Edge-Seeded Effects

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In physics-based graphic simulations, the behavior of cells at the grid boundaries (boundary conditions) plays a critical role in dictating the waves, forces, and movement that occur inside the grid.

What is an "Edge-Seeded Effect"?

An edge-seeded effect is a simulation dynamic driven entirely by boundary conditions that vary over space and time. Instead of applying forces or adding noise globally to the entire grid (which can clutter the center of the screen), we "seed" or inject inputs strictly at the edges of the grid.

How it Works

For example, in a water ripple simulation:

• We can simulate wind blowing waves across the screen by driving the left-edge cells with a sine wave over time: Grid(0, y) = sin(t + y).
• These inputs serve as "seeds" that propagate inward across the domain via the discrete wave equations, creating diagonal waves moving across the screen naturally.

Because these effects depend heavily on boundaries acting as physical, non-wrapping sources of input, forcing the texture to wrap around the mesh periodically (toroidal mapping) would destroy the directional flow, causing the waves to wrap back around and collide with themselves, ruining the effect.