This free online interactive simulator allows you to experiment with light propagation and shadows. No sign-up required.
Experiment with light sources, time of day, and object distance to understand how shadows are formed in real-time. Perfect for designers, artists, and educators.
Key Concepts
Play
Interactive Real-time Simulation
Instantly see how changes in light position and time of day affect shadows on a 2D canvas.
MousePointer
Intuitive Controls
Drag and drop light sources in 'Theater' mode, or use a simple slider for 'Sundial' mode. No complex setup required.
Calculator
Two Dynamic Modes
Switch between 'Theater' mode for precise light manipulation and 'Sundial' mode for simulating celestial light paths.
ShieldCheck
Accurate Shadow Casting
The simulator uses physics-based principles to render realistic shadow behavior.
Zap
Adjustable Light Distance
Control the blurriness and size of shadows by adjusting the distance between the light source and the object in 'Theater' mode.
Clock
Simulate Time of Day
In 'Sundial' mode, move the time slider to observe how the sun's angle impacts shadow length throughout the day.
The Science of Shadows
Light travels in straight lines. When an opaque object blocks the path of light, a shadow is formed behind it. The properties of that shadow depend entirely on the relative positions of the light source, the object, and the surface the shadow falls on.
Distance and Shadow Size
If you move a flashlight closer to your hand, your hand blocks more of the light rays spreading out from the bulb. As a result, the shadow cast on the wall behind becomes much larger. Moving the flashlight further away makes the rays hitting your hand more parallel, creating a smaller, sharper shadow closer to your hand's actual size.
The Sundial
A sundial works because the Earth rotates, making the sun appear to move across the sky. In the early morning and late evening, the sun is low on the horizon, casting long shadows. At noon, the sun is at its highest point, casting the shortest shadows of the day. The direction of the shadow also sweeps across the ground, allowing us to read the time.
