man glVertexAttribPointer (3): define an array of generic vertex attribute data

C SPECIFICATION

void glVertexAttribPointer(GLuint index, GLint size, GLenum type, GLboolean normalized, GLsizei stride, const GLvoid * pointer);
void glVertexAttribIPointer(GLuint index, GLint size, GLenum type, GLsizei stride, const GLvoid * pointer);
void glVertexAttribLPointer(GLuint index, GLint size, GLenum type, GLsizei stride, const GLvoid * pointer);

PARAMETERS

index

: Specifies the index of the generic vertex attribute to be modified.

size

: Specifies the number of components per generic vertex attribute. Must be 1, 2, 3, 4. Additionally, the symbolic constant GL_BGRA is accepted by glVertexAttribPointer. The initial value is 4.

type

: Specifies the data type of each component in the array. The symbolic constants GL_BYTE, GL_UNSIGNED_BYTE, GL_SHORT, GL_UNSIGNED_SHORT, GL_INT, and GL_UNSIGNED_INT are accepted by glVertexAttribPointer and glVertexAttribIPointer. Additionally GL_HALF_FLOAT, GL_FLOAT, GL_DOUBLE, GL_FIXED, GL_INT_2_10_10_10_REV, and GL_UNSIGNED_INT_2_10_10_10_REV are accepted by glVertexAttribPointer. GL_DOUBLE is also accepted by glVertexAttribLPointer and is the only token accepted by the type parameter for that function. The initial value is GL_FLOAT.

normalized

: For glVertexAttribPointer, specifies whether fixed-point data values should be normalized (GL_TRUE) or converted directly as fixed-point values (GL_FALSE) when they are accessed.

stride

: Specifies the byte offset between consecutive generic vertex attributes. If stride is 0, the generic vertex attributes are understood to be tightly packed in the array. The initial value is 0.

pointer

: Specifies a offset of the first component of the first generic vertex attribute in the array in the data store of the buffer currently bound to the GL_ARRAY_BUFFER target. The initial value is 0.

DESCRIPTION

glVertexAttribPointer, glVertexAttribIPointer and glVertexAttribLPointer specify the location and data format of the array of generic vertex attributes at index index to use when rendering. size specifies the number of components per attribute and must be 1, 2, 3, 4, or GL_BGRA. type specifies the data type of each component, and stride specifies the byte stride from one attribute to the next, allowing vertices and attributes to be packed into a single array or stored in separate arrays.

For glVertexAttribPointer, if normalized is set to GL_TRUE, it indicates that values stored in an integer format are to be mapped to the range [-1,1] (for signed values) or [0,1] (for unsigned values) when they are accessed and converted to floating point. Otherwise, values will be converted to floats directly without normalization.

For glVertexAttribIPointer, only the integer types GL_BYTE, GL_UNSIGNED_BYTE, GL_SHORT, GL_UNSIGNED_SHORT, GL_INT, GL_UNSIGNED_INT are accepted. Values are always left as integer values.

glVertexAttribLPointer specifies state for a generic vertex attribute array associated with a shader attribute variable declared with 64-bit double precision components. type must be GL_DOUBLE. index, size, and stride behave as described for glVertexAttribPointer and glVertexAttribIPointer.

If pointer is not NULL, a non-zero named buffer object must be bound to the GL_ARRAY_BUFFER target (see glBindBuffer()), otherwise an error is generated. pointer is treated as a byte offset into the buffer object's data store. The buffer object binding (GL_ARRAY_BUFFER_BINDING) is saved as generic vertex attribute array state (GL_VERTEX_ATTRIB_ARRAY_BUFFER_BINDING) for index index.

When a generic vertex attribute array is specified, size, type, normalized, stride, and pointer are saved as vertex array state, in addition to the current vertex array buffer object binding.

To enable and disable a generic vertex attribute array, call glEnableVertexAttribArray() and glDisableVertexAttribArray() with index. If enabled, the generic vertex attribute array is used when glDrawArrays(), glMultiDrawArrays(), glDrawElements(), glMultiDrawElements(), or glDrawRangeElements() is called.

NOTES

Each generic vertex attribute array is initially disabled and isn't accessed when glDrawElements(), glDrawRangeElements(), glDrawArrays(), glMultiDrawArrays(), or glMultiDrawElements() is called.

ERRORS

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

GL_INVALID_VALUE is generated if size is not 1, 2, 3, 4 or (for glVertexAttribPointer), GL_BGRA.

GL_INVALID_ENUM is generated if type is not an accepted value.

GL_INVALID_VALUE is generated if stride is negative.

GL_INVALID_OPERATION is generated if size is GL_BGRA and type is not GL_INT_2_10_10_10_REV or GL_UNSIGNED_INT_2_10_10_10_REV.

GL_INVALID_OPERATION is generated if type is GL_INT_2_10_10_10_REV or GL_UNSIGNED_INT_2_10_10_10_REV and size is not 4 or GL_BGRA.

GL_INVALID_OPERATION is generated by glVertexAttribPointer if size is GL_BGRA and noramlized is GL_FALSE.

GL_INVALID_OPERATION is generated if zero is bound to the GL_ARRAY_BUFFER buffer object binding point and the pointer argument is not NULL.

ASSOCIATED GETS

glGet() with argument GL_MAX_VERTEX_ATTRIBS

glGetVertexAttrib() with arguments index and GL_VERTEX_ATTRIB_ARRAY_ENABLED

glGetVertexAttrib() with arguments index and GL_VERTEX_ATTRIB_ARRAY_SIZE

glGetVertexAttrib() with arguments index and GL_VERTEX_ATTRIB_ARRAY_TYPE

glGetVertexAttrib() with arguments index and GL_VERTEX_ATTRIB_ARRAY_NORMALIZED

glGetVertexAttrib() with arguments index and GL_VERTEX_ATTRIB_ARRAY_STRIDE

glGetVertexAttrib() with arguments index and GL_VERTEX_ATTRIB_ARRAY_BUFFER_BINDING

glGet() with argument GL_ARRAY_BUFFER_BINDING

glGetVertexAttribPointerv() with arguments index and GL_VERTEX_ATTRIB_ARRAY_POINTER

COPYRIGHT

Copyright © 2003-2005 3Dlabs Inc. Ltd. This material may be distributed subject to the terms and conditions set forth in the Open Publication License, v 1.0, 8 June 1999. m[blue]http://opencontent.org/openpub/m[].