The Sand Box - Particle Physics Simulator
The Sand Box is a browser-based particle physics simulator that lets you create mesmerizing chain reactions with thousands of interacting pixels. Draw with sand, water, acid, oil, stone, and fire across a canvas while manipulating gravity, temperature, and wind to watch materials flow, burn, dissolve, and interact in real-time. Perfect for ASMR satisfaction, creative experimentation, or understanding basic physics principles through play. Each material has unique density and properties water flows sideways, acid dissolves solids, fire spreads through flammable materials, and oil floats on water. The simulation runs entirely client-side with no signup required, delivering instant relaxation and creative expression.
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How to Use This Simulator
- Step 1 - Select a material (sand, water, acid, oil, stone, or fire) from the palette on the right side of the canvas.
- Step 2 - Click and drag on the canvas to draw particles. Adjust brush size with the slider to create fine details or broad strokes.
- Step 3 - Modify gravity (0-2x), temperature (0-200°C), and use arrow keys to create wind effects. Watch materials interact, fall, flow, burn, and dissolve based on their physical properties.
- Step 4 - Use the Pause button to freeze the simulation, or Clear to start over. Experiment with layering materials to create unique reactions.
Why This Particle Simulation?
The Sand Box uses a cellular automaton simulation where each pixel follows simple physics rules that create complex emergent behavior. Materials have density values that determine how they interact higher density materials (stone = 5) sink through lower density ones (oil = 1), while liquids flow horizontally to fill spaces. The simulation updates at 60 FPS using a double-buffered grid system to prevent race conditions during parallel updates.
Fire propagation uses probabilistic spreading to flammable neighbors, creating organic flame patterns. Acid employs a dissolution algorithm that randomly erodes adjacent dissolvable materials. Temperature affects fire lifespan, and wind applies lateral force to low-density particles. These simple rules, inspired by classic falling sand games like Powder Game and Noita, produce satisfying, unpredictable results that feel intuitive yet endlessly replayable.
Pro tip: Layer oil on top of water, then ignite it with fire to create a dramatic burning oil slick effect. Or use acid to carve intricate tunnels through stone structures as sand flows through. Experiment with high gravity and large brush sizes for explosive cascades, or low gravity and fine detail for zen-like drifting particle art.