390 No Time for Squares
390 : No Time for Squares
- Author: Tommy Thorn
- Description: It's a 12-hour clock, drawn with triangles rendered by a race-the-beam triangle render
- GitHub repository
- Clock: 31500000 Hz
How it works
Every frame the 640x480 VGA matrix is scanned, advancing the state of the intersecting lines of the three triangles. If the (x,y) coordinate of the "beam" lines on the positive side of each line, the beam is inside the triangle. Among the visible triangles, the highest priority triangle sets the color, else we default to a grey color. Twelve dots are also marked, to make it easier to read the clock.
The algorithm might be easily understood by examining the
software model in Rust, in the sw directory.
How to test
Hook up the Tiny VGA interface and connect a VGA monitor. Hope it works.
External hardware
TinyVGA, 31.5 MHz clock, reset, hour & min buttons
IO
| # | Input | Output | Bidirectional |
|---|---|---|---|
| 0 | clock | R1 | debug\[7] |
| 1 | reset | G1 | debug\[6] |
| 2 | hour, advance hour | B1 | debug\[5] |
| 3 | minute, advance minute | vsync | debug\[4] |
| 4 | R0 | debug\[3] | |
| 5 | G0 | debug\[2] | |
| 6 | debugsel\[1] | B0 | debug\[1] |
| 7 | debugsel\[0] | hsync | debug\[0] |