Functional Reactive Programming

Chapter 9. Continuous time

This chapter covers

• Continuously varying cells
• Sampling a continuous time model
• Measuring time

The video games we’ve shown so far use a frame—of 1/60th of a second or whatever—as a basic unit of time. We’ll show you how continuous time lets you remove the concept of a frame, and model the animation in a clean, natural, declarative way that’s closer to the underlying concept. If it’s a physics simulation, the model can more or less directly express the physics.

9.1. Rasterizing time

The difference between a discrete (or frame-based) and continuous representation of time is analogous to the representation of space in images. There are two basic models of images:

• Raster graphics— The image is represented as ...