/**
* Return GL_TRUE if the state of the image unit passed as argument is valid
* and access from the shader is allowed. Otherwise loads from this unit
* should return zero and stores should have no effect.
*
* The result depends on context state other than the passed image unit, part
/**
* Return GL_TRUE if the state of the image unit passed as argument is valid
* and access from the shader is allowed. Otherwise loads from this unit
* should return zero and stores should have no effect.
*
* The result depends on context state other than the passed image unit, part