+ virtual void get_output_size(unsigned *width, unsigned *height, unsigned *virtual_width, unsigned *virtual_height) const {
+ *width = this->width;
+ *height = this->height;
+ *virtual_width = this->virtual_width;
+ *virtual_height = this->virtual_height;
+ }
+
+ void set_gl_state(GLuint glsl_program_num, const std::string &prefix, unsigned *sampler_num);
+ void clear_gl_state();