glValidateProgram — Validates a program object
void glValidateProgram( | GLuint | program); |
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.
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.
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.
glGetProgram
with arguments program and
GL_VALIDATE_STATUS
glGetProgramInfoLog
with argument program
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/.