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Unigine Basics
1. Introduction
2. Managing Virtual Worlds
3. Preparing 3D Models
4. Materials
5. Cameras and Lighting
7. Making Cutscenes and Recording Videos
8. Preparing Your Project for Release
9. Physics
10. Optimization Basics
11. PROJECT2: First-Person Shooter
12. PROJECT3: Third-Person Cross-Country Arcade Racing Game
13. PROJECT4: VR Application With Simple Interaction

Moving and Rotating an Object

The objects existing in the virtual world are often moving somewhere and rotating, in general, transforming. Each node has a transformation matrix that encodes its position, rotation, and scale in the world. If a node is a child of another node (part of its hierarchy), it has a transformation matrix associated with the parent (local). This is why the Node class has two different properties: Transform and WorldTransform, which handle local and world transformation matrices respectively.

The following code shows how basic node transformations are performed:

Source code (C#)
// move the node by X, Y, Z units along the corresponding axes
node.WorldPosition = node.WorldPosition + new vec3(X, Y, Z);

// move the node by one unit along the Y axis
node.WorldTranslate(0.0f, 1.0f, 0.0f);

// rotate the node around the axis (X, Y, Z) by the Alpha angle
node.SetWorldRotation(node.GetWorldRotation() * new quat(new vec3(X, Y, Z), Alpha));

// rotate the node around X, Y, and Z axes by the corresponding angle (angle_X, angle_Y, angle_Z)
node.SetWorldRotation(node.GetWorldRotation() * new quat(angle_X, angle_Y, angle_Z));

// rotate the node by 45 degrees along the Z axis
node.WorldRotate(0.0f, 0.0f, 45.0f);

// orient the node using a direction vector and a vector pointing upwards
node.SetWorldDirection(new vec3(0.5f, 0.5f, 0.0f), vec3.UP, MathLib.AXIS.Y);

// set the node scale to Scale_X, Scale_Y, Scale_Z along the corresponding axes
node.WorldScale = new vec3(Scale_X, Scale_Y, Scale_Z);

// set a new transformation matrix to scale the node 2 times along all axes, 
// rotate it by 45 degrees around the Z-axis and move it by 1 unit along all axes
dmat4 transform = new dmat4(MathLib.Translate(1.0f, 1.0f, 1.0f) 
					* MathLib.Rotate(new quat(0.0f, 0.0f, 1.0f, 45.0f)) 
					* MathLib.Scale(new vec3(2.0f)));

// set the node transformation matrix relative to its parent
node.Transform = transform;

// set the node transformation matrix relative to the world origin
node.WorldTransform = transform;


Let's add a fan to our scene and try to breathe life into it:

  1. Open the archviz/interior/fan folder in the Asset Browser, drag the fan asset fan.fbx to the scene and place it on the table near the bed.
  2. Open the archviz/interior/fan/materials folder and drag the fan_body_mat_0 material to the fan body, and the fan_propeller_mat_0 material — to the blades.

  3. Now, let's write a component that will rotate its blades. Create a new component, name it Fan and write the following code:

    Source code (C#)
    using System;
    using System.Collections;
    using System.Collections.Generic;
    using Unigine;
    [Component(PropertyGuid = "AUTOGENERATED_GUID")] // <-- identifier is generated automatically for a new component
    public class Fan : Component
    	public Node fan_node = null;
    	public float speed = 10.0f;
    	private void Update()
    		// if the fan blades node is not assigned, nothing happens
    		// rotate the node with the specified speed
    		fan_node.Rotate(0, speed, 0);
  4. Create NodeDummy, name it fan_rotator, and assign the Fan component to it. Customize the Fan component by dragging the fan_table_propeller node into the Fan Node field and setting the rotation speed of the blades.

  5. Let's add fan_rotator to the child nodes of fan_table, assign the Toggle component to the fan_table_switch node, and drag the fan_rotator node into the Control Node field.
  6. Now we can press Play and check the result.
Last update: 2024-04-19
Build: ()