+ // Whether this effect expects mipmaps or not. If you set this to
+ // true, you will be sampling with bilinear filtering; if not,
+ // you could be sampling with simple linear filtering and no mipmaps
+ // (although there is no guarantee; if a different effect in the chain
+ // needs mipmaps, you will also get them).
+ virtual bool needs_mipmaps() const { return false; }
+
+ // How many inputs this effect will take (a fixed number).
+ // If you have only one input, it will be called INPUT() in GLSL;
+ // if you have several, they will be INPUT1(), INPUT2(), and so on.
+ virtual unsigned num_inputs() const { return 1; }
+
+ // Requests that this effect adds itself to the given effect chain.
+ // For most effects, the default will be fine, but for effects that
+ // consist of multiple passes, it is often useful to replace this
+ // with something that adds completely different things to the chain.
+ virtual void add_self_to_effect_chain(EffectChain *graph, const std::vector<Effect *> &inputs);
+
+ // Outputs one GLSL uniform declaration for each registered parameter
+ // (see below), with the right prefix prepended to each uniform name.
+ // If you do not want this behavior, you can override this function.
+ virtual std::string output_convenience_uniforms() const;
+
+ // Returns the GLSL fragment shader string for this effect.
+ virtual std::string output_fragment_shader() = 0;
+
+ // Set all OpenGL state that this effect needs before rendering.
+ // The default implementation sets one uniform per registered parameter,
+ // but no other state.
+ //
+ // <sampler_num> is the first free texture sampler. If you want to use
+ // textures, you can bind a texture to GL_TEXTURE0 + <sampler_num>,
+ // and then increment the number (so that the next effect in the chain
+ // will use a different sampler).
+ virtual void set_gl_state(GLuint glsl_program_num, const std::string& prefix, unsigned *sampler_num);
+
+ // If you set any special OpenGL state in set_gl_state(), you can clear it
+ // after rendering here. The default implementation does nothing.
+ virtual void clear_gl_state();
+
+ // Set a parameter; intended to be called from user code.
+ // Neither of these take ownership of the pointer.
+ virtual bool set_int(const std::string&, int value);
+ virtual bool set_float(const std::string &key, float value);
+ virtual bool set_vec2(const std::string &key, const float *values);
+ virtual bool set_vec3(const std::string &key, const float *values);