Babylon.GUI

The Babylon.js GUI library is an extension you can use to generate interactive user interface. It is build on top of the DynamicTexture.

The latest version can be found here: https://github.com/BabylonJS/Babylon.js/tree/master/dist/preview%20release/gui.

And the source code is available on the main Babylon.js repo: https://github.com/BabylonJS/Babylon.js/tree/master/gui.

You can find a complete demo here: http://www.babylonjs.com/demos/gui/

Introduction

Babylon.GUI uses a DynamicTexture to generate a fully functionnal user interface. It is an alternative to Canvas2D.

The main difference is that Canvas2D is full GPU oriented (text constructrion, animations, etc..) where Babylon.GUI relies on HTML canvas API.

While it could be seen as a less performant approach, it is also more flexible. Furthermore, HTML canvas is also GPU accelerated on most recent browsers.

AdvancedDynamicTexture

To begin with Babylon.GUI, you first need an AdvancedDynamicTexture object.

Babylon.GUI has two modes:

• Fullscreen mode: In this mode, Babylon.GUI will cover the entire screen and will rescale to always adapt to your rendering resolution. It will also intercept clicks (including touches). To create an AdvancedDynamicTexture in fullscreen mode, just run this code:

var advancedTexture = BABYLON.GUI.AdvancedDynamicTexture.CreateFullscreenUI("myUI");

Here is an example of a simple fullscreen mode GUI: https://www.babylonjs-playground.com/#XCPP9Y#1 -

• Texture mode: In this mode, BABYLON.GUI will be used as a texture for a given mesh. You will have to define the resolution of your texture. To create an AdvancedDynamicTexture in texture mode, just run this code:

var advancedTexture2 = BABYLON.GUI.AdvancedDynamicTexture.CreateForMesh(myPlane, 1024, 1024);

Here is an example of a simple texture mode GUI: https://www.babylonjs-playground.com/#ZI9AK7#1 -

Please note that handling pointer move events could be costly on complex meshes, so you can turn off supporting pointer move events with a fourth parameter:

var advancedTexture2 = BABYLON.GUI.AdvancedDynamicTexture.CreateForMesh(myPlane, 1024, 1024, false);

Once you have an AdvancedDynamicTexture object, you can start adding controls.

General properties

Events

All controls have the following observables:

Observables	Comments
onPointerMoveObservable	Raised when the cursor moves over the control. Only available on fullscreen mode
onPointerEnterObservable	Raised when the cursor enters the control. Only available on fullscreen mode
onPointerOutObservable	Raised when the cursor leaves the control. Only available on fullscreen mode
onPointerDownObservable	Raised when pointer is down on the control.
onPointerUpObservable	Raised when pointer is up on the control.

You can also define that a control is invisble to events (so you can click through it for instance). To do so, just call control.isHitTestVisible.

Please note that onPointerMoveObservable, onPointerDownObservable and onPointerUpObservable will receive a Vector2 parameter containing the pointer coordinates. If you want to get the pointer coordinates in local control space, you have to call control.getLocalCoordinates(coordinates).

Here is an example of how to use observables: https://www.babylonjs-playground.com/#XCPP9Y#121 -

Alignments

You can define the alignments used by your control with the following properties:

Property	Default	Comments
horizontalAlignment	BABYLON.GUI.Control.HORIZONTAL_ALIGNMENT_CENTER	Can be set to left, right or center.
verticalAlignment	BABYLON.GUI.Control.VERTICAL_ALIGNMENT_CENTER	Can be set to top, bottom and center.

