366 VGA Rings
366 : VGA Rings
- Author: Uri Shaked
- Description: Hypnotic concentric rings effect
- GitHub repository
- Open in 3D viewer
- Clock: 0 Hz
How it works
This project generates a mesmerizing VGA display of hypnotic concentric rings that expand or contract from the center of the screen. It's designed as a demoscene-style visual effect for the Tiny Tapeout platform.
Technical Details
Distance Calculation: The distance from center is approximated using the formula: max(|x|, |y|) + min(|x|, |y|)/2, which provides a reasonable octagonal approximation of Euclidean distance without requiring multiplication or square roots.
Animation: A frame counter increments each video frame. The animated radius is computed by adding (or subtracting, depending on direction) the frame counter to the distance value, creating the illusion of expanding or contracting rings.
Color Generation: The 8-bit animated radius value is mapped to RGB222 color outputs by selecting different bit slices for each color channel, creating smooth color cycling through the rings.
How to test
- Connect a VGA PMOD (such as the Tiny VGA PMOD) to the output pins
- Connect a VGA monitor
- Apply power and release reset
Controls
-
ui_in[0]: Speed control
- 0 = Normal speed (1 frame step per vsync)
- 1 = Fast speed (2 frame steps per vsync)
-
ui_in[1]: Direction control
- 0 = Rings expand outward from center
- 1 = Rings contract inward toward center
External hardware
- Tiny VGA PMOD (or compatible RGB222 VGA PMOD)
- VGA monitor or display with VGA input
IO
| # | Input | Output | Bidirectional |
|---|---|---|---|
| 0 | speed | R1 | |
| 1 | direction | G1 | |
| 2 | B1 | ||
| 3 | VSync | ||
| 4 | R0 | ||
| 5 | G0 | ||
| 6 | B0 | ||
| 7 | HSync |