Height testing not working on specific computers

General Grid graph
1
  • A* version: [5.4.4]
  • Unity version: [6000.0.59f2]

Hi there! :slight_smile:

I am using a single grid graph for my project. The graph itself is relatively simple, as I just have a flat, walkable surface on the “Tile“ layer, and obstacles on the “Obstacle“ and “Structure“ layers. The graph settings are visible on the screenshots below.

Everything worked well on my computer, but when testing the game on a different laptop, the height testing did not work at all, leading to no ground being detected. This issue also persists in builds.

I then tested the project with identical settings on multiple PCs and laptops. On five different PCs, the graph scanning and height testing worked normally, but on two laptops, it again didn’t. The laptops have better hardware than some of the tower PCs I used, so computing power does not seem to be the issue.

To better understand the problem, I created a testing scene with a plane and four cubes on the corresponding “Tile“ and “Structure“ layers. Below, I have included multiple screenshots of the same situation on multiple computers that illustrate the issue.

These are the computers used for the example:

A) Tower PC (height testing works)
CPU: AMD Ryzen 7 7800X3D
GPU: NVIDIA GeForce RTX 4070 SUPER
RAM: 32GB
OS: Windows 11

B) Laptop (height testing doesn’t work)
CPU: Intel i9-13900HX
GPU: NVIDIA GeForce RTX 4070 Laptop GPU
RAM: 32GB
OS: Windows 11

1A&B) Height testing disabled (until here, the computers behave identically)

image
image1533×652 399 KB

2A) Height testing enabled

image
image1531×652 397 KB

2B) Height testing enabled (ground is unwalkable, even though “unwalkable when no ground“ checkmark is set to false)

image
image1536×650 303 KB

3A) “Unwalkable when no ground“ set to true

image
image1532×652 444 KB

3B) “Unwalkable when no ground“ set to true (everything is unwalkable, ground on “Tile“ layer is still not detected)

image
image1542×648 341 KB

No matter what I try, as soon as I enable height testing on some computers, the ground is not detected. These are the options I tried:

  • shifting the graph slightly op and down
  • changing the ray length and using thick raycast
  • using different layers
  • using different grid graph shapes

If I have not missed something obvious, this seems to be some kind of hardware-related issue, and I am really at my wit’s end. Not knowing if the game will run at all depending on the computer is really scary, so I really hope this issue can be solved :smiley:

Thank you so much in advance!

Luca

2

Hi

It looks like potentially a floating point edge case. Have you tried setting the center of the graph (not the pivot of the a* object) to something like -0.01 to see if that makes it consistent across computers?

3

Hi,

thank you for your quick reply! Yes, I read about the floating point errors in another discussion and tried moving the A* center up and down, but that did not change anything.

Yesterday, a friend tried it on his laptop, and it also did not work. Right now, all 6 tower PCs work, and all 3 laptops don’t. I don’t know how that would make sense, but currently, it’s pretty consistent between tower PCs and laptops.

4

I see you have Max Slope set to 0. This could potentially lead to floating point issues even if the surfaces are exactly horizontal. I should fix this so that 0 actually means it’s clamped to a small value like 0.001.

Try to set Max Slope to 0.001 or larger.

5

Yes, that fixed it! Now it works perfectly, thank you so much! :smile:

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