glGetActiveSubroutineUniformName

glGetActiveSubroutineUniformName: man4/glGetActiveSubroutineUniformName.xml

glGetActiveSubroutineUniformName retrieves the name of an active shader subroutine uniform. program contains the name of the program containing the uniform. shadertype specifies the stage for 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. The uniform name is returned as a null-terminated string in name. The actual number of characters written into name, excluding the null terminator is returned in length. If length is null, no length is returned. The maximum number of characters that may be written into name, including the null terminator, is specified by bufsize. The length of the longest subroutine uniform name in program and shadertype is given by the value of GL_ACTIVE_SUBROUTINE_UNIFORM_MAX_LENGTH, which can be queried with glGetProgramStage.