For these flickering oriented bar stimuli I didn't want bars to have any overlap, and for bars to have faded edges (but without using Alpha Blending, which would slow down the code too much). So I wrote two Matlab functions which can be implemented using Psychtoolbox.

Smoothbars.m creates a matrix that can be plugged into Screen('MakeTexture'). You can specify the color of your bar, color of the background, size of your bar, etc. Once a texture is created, you can draw many bars at once using Screen('DrawTextures'). Now, where do you want to draw your bars to on the screen?

FlickeringBarInfo.m will generate the rest of the information you need for Screen('DrawTextures')on every frame refresh. It also allows you to set a coherency level for your bars (i.e. percentage of bars that share an orientation), when you want coherence to start, and the orientation at which you want bars to cohere.