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--- tutorials:rgg-code-structure [2024/10/11 11:03] – [Instantiation] tim
+++ tutorials:rgg-code-structure [2025/01/10 11:16] (current) – gaetan
@@ Line 17: / Line 17: @@
 Additionally there are several functions predefined that can be used to change the behavior of the simulation. At this point we will only talk about the initialization: ''protected void init ()''. this function is executed after the compilation or a model reset.
+<code java>
+protected void init ()
+[
+	{println("hallo");}
+	Axiom ==> A(parameters.length);
+]
+</code>
+The Axiom is the node that is added to the graph in the very beginning of the simulation and is used as an access point.
 ===== Java blocks =====
@@ Line 48: / Line 56: @@
 It is also possible to have modules that do not extend any other object and have no direct effect on the graph. These nodes can be useful for aggregations, multi scaling or just as place holders.
-==== Queries ====
+==== Instantiation ====
-<code java>
+While in theory every part/organ/etc... of the simulated object (normally a plant) is suppose to be represented in the graph, it is not allays suitable to add all geometrical objects that represent an object individually. Therefore the concept of instantiations was included.
-public void growRadius(){
+Using the syntax below the module Branch is one object in the graph and is during the creation of the object interpreted as an extension of M. Yet for the visualization and the ray tracing it is represented by the four F objects with the different shaders.
-	(*A*)[radius]+=0.1;
-}
+<code java >
+module Branch(float len) extends M(len)==>
+     F(len/4).(setShader(GREEN))
+     F(len/4).(setShader(BLUE))
+     F(len/4).(setShader(GREEN))
+     F(len/4).(setShader(BLUE));
 </code>
+On the right side of the ''%%==>%%'' operator a syntax similar to the production part of a rule can be used.
+It has to be noticed that even so instantiations create a smaller graph they tempt to slow down the visualization.
+==== Queries ====
+In GroIMP the project graph is considered to hold almost all information on the simulation. Therefore it can also be seen as a knowledge graph. To retrieve this knowledge rgg uses the [[tutorials:common_graph_queries|XL query system]]. To use this queries in a java block they have to be framed by ''(*...*)'' as shown in the examples below. In that way they return a collection object, which then can be like other java objects. Moreover GroIMP comes with a set of predefined  [[:groimp-platform:xl-builtin-methods|Analytical methods]] to analyze this collections.
+As shown in the example below in ''%%count((*M*))%%'' this queries work with the concept of java objects. Therefore ''(*M*)'' is selecting all instances of Branch because Branch extends M. This also works with interfaces.
 <code java>
 public void calc(){
 	long countA = count((*RU(30) RH(90) A*));
-	long countF = count((*F*));
+	long countM = count((*M*));
-	if(countF>0){
+	if(countM>0){
-		println((float)countA/(float)countF);
+		println((float)countA/(float)countM);
 	}
+	println(sum((*Branch*).len));
 }
 </code>
-==== Instantiation ====
+in the last line of the example above: ''%%println(sum((*Branch*).len));%%'' one way to access attributes (or functions) of modules is shown. The other way is shown below in: ''%% (*A*)[radius]+=0.1; %%''.
+The first way is more in the style of java while the second way is better adapted to GroIMP. Therefore the second way is not only changing the attribute of the object but also notifies the change to the platform.
+Moreover it manages the access of the attributes differently, (for instance would ''%%(*A*).radius%%'' not be allowed because radius is not accessible in a java way.
-<code java >
+<code java>
+public void growRadius(){
+	(*A*)[radius]+=0.1;
+}
+</code>
-module Branch(float len) extends M(len)==>
-     F(len/4).(setShader(GREEN))
-     F(len/4).(setShader(BLUE))
-     F(len/4).(setShader(GREEN))
-     F(len/4).(setShader(BLUE));
-</code>
 ==== Lambda expressions ====
+Since java 1.6 did not include lamda expression, an own implementation was added to rgg.
