2) * (SQRT2_MINUS_1 * 0.5f));
}
path.OpenCandidateConnection(pathNodeIndex, other.NodeIndex, gScore, cost, 0, other.position);
Please, would you officially support this as some boolean flag on grid graph or agents? Because I imagine many other people would want to enable this functionality, and now its only possible to do this manually after every upgrade.
I still have to make official request for this feature to be as some optional UI toggle in the grid graph settings.
Because now, we have to each time manually update the package, copy it as embedded package, find this class and replace the code, if you change the class, it will not longer work as well.
I presume this setting could be used by other users.
We really need your support in this issue.