2010 Khronos Group
glBindFragDataLocationIndexed 3G
glBindFragDataLocationIndexed bind a user-defined varying out variable to a fragment shader color number and index

## C Specification

void `glBindFragDataLocationIndexed` GLuint program GLuint colorNumber GLuint index const char *name

## Parameters

program

  The name of the program containing varying out variable whose binding to modify

colorNumber

  The color number to bind the user-defined varying out variable to

index

  The index of the color input to bind the user-defined varying out variable to

name

  The name of the user-defined varying out variable whose binding to modify

## Description

`glBindFragDataLocationIndexed` specifies that the varying out variable name in program should be bound to fragment color colorNumber when the program is next linked. index may be zero or one to specify that the color be used as either the first or second color input to the blend equation, respectively.

The bindings specified by `glBindFragDataLocationIndexed` have no effect until program is next linked. Bindings may be specified at any time after program has been created. Specifically, they may be specified before shader objects are attached to the program. Therefore, any name may be specified in name, including a name that is never used as a varying out variable in any fragment shader object. Names beginning with `gl_` are reserved by the GL.

If name was bound previously, its assigned binding is replaced with colorNumber and index. name must be a null-terminated string. index must be less than or equal to one, and colorNumber must be less than the value of `GL_MAX_DRAW_BUFFERS` if index is zero, and less than the value of `GL_MAX_DUAL_SOURCE_DRAW_BUFFERS` if index is greater than or equal to one.

In addition to the errors generated by `glBindFragDataLocationIndexed`, the program program will fail to link if:

- The number of active outputs is greater than the value `GL_MAX_DRAW_BUFFERS`.

- More than one varying out variable is bound to the same color number.

## Notes

Varying out varyings may have locations assigned explicitly in the shader text using a `location` layout qualifier. If a shader statically assigns a location to a varying out variable in the shader text, that location is used and any location assigned with `glBindFragDataLocation` is ignored.

## Errors

`GL_INVALID_VALUE` is generated if colorNumber is greater than or equal to `GL_MAX_DRAW_BUFFERS`.

`GL_INVALID_VALUE` is generated if colorNumber is greater than or equal to `GL_MAX_DUAL_SOURCE_DRAW_BUFFERS` and index is greater than or equal to one.

`GL_INVALID_VALUE` is generated if index is greater than one.

`GL_INVALID_OPERATION` is generated if name starts with the reserved `gl_` prefix.

`GL_INVALID_OPERATION` is generated if `program` is not the name of a program object.

## Associated Gets

glGetFragDataLocation with a valid program object and the the name of a user-defined varying out variable

glGetFragDataIndex with a valid program object and the the name of a user-defined varying out variable

## See Also

glCreateProgram, glLinkProgram glGetFragDataLocation, glGetFragDataIndex glBindFragDataLocation

## 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/.