Bulge¶
LibLathe uses a simplified geometry representation which consists of a single type; the segment. Segments consist of 3 bit of data:
- Start Point
- End Point
- Bulge
These 3 bits of data give Liblathe all the information required to calculate the position, size and direction of lines and arcs.
Bulge values are calculated:
bulge = tan(theta/4)
theta is the central arc angle between the start and end points.
Direction:
bulge > 0 = CCW and bulge < 0 = CW
Positive bulge values represent arcs with a counter clockwise direction
Negative bulge values represent arcs with a clockwise direction
Segments where the bulge is equal to zero represent a line
Parameters:¶
| Name | Description |
|---|---|
| theta | included angle |
| eta | half included angle |
| epsilon | quarter included angle |
| phi | pi - epsilon |
| gamma | pi - eta |
| tau | see phi |
| radius | distance between start and end / 2 |
| sagitta | arc height |
| apothem | radius - sagitta |