Replace an animation

Find the clip

1. Open Source 2 Viewer.
2. Open game/citadel/pak01_dir.vpk.
3. Go to models/heroes_staging/<codename>/ or models/heroes_wip/<codename>/. Older heroes are in heroes_staging, newer ones in heroes_wip. Look up the codename in Hero names and file paths.
4. Open the clips folder. Each .vnmclip_c file is one animation.
5. Click a clip to preview it. Haze's ultimate, for example, is ability_bullet_flurry.
6. Write down the FPS, duration, and frame count from the Data section. Haze's ultimate loop has 34 frames.
7. Write down the clip's full path and name.
8. Open the hero's model (.vmdl_c) and check its Data tab for the skeleton path.

The skeleton is not always next to the model. Pocket's model is in heroes_wip/pocket/, but its skeleton is heroes_staging/synth/synth.vnmskel. The clips sit next to the skeleton.

Set up the addon

1. In the CSDK 12 launcher, create an addon. Use lowercase and no spaces, like haze_dance.
2. Right-click the addon and choose Explore Content Folder.
3. Rebuild the skeleton's folder path inside it, plus a clips folder. Example: models/heroes_staging/haze/clips/.
4. In Source 2 Viewer, right-click the hero's .vnmskel_c and choose Decompile & export. Save it in the skeleton's folder. You get a .vnmskel and a .dmx.
5. Right-click the clip you will replace and choose Decompile & export. Save it in clips. You get a .vnmclip and a .dmx.

Bring the hero into Blender

1. In Source 2 Viewer, right-click the hero's model and choose Decompile & export.
2. Set the type to glTF. Save it in a work folder outside your addon.
3. In Blender, choose FileImportglTF 2.0File, then Import, then glTF 2.0 and pick that file.
4. Tick the option that disables bone shapes, then import.
5. Wait. Older heroes import slowly, because all their animations come along.
6. Fix the armature's scale and facing. Follow the video at 5:01, then check the result against the original clip.
7. Set the scene frame rate to the clip's FPS, rounded to a whole number.
8. Set the frame range to the clip's frame count.
9. Save your .blend file.

You can also import the clip's DMX with PulseSrcOps instead of using glTF. The VnmClip guide takes this route.

Retarget or animate

Animate by hand on the hero's armature, or copy motion from another skeleton. Copying motion between skeletons is called retargeting. Here is how with Rokoko:

1. Import your source animation, for example with FileImportFBXFile, then Import, then FBX.
2. Rotate and scale it to roughly match the hero.
3. Select its armature, enter Pose Mode, and press A. Then press Alt+G, Alt+R, and Alt+S to clear the pose.
4. Pose it roughly like the hero. Close is enough.
5. Press N to open the sidebar, then click the Rokoko tab.
6. Open Retargeting. Set Source to your animation's armature and Target to the hero's armature.
7. Click Build Bone List. Match any bones it could not pair.
8. Untick Auto Scale. Set Use Pose to Current.
9. Click Retarget Animation.
10. Hide the source armature and play the animation to check it.

If Rokoko fails after you install it, try its beta version. Pugzilla needed it.

Downloaded animations have their own terms. Read them before you share your mod, and see Credits, licenses, and permissions.

Add IK constraints and bake

Without these constraints, limbs can flip or break in game. Haze needs them, and they do no harm on other heroes.

1. Select the hero's armature and enter Pose Mode.
2. Open the Bone Constraints tab.
3. Expand the armature in the Outliner. IK bones sit outside the Pelvis hierarchy.
4. Add Copy Location and Copy Rotation to each IK target bone. Set the target to the hero's armature, and the bone to the matching Hand or Ankle bone.
5. Do the same for each IK offset bone. Use the matching Lower_arm or Lower_leg bone.
6. For a weapon or prop bone, go to frame 1, add a Child Of constraint, and click Set Inverse.
7. Delete the keys on the Root_motion bone, unless your move needs them. Extra keys there flip or offset the hero.
8. Check every pair once more.
9. Bake the animation, so the constraints turn into keys.

Export the DMX

1. Turn off any other Source Tools add-ons. They clash with PulseSrcOps.
2. Open the Scene properties and find Source Engine Export.
3. Set the DMX version to Binary 9 and the model format to 22.
4. Set the export path to your addon's clips content folder.
5. In the exportables list, untick everything except your animation.
6. Click export.
7. Move the new DMX out of the anims subfolder into clips. Delete anims.
8. Give the DMX a short name, like my_dance.dmx.

Point the clip at your DMX

1. Open the decompiled .vnmclip in a text editor.
2. Find the source file name near the top. It names the original DMX, such as ability_bullet_flurry.dmx.
3. Change it to your DMX, such as my_dance.dmx.
4. Leave everything else alone. The file also holds events the game needs.
5. Save. Do not rename the .vnmclip itself.

Compile

1. In the CSDK 12 launcher, select your addon and click Launch Tools.
2. In the Asset Browser, right-click your .vnmclip and choose RecompileFullRecompile, then Full.
3. Right-click your addon in the launcher and choose Explore Game Folder.
4. Open the same path, such as models/heroes_staging/haze/clips/. Your .vnmclip_c is there.

CSDK 12 writes clips in an older format, says the VnmClip guide. Pugzilla's simple clip still worked. If yours fails in game, compile it with CS2 Workshop Tools instead.

Pack only the clip

1. Make a staging folder, like haze_dance_pack.
2. Inside it, rebuild the clip's path: models/heroes_staging/haze/clips/.
3. Copy only your compiled .vnmclip_c into it.
4. Pack the folder into a VPK. Follow Pack your mod into a VPK.
5. Test the animation in a private match. Follow Test your mod in game.

Never pack the skeleton (.vnmskel_c). It replaces the game's skeleton, so a later update breaks your hero's other animations. It can also break other mods for that hero.