Im thinking about doing one of those led cubes you see on youtube for my senior project. After doing some research on how its done I came up with basically how it works. But my question comes when RGB led's are involved.
In a single color cube of 512 leds, you could use 4 led drivers or shift registers to control the 64 columns with serial data from only 1 arduino port. Use 8 other ports for the rows. With this you can send in data to the shift registers to get your pattern for one layer at a time. Cycle through the layers fast enough and make displays. Sounds pretty straight forward to me.
With RGB leds, each led has 4 leads. So assuming I make each row common cathode, I now need 192 PWM outputs (64 columns x 3 for the RGB lines) to be able to control the cube!!!! Thats 12 PWM shift registers or led driver IC's. Does this sound right? How else would I control that many leds so that I can have an RGB led cube?