glBindFragDataLocationIndexed - bind a user-defined varying out variable to a fragment shader color

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

voidglBindFragDataLocationIndexed(GLuintprogram,GLuintcolorNumber,GLuintindex,constchar*name);

       Copyright © 2010-2014 Khronos Group

[FIXME: source]                                    11/18/2024                           GLBINDFRAGDATALOCATI(3G)

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.

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.

       glBindFragDataLocationIndexed - bind a user-defined varying out variable to a fragment shader color
       number and index

       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.

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

glCreateProgram(), glLinkProgram() glGetFragDataLocation(), glGetFragDataIndex() glBindFragDataLocation()

       ┌───────────────────────────────┬───────────────────────────────────────────────────────────────────────┐
       │                               │                OpenGLVersion                                         │
       ├───────────────────────────────┼─────┬─────┬─────┬─────┬─────┬─────┬─────┬─────┬─────┬─────┬─────┬─────┤
       │ Function                      │ 2.0 │ 2.1 │ 3.0 │ 3.1 │ 3.2 │ 3.3 │ 4.0 │ 4.1 │ 4.2 │ 4.3 │ 4.4 │ 4.5 │
       │ /                             │     │     │     │     │     │     │     │     │     │     │     │     │
       │ Feature                       │     │     │     │     │     │     │     │     │     │     │     │     │
       │ Name                          │     │     │     │     │     │     │     │     │     │     │     │     │
       ├───────────────────────────────┼─────┼─────┼─────┼─────┼─────┼─────┼─────┼─────┼─────┼─────┼─────┼─────┤
       │ glBindFragDataLocationIndexed │  -  │  -  │  -  │  -  │  ✔  │  ✔  │  ✔  │  ✔  │  ✔  │  ✔  │  ✔  │  ✔  │
       └───────────────────────────────┴─────┴─────┴─────┴─────┴─────┴─────┴─────┴─────┴─────┴─────┴─────┴─────┘