OneTaskBy Tim King · Updated
3D Physics Sandbox
Drop, Stack and Blast Objects with Real Physics in Your Browser
OneTask is free, with no sign-up, and built by one person.
If this tool saved you time, a coffee helps keep new ones coming.
How the 3D Physics Sandbox works
This 3D physics sandbox lets you throw and stack shapes. The arena starts with a batch of shapes tumbling in from above. Click anywhere on the floor or on the pile to drop another shape at that spot, press Drop more for a whole batch, and Blast to throw everything into the air at once. Gravity and bounciness apply immediately when you move the sliders, so you can watch a settled pile suddenly float under moon gravity or bounce like rubber. The stats count how many objects are on the floor and how many are still moving. Drag to orbit, scroll to zoom, Save PNG to keep a picture.
3D physics sandbox: what to know first
This is a rigid body playground: every box, ball, cylinder and capsule is a solid object with mass, friction and bounce, and a real 3D physics engine running in your browser resolves every collision between them and with the floor and the glass walls. Nothing is scripted, so a stack that survives one run may collapse the next, and a Blast never lands the same way twice.
Shape picks what the next drops and clicks produce. Mixed uses all four at random. Balls roll away and settle in the corners; boxes and cylinders stack and wedge; capsules do a bit of both. Size applies to new objects only, so you can build a pile of large boxes and then rain small balls over it. Objects per drop sets how many arrive with each Drop more press.
Gravity is the acceleration pulling everything down, in metres per second squared. Earth is 9.8, the Moon is about 1.6, Jupiter is nearly 25. Turn it low and a Blast sends the objects into a long, slow arc; turn it high and even the balls barely bounce. Bounciness is the restitution of each object, from a dead thud at zero to nearly perfect at the top of the scale. The change is applied to everything already in the arena, not just new objects.
Blast pushes every object upward and outward from the centre with an impulse scaled to its mass, so heavy and light objects fly the same way and it is the collisions that sort them out on the way down. Clear empties the arena, Restart rebuilds it with the current settings. Everything is calculated locally in the page; nothing is uploaded.
FAQ
Why does the same Blast never land the same way?
Rigid body collisions are chaotic: a tiny difference in where two objects touch changes everything after it. Nothing is scripted, so no two runs match.
Why does changing size not affect existing objects?
Size applies to new objects only, so you can mix scales. Gravity and bounciness apply to everything immediately, since they are properties of the world rather than the shapes.
Can I build a stable stack?
Yes, with boxes. Click precisely on top of a box to drop the next one; at low bounciness they settle without sliding off. Cylinders on their sides and balls will not stack.
What is the object limit?
A few hundred before the frame rate drops on a laptop, fewer on a phone. Clear empties the arena without changing the settings, which is the quickest way to recover a stuttering scene.
See also: all Simulations & Screensavers tools, Images, Audio, Video & Screen, PDF, SVG, Generative Art, Chart Makers, 3D Model Viewers, Drawing Pads, Mockups & 3D Making, Diagram Makers, 3D Science, Tracker Music.
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