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);
53 // An identifier for this type of effect, mostly used for debug output
54 // (but some special names, like "ColorSpaceConversionEffect", holds special
55 // meaning). Same as the class name is fine.
56 virtual std::string effect_type_id() const = 0;
58 // Whether this effects expects its input (and output) to be in
59 // linear gamma, ie. without an applied gamma curve. Most effects
60 // will want this, although the ones that never actually look at
61 // the pixels, e.g. mirror, won't need to care, and can set this
62 // to false. If so, the input gamma will be undefined.
64 // Also see the note on needs_texture_bounce(), below.
65 virtual bool needs_linear_light() const { return true; }
67 // Whether this effect expects its input to be in the sRGB
68 // color space, ie. use the sRGB/Rec. 709 RGB primaries.
69 // (If not, it would typically come in as some slightly different
70 // set of RGB primaries; you would currently not get YCbCr
71 // or something similar).
73 // Again, most effects will want this, but you can set it to false
74 // if you process each channel independently, equally _and_
75 // in a linear fashion.
76 virtual bool needs_srgb_primaries() const { return true; }
78 // Whether this effect expects its input to come directly from
79 // a texture. If this is true, the framework will not chain the
80 // input from other effects, but will store the results of the
81 // chain to a temporary (RGBA fp16) texture and let this effect
82 // sample directly from that.
84 // There are two good reasons why you might want to set this:
86 // 1. You are sampling more than once from the input,
87 // in which case computing all the previous steps might
88 // be more expensive than going to a memory intermediate.
89 // 2. You rely on previous effects, possibly including gamma
90 // expansion, to happen pre-filtering instead of post-filtering.
91 // (This is only relevant if you actually need the filtering; if
92 // you sample 1:1 between pixels and texels, it makes no difference.)
94 // Note that in some cases, you might get post-filtered gamma expansion
95 // even when setting this option. More specifically, if you are the
96 // first effect in the chain, and the GPU is doing sRGB gamma
97 // expansion, it is undefined (from OpenGL's side) whether expansion
98 // happens pre- or post-filtering. For most uses, however,
99 // either will be fine.
100 virtual bool needs_texture_bounce() const { return false; }
102 // Whether this effect expects mipmaps or not. If you set this to
103 // true, you will be sampling with bilinear filtering; if not,
104 // you could be sampling with simple linear filtering and no mipmaps
105 // (although there is no guarantee; if a different effect in the chain
106 // needs mipmaps, you will also get them).
107 virtual bool needs_mipmaps() const { return false; }
109 // Whether this effect wants to output to a different size than
110 // its input(s) (see inform_input_size(), below). If you set this to
111 // true, the output will be bounced to a texture (similarly to if the
112 // next effect set needs_texture_bounce()).
113 virtual bool changes_output_size() const { return false; }
115 // If changes_output_size() is true, you must implement this to tell
116 // the framework what output size you want.
118 // Note that it is explicitly allowed to change width and height
119 // from frame to frame; EffectChain will reallocate textures as needed.
120 virtual void get_output_size(unsigned *width, unsigned *height) const {
124 // Tells the effect the resolution of each of its input.
125 // This will be called every frame, and always before get_output_size(),
126 // so you can change your output size based on the input if so desired.
128 // Note that in some cases, an input might not have a single well-defined
129 // resolution (for instance if you fade between two inputs with
130 // different resolutions). In this case, you will get width=0 and height=0
131 // for that input. If you cannot handle that, you will need to set
132 // needs_texture_bounce() to true, which will force a render to a single
133 // given resolution before you get the input.
134 virtual void inform_input_size(unsigned input_num, unsigned width, unsigned height) {}
136 // How many inputs this effect will take (a fixed number).
137 // If you have only one input, it will be called INPUT() in GLSL;
138 // if you have several, they will be INPUT1(), INPUT2(), and so on.
139 virtual unsigned num_inputs() const { return 1; }
141 // Let the effect rewrite the effect chain as it sees fit.
142 // Most effects won't need to do this, but this is very useful
143 // if you have an effect that consists of multiple sub-effects
144 // (for instance, two passes). The effect is given to its own
145 // pointer, and it can add new ones (by using add_node()
146 // and connect_node()) as it sees fit. This is called at
147 // EffectChain::finalize() time, when the entire graph is known,
148 // in the order that the effects were originally added.
150 // Note that if the effect wants to take itself entirely out
151 // of the chain, it must set “disabled” to true and then disconnect
152 // itself from all other effects.
153 virtual void rewrite_graph(EffectChain *graph, Node *self) {}
155 // Outputs one GLSL uniform declaration for each registered parameter
156 // (see below), with the right prefix prepended to each uniform name.
157 // If you do not want this behavior, you can override this function.
158 virtual std::string output_convenience_uniforms() const;
160 // Returns the GLSL fragment shader string for this effect.
161 virtual std::string output_fragment_shader() = 0;
163 // Set all OpenGL state that this effect needs before rendering.
164 // The default implementation sets one uniform per registered parameter,
165 // but no other state.
167 // <sampler_num> is the first free texture sampler. If you want to use
168 // textures, you can bind a texture to GL_TEXTURE0 + <sampler_num>,
169 // and then increment the number (so that the next effect in the chain
170 // will use a different sampler).
171 virtual void set_gl_state(GLuint glsl_program_num, const std::string& prefix, unsigned *sampler_num);
173 // If you set any special OpenGL state in set_gl_state(), you can clear it
174 // after rendering here. The default implementation does nothing.
175 virtual void clear_gl_state();
177 // Set a parameter; intended to be called from user code.
178 // Neither of these take ownership of the pointer.
179 virtual bool set_int(const std::string&, int value);
180 virtual bool set_float(const std::string &key, float value);
181 virtual bool set_vec2(const std::string &key, const float *values);
182 virtual bool set_vec3(const std::string &key, const float *values);
185 // Register a parameter. Whenever set_*() is called with the same key,
186 // it will update the value in the given pointer (typically a pointer
187 // to some private member variable in your effect).
189 // Neither of these take ownership of the pointer.
191 // int is special since GLSL pre-1.30 doesn't have integer uniforms.
192 // Thus, ints that you register will _not_ be converted to GLSL uniforms.
193 void register_int(const std::string &key, int *value);
195 // These correspond directly to float/vec2/vec3 in GLSL.
196 void register_float(const std::string &key, float *value);
197 void register_vec2(const std::string &key, float *values);
198 void register_vec3(const std::string &key, float *values);
200 // This will register a 1D texture, which will be bound to a sampler
201 // when your GLSL code runs (so it corresponds 1:1 to a sampler2D uniform
204 // Note that if you change the contents of <values>, you will need to
205 // call invalidate_1d_texture() to have the picture re-uploaded on the
206 // next frame. This is in contrast to all the other parameters, which are
207 // set anew every frame.
208 void register_1d_texture(const std::string &key, float *values, size_t size);
209 void invalidate_1d_texture(const std::string &key);
219 std::map<std::string, int *> params_int;
220 std::map<std::string, float *> params_float;
221 std::map<std::string, float *> params_vec2;
222 std::map<std::string, float *> params_vec3;
223 std::map<std::string, Texture1D> params_tex_1d;
226 #endif // !defined(_EFFECT_H)