X muscle system for Blender and game frameworks like Unity

This post consist on a tutorial showing how to use X Muscle addon for blender. It includes all the pipeline from a rigged avatar in FBX on blender, to the same avatar with blendshapes animated automatically in Unity3D. The tutorial is quite basic regarding muscle details, it shows mainly how to place the muscles without getting in very specific details such as radius of affection. A human body may have between 740-850 muscles (depending on whom you ask) but it would be senseless and not usable at all to add all those to an avatar, that’s why I’ll show just some of them on arms and legs, most noticeable ones, those that increase realism but keep balance with performance.

In the tutorial I use two scripts created by me, one in Blender, used to copy muscle’s shape from half body to the other half, to save editing time, and one script in Unity3D, to automate muscle movements, it is, in Unity you can’t use muscles directly, they have to be used through blendshapes. Therefore, Unity script calculates normals of the bones to predict if muscle should be flexed or extended and moving blendshape weights.

Showcase of leg muscles on Unity:

Arms V2 showcase (in the playlist there’s also V1):

Full tutorial: