The Problem: Mesh colliders on some rigidbody objects are passing through colliders on other objects.
Things I have tried:
With the assumption A is a GameObject with a RigidBody attached and B is a normal GameObject with a collider.
Give A a convex mesh collider
Give A a non-convex mesh collider
Give B a convex mesh collider
Give B a non-convex mesh collider
give B a box collider
give B a convex mesh and box collider
give B a non-convex mesh and box collider
Adjusting the weight of the rigidbody
I have tried all of these in all combinations of A and B.
In addition,
Colliders are not marked as triggers
All objects are on the default layer (0)
Checking isKinematic; doing this seemed to make gravity stop affecting the object, so I have left it as false.
Constraints: I want A to use a mesh collider since most of the objects involved are moderately complex, and fitting other colliders to them would take a while.
Weird Behaviour: I have some objects with both rigidbody and convex mesh collider where the collision is working fine with a non-convex mesh collider. This is inconsistent with other gameobjects. The objects have all of the same settings.
I am using unity version 2019.3.11f1 if that is relevant.
The object being used are from this package. Specifically, the filing cabinet with rigidbodies on the drawers works fine. The desk, office chair, pen, and open laptop all fall through the "floor" (a cube with all of the above colliders tested on it).
Do you have 'isKinematic' checked on the objects with rigidbodies that are going through other colliders? If so uncheck it so that external forces affect it.
edit you also need to click convex on the mesh colliders if they are colliding with other mesh colliders, Convex Mesh Colliders are limited to 255 triangles, are the objects that are not passing through have more than 255 triangles in geometry?
I am Assuming you have set your Collision Detection to Discrete In your gameObject's RigidBody, if so, please make sure to select Collision Detection to Continuous In your gameObject's RigidBody.
Reason Why this is not working
You are trying to use collision that has (speed > your Computer's frame speed) so, the frame is not catching the collider properly some time catches and some time fails to catch.
You are moving your GameObjects with tranform.translate or position etc. If so then make sure to use Rigidbody Related function for Positioning, rotating.
Solution Image For First Problem
I'm assuming
-you game object which contain the mesh component is very small ( bellow 0.7 size(x,y,z) so the game engine is little difficult to detect it)
and also
for the colliding objects at-least one rigid-body component must be attach to one object
This seems to be a common big problem, and I have been struggling with the same issue for days, and have finally fixed it, so am feeling like I should highlight one important thing:
move Rigidbody via MovePosition, not via just changing its position field directly, nor via changing position of GameObject holding it.
Changing position via "wrong" ways will "teleport" your rigidbody, physics won't fully work on it in that case.
Related
I'm using Unity 2019.4.2f1 personal
I'm getting exception :
Non-convex MeshCollider with non-kinematic Rigidbody is no longer supported since Unity 5.
If you want to use a non-convex mesh either make the Rigidbody kinematic or remove the Rigidbody component. Scene hierarchy path
I have a parent GameObject with some components including a Rigidbody :
Then there are some children of this parent and somewhere inside there is this child name NAVI and all the polySurface34 children of NAVI have a Mesh Collider with Convex unchecked option.
I know that if I uncheck and disable the Mesh Collider on all the polySurface34 objects it will make the error exception to be gone but I'm not sure if this is the right solution if at all.
As the issue says, you can't use non-convex mesh colliders with non-kinematic rigidbodies anymore.
AFAIK this can be solved in at least these 2 ways:
Use a convex mesh collider, which will be less accurate but actually work
Use multiple primitive colliders (this is usually the best solution for player/humanoids) as it's efficient and you can place the colliders on the rig itself and they will move with your animations
Attached is a visualization of the hitboxes of one of the characters from Overwatch.
As you can see, they use multiple sphere & capsule colliders to approximate the character (notice that it's also slightly larger than the actual model, this is a game design choice to make hitting a character easier/harder).
Also note that the red capsule in the middle is used to very efficiently identify critical headshots; and this is another advantage of using multiple colliders vs. a mesh collider for characters
I have a mesh that updates it's shape according to the user's input, how can I get the collider to match the new shape of the mesh ?
As an important note : the mesh is always always convex ( no exceptions ). I saw that it is important in order for the collider to work properly.
I have found the following video that does it here but the collider is simply erased and recalculated for each frame by doing meshCollider.sharedMesh = null and then meshCollider.sharedMesh = updatedMesh.
Since I am already calculating the position of each vertex, edge and triangle of my mesh, is it possible to me to use those values for the mesh collider ?
