3 - Intermediate Animating tank tracks with WWSkin

[moonsense715]

Author: danpaul88

Skill level: 3

 

Foreword

Before I start, this is only the second tutorial I have ever written, so bear with me. I will try to cover all the possible pitfalls and things to watch out for, and explain each step in detail, if you think something needs clarifying or altering do let me know. Thanks.

 

 

About this tutorial

This tutorial will explain the use of WWSkin objects to animate meshes using their verticies, which can create effects that could never be achieved using standard animation techniques. This is how Tank Tracks are able to move up and down with their wheels, and can also be used on any other object.

 

 

Before you start

Some important notes about WWSkin that you should be aware of before you start trying to apply it;

• WWSkin animation ONLY works in RenX, as the 3DS Max version of the Renegade W3D tools does not support WWSkin. Therefore, if you model in 3DS Max you must export your model and import it into RenX to setup the WWSkin binding. UPDATE: Apparently it DOES work in 3DS Max, but it's harder to find.
• Once you have bound a mesh to a WWSkin you cannot change that mesh without removing the WWSkin first, otherwise RenX generally crashes. Therefore it is a good idea to save a copy before you start applying the WWSkin, so that you can go back to that if you realise you need to change something.

The Tutorial

I will use a simple tank tread as an example, taken a WIP version of the AR Chronominer. I have deleted all the other meshes in the scene to make it easier to see what's happening in screenshots. Before this I start explaining WWSkin you should know that the wheel bones are setup as normal, the wheels linked to the WheelC bones and those linked to the WheelP bones, which are at the same Z height as the bottom of the track mesh. These first two screenshot shows that the wheels moving up and down do not affect the position of the mesh, which would cause it to clip through the terrain.

 

You should also note how the bottom of the Track mesh has been cut into slices as long as the gap between each wheel bone, we have to do this so we have vertices in the right place to link to the bones later on.

 

 

Now that we have seen what happens without WWSkin binding applied to the treads, lets setup WWSkin binding and see what difference this makes. The first thing to do is create our WWSkin object, so go to the toolbar at the top and hit the button labelled 'Create a Renedage Skin' (yes, it really is spelt wrong in the W3D Tools). If your using 1024x768 like I am you will only about half of the icon, because it runs off the end of the toolbar, if you can't see it at all click on one of the || dividers on the toolbar and drag it to the left until it comes into view.

 

For 3DS Max users

If your using 3DS Max you can find the WWSkin object under the Spacewarps tab on the meshes section of the right hand side menu.

 

 

Once you click the button you then have to click on your scene to create what looks like a set of crossed bones. Place this anywhere on your scene, it does not matter where, but if your using more than one on your scene it would be a good idea to place it somewhere near the mesh you are using it on. Select this new object and click the 'Add Bones' button on the right hand side.

 

A window will pop up listing all the objects in your scene. You need to select all the bones that you will use to animate this mesh, and then click OK. In this example we are rigging a tank tread, so we need to choose all the WheelP bones for this tread. Once you have clicked OK they should appear in the list of bones for the WWSkin on the right.

 

Ok, now that we have selected the bones that will be used in this WWSkin we have to link it to a mesh. You can only link one mesh to each WWSkin object, so if you need to animate multiple meshes you must create additional WWSkin objects. Bones can be used by more than one WWSkin object, so if a bone needs to move two or more meshes it can be linked to the WWSkin objects for all of those meshes.

 

Select the 'Bind to Spacewarp' button on the toolbar (again, if like me your using 1024x768 this will appear off the end of the screen, click one of the | dividers on the toolbar and drag it to the left until you can see the button shown in the screnshot). Now click on your mesh, hold the mouse button, drag the icon to the WWSkin object and release, the same way you would to link objects to bones. The mesh should now have a 'WWSkin Binding' modifier on the right, and it's verticies will be highlighted.

 

For 3DS Max users

If your using 3DS Max the 'Bind to Spacewarp' button looks the same as it does in RenX, but is positioned on the far left of the toolbar, next to the buttons for linking and unlinking meshes.

 

Handy Tip

If your mesh changes position or size or does other wierd things when you bind it to the WWSkin hit undo the remove the WWSkin binding, and reset the meshes Xform by going to the Utilities tab (Hammer Icon) and choosing 'Reset Xform', and then click 'Reset Selected' with the mesh selected. This may turn your mesh inside out, if so go back to the Modify tab, select Polygon editing mode from the Editable Mesh dropdown, select all the polygons on your mesh and hit 'Flip Normal' to turn it the right way out again. You can then link to the WWSkin as normal

 

Ok, now your mesh is linked to the WWSkin, the final step is to link the mesh vertices to their bones. Select the vertices that need to move with a particular bone, and then click 'Link to Bone by Name' on the right. Then simply select the bone to link them to from the list, and click OK. Select the next group of vertices to move with the next bone and do the same to link them to that bone, and repeat until all the vertices that need to move with a bone are linked to that bone. Each vertex can only be linked to a single bone.

 

Note, you can also use 'Link to Bone' instead of 'Link to Bone by Name', which allows you to click a bone on the scene to link to, but I find it easier to use the object listing to do it. This is down to personal preference though.

 

Once you are done linking vertices click the + icon next to the 'WWSkin Binding' and click the vertices text that comes up below this to allow you to deselect the mesh.

 

You can only link vertices to bones that you previously added to the WWSkin object, if you need to add more bones select the WWSkin object and add them the same way we did earlier.

 

The final result

Ok, so what did we achieve by doing that? If you scroll up you will see the first image showed that moving the wheel bones up and down caused the wheel bones to clip through the mesh, so lets see what happens now that we have used WWSkin binding on the tread mesh to link it to the wheel bones.

 

Create a 1 frame animation and move some of the WheelP bones up or down while in animation mode. The mesh will move with the bones, creating a much more realistic appearance. In our tread example, the treads will now fluctuate up and down with the terrain, instead of just being flat all the time. Exactly what we wanted to achieve.

 

 

You can download my example file here to look at how it is setup, this is the completed gmax file I created while doing this tutorial. I trust that whoever created this simply tread for the Chronominer does not mind me using it for this tutorial example.

 

WWSkin_Binding_Example.zip

 

 

Footnote

If you have any further questions, or suggestions to improve this tutorial, please do post them. I have tried to be thorough and cover the entire process from start to finish, but it is easy to forget to mention a step that seems obvious to you because you do it all the time, so if I missed something out please do mention it and I will update the tutorial. Good luck, and happy modding!