XRWebGLBinding: createCylinderLayer() method

The createCylinderLayer() method of the XRWebGLBinding interface returns an XRCylinderLayer object, which is a layer that takes up a curved rectangular space in the virtual environment.

Syntax

createCylinderLayer(init)

Parameters

init

An object to configure the XRCylinderLayer. It must have the space, viewPixelHeight, and viewPixelWidth properties. init has the following properties:

aspectRatio Optional

A number indicating the ratio of the visible cylinder section. It is the ratio of the width of the visible section of the cylinder divided by its height. The width is calculated by multiplying the radius with the centralAngle. The default value is 2.0.

centralAngle Optional

A number indicating the angle in radians of the visible section of the cylinder. Default value: 0.78539 (π / 4).

colorFormat Optional

A GLenum defining the data type of the color texture data. Possible values:

• gl.RGB
• gl.RGBA Additionally, for contexts with the EXT_sRGB extension enabled:
• ext.SRGB_EXT
• ext.SRGB_ALPHA_EXT Additionally, for WebGL2RenderingContext contexts:
• gl.RGBA8
• gl.RGB8
• gl.SRGB8
• gl.RGB8_ALPHA8 Additionally, for contexts with the WEBGL_compressed_texture_etc extension enabled:
• ext.COMPRESSED_RGB8_ETC2
• ext.COMPRESSED_RGB8_PUNCHTHROUGH_ALPHA1_ETC2
• ext.COMPRESSED_RGBA8_ETC2_EAC
• ext.COMPRESSED_SRGB8_ETC2
• ext.COMPRESSED_SRGB8_PUNCHTHROUGH_ALPHA1_ETC2
• ext.COMPRESSED_SRGB8_ALPHA8_ETC2_EAC Additionally, for contexts with the WEBGL_compressed_texture_astc extension enabled:
• All of the formats the extension supports. The default value is gl.RGBA.

depthFormat Optional

A GLenum defining the data type of the depth texture data or 0 indicating that the layer should not provide a depth texture (in that case XRProjectionLayer.ignoreDepthValues will be true). Possible values within WebGLRenderingContext contexts with the WEBGL_depth_texture extension enabled, or within WebGL2RenderingContext contexts (no extension required):

• gl.DEPTH_COMPONENT
• gl.DEPTH_STENCIL Additionally, for WebGL2RenderingContext contexts:
• gl.DEPTH_COMPONENT24
• gl.DEPTH24_STENCIL24 The default value is gl.DEPTH_COMPONENT.

isStatic Optional

A boolean that, if true, indicates you can only draw to this layer when needsRedraw is true. The default value is false.

layout Optional

A string indicating the layout of the layer. Possible values:

default

The layer accommodates all views of the session.

mono

A single XRSubImage is allocated and presented to both eyes.

stereo

The user agent decides how it allocates the XRSubImage (one or two) and the layout (top/bottom or left/right).

stereo-left-right

A single XRSubImage is allocated. Left eye gets the left area of the texture, right eye the right.

stereo-top-bottom

A single XRSubImage is allocated. Left eye gets the top area of the texture, right eye the bottom. The default value is mono.

mipLevels Optional

A number specifying desired number of mip levels. The default value is 1.

radius Optional

A number indicating the radius of the cylinder. Default value: 2.0.

space Required

An XRSpace object defining the layer's spatial relationship with the user's physical environment.

textureType Optional

A string defining the type of texture the layer will have. Possible values:

• texture: The textures of XRWebGLSubImage will be of type gl.TEXTURE_2D.
• texture-array: the textures of XRWebGLSubImage will be of type gl.TEXTURE_2D_ARRAY (WebGL 2 contexts only). The default value is texture.

transform Optional

An XRRigidTransform object defining the offset and orientation relative to space.

viewPixelHeight Required

A number specifying the pixel height of the layer view.

viewPixelWidth Required

A number specifying the pixel width of the layer view.

Return value

An XRCylinderLayer object.

Examples

Creating an XRCylinderLayer

Configure the cylinder layer using the properties listed above in a call to createCylinderLayer(). To present layers to the XR device, add them to the layers render state using XRSession.updateRenderState().

function onXRSessionStarted(xrSession) {
  const glCanvas = document.createElement("canvas");
  const gl = glCanvas.getContext("webgl2", { xrCompatible: true });
  const xrGlBinding = new XRWebGLBinding(xrSession, gl);
  const cylinderLayer = xrGlBinding.createCylinderLayer({
    space: xrReferenceSpace,
    viewPixelWidth: 1200,
    viewPixelHeight: 600,
    centralAngle: (60 * Math.PI) / 180,
    aspectRatio: 2,
    radius: 2,
    transform: new XRRigidTransform(/* … */),
  });

  xrSession.updateRenderState({
    layers: [cylinderLayer],
  });
}

Specifications

Browser compatibility

See also

• XRCylinderLayer
• WebGL constants