This is too nifty to wait for an end of week post. 🙂

I was messing around with Blender’s vector blur node. I found out if you separate the Speed pass and zero the last two parameters before connecting it to Vector Blur, you can confine the direction of the blur to a trail. This gives you a nice crisp leading edge and a blurry trailing edge, just like the old cartoon days. 🙂

You can use the Separate RGBA and Combine RGBA nodes on the Speed vector to split it up. If you only connect the R and the G (not the B or A), you get a trailing blur. If you want a forward blur, connect the B and the A but not the R and the G. Connect the Combine RGBA to the Speed slot of the Vector Blur node along with Image and Z and voila – trailing blur!

It doesn’t work super-well on shaded objects but it works pretty great on shadeless ones (YouTube video).