glGetActiveSubroutineUniformiv

glGetActiveSubroutineUniform: man4/glGetActiveSubroutineUniform.xml

glGetActiveSubroutineUniform queries a parameter of an active shader subroutine uniform. program contains the name of the program containing the uniform. shadertype specifies the stage which which the uniform location, given by index, is valid. index must be between zero and the value of GL_ACTIVE_SUBROUTINE_UNIFORMS minus one for the shader stage. If pname is GL_NUM_COMPATIBLE_SUBROUTINES, a single integer indicating the number of subroutines that can be assigned to the uniform is returned in values. If pname is GL_COMPATIBLE_SUBROUTINES, an array of integers is returned in values, with each integer specifying the index of an active subroutine that can be assigned to the selected subroutine uniform. The number of integers returned is the same as the value returned for GL_NUM_COMPATIBLE_SUBROUTINES. If pname is GL_UNIFORM_SIZE, a single integer is returned in values. If the selected subroutine uniform is an array, the declared size of the array is returned; otherwise, one is returned. If pname is GL_UNIFORM_NAME_LENGTH, a single integer specifying the length of the subroutine uniform name (including the terminating null character) is returned in values.