WebGLRenderingContext.getFramebufferAttachmentParameter

The WebGLRenderingContext.getFramebufferAttachmentParameter() method of the WebGL API returns information about a framebuffer's attachment.

Syntax

any gl.getFramebufferAttachmentParameter(target, attachment, pname);

Parameters

target

A GLenum specifying the binding point (target). Possible values:

• gl.FRAMEBUFFER: Collection buffer data storage of color, alpha, depth and stencil buffers used to render an image.
• When using a WebGL 2 context, the following values are available additionally:
  • gl.DRAW_FRAMEBUFFER: Equivalent to gl.FRAMEBUFFER. Used as a destination for drawing, rendering, clearing, and writing operations.
  • gl.READ_FRAMEBUFFER: Used as a source for reading operations.

attachment

A GLenum specifying the attachment point for the texture. Possible values:

• gl.COLOR_ATTACHMENT0: Texture attachment for the framebuffer's color buffer.
• gl.DEPTH_ATTACHMENT: Texture attachment for the framebuffer's depth buffer.
• gl.STENCIL_ATTACHMENT: Texture attachment for the framebuffer's stencil buffer.
• When using a WebGL 2 context, the following values are available additionally:
  • gl.DEPTH_STENCIL_ATTACHMENT: Texture attachment for both, the depth and stencil buffer.
  • gl.COLOR_ATTACHMENT1
gl.COLOR_ATTACHMENT2
gl.COLOR_ATTACHMENT3
gl.COLOR_ATTACHMENT4
gl.COLOR_ATTACHMENT5
gl.COLOR_ATTACHMENT6
gl.COLOR_ATTACHMENT7
gl.COLOR_ATTACHMENT8
gl.COLOR_ATTACHMENT9
gl.COLOR_ATTACHMENT10
gl.COLOR_ATTACHMENT11
gl.COLOR_ATTACHMENT12
gl.COLOR_ATTACHMENT13
gl.COLOR_ATTACHMENT14
gl.COLOR_ATTACHMENT15
• When using the WEBGL_draw_buffers extension:
  • ext.COLOR_ATTACHMENT0_WEBGL (same as gl.COLOR_ATTACHMENT0)
    ext.COLOR_ATTACHMENT1_WEBGL
ext.COLOR_ATTACHMENT2_WEBGL
ext.COLOR_ATTACHMENT3_WEBGL
ext.COLOR_ATTACHMENT4_WEBGL
ext.COLOR_ATTACHMENT5_WEBGL
ext.COLOR_ATTACHMENT6_WEBGL
ext.COLOR_ATTACHMENT7_WEBGL
ext.COLOR_ATTACHMENT8_WEBGL
ext.COLOR_ATTACHMENT9_WEBGL
ext.COLOR_ATTACHMENT10_WEBGL
ext.COLOR_ATTACHMENT11_WEBGL
ext.COLOR_ATTACHMENT12_WEBGL
ext.COLOR_ATTACHMENT13_WEBGL
ext.COLOR_ATTACHMENT14_WEBGL
ext.COLOR_ATTACHMENT15_WEBGL

pname

A GLenum specifying information to query. Possible values:

• gl.FRAMEBUFFER_ATTACHMENT_OBJECT_TYPE: The type which contains the attached image.
• gl.FRAMEBUFFER_ATTACHMENT_OBJECT_NAME: The texture or renderbuffer of the attached image (WebGLRenderbuffer or WebGLTexture).
• gl.FRAMEBUFFER_ATTACHMENT_TEXTURE_LEVEL: Mipmap level. Default value: 0.
• gl.FRAMEBUFFER_ATTACHMENT_TEXTURE_CUBE_MAP_FACE: The name of cube-map face of the texture.
• When using the EXT_sRGB extension:
  • ext.FRAMEBUFFER_ATTACHMENT_COLOR_ENCODING_EXT: The framebuffer color encoding.
• When using a WebGL 2 context, the following values are available additionally:
  • gl.FRAMEBUFFER_ATTACHMENT_ALPHA_SIZE
  • gl.FRAMEBUFFER_ATTACHMENT_BLUE_SIZE
  • gl.FRAMEBUFFER_ATTACHMENT_COLOR_ENCODING
  • gl.FRAMEBUFFER_ATTACHMENT_COMPONENT_TYPE
  • gl.FRAMEBUFFER_ATTACHMENT_DEPTH_SIZE
  • gl.FRAMEBUFFER_ATTACHMENT_GREEN_SIZE
  • gl.FRAMEBUFFER_ATTACHMENT_RED_SIZE
  • gl.FRAMEBUFFER_ATTACHMENT_STENCIL_SIZE
  • gl.FRAMEBUFFER_ATTACHMENT_TEXTURE_LAYER

Return value

Depends on the requested information (as specified with pname). Either a GLint, a GLenum, a WebGLRenderbuffer, or a WebGLTexture.

