This section present the RGG and language XL as well as graph management & queries.
Growth grammars are a rule-based approach to the modelling of dynamic systems. In contrast to conventional imperative programming languages, rule-based approaches provide a natural and concise way of modelling: Most systems to be modeled behave according to a set of rules, and our perception works this way and not imperatively using a list of operations which have to be processed step by step.
The programming language XL is defined as an extension of the Java programming language.
This section presents the model graphs. Model graphs (or query graphs) are used at runtime to perform queries onto a data graph. The query graph is responsible for matching the pattern on the data graph and executing the production statements. Each instance of a model graph is linked to a data graph, thus, it is possible to use different model graph of the same type, to run rules on different data graphs. Also, several model graph can be linked to the same data graph.
It is possible to specify which model graph is to be used for a given rule with the syntax:
RGGGraph qgraph = rgggraph(); // get or create a rgggraph qgraph.[ /* a rule block */]; // to use the model graph on the rule block qgraph.(* /* a query expr */ *); // or on a query expression
In GroIMP 3d movement in the scene are managed by turtle commands. In turtle geometry a sequence of commands can be used to describe a structure. These commands are processed by a “turtle” and change either the state or the position of the turtle. By doing so the turtle can add cylinders (with the additions of RGG also other objects) to the scene.