WebGLRenderingContext.getFramebufferAttachmentParameter() - Web APIs 编辑

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.
• gl.DEPTH_STENCIL_ATTACHMENT: Texture attachment for both, the depth and stencil buffer.
• When using a WebGL 2 context, the following values are available additionally:
  • 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
• When using the OVR_multiview2 extension:
  • ext.FRAMEBUFFER_ATTACHMENT_TEXTURE_NUM_VIEWS_OVR: the number of views of the framebuffer object attachment.
  • ext.FRAMEBUFFER_ATTACHMENT_TEXTURE_BASE_VIEW_INDEX_OVR:  the base view index of the framebuffer object attachment.

Return value

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

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

Browser compatibility

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The compatibility table in this page is generated from structured data. If you'd like to contribute to the data, please check out https://github.com/mdn/browser-compat-data and send us a pull request.

See also

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