GLGETFRAMEBUFFERATTA(3G)

NAME
glGetFramebufferAttachmentParameteriv - retrieve information about attachments of a bound framebuffer object

C SPECIFICATION

void glGetFramebufferAttachmentParameter(GLenum target, GLenum attachment, GLenum pname, GLint *params);

PARAMETERS

target
    Specifies the target of the query operation.

attachment
    Specifies the attachment within target

pname
    Specifies the parameter of attachment to query.

params
    Specifies the address of a variable receive the value of pname for attachment.

DESCRIPTION

glGetFramebufferAttachmentParameter returns information about attachments of a bound framebuffer object. target specifies the framebuffer binding point and must be GL_DRAW_FRAMEBUFFER, GL_READ_FRAMEBUFFER or GL_FRAMEBUFFER. GL_FRAMEBUFFER is equivalent to GL_DRAW_FRAMEBUFFER.

If the default framebuffer is bound to target then attachment must be one of GL_FRONT_LEFT, GL_FRONT_RIGHT, GL_BACK_LEFT, or GL_BACK_RIGHT, identifying a color buffer, GL_DEPTH, identifying the depth buffer, or GL_STENCIL, identifying the stencil buffer.

If a framebuffer object is bound, then attachment must be one of GL_COLOR_ATTACHMENTi, GL_DEPTH_ATTACHMENT, GL_STENCIL_ATTACHMENT, or GL_DEPTH_STENCIL_ATTACHMENT. i in GL_COLOR_ATTACHMENTi must be in the range zero to the value of GL_MAX_COLOR_ATTACHMENTS - 1.

If attachment is GL_DEPTH_STENCIL_ATTACHMENT and different objects are bound to the depth and stencil attachment points of target the query will fail. If the same object is bound to both attachment points, information about that object will be returned.

Upon successful return from glGetFramebufferAttachmentParameteriv, if pname is GL_FRAMEBUFFER_ATTACHMENT_OBJECT_TYPE, then params will contain one of GL_NONE, GL_FRAMEBUFFER_DEFAULT, GL_TEXTURE, or GL_RENDERBUFFER, identifying the type of object which contains the attached image. Other values accepted for pname depend on the type of object, as described below.

If the value of GL_FRAMEBUFFER_ATTACHMENT_OBJECT_TYPE is GL_NONE, no framebuffer is bound to target. In this case querying pname GL_FRAMEBUFFER_ATTACHMENT_OBJECT_NAME will return zero, and all other queries will generate an error.

If the value of GL_FRAMEBUFFER_ATTACHMENT_OBJECT_TYPE is not GL_NONE, these queries apply to all other framebuffer types:

    • If pname is GL_FRAMEBUFFER_ATTACHMENT_RED_SIZE, GL_FRAMEBUFFER_ATTACHMENT_GREEN_SIZE, GL_FRAMEBUFFER_ATTACHMENT_BLUE_SIZE, GL_FRAMEBUFFER_ATTACHMENT_ALPHA_SIZE, GL_FRAMEBUFFER_ATTACHMENT_DEPTH_SIZE, or GL_FRAMEBUFFER_ATTACHMENT_STENCIL_SIZE, then params will contain the number of bits in the corresponding red, green, blue, alpha, depth, or stencil component of the specified attachment. Zero is returned if the requested component is not present in attachment.

    • If pname is GL_FRAMEBUFFER_ATTACHMENT_COMPONENT_TYPE, params will contain the format of components of the specified attachment, one of GL_FLOAT, GL_INT, GL_UNSIGNED_INT, GL_SIGNED_NORMALIZED, or GL_UNSIGNED_NORMALIZED for floating-point, signed integer, unsigned integer, signed normalized fixed-point, or unsigned normalized fixed-point components respectively. Only color buffers may have integer components.

    • If pname is GL_FRAMEBUFFER_ATTACHMENT_COLOR_ENCODING, param will contain the encoding of components of the specified attachment, one of GL_LINEAR or GL_SRGB for linear or sRGB-encoded components, respectively. Only color buffer components may be sRGB-encoded; such components are treated as described in sections 4.1.7 and 4.1.8. For the default framebuffer, color encoding is determined by the implementation. For framebuffer objects, components are sRGB-encoded if the internal format of a color attachment is one of the color-renderable SRGB formats.

If the value of GL_FRAMEBUFFER_ATTACHMENT_OBJECT_TYPE is GL_RENDERBUFFER, then:

    • If pname is GL_FRAMEBUFFER_ATTACHMENT_OBJECT_NAME, params will contain the name of the renderbuffer object which contains the attached image.

If the value of GL_FRAMEBUFFER_ATTACHMENT_OBJECT_TYPE is GL_TEXTURE, then:

    • If pname is GL_FRAMEBUFFER_ATTACHMENT_OBJECT_NAME, then params will contain the name of the texture object which contains the attached image.

    • If pname is GL_FRAMEBUFFER_ATTACHMENT_TEXTURE_LEVEL, then params will contain the mipmap level of the texture object which contains the attached image.

    • If pname is GL_FRAMEBUFFER_ATTACHMENT_TEXTURE_CUBE_MAP_FACE and the texture object named GL_FRAMEBUFFER_ATTACHMENT_OBJECT_NAME is a cube map texture, then params will contain the cube map face of the cubemap texture object which contains the attached image. Otherwise params will contain the value zero.

    • If pname is GL_FRAMEBUFFER_ATTACHMENT_TEXTURE_LAYER and the texture object named GL_FRAMEBUFFER_ATTACHMENT_OBJECT_NAME is a layer of a three-dimensional texture or a one-or two-dimensional array texture, then params will contain the number of the texture layer which contains the attached image. Otherwise params will contain the value zero.

    • If pname is GL_FRAMEBUFFER_ATTACHMENT_LAYERED, then params will contain GL_TRUE if an entire level of a three-dimesional texture, cube map texture, or one-or two-dimensional array texture is attached. Otherwise, params will contain GL_FALSE.

Any combinations of framebuffer type and pname not described above will generate an error.

ERRORS

GL_INVALID_ENUM is generated if target is not one of the accepted tokens.

GL_INVALID_ENUM is generated if pname is not valid for the value of GL_FRAMEBUFFER_ATTACHMENT_OBJECT_TYPE.

GL_INVALID_OPERATION is generated if attachment is not the accepted values for target.

GL_INVALID_OPERATION is generated if attachment is GL_DEPTH_STENCIL_ATTACHMENT and different objects are bound to the depth and stencil attachment points of target.

GL_INVALID_OPERATION is generated if the value of GL_FRAMEBUFFER_ATTACHMENT_OBJECT_TYPE is GL_NONE and pname is not GL_FRAMEBUFFER_ATTACHMENT_OBJECT_NAME.

SEE ALSO

glGenFramebuffers(), glBindFramebuffer()

COPYRIGHT

Copyright © 2010 Khronos Group. This material may be distributed subject to the terms and conditions set forth in the Open Publication License, v 1.0, 8 June 1999. http://opencontent.org/openpub/.