No way to do it as colliders do not have constructors for this. What you are doing is explicitly frowned upon in unity docs
'You should not modify mesh geometry that is used for colliders because the physics engine has to rebuild an internal mesh collision acceleration structure every time you change the mesh. This causes a substantial performance overhead. For meshes that need to collide and change at runtime, it is often better to approximate the mesh shape with primitive colliders like capsules, spheres and boxes.'
One work around is to use InvokeRepeating on your method and create the new mesh collider every second instead of every frame (you can test and make it 0.1 second , 2 second, whatever can run without frame drops). You can call CancelInvoke when the object is done shifting.
How to get/generate a proper mesh collider in Unity using a model exported from Blender (.obj/.fbx)?
This is my second day using Blender and I'm hitting a roadblock. I've tried fiddling with the Rigid Body Collisions, i.e., setting "Shape" to Convex Hull and "Source" to Final/Deformed (Blender docs specify that these two settings capture modifiers), I've tried "Generate Colliders" inside Unity and the mesh collider always comes out as above. A box.
How to assign mesh collider to the exact mesh? I started with a circle and used a boolean modifier to create the cutout. Desire is to have the mesh collider around the mesh exactly, meaning no collider on the cutout. How to do this?
Make sure you have a Mesh Collider component on your object with the correct mesh set. Watch out for the convex parameter for flat objects, as it can sometimes fail and give you a box collider instead.
Edit:
I just noticed you said you were using a RigidBody, which means you need to have Convex set. A solution to this is to make a second mesh in Blender with a third dimension to it, then set the flat one on the Mesh Filter and the one with thickness to the Mesh Collider.
In importing a .obj or a .fbx, select the asset. make sure you have generate colliders selected.
Here I have imported an FBX into unity, but there are no colliders.
Sellect the asset, and turn on generate colliders if you want a collider around the mesh:
So when using rigidbody physics on a 2d sphere and a spinning animated 2d rectangle it only pushes the sphere aside when it collides. What I'm wanting is the sphere to fly off when collided (don't ask if it's if it's a problem with it colliding or not).
I've tried the physics materials and adjusting the rigidbody and such but nothing works. There's not a single thing online about it so attempting to code physics would be very difficult.
If I understand correctly.
You could apply AddForce or AddForceAtPosition function with ForceMode.Impulse argument to sphere when Collider2D.OnCollisionEnter2D(Collision2D) event trigger.
Or Just modify sphere speed when Collider2D.OnCollisionEnter2D(Collision2D) event trigger.
Note that Collision2D have contacts and relativeVelocity which may help you calc the force vector.
Hello Peeps (first post yay).
I have just started to learn about unity and still going through various tutorials and learning the interface along with C#.
I am running Unity 4 and downloaded a free asset from the Unity store:
https://www.assetstore.unity3d.com/#/content/3174
The Problem.
I created a Plane in Unity.
Went to the Character and created colliders and imported it as a humanoid.
Then added a rigid body = The character fell through the plane
I then added a Mesh collider and attached the mesh for the character to the collider. The mesh does NOT align correctly to the character = the character fell through the plane.
I then tried box and capsule colliders and they worked fine. Attached these and the character would not fall through.
I then tried a character controller = Character did not fall through.
I want to have an accurate mesh for this test character so when an enemy hits him, there is an actual hit.
I have tried several other free characters from the store and they all have the same problem. Can someone please tell me how I can fix this? It seems I just either doing something completely wrong, missing a step or just plain lost.
Link below to image of the issue taken:
Using a mesh collider on a skinned, animated character is a wrong approach. Mesh colliders are generally used for environment geometry and rigid objects. This is all due to the amount of work it is needed for the Unity engine to accurately calculate the shape of the mesh collider, based on the provided mesh. More triangles means more work, and for the reasonably complex low poly character mesh of 10k to 30k triangles it is clear that the fps would most definitely drop to an unplayable level.
For our game we are using all primitive colliders, distributed on the adequate bone game objects. So, head bone has a sphere collider, spine has a box collider (for lungs), forearm has a capsule collider etc. That way,with a little bit of scripting, you can detect a hit and know exactly what part of body is damaged.
If your collider doesn't exactly match your mesh, then it's likely that you have the mesh applied to the wrong part of the object.
Try applying the Mesh Collider to the mesh, instead of the complete object.
You have a pretty complex character mesh, so using mesh collider probably isn't the best way to go. In many cases, character controller or capsule collider works fine; otherwise, you can just use compound collider and create a box or a sphere around various body parts of the character.
This once happened to me. The mistake i made was, i applied the mesh collider after i did some rotation and scaling. So i added the mesh collider as soon as i imported the model. And then it should be alright when you scale/edit the model. Also check with right/left handed co-ordinate system with unity and 3D MAX/Maya.