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

## C Specification

void `glBindFragDataLocation` GLuint program GLuint colorNumber 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

name

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

## Description

`glBindFragDataLocation` explicitly specifies the binding of the user-defined varying out variable name to fragment shader color number colorNumber for program program. If name was bound previously, its assigned binding is replaced with colorNumber. name must be a null-terminated string. colorNumber must be less than `GL_MAX_DRAW_BUFFERS`.

The bindings specified by `glBindFragDataLocation` 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.

In addition to the errors generated by `glBindFragDataLocation`, 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 indexed 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_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

## See Also

glCreateProgram, glGetFragDataLocation

## 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/.