virtual void inform_input_size(unsigned input_num, unsigned width, unsigned height);
void set_gl_state(GLuint glsl_program_num, const std::string &prefix, unsigned *sampler_num);
private:
virtual void inform_input_size(unsigned input_num, unsigned width, unsigned height);
void set_gl_state(GLuint glsl_program_num, const std::string &prefix, unsigned *sampler_num);
private: