glValidateProgram
3G

# glValidateProgram

Validates a program object

## C Specification

    		void glValidateProgram
    		GLuint program

## Parameters

`program`

  Specifies the handle of the program object to be validated.

## Description

`glValidateProgram` checks to see whether the executables contained in `program` can execute given the current OpenGL state. The information generated by the validation process will be stored in `program`'s information log. The validation information may consist of an empty string, or it may be a string containing information about how the current program object interacts with the rest of current OpenGL state. This provides a way for OpenGL implementers to convey more information about why the current program is inefficient, suboptimal, failing to execute, and so on.

The status of the validation operation will be stored as part of the program object's state. This value will be set to `GL_TRUE` if the validation succeeded, and `GL_FALSE` otherwise. It can be queried by calling glGetProgram with arguments `program` and `GL_VALIDATE_STATUS`. If validation is successful, `program` is guaranteed to execute given the current state. Otherwise, `program` is guaranteed to not execute.

This function is typically useful only during application development. The informational string stored in the information log is completely implementation dependent; therefore, an application should not expect different OpenGL implementations to produce identical information strings.

## Notes

`glValidateProgram` is available only if the GL version is 2.0 or greater.

This function mimics the validation operation that OpenGL implementations must perform when rendering commands are issued while programmable shaders are part of current state. The error `GL_INVALID_OPERATION` will be generated by glBegin, glRasterPos, or any command that performs an implicit call to glBegin if:

- any two active samplers in the current program object are of different types, but refer to the same texture image unit,

- any active sampler in the current program object refers to a texture image unit where fixed-function fragment processing accesses a texture target that does not match the sampler type, or

- the sum of the number of active samplers in the program and the number of texture image units enabled for fixed-function fragment processing exceeds the combined limit on the total number of texture image units allowed.

It may be difficult or cause a performance degradation for applications to catch these errors when rendering commands are issued. Therefore, applications are advised to make calls to `glValidateProgram` to detect these issues during application development.

## Errors

`GL_INVALID_VALUE` is generated if `program` is not a value generated by OpenGL.

`GL_INVALID_OPERATION` is generated if `program` is not a program object.

`GL_INVALID_OPERATION` is generated if `glValidateProgram` is executed between the execution of glBegin and the corresponding execution of glEnd.

## Associated Gets

glGetProgram with arguments `program` and `GL_VALIDATE_STATUS`

glGetProgramInfoLog with argument `program`

glIsProgram

## See Also

glLinkProgram, glUseProgram

## 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. http://opencontent.org/openpub/.