std::string output_fragment_shader() override;
void set_gl_state(GLuint glsl_program_num, const std::string &prefix, unsigned *sampler_num) override;
AlphaHandling alpha_handling() const override { return DONT_CARE_ALPHA_TYPE; }
std::string output_fragment_shader() override;
void set_gl_state(GLuint glsl_program_num, const std::string &prefix, unsigned *sampler_num) override;
AlphaHandling alpha_handling() const override { return DONT_CARE_ALPHA_TYPE; }