Atan

During my third year at BUAS I worked on a team project in Unreal for 8 months, as a Gameplay Programmer. The game, Atan, is about a Mayan boy that is climbing a gigantic colossus.

The game is available for free on Steam!

I worked on a couple gameplay systems using C++, including the character movement, but what I'm most proud of is the rope system I created.

The rope wrapping works using raycasts. The wrapping points are added and removed as the rope wraps around the object. The added wrapping points are attached to the object. The Verlet particle sim gets constrained to the wrapping points, and a mesh gets generated from the particles.

In this video from earlier in development you can see how the system works under the hood. Particles get added and removed dynamically based on the length of the rope. And the particles flow freely trough the wrap point constraints.

Using the Verlet particles and wrap point positions, I generate a mesh, by creating vertex rings around them. Based on the angle that 3 consecutive positions make, I can generate additional rings to make the rope curve more naturally. In the video above you can see how the rope curves quite nicely, despite the low particle density.

Using the warping points has a couple of advantages over using a more traditional plain chain of constraints.

• It improves the character swinging movement, the character only has to solve a single constraint, from the character to the last wrap point of the rope. Meaning, that the stretching of the Verlet rope sim won't affect the character's movement.
• The Verlet particles can smoothly travel around corners, because the constraints between the particles around a wrap point are solved trough it.
• As part of the rope mesh generation, we can generate extra vertex rings around the wrap points. This way the rope mesh stays solidly above the corner as particles travel around it.
• And we can get away with a way lower particle density because of the previous two reasons.