Graphoon/README.md
2016-01-12 02:30:52 +01:00

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# Graphoon
A force directed algorithm written in Lua.
## Basic Usage
The basic idea is that you create a new graph object, to which you can then add nodes and edges.
```
local GraphLibrary = require('Graphoon').Graph
graph = GraphLibrary.new()
graph:addNode( "Ash Williams" )
graph:addNode( "Necronomicon" )
graph:connectIDs( "Ash Williams", "Necronomicon" )
```
By itself Graphoon only provides functionality for creating the graph and calculating the layout based on physical attraction and repulsion forces.
It provides a ```draw``` and ```update``` function, which can be used to easily write your own rendering code.
The ```draw``` function should be called with two callback functions. The first callback will be used for all nodes and the second one for all the edges.
```
graph:draw( function( node )
local x, y = node:getPosition()
drawCircle( 'fill', x, y, 10 )
end,
function( edge )
local ox, oy = edge.origin:getPosition()
local tx, ty = edge.target:getPosition()
drawLine( ox, oy, tx, ty )
end)
```
At its simplest the force calculations can be updated via ```graph:update( dt )```, but the ```update``` function also can receive optional callbacks for both nodes and edges.
## Advanced usage
### Using anchors
Anchors can be used to attach a node to a certain position on the screen. This can be useful if you want to center a certain node for example.
This can either be done directly via the constructor of the node:
```
-- Anchor the node to the center of the screen.
graph:addNode( "Ash Williams", screenX * 0.5, screenY * 0.5, true )
```
Or by using the ```setAnchor``` function:
```
-- Invert anchor status
node:setAnchor( not node:isAnchor() )
```