If I want to add new animations to model. What shall I start with?

So, I sort of decided to make a new mod. And well I need to make a new animations for default HL2 characters. How would I do that? I even need to change idle animation to the one I need. I was thinking of doing this way:

Taking lets say combine_soldier. [dx80.vtx, dx90.vtx, mdl, phy , sw.vtx , vvd , ani]
And decompiling it. Then opening idle.smd and editing it the way I need. THen compiling model again. But here is question: Will that work? ANd if it will work will my mod have the idle animation I set not the default source anim ? Anyone mind also explaining what are those and are they important: [dx80.vtx, dx90.vtx, mdl, phy , sw.vtx , vvd , ani] ?

Example: Default Idle animation is like character standing and a bit moving. Let’s say I need him to just stand and fap. So when in my mod I spawn him, he would fap instead of idle.

P.S - I am no pervert to use “fap” as a example. It’s just probably best way to give example on facepunch.

I’ve not yet found a way to decompile animation mdls that have a ani attached to them, the decompiler just wont load them, but yes in theory, if you could decompile them you could replace an exisitng anim with a different one by recompiling with a different set of SMDs.

(strangely at this very moment I am compiling an animation mdl @.@ but nothing as complex as this though).

What I would like to know is if you can transfer an animation from a custom/other boneset to the Valve Biped (i’ve found this but A. I don’t have 3dsmax but if it can do this I might actually be interested in it finally, and B its confusing).

Basically this. When you decompile a model, it will dump all the SMD’s into a folder. In this case, it will have a reference SMD which is the mesh and skeleton. In most cases, you’ll also have an SMD for the physics model. All the other SMD’s will only be the skeleton, and possess one animation sequence. Just copy the reference SMD, remove the mesh, and animate the skeleton yourself. You’ll need to add a line in the QC file to define the sequence name and link it to an SMD. Then you recompile it.