Here is an example of how to use alignments: https://www.babylonjs-playground.com/#XCPP9Y#13 -

Position and size

You can set controls' position with the following properties:

Property	Type	Default	Default unit
left	valueAndUnit	0	Pixel
top	valueAndUnit	0	Pixel

Size can be set with:

Property	Type	Default	Default unit
width	valueAndUnit	100%	Percentage
height	valueAndUnit	100%	Percentage

Paddings can be set with:

Property	Type	Default	Default unit
paddingTop	valueAndUnit	0px	Pixel
paddingBottom	valueAndUnit	0px	Pixel
paddingLeft	valueAndUnit	0px	Pixel
paddingRight	valueAndUnit	0px	Pixel

Please note that paddings are inside the control. This means that the usableWidth = width - paddingLeft - paddingRight. Same for usableHeight = height - paddingTop - paddingBottom.

All these properties can be defined using pixel or percentage as unit. To set value as pixel, use this construct: control.left = "50px" To set value as percentage, use this construct: control.left = "50%"

You can also not define the unit (In this case the default unit will be used): control.width = 0.5 (which is equivalent to control.width = "50%")

Here is an example of how to use positions and sizes: https://www.babylonjs-playground.com/#XCPP9Y#14 -

Tracking positions

All controls can be moved to track position of a mesh. To do this, just call control.linkWithMesh(mesh). You can then offset the position with control.linkOffsetX and control.linkOffsetY.

Here is an example of a trackable label: https://www.babylonjs-playground.com/#XCPP9Y#16 -

Please note that controls that want to track position of a mesh must be at root level (at AdvancedDynamicTexture level).

You can also move a control to a specific coordinates in your scene with control.moveToVector3(position). Please note that the control will not stick with the vector if you change it afterwards.

For Line control, you can also attach the second point to a control with line.connectedControl = control. In this case the x2 and y2 properties are used to offset the second point from the connected control.

With these 2 options, you can create a complete trackable label: https://www.babylonjs-playground.com/#XCPP9Y#20 -

Adaptive scaling

When in fullscreen UI, you can decide to define your UI with a fixed resolution. To define this resolution, just set myAdvancedDynamicTexture.idealWidth = 600 or myAdvancedDynamicTexture.idealHeight = 400.

If both are set, the idealWidth will be used.

When ideal resolution is set, all values expressed in pixels are considered relatively to this resolution and scaled accordingly to match the current resolution.

Even when ideal size is set, the fullscreen UI will be rendered at the same resolution of your canvas, but you can decide (mostly for performance reason) to force the texture to use the ideal size for resolution as well. To do so, just call myAdvancedDynamicTexture.renderAtIdealSize = true.

Here is an example of how to use horizontal adaptive scaling: https://www.babylonjs-playground.com/#XCPP9Y#39 -

Rotation and Scaling

Controls can be transformed with the following properties:

Property	Type	Default	Comments
rotation	number	0	Value is in radians
scaleX	number	1
scaleY	number	1
transformCenterX	number	0.5	Define the center of transformation on X axis. Value is between 0 and 1
transformCenterY	number	0.5	Define the center of transformation on Y axis. Value is between 0 and 1

Please be aawre that transformations are done at rendering level so after all computations. This means that alignment or positioning will be done first without taking transform in account.

Here is an example of how to use rotation and scaling: https://www.babylonjs-playground.com/#XCPP9Y#22 -

Controls

A control is an abstraction of a piece of UI. There are two kinds of controls:

• Pure controls: A pure control defines an action or an information useful for the user. It could be a TextBlock or a Button.
• Containers: Containers are used to organize your UI. They can contain other controls or containers.

All controls share the following properties:

Property	Type	Default	Comments
alpha	number	1	Between 0 and 1. 0 means completely transparent. 1 means fully opaque
color	string	Black	Foreground color
fontFamily	string	Arial	Font family can be inherited. This means that if you set it on a container, it will be transmitted to all children of the container
fontSize	number	18	Can be inherited
zIndex	number	0	the zIndex can be used to reorder controls on the z axis

Controls can be added directly to the AdvancedDynamicTexture or to a container with:

container.addControl(control);

They can be removed with:

container.removeControl(control);

You can also control the control visibility with control.isVisible = false.

