+ virtual bool needs_srgb_primaries() const { return false; }
+ virtual AlphaHandling alpha_handling() const { return DONT_CARE_ALPHA_TYPE; }
+
+ 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);