Probably you've played some (older) video game and there is something odd about the character. When they walk forwards they seem to slide across the ground. This is called foot sliding. If you still don't understand, then you can look at celtst inside CEL to see it happening clearly.
Why does it happen?
Essentially the walk cycle of the character is not in synchronisation with the speed at which it is moving forwards. It can either be animated too fast or too slow for the speed at which it is moving.
When you walk there is a point in your walking where one stationary point remains on the ground. If the speed at which it is animated doesn't match its forward movement speed then this point in the foot of your character will move and it will look like it's doing the Michael Jackson moonwalk.
Normally the game predefines a forward movement speed (like 0.2m/s) and you animate to that speed. There are 2 ways to do this.
- Animate your character object moving forwards at a fixed speed before animating. You then animate to this movement speed so you don't get foot sliding. It is difficult though since you have to calculate the play rate of your timeline and gauge the time in milliseconds when animating constantly. Some game engines actually just calculate the forward speed as the animator has animated it and exports that to the game!
- Another common approach is to use ruler guidelines for the ground. By editing the rulers in Image:Animguide.blend blender file you can set the stride and foot length.
Image:Animguide.blend Animation guideline rulers used when animating characters walk cycles to avoid foot sliding problem.
Image:Animguide-example.blend Rulers being used in an example animation