Hand-posed, not captured

The fastest way to animate a sword strike is to take one off a motion-capture library. I tried it first, and it was the wrong animation.

What was wrong with it

The captured strike looked fine in isolation and wrong in the game, and I could not say why until I measured it. At the moment of contact the character was at her tallest, most upright point. Her hips never travelled, her feet were planted across all twelve frames, and she had no reach. A real strike commits your whole body: you drop, you lunge, you cover ground. Mine stood still and waved a sword.

So I threw it out and posed the strike by hand.

How it works now

Renzy is a 3D model with a skeleton. I pose her myself, key pose by key pose, in Blender, and render each action to a flipbook of sprites that the game plays. The game itself stays 2D and light, and every frame comes from a pose I decided on.

The strike is built from two poses. She coils low, with the sword drawn back, and holds there for a beat. Then she travels to the contact pose, with the blade fully extended, in about the time it takes to blink. Then she eases back to her stance. The game adds a forward lunge across the ground and a streak that follows the blade, because her feet should cover distance when the sword does.

The left and right strikes are not mirror images of each other. She holds the sword in her left hand and coils the same way for both, and her feet and arms are placed differently for each side, so reach and finish height differ slightly. That asymmetry reads more like a person than a flip does.

Measured, not guessed

The blade's reach, and where its tip is at the coil and at contact, are measured from the rendered frames and fed into the game, so the lunge and the streak follow the real sword instead of a number I made up. After any change to a pose, I re-render and re-measure.

A practice mode

Judging a strike at full speed is hopeless, so the development build has a practice mode. Enemies stand still at a distance I choose, I strike them through the real game code, and sliders adjust the timing, the lunge and the streak live, with slow motion. The numbers I settle on are exported back into the game.

One exception

The Hollow Clan's run cycles and Renzy's death use captured motion. Running and falling do not need the same authored intent as a strike, and they are not the part of Renzy that has to carry the game's feel. Strikes, parries, ripostes and whiffs stay hand-posed.