# Usage

The genplotting library use, as a backend, an external 
[software](https://git.tetalab.org/tTh/libtthimage/src/branch/master/Tools/genplot2.c)
who can be installed with the [libtthimage](https://git.tetalab.org/tTh/libtthimage) and convert scratchfiles to
[Targa](https://en.wikipedia.org/wiki/Truevision_TGA) image file. 

For drawing an *useless graphic*, you have to follow three steps:
initialize, use and terminating.

## Initialize

Call the subroutine `genp_init` with two parameters.
The first is an integer and must be 0. 
The second is the filename for recording the plottings instructions,
if this filename is an empty string, *stdout* will be used.

## Use it

- real xa, ya, xb, yb
- integer color
- call genp_move(xa, ya)
- call genp_draw(xa, ya, color)
- call genp_line(xa, ya, xb, yb, color)

## Terminator

- call genp_end(0)