physic cube entering physic volume

[YouGroove]

Hi,

 

I have some 2.5D prorotype, i use PhysicsSetPosition.

The problem is the charcater have a box collision and moving it in direction to a cube it will go trhought that cube volume, and we should expect collision to prevent that.

 

 

How to test :

- create a new project

- dezip files

- place 25D.lua in "Scripts/objects/Player" folder

- place 25D.map in "Map" folder

 

Use Q and D to move the character, and keep Q down continuously to make the character going left to the big cube , it will go inside and move throught the left big cube after some second.

25D.zip

[Josh]

This is pretty much how I would expect it to act. You're applying very very large forces to the body. Is there a reason you're not using the character controller for this?

[YouGroove]

Yes , it was to keep constraint axis, i mean moving objects only on X and Y like many 2.5 D games.

I didnt' know it worked using big forces.

 

So i see two solutions :

- using some raycast at diffrent height from player center to direction it is facing and stop calling PhysicsSetposition if the ray hits something and player is near

- stop calling PhysicsSetPosition if character is in collision with Level geometry

[Josh]

I would use the player controller and just call SetInput to move it back towards the center if the z value is non-zero. You can probably even just call entity->SetPosition(x,y,0.0) safely since the player controller doesn't use "real" physics.

[YouGroove]

The problem with character controller it will always go a little front or back in Z , while a real XY constraint system there is not possible to have any move on Z. But i agree using SetPosition could be a way.

[Josh]

You can also manually position the visual mesh at the XY position of the character, with Z set to 0.

[YouGroove]

Using a character controller , if it collides with a barrel while walking , it will go on the sides with Z values to avoid the obstacle and continue forward on X.

While we want the character physics to always stay at Z=0 and push the barrel that itself could not move in Z axis and also stay on Z=0.

 

So the only way is PhysicsSetPosition() combined with Raycast or collision detection with obstacle to stop moving.

[Josh]

Maybe your barrel should be set up on a hinge joint or something so that it only rotates around the z axis. I would think for 2D physics you would want this behavior anyways.

 

Hmmm, a hinge joint that only affected rotation would be very useful. We actually have something like that already in Newton.

[YouGroove]

Maybe your barrel should be set up on a hinge joint or something so that it only rotates around the z axis.

I'm not sure as the barrel should be able to be pushed or thrown anywhere on space, it would only not move on 2 axis.

And workflow would be longer creating physic joints for every object that could be dynamic.

 

I just found the solution that works for 2.5D physics constraint on Z for physic objects

 

function Script:UpdateWorld()

local vel = self.entity:GetVelocity(true)
if vel.z > 0 or vel.z < 0 then

vel.z = 0
self.entity:SetVelocity(vel,true)
end


end

 

Some 2.5D character controller could be using SetVelocity on X , combined with AddForce() for jumping, and perhaps some collision or ray detection for special cases.

[Josh]

I'm not sure as the barrel should be able to be pushed or thrown anywhere on space, it would only not move on 2 axis.

That's what 2D physics is. I think for puzzles this would be the desired behavior.