glGetVertexAttrib

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Return a generic vertex attribute parameter.

C Specification[edit]

void glGetVertexAttribdv( GLuint index, GLenum pname, GLdouble * params );
void glGetVertexAttribfv( GLuint index, GLenum pname, GLfloat * params );
void glGetVertexAttribiv( GLuint index, GLenum pname, GLint * params );
void glGetVertexAttribIiv( GLuint index, GLenum pname, GLint * params );
void glGetVertexAttribIuiv( GLuint index, GLenum pname, GLuint * params );
void glGetVertexAttribLdv( GLuint index, GLenum pname, GLdouble * params );


Parameters[edit]

index - Specifies the generic vertex attribute parameter to be queried.
pname - Specifies the symbolic name of the vertex attribute parameter to be queried. Accepted values are GL_VERTEX_ATTRIB_ARRAY_BUFFER_BINDING , GL_VERTEX_ATTRIB_ARRAY_ENABLED , GL_VERTEX_ATTRIB_ARRAY_SIZE , GL_VERTEX_ATTRIB_ARRAY_STRIDE , GL_VERTEX_ATTRIB_ARRAY_TYPE , GL_VERTEX_ATTRIB_ARRAY_NORMALIZED , GL_VERTEX_ATTRIB_ARRAY_INTEGER , GL_VERTEX_ATTRIB_ARRAY_LONG , GL_VERTEX_ATTRIB_ARRAY_DIVISOR , GL_VERTEX_ATTRIB_BINDING , GL_VERTEX_ATTRIB_RELATIVE_OFFSET or GL_CURRENT_VERTEX_ATTRIB .
params - Returns the requested data.


Description[edit]

 glGetVertexAttrib returns in params the value of a generic vertex attribute parameter. The generic vertex attribute to be queried is specified by index , and the parameter to be queried is specified by pname .

The accepted parameter names are as follows:


GL_VERTEX_ATTRIB_ARRAY_BUFFER_BINDING  -  params returns a single value, the name of the buffer object currently bound to the binding point corresponding to generic vertex attribute array index . If no buffer object is bound, 0 is returned. The initial value is 0.
GL_VERTEX_ATTRIB_ARRAY_ENABLED  -  params returns a single value that is non-zero (true) if the vertex attribute array for index is enabled and 0 (false) if it is disabled. The initial value is GL_FALSE .
GL_VERTEX_ATTRIB_ARRAY_SIZE  -  params returns a single value, the size of the vertex attribute array for index . The size is the number of values for each element of the vertex attribute array, and it will be 1, 2, 3, or 4. The initial value is 4.
GL_VERTEX_ATTRIB_ARRAY_STRIDE  -  params returns a single value, the array stride for (number of bytes between successive elements in) the vertex attribute array for index . A value of 0 indicates that the array elements are stored sequentially in memory. The initial value is 0.
GL_VERTEX_ATTRIB_ARRAY_TYPE  -  params returns a single value, a symbolic constant indicating the array type for the vertex attribute array for index . Possible values are GL_BYTE , GL_UNSIGNED_BYTE , GL_SHORT , GL_UNSIGNED_SHORT , GL_INT , GL_UNSIGNED_INT , GL_FLOAT , and GL_DOUBLE . The initial value is GL_FLOAT .
GL_VERTEX_ATTRIB_ARRAY_NORMALIZED  -  params returns a single value that is non-zero (true) if fixed-point data types for the vertex attribute array indicated by index are normalized when they are converted to floating point, and 0 (false) otherwise. The initial value is GL_FALSE .
GL_VERTEX_ATTRIB_ARRAY_INTEGER  -  params returns a single value that is non-zero (true) if fixed-point data types for the vertex attribute array indicated by index have integer data types, and 0 (false) otherwise. The initial value is 0 ( GL_FALSE ).
GL_VERTEX_ATTRIB_ARRAY_LONG  -  param returns a single value that is non-zero (true) if a vertex attribute is stored as an unconverted double, and 0 (false) otherwise. The initial value is 0 ( GL_FALSE ).
GL_VERTEX_ATTRIB_ARRAY_DIVISOR  -  params returns a single value that is the frequency divisor used for instanced rendering. See glVertexAttribDivisor . The initial value is 0.
GL_VERTEX_ATTRIB_BINDING  -  params returns a single value, the vertex buffer binding of the vertex attribute array index .
GL_VERTEX_ATTRIB_RELATIVE_OFFSET  -  params returns a single value that is the byte offset of the first element relative to the start of the vertex buffer binding specified attribute fetches from. The initial value is 0.
GL_CURRENT_VERTEX_ATTRIB  -  params returns four values that represent the current value for the generic vertex attribute specified by index. Generic vertex attribute 0 is unique in that it has no current state, so an error will be generated if index is 0. The initial value for all other generic vertex attributes is (0,0,0,1). glGetVertexAttribdv and glGetVertexAttribfv return the current attribute values as four single-precision floating-point values; glGetVertexAttribiv reads them as floating-point values and converts them to four integer values; glGetVertexAttribIiv and glGetVertexAttribIuiv read and return them as signed or unsigned integer values, respectively; glGetVertexAttribLdv reads and returns them as four double-precision floating-point values.

All of the parameters except GL_CURRENT_VERTEX_ATTRIB represent state stored in the currently bound vertex array object.


Notes[edit]

If an error is generated, no change is made to the contents of params .


Errors[edit]

 GL_INVALID_OPERATION is generated if pname is not GL_CURRENT_VERTEX_ATTRIB and there is no currently bound vertex array object.

 GL_INVALID_VALUE is generated if index is greater than or equal to GL_MAX_VERTEX_ATTRIBS .

 GL_INVALID_ENUM is generated if pname is not an accepted value.

 GL_INVALID_OPERATION is generated if index is 0 and pname is GL_CURRENT_VERTEX_ATTRIB .


Associated Gets[edit]

 glGet with argument GL_MAX_VERTEX_ATTRIBS 

 glGetVertexAttribPointerv with arguments index and GL_VERTEX_ATTRIB_ARRAY_POINTER 


Version Support[edit]

 glGetVertexAttribIiv  3.0+
 glGetVertexAttribIuiv  3.0+
 glGetVertexAttribLdv  4.1+
 glGetVertexAttribdv  2.0+
 glGetVertexAttribfv  2.0+
 glGetVertexAttribiv  2.0+

See Also[edit]

 glBindAttribLocation , glBindBuffer , glDisableVertexAttribArray , glEnableVertexAttribArray , glVertexAttrib , glVertexAttribDivisor , glVertexAttribPointer 


Copyright[edit]

Copyright© 2003-2005 3Dlabs Inc. Ltd. Copyright© 2010-2014 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/.