TextBlock

The TextBlock is a simple control used to display text: https://www.babylonjs-playground.com/#XCPP9Y#2 -

Here are the properties you can define:

Property	Type	Default	Comments
text	string	null	Text to display
textWrapping	boolean	false	Can be set to true to enable text wrapping.
textHorizontalAlignment	number	BABYLON.GUI.Control.HORIZONTAL_ALIGNMENT_CENTER	Can be set to left, right or center
textVerticalAlignment	number	BABYLON.GUI.Control.VERTICAL_ALIGNMENT_CENTER	Can be set to top, bottom or center

Button

A button can be used to interact with your user. Please see the events chapter to see how to connect your events with your buttons.

There are three kinds of buttons available out of the box:

• ImageButton: An image button is a button made with an image and a text. You can create one with:

var button = BABYLON.GUI.Button.CreateImageButton("but", "Click Me", "textures/grass.png");

You can try it here: https://www.babylonjs-playground.com/#XCPP9Y#3 -

• SimpleButton: A simple button with text only

var button = BABYLON.GUI.Button.CreateSimpleButton("but", "Click Me");

You can try it here: https://www.babylonjs-playground.com/#XCPP9Y#4 -

• ImageOnlyButton:

var button = BABYLON.GUI.Button.CreateImageOnlyButton("but", "textures/grass.png");

You can try it here: https://www.babylonjs-playground.com/#XCPP9Y#28 -

Visual animations

By default a button will change its opacity on pointerover and will change it scale when clicked. You can define your own animations with the following callbacks:

• pointerEnterAnimation
• pointerOutAnimation
• pointerDownAnimation
• pointerUpAnimation

Custom button

You can also create a complete custom button by manually adding children to the button. Here is how the ImageButton is built:

var result = new Button(name);

// Adding text
var textBlock = new BABYLON.GUI.TextBlock(name + "_button", text);
textBlock.textWrapping = true;
textBlock.textHorizontalAlignment = BABYLON.GUI.Control.HORIZONTAL_ALIGNMENT_CENTER;
textBlock.paddingLeft = "20%";
result.addControl(textBlock);   

// Adding image
var iconImage = new BABYLON.GUI.Image(name + "_icon", imageUrl);
iconImage.width = "20%";
iconImage.stretch = BABYLON.GUI.Image.STRETCH_UNIFORM;
iconImage.horizontalAlignment = BABYLON.GUI.Control.HORIZONTAL_ALIGNMENT_LEFT;
result.addControl(iconImage);            

return result;

Checkbox

The checkbox is used to control a boolean value. You can specify the value with checkbox.isChecked.

Changing the isChecked property will raise an observable called checkbox.onIsCheckedChangedObservable.

The control is rendered using the following properties:

Property	Type	Default	Comments
color	string	white	Foreground color
background	string	black	Background color
checkSizeRatio	number	0.8	Define the ratio used to compute the size of the inner checkbox (0.8 by default, which means the inner check size is equal to 80% of the control itself)

Here is an example of a checkbox: https://www.babylonjs-playground.com/#U9AC0N#2 -

RadioButton

The radio button is used to define a value among a list by using a group of radio buttons where only one can be true. You can specify the selected value with radiobutton.isChecked.

Changing the isChecked property will raise an observable called checkbox.onIsCheckedChangedObservable. Furthermore, if you select a radio button, all other radio buttons within the same group will turn to false.

The control is rendered using the following properties:

Property	Type	Default	Comments
color	string	white	Foreground color
background	string	black	Background color
checkSizeRatio	number	0.8	Define the ratio used to compute the size of the inner checkbox (0.8 by default, which means the inner check size is equal to 80% of the control itself)
group	string	empty string	Use the group property to gather radio buttons working on the same value set

Here is an example of a radiobutton: https://www.babylonjs-playground.com/#U9AC0N#13 -

Slider

The slider is used to control a value within a range. You can specify the range with slider.minimum and slider.maximum.

