Physical Modeling Inside a Shader

Author

Bass Jansson

Edited

Apr 6, 2026 9:24 PM

The idea is to create a Shader that models certain particle behavior, as if each pixel contains a particle and each neighbouring pixel interacts with that particle.

Pipeline will be one feedback shader that contains the particle information and updates it. Then a second shader will interpret the output of the first shader and transform it into a pretty image.

We start off by having a few rules.

• Every pixel can only contain one particle or no particle at all
• A particle has the following properties:
• Mass (also density, type)
• Speed
• Direction (of movement)
• Position (within the pixel)
• Every frame call updates the pixel and the particle it contains, taking the neighbouring pixels into account
• When two pixels collide, they bounce off of each other, in general, but if the force is great enough, small particles will merge while large particles will split
• Use momentum and impulse formulas to calculate the collisions
• Speed cannot be greater than the width of a pixel (harsh limitation? Higher frame rate? Render and then speed up? Compute by taking even further neighbouring pixels?)