pname parameter	Return value
gl.FRAMEBUFFER_ATTACHMENT_OBJECT_TYPE	A GLenum indicating the type of the texture. Either gl.RENDERBUFFER, gl.TEXTURE, or if no image is attached, gl.NONE.
gl.FRAMEBUFFER_ATTACHMENT_OBJECT_NAME	The texture (WebGLTexture) or renderbuffer (WebGLRenderbuffer) of the attached image.
gl.FRAMEBUFFER_ATTACHMENT_TEXTURE_LEVEL	A GLint indicating the mipmap level. Default value: 0.
gl.FRAMEBUFFER_ATTACHMENT_TEXTURE_CUBE_MAP_FACE	A GLenum indicating the name of cube-map face of the texture. Possible values: gl.TEXTURE_CUBE_MAP_POSITIVE_X: Image for the positive X face of the cube. gl.TEXTURE_CUBE_MAP_NEGATIVE_X: Image for the negative X face of the cube. gl.TEXTURE_CUBE_MAP_POSITIVE_Y: Image for the positive Y face of the cube. gl.TEXTURE_CUBE_MAP_NEGATIVE_Y: Image for the negative Y face of the cube. gl.TEXTURE_CUBE_MAP_POSITIVE_Z: Image for the positive Z face of the cube. gl.TEXTURE_CUBE_MAP_NEGATIVE_Z: Image for the negative Z face of the cube.
gl.FRAMEBUFFER_ATTACHMENT_ALPHA_SIZE	A GLint indicating the number of bits in the alpha component of the attachment.
gl.FRAMEBUFFER_ATTACHMENT_BLUE_SIZE	A GLint indicating the number of bits in the blue component of the attachment.
gl.FRAMEBUFFER_ATTACHMENT_COLOR_ENCODING	A GLenum indicating the encoding of components of the specified attachment. Either gl.LINEAR or gl.SRGB.
gl.FRAMEBUFFER_ATTACHMENT_COMPONENT_TYPE	A GLenum indicating the format of the components of the specified attachment. Either gl.FLOAT, gl.INT, gl.UNSIGNED_INT, gl.SIGNED_NORMALIZED, or gl.UNSIGNED_NORMALIZED.
gl.FRAMEBUFFER_ATTACHMENT_DEPTH_SIZE	A GLint indicating the number of bits in the depth component of the attachment.
gl.FRAMEBUFFER_ATTACHMENT_GREEN_SIZE	A GLint indicating the number of bits in the green component of the attachment.
gl.FRAMEBUFFER_ATTACHMENT_RED_SIZE	A GLint indicating the number of bits in the red component of the attachment.
gl.FRAMEBUFFER_ATTACHMENT_STENCIL_SIZE	A GLint indicating the number of bits in the stencil component of the attachment.
gl.FRAMEBUFFER_ATTACHMENT_TEXTURE_LAYER	A GLint indicating the number of the texture layer which contains the attached image.
ext.FRAMEBUFFER_ATTACHMENT_COLOR_ENCODING_EXT	A GLenum indicating the framebuffer color encoding. Either gl.LINEAR or ext.SRGB_EXT.

Exceptions

• A gl.INVALID_ENUM error is thrown if target is not gl.FRAMEBUFFER, gl.DRAW_FRAMEBUFFER, gl.READ_FRAMEBUFFER or if attachment is not one of the accepted attachment points.

Examples

gl.getFramebufferAttachmentParameter(gl.FRAMEBUFFER, gl.COLOR_ATTACHMENT0, 
                                     gl.FRAMEBUFFER_ATTACHMENT_OBJECT_TYPE);

Specifications

Specification	Status	Comment
WebGL 1.0 The definition of 'getFramebufferAttachmentParameter' in that specification.	Recommendation	Initial definition for WebGL.
OpenGL ES 2.0 The definition of 'glGetFramebufferAttachmentParameteriv' in that specification.	Standard	Man page of the (similar) OpenGL API.
WebGL 2.0 The definition of 'getFramebufferAttachmentParameter' in that specification.	Editor's Draft	Updated definition for WebGL 2.
OpenGL ES 3.0 The definition of 'glGetFramebufferAttachmentParameteriv' in that specification.	Standard	Man page of the (similar) OpenGL ES 3 API.

Browser compatibility

[1] WebGL 2 is enabled by default in Firefox Nightly. To enable it in a release version of Firefox, set the preference webgl.enable-prototype-webgl2 to true in about:config.

[2] To use an experimental implementation of WebGL 2 in Chrome, you have to start Chrome with the runtime flag --enable-unsafe-es3-apis.

See also

• WebGLRenderingContext.createFramebuffer()
• WebGLRenderingContext.deleteFramebuffer()
• WebGLRenderingContext.isFramebuffer()
• Other buffers: WebGLBuffer, WebGLRenderbuffer
• EXT_sRGB
• WEBGL_draw_buffers