4 // Effect is the base class for every effect. It basically represents a single
5 // GLSL function, with an optional set of user-settable parameters.
7 // A note on naming: Since all effects run in the same GLSL namespace,
8 // you can't use any name you want for global variables (e.g. uniforms).
9 // The framework assigns a prefix to you which will be unique for each
10 // effect instance; use the macro PREFIX() around your identifiers to
11 // automatically prepend that prefix.
25 // Can alias on a float[2].
27 Point2D(float x, float y)
33 // Can alias on a float[3].
35 RGBTriplet(float r, float g, float b)
41 // Convenience functions that deal with prepending the prefix.
42 GLint get_uniform_location(GLuint glsl_program_num, const std::string &prefix, const std::string &key);
43 void set_uniform_int(GLuint glsl_program_num, const std::string &prefix, const std::string &key, int value);
44 void set_uniform_float(GLuint glsl_program_num, const std::string &prefix, const std::string &key, float value);
45 void set_uniform_float_array(GLuint glsl_program_num, const std::string &prefix, const std::string &key, const float *values, size_t num_values);
46 void set_uniform_vec2(GLuint glsl_program_num, const std::string &prefix, const std::string &key, const float *values);
47 void set_uniform_vec3(GLuint glsl_program_num, const std::string &prefix, const std::string &key, const float *values);
48 void set_uniform_vec4_array(GLuint glsl_program_num, const std::string &prefix, const std::string &key, const float *values, size_t num_values);
49 void set_uniform_mat3(GLuint glsl_program_num, const std::string &prefix, const std::string &key, const Matrix3x3 matrix);
55 // An identifier for this type of effect, mostly used for debug output
56 // (but some special names, like "ColorSpaceConversionEffect", holds special
57 // meaning). Same as the class name is fine.
58 virtual std::string effect_type_id() const = 0;
60 // Whether this effects expects its input (and output) to be in
61 // linear gamma, ie. without an applied gamma curve. Most effects
62 // will want this, although the ones that never actually look at
63 // the pixels, e.g. mirror, won't need to care, and can set this
64 // to false. If so, the input gamma will be undefined.
66 // Also see the note on needs_texture_bounce(), below.
67 virtual bool needs_linear_light() const { return true; }
69 // Whether this effect expects its input to be in the sRGB
70 // color space, ie. use the sRGB/Rec. 709 RGB primaries.
71 // (If not, it would typically come in as some slightly different
72 // set of RGB primaries; you would currently not get YCbCr
73 // or something similar).
75 // Again, most effects will want this, but you can set it to false
76 // if you process each channel independently, equally _and_
77 // in a linear fashion.
78 virtual bool needs_srgb_primaries() const { return true; }
80 // Whether this effect expects its input to come directly from
81 // a texture. If this is true, the framework will not chain the
82 // input from other effects, but will store the results of the
83 // chain to a temporary (RGBA fp16) texture and let this effect
84 // sample directly from that.
86 // There are two good reasons why you might want to set this:
88 // 1. You are sampling more than once from the input,
89 // in which case computing all the previous steps might
90 // be more expensive than going to a memory intermediate.
91 // 2. You rely on previous effects, possibly including gamma
92 // expansion, to happen pre-filtering instead of post-filtering.
93 // (This is only relevant if you actually need the filtering; if
94 // you sample 1:1 between pixels and texels, it makes no difference.)
96 // Note that in some cases, you might get post-filtered gamma expansion
97 // even when setting this option. More specifically, if you are the
98 // first effect in the chain, and the GPU is doing sRGB gamma
99 // expansion, it is undefined (from OpenGL's side) whether expansion
100 // happens pre- or post-filtering. For most uses, however,
101 // either will be fine.
102 virtual bool needs_texture_bounce() const { return false; }
104 // Whether this effect expects mipmaps or not. If you set this to
105 // true, you will be sampling with bilinear filtering; if not,
106 // you could be sampling with simple linear filtering and no mipmaps
107 // (although there is no guarantee; if a different effect in the chain
108 // needs mipmaps, you will also get them).
109 virtual bool needs_mipmaps() const { return false; }
111 // Whether this effect wants to output to a different size than
112 // its input(s) (see inform_input_size(), below). If you set this to
113 // true, the output will be bounced to a texture (similarly to if the
114 // next effect set needs_texture_bounce()).
115 virtual bool changes_output_size() const { return false; }
117 // If changes_output_size() is true, you must implement this to tell
118 // the framework what output size you want.
