Stimulus

You can use spot, bar, edge, or grating stimuli. Here's what the stimuli look like:

 

Stimulus Hot keys

 

Why these stimuli?

These stimuli are a small subclass of all possible stimuli, but they are special in terms of the simulation because their intersections with the photoreceptor shapes can be rapidly computed using techniques borrowed from computer graphics for computing the intersections of convex polygons. This computation--which comes for free when you use optics and an imaging surface--is the most compute-intensive part of the simulation. Using these rapidly-computable intersection algorithms to compute the excitation of the photoreceptors allows us to devote more time in the simulation to computing the dynamics of the cell responses.

The fact that we can only rapidly compute the responses to the polygon shapes means that it is not easy to create stimuli that have varying brightness. So forget about using sinusoidal grating stimuli.

You may notice that when you use a grating stimulus, the responses of the neurons greatly slow down.  Even a simple grating stimulus is pretty tough to compute, because the redraw of the stimulus by Java's graphics competes with the computation of the responses.