glGetProgramInterfaceiv

glGetProgramInterface: man4/glGetProgramInterface.xml

glGetProgramInterfaceiv queries the property of the interface identifed by programInterface in program, the property name of which is given by pname. program must be the name of an existing program object. programInterface is the name of the interface within program to query and must be one of the following values: pname identifies the property of programInterface to return in params. If pname is GL_ACTIVE_RESOURCES, the value returned is the number of resources in the active resource list for programInterface. If the list of active resources for programInterface is empty, zero is returned. If pname is GL_MAX_NAME_LENGTH, the value returned is the length of the longest active name string for an active resource in programInterface. This length includes an extra character for the null terminator. If the list of active resources for programInterface is empty, zero is returned. It is an error to specify GL_MAX_NAME_LENGTH when programInterface is GL_ATOMIC_COUNTER_BUFFER, as active atomic counter buffer resources are not assigned name strings. If pname is GL_MAX_NUM_ACTIVE_VARIABLES, the value returned is the number of active variables belonging to the interface block or atomic counter buffer resource in programInterface with the most active variables. If the list of active resources for programInterface is empty, zero is returned. When pname is GL_MAX_NUM_ACTIVE_VARIABLES, programInterface must be GL_UNIFORM_BLOCK, GL_ATOMIC_COUNTER_BUFFER, or GL_SHADER_STORAGE_BLOCK. If pname is GL_MAX_NUM_COMPATIBLE_SUBROUTINES, the value returned is the number of compatible subroutines belonging to the active subroutine uniform in programInterface with the most compatible subroutines. If the list of active resources for programInterface is empty, zero is returned. When pname is GL_MAX_NUM_COMPATIBLE_SUBROUTINES, programInterface must be one of GL_VERTEX_SUBROUTINE_UNIFORM, GL_TESS_CONTROL_SUBROUTINE_UNIFORM, GL_TESS_EVALUATION_SUBROUTINE_UNIFORM, GL_GEOMETRY_SUBROUTINE_UNIFORM, GL_FRAGMENT_SUBROUTINE_UNIFORM, or GL_COMPUTE_SUBROUTINE_UNIFORM.