120 // Note that it is explicitly allowed to change width and height
121 // from frame to frame; EffectChain will reallocate textures as needed.
122 virtual void get_output_size(unsigned *width, unsigned *height) const {
126 // Tells the effect the resolution of each of its input.
127 // This will be called every frame, and always before get_output_size(),
128 // so you can change your output size based on the input if so desired.
130 // Note that in some cases, an input might not have a single well-defined
131 // resolution (for instance if you fade between two inputs with
132 // different resolutions). In this case, you will get width=0 and height=0
133 // for that input. If you cannot handle that, you will need to set
134 // needs_texture_bounce() to true, which will force a render to a single
135 // given resolution before you get the input.
136 virtual void inform_input_size(unsigned input_num, unsigned width, unsigned height) {}
138 // How many inputs this effect will take (a fixed number).
139 // If you have only one input, it will be called INPUT() in GLSL;
140 // if you have several, they will be INPUT1(), INPUT2(), and so on.
141 virtual unsigned num_inputs() const { return 1; }
143 // Let the effect rewrite the effect chain as it sees fit.
144 // Most effects won't need to do this, but this is very useful
145 // if you have an effect that consists of multiple sub-effects
146 // (for instance, two passes). The effect is given to its own
147 // pointer, and it can add new ones (by using add_node()
148 // and connect_node()) as it sees fit. This is called at
149 // EffectChain::finalize() time, when the entire graph is known,
150 // in the order that the effects were originally added.
152 // Note that if the effect wants to take itself entirely out
153 // of the chain, it must set “disabled” to true and then disconnect
154 // itself from all other effects.
155 virtual void rewrite_graph(EffectChain *graph, Node *self) {}
157 // Outputs one GLSL uniform declaration for each registered parameter
158 // (see below), with the right prefix prepended to each uniform name.
159 // If you do not want this behavior, you can override this function.
160 virtual std::string output_convenience_uniforms() const;
162 // Returns the GLSL fragment shader string for this effect.
163 virtual std::string output_fragment_shader() = 0;
165 // Set all OpenGL state that this effect needs before rendering.
166 // The default implementation sets one uniform per registered parameter,
167 // but no other state.
169 // <sampler_num> is the first free texture sampler. If you want to use
170 // textures, you can bind a texture to GL_TEXTURE0 + <sampler_num>,
171 // and then increment the number (so that the next effect in the chain
172 // will use a different sampler).
173 virtual void set_gl_state(GLuint glsl_program_num, const std::string& prefix, unsigned *sampler_num);
175 // If you set any special OpenGL state in set_gl_state(), you can clear it
176 // after rendering here. The default implementation does nothing.
177 virtual void clear_gl_state();
179 // Set a parameter; intended to be called from user code.
180 // Neither of these take ownership of the pointer.
181 virtual bool set_int(const std::string&, int value);
182 virtual bool set_float(const std::string &key, float value);
183 virtual bool set_vec2(const std::string &key, const float *values);
184 virtual bool set_vec3(const std::string &key, const float *values);
187 // Register a parameter. Whenever set_*() is called with the same key,
188 // it will update the value in the given pointer (typically a pointer
189 // to some private member variable in your effect).
191 // Neither of these take ownership of the pointer.
193 // int is special since GLSL pre-1.30 doesn't have integer uniforms.
194 // Thus, ints that you register will _not_ be converted to GLSL uniforms.
195 void register_int(const std::string &key, int *value);
197 // These correspond directly to float/vec2/vec3 in GLSL.
198 void register_float(const std::string &key, float *value);
199 void register_vec2(const std::string &key, float *values);
200 void register_vec3(const std::string &key, float *values);
202 // This will register a 1D texture, which will be bound to a sampler
203 // when your GLSL code runs (so it corresponds 1:1 to a sampler2D uniform
206 // Note that if you change the contents of <values>, you will need to
207 // call invalidate_1d_texture() to have the picture re-uploaded on the
208 // next frame. This is in contrast to all the other parameters, which are
209 // set anew every frame.
210 void register_1d_texture(const std::string &key, float *values, size_t size);
211 void invalidate_1d_texture(const std::string &key);
221 std::map<std::string, int *> params_int;
222 std::map<std::string, float *> params_float;
223 std::map<std::string, float *> params_vec2;
224 std::map<std::string, float *> params_vec3;
225 std::map<std::string, Texture1D> params_tex_1d;
228 #endif // !defined(_EFFECT_H)