+The syntax an the explanation can be found [[groimp-platform:xl-lambda|here]]
 ===== XL Blocks =====
+While using XL queries mainly two rules are used: replacement rules(''%%==>%%'') and execution rule (''%%::>%%'').
+==== Replacement rules ====
+The concept of an replacement rule is basically that all part of the project graph that are similar to the left part (before ''%%==>%%'') are replaced by the right part( behind ''%%==>%%'').
+The left part can thereby be any [[tutorials:common_graph_queries|xl-query]].
+The right part (the production) is a collection of Nodes ( instances of either turtle commands, 3d objects or modules) which are linked by different edges. In the example below only successor- and branch-edges are used. A node that is separated to its predecessor by only a white space is added as a sucessor to the predecessor. A Node or a set of nodes framed by square brackets in that is added to the predecessor with a branch-edge.
+The most noticeable difference between these edges is that a Node should always only have one successor child. Therefore branches are needed to grow into different directions based on the way nodes interpreted by the visualization. In very simple terms this interpretation means that the transformation (rotation, location ...) of a Node is the sum of all its predecessors.
+In our example the first A on the right side would be moved a distance of ''x'' in the current rotation axis (based on the ''F(x)'') and be rotated  on the up/x axis by 30 (''RU(30)'') and on the head/z axis 90 (''RH(90)'') degrees.
 <code java>
@@ Line 87: / Line 127: @@
 ]
 </code>
+As shown above it is also possible to forward parameters from the left side to the right (similar to a parametric rewriting rule in formal systems). Moreover it is possible to use ''a:A''  instead of ''A(x)'' and then on the right side ''a.len'' instead of ''x''.
+==== Execution rule ====
+The left side of an execution rule is similar to the left side of the production rule. Yet the main difference is that the nodes (or pattern of nodes) found by the query are not replaced. Instead the code on the right side is applied on them.
 <code java>
 public void getDiameter()[
     	a:A::>{println(a.getDiameter());}
+]
+</code>
+This works very similar to looping over the result of the query. This also works with manipulation several nodes at the same time:
+<code java>
+public void change()[
+	l:RU h:RH ::> {
+		float a = h[angle];
+		h[angle]=l[angle];
+		l[angle]=a;
+	}
+]
+</code>
+==== Working with several Files ====
+{{ :tutorials:file_explorer.png?260|}}
+In GroIMP it is possible to split your code into several files and folders to improve the structure and keep an overview.
+<color #ed1c24>It is highly recommended to only have public void functions in one file. Otherwise your project will have several rest buttons that do different things... </color>
+To use function from another file this file needs to be imported similar to a java class or package.
+Yet in the case of GroIMP all files are imported by their name without the directories, therefore to import all modules, and classes in ''param/parameters.rgg'' you just write:
+<code java>
+import parameters.YourModule;
+</code>
+To get this a bit clearer lets assume our parameters.rgg file contains the following code:
+<code java>
+public static int length = 1;
+public static float diameter = 0.1;
+module Leaf() ==> leaf3d(1);
+module Shoot() extends F(1);
+</code>
+To import one specific object once, you can simply do ''parameters.length'' as for example in ''A(parameters.length'' in the new RGG project. Or to use module:
+<code java>
+protected void init ()
+[
+Axiom ==> parameters.Leaf();
+]
+</code>
+If you want to use your module several times you can also import it one in the beginning and then reuse it:
+<code java>
+import parameters.Leaf;
+protected void init ()
+[
+Axiom ==> Leaf()[RL(180) Leaf()];
+]
+</code>
+Finally you can import all modules with the * operator:
+<code java>
+import parameters.*;
+protected void init ()
+[
+Axiom ==> Shoot() Leaf()[RL(180) Leaf()];
+]
+</code>
+This can also be done with the static variables using static import:
+<code java>
+import static parameters.*;
+protected void init ()
+[
+	Axiom ==> F(length,diameter);
 ]
 </code>