The value itself is specified with slider.value and will raise an observable everytime it is changed (slider.onValueChangedObservable).

The control is rendered using the following properties:

Property	Type	Default	Comments
borderColor	string	white	Color used to render the border of the thumb
color	string	white	Foreground color
background	string	black	Background color
barOffset	valueAndUnit	5px	Offset used vertically to draw the background bar
thumbWidth	valueAndUnit	30px	Width of the thumb

Here is an example of a slider: https://www.babylonjs-playground.com/#U9AC0N#1 -

Line

The line will draw a line (!!) between two points.

Here are the properties you can define:

Property	Type	Default	Comments
x1	number	0	X coordinate of the first point
y1	number	0	Y coordinate of the first point
x2	number	0	X coordinate of the second point
y2	number	0	Y coordinate of the second point
dash	array of numbers	Empty array	Defines the size of the dashes
lineWidth	number	1	Width in pixel

Here is an example of a line: https://www.babylonjs-playground.com/#XCPP9Y#6 -

Image

Use the image control to display an image in your UI. You can control the stretch used by the image with image.stretch property. You can set it to one of these values:

• BABYLON.GUI.Image.STRETCH_NONE: Use original size
• BABYLON.GUI.Image.STRETCH_FILL: Scale the image to fill the container (This is the default value)
• BABYLON.GUI.Image.STRETCH_UNIFORM: Scale the image to fill the container but maintain aspect ratio
• BABYLON.GUI.Image.STRETCH_EXTEND: Scale the container to adapt to the image size.

You may want to have the Image control adapt its size to the source image. To do so just call image.autoScale = true.

You can change image source at any time with image.source="myimage.jpg".

You can also define which part of the source image you want to use with the following properties:

• sourceLeft: x coordinate in the source image (in pixel)
• sourceTop: y coordinate in the source image (in pixel)
• sourceWidth: width of the source image you want to use (in pixel)
• sourceHeight: height of the source image you want to use (in pixel)

Here is an example of an image: https://www.babylonjs-playground.com/#XCPP9Y#7 -

Containers

The containers are controls used to host other controls. Use them to organize your UI. Containers has one specific property: container.background. Use it to define the background color of your container.

Rectangle

The Rectangle is a rectangular container with the following properties:

Property	Type	Default	Comments
thickness	number	1	Thickness of the border
cornerRadius	number	0	Size in pixel of each corner. Used to create rounded rectangles

Here is an example of a rectangle control: https://www.babylonjs-playground.com/#XCPP9Y#8 -

Ellipse

The Ellipse is a ellipsoidal container with the following properties:

Property	Type	Default	Comments
thickness	number	1	Thickness of the border

Here is an example of an ellipse control: https://www.babylonjs-playground.com/#XCPP9Y#10 -

StackPanel

The StackPanel is a control which stacks its children based on its orientation (can be horizontal or vertical). All children must have a defined width or height (depending on the orientation).

The height (or width) of the StackPanel is defined automatically based on children.

Here is an example of a StackPanel: https://www.babylonjs-playground.com/#XCPP9Y#11 -

ColorPicker

The color picker control allows users to set colors in your scene.

Whenever a user interacts with the color picker an observable is triggered (colorPicker.onValueChangedObservable) which returns the current value (Color3) of the color picker.

The control is rendered using the following properties:

Property	Type	Default	Comments
size	string or number	"200px"	The size, width, and height property will always be the same value since the color picker can only be a square.

Here is an example of a color picker: https://www.babylonjs-playground.com/#91I2RE#1 -

Helpers

To reduce the amount of code required to achieve frequent tasks you can use the following helpers:

• BABYLON.GUI.Control.AddHeader(control, text, size, options { isHorizontal, controlFirst }): This function will create a StackPanel (horizontal or vertical based on options) and will add your control plus a TextBlock in it. Options can also be used to specify if the control is inserted first of after the header. Depending on the orientation, size will either specify the widht or the height used for the TextBlock.