+// Convenience functions that deal with prepending the prefix.
+void set_uniform_float(GLuint glsl_program_num, const std::string &prefix, const std::string &key, float value);
+void set_uniform_vec2(GLuint glsl_program_num, const std::string &prefix, const std::string &key, const float *values);
+void set_uniform_vec3(GLuint glsl_program_num, const std::string &prefix, const std::string &key, const float *values);
+