Adding Scripts to the Project

To add logic that will rotate the box, you should modify the <your_project_name>.cpp world script file in a plain text editor.

1. Open the project folder via the SDK Browser.

   

2. Open <your_project_name>.cpp script file located in your data/<your_project_name> folder by using plain text editor.

   Source code (UnigineScript)

   #include <core/unigine.h>
   
   int init() {
   	PlayerSpectator camera = new PlayerSpectator();
   	camera.setPosition(Vec3(2.0f,0.0f,1.5f));
   	camera.setDirection(Vec3(-1.0f,0.0f,-0.5f));
   	engine.game.setPlayer(camera);
   									
   	return 1;
   }
   
   int shutdown() {
   	return 1;
   }
   
   int update() {
   	return 1;
   }

   The world script contains the following functions by default:

   • init() function is used to create objects and initialize all other necessary resources on the world load.
   • update() function is used to code project logic and executed every frame.
   • shutdown() function is used to code project logic and executed when the world is unloaded.

   This part of init() function code creates a new free-flying game camera that collides with objects (but does not push or interact with them). Read more about engine functions.

   Source code (UnigineScript)

   // create a new spectator player
   PlayerSpectator camera = new PlayerSpectator();
   
   // turn it in the specified direction
   camera.setPosition(Vec3(2.0f,0.0f,1.5f));
   
   // place it in the specified point
   camera.setDirection(Vec3(-1.0f,0.0f,-0.5f));
   
   // set the player as default one
   engine.game.setPlayer(camera);

   Notice

   Comments were added to explain to you the meaning of each line of code.
3. Add a variable to handle the required box node before the init() function.
   Warning

   We do NOT recommend you to create global variables for the real project.
   Source code (UnigineScript)

   Node box; // add a box node
   
   int init() {
   	/* ... */
   	}

4. Put this code into the init() function to get the box node.
   Source code (UnigineScript)

   Node box; // add a box node	
   
   int init() {
   	/* ... */
   						
   	// search the node by the specified name
   	int index = engine.editor.findNode("box");
   								
   	// get the node by its index
   	if(index != -1) {
   		box = engine.editor.getNode(index);
   	}
   									
   	return 1;
   }

   Notice

   Though nodes can be handled by any of the scripts (world, system or editor one) and Unigine Engine Editor (that loads and stores all the nodes from the world file), they should be owned only by one of them. Otherwise, such nodes can cause engine crash or memory leak problems.
   See Memory Management article for details.
5. Set the node transformation in the update() loop. Note that it is necessary to scale the rotation angle each frame with the frame duration (because it's different for each individual frame) to get constant angular velocity.
   Source code (UnigineScript)

   /* ... */
   
   int update() {
   
   	// check whether the node exists
   	if(box != NULL) {
   											
   		// get the frame duration
   		float ifps = engine.game.getIFps();
   											
   		// set the angle of rotation
   		float angle = ifps * 90.0f;
   											
   		// get the current transformation of the node and apply rotation
   		mat4 transform = box.getTransform() * rotateZ(angle);
   											
   		// set new transformation to the node
   		box.setTransform(transform);
   	}
   	return 1;
   }

   Thus, the resulting script is:
   Source code (UnigineScript)

   #include <core/unigine.h>
   						
   Node box; // add a box node
   							
   int init() {
   
   	// create a new spectator player
   	PlayerSpectator player = new PlayerSpectator();
   							
   	// place it in the specified point
   	player.setPosition(vec3(3.5,0.0,1.3));
   							
   	// turn it in the specified direction
   	player.setDirection(vec3(-1.0,0.0,-0.3));
   							
   	// set the player as default one
   	engine.game.setPlayer(player);
   							
   	// search the node by the specified name
   	int index = engine.editor.findNode("box");
   							
   	// get the node by its index
   	if(index != -1) {
   		box = engine.editor.getNode(index);
   	}		
   	return 1;
   	}
   
   int shutdown() {
   	return 1;
   }
   
   int update() {
   
   	// check whether the node exists
   	if(box != NULL) {
   								
   		// get the frame duration
   		float ifps = engine.game.getIFps();
   								
   		// set the angle of rotation
   		float angle = ifps * 90.0f;
   								
   		// get the current transformation of the node and calculate rotation
   		mat4 transform = box.getTransform() * rotateZ(angle);
   								
   		// set new transformation to the node
   		box.setTransform(transform);
   	}
   	return 1;
   }

6. Save all the changes in the <your_project_name>.cpp world script file.
7. If you have already opened your project, open console by pressing the grave accent (`) key, placed under the ESC key.

   

8. Type the command and press Enter to see the result.
   Source code

   world_reload

   

You can add the script to the box by using the WorldExpression object.

1. On the Menu bar, choose Create -> World -> Expression to create the WorldExpression object.

   

2. Click the left mouse button to place the box.

   

3. On the Menu bar, click Windows -> Nodes or press N to open the Nodes window.

   

4. Choose the added WorldExpression node and change the position to 1, -1, 0.5. Now you have the primitive box and the World Expression object on a plane.

   

5. Choose the WorldExpression node and open the Expression tab.

   

6. Put code into the Source field.
   Source code (UnigineScript)

   {
   	// get the WorldExpression node via its internal function
   	Node worldExpression = getNode();
   	
   	// get the frame duration
   	float ifps = engine.game.getIFps();
   
   	// set the angle of rotation
   	float angle = ifps * 90.0f;
   
   	// get the current transformation of the node and apply rotation
   	mat4 transform = worldExpression.getTransform() * rotateZ(angle);
   
   	// set new transformation to the node
   	worldExpression.setTransform(transform);
   }

   Warning

   Curly braces are mandatory!

   Other ways of attaching scripts to the World Expression object you can read here.

7. Drag the box node with ALT button pressed to the worldExpression node in the Nodes hierarchy list.

   

   Now the box object is the child of the worldExpression object. It means that the box object inherits all expression transformations of the World Expression object.
   Notice

   All the objects that are children of the World Expression object inherit expression transformations.
   If the box node gets outside the viewing frustum, but the bounding box is still in the viewing frustum or the camera is inside this bounding box, the playback of the transformation sequence will continue.
8. Close the Nodes window to see the result.