Traceline Problem

[Thongs]

I've had Traceline implemented for a while to help my flying navigation, and have tracked down a serious problem that I'm having with it. Sometimes, if Traceline is being called while my character is updating his movement, it will return NoCollision instead of Collision (when there is clearly a collision).

To test this: I put one static location on one side of a tree, and another static location on the other side of the tree. Then, I called Traceline every frame, printing the result. When I stand completely still, it constantly returns "Collision" as it should. However, when I hold my mouse button down and rapidly look around (back and fourth, basically just spinning my mouse), it sporadically returns NoCollision. I'd say that when I'm spinning my mouse as fast as I can, about 10% of the time it'll return NoCollision. This occurs whether I use my right mouse button or left mouse button.

Also, I've found that when this occurs, it doesn't matter how many times I've called Traceline. Even if I set three different static locations that should all return Collision, all three will bug out simultaneously when I'm spinning my mouse.

Any thoughts on how to fix this? I suppose that I could simply call Traceline several times of a few frames, but that's quite messy and I'd obviously prefer not to.

[boredevil]

i´s got to do with your camera/facing/what you see on screen.
tracelines in front of your char are pretty accurate, but trees and smaller stuff starts getting ignored if you go like 50 - 60 yards infront of you.
if you traceline behind your char, it´s even worse. depending on your cameraposition/fov it sometimes starts failing 10yards away.

if you for example look against a wall. and want to traceline the area behind the wall, it will just ignore small stuff like tables, as long you can´t see em. even if you are just 2 yards away...
step to the side so you can see the table through the door, and traceline will take it into account again

[-Ryuk-]

I use this method for flying navigation, and have no issues...

You might want to check your code

[andy2002ua]

I found the same problem. Apparently, Traceline called from EndScene didn't working correctly. I think it's because in EndScene time WoW already changed some internal variables associated with the position of the camera in the next frame.

I faced with the problem of tracking objects out of sight too (chairs, boxes, etc.). It seems that WoW loads those objects as needed, and after it, further calls of Traceline are working fine, even if the object is not seen again.

Did anyone managed to solve these problems? Is there a way to force Wow load invisible objects? Is there a way to force Traceline work correct in motion?

Sorry for bad English.

[Frosttall]

Are you sure that you're using the correct flags? I have no problems with TraceLine and I'm not calling it in EndScene, but that shouldn't matter.

[andy2002ua]

I'm sure. I did a lot of tests with the visualization of TraceLine and it clearly shows that when the trace is in close proximity to an object, when the camera moves, the trace returns the intersection. But from where you calling TraceLine?