1 #ifndef _MOVIT_EFFECT_H
2 #define _MOVIT_EFFECT_H 1
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.
26 // Can alias on a float[2].
29 Point2D(float x, float y)
35 // Can alias on a float[3].
38 RGBTriplet(float r, float g, float b)
44 // Can alias on a float[4].
47 RGBATuple(float r, float g, float b, float a)
48 : r(r), g(g), b(b), a(a) {}
57 // An identifier for this type of effect, mostly used for debug output
58 // (but some special names, like "ColorspaceConversionEffect", holds special
59 // meaning). Same as the class name is fine.
60 virtual std::string effect_type_id() const = 0;
62 // Whether this effects expects its input (and output) to be in
63 // linear gamma, ie. without an applied gamma curve. Most effects
64 // will want this, although the ones that never actually look at
65 // the pixels, e.g. mirror, won't need to care, and can set this
66 // to false. If so, the input gamma will be undefined.
68 // Also see the note on needs_texture_bounce(), below.
69 virtual bool needs_linear_light() const { return true; }
71 // Whether this effect expects its input to be in the sRGB
72 // color space, ie. use the sRGB/Rec. 709 RGB primaries.
73 // (If not, it would typically come in as some slightly different
74 // set of RGB primaries; you would currently not get YCbCr
75 // or something similar).
77 // Again, most effects will want this, but you can set it to false
78 // if you process each channel independently, equally _and_
79 // in a linear fashion.
80 virtual bool needs_srgb_primaries() const { return true; }
82 // How this effect handles alpha, ie. what it outputs in its
83 // alpha channel. The choices are basically blank (alpha is always 1.0),
84 // premultiplied and postmultiplied.
86 // Premultiplied alpha is when the alpha value has been be multiplied
87 // into the three color components, so e.g. 100% red at 50% alpha
88 // would be (0.5, 0.0, 0.0, 0.5) instead of (1.0, 0.0, 0.0, 0.5)
89 // as it is stored in most image formats (postmultiplied alpha).
90 // The multiplication is taken to have happened in linear light.
91 // This is the most natural format for processing, and the default in
92 // most of Movit (just like linear light is).
94 // If you set INPUT_AND_OUTPUT_PREMULTIPLIED_ALPHA or
95 // INPUT_PREMULTIPLIED_ALPHA_KEEP_BLANK, all of your inputs
96 // (if any) are guaranteed to also be in premultiplied alpha.
97 // Otherwise, you can get postmultiplied or premultiplied alpha;
98 // you won't know. If you have multiple inputs, you will get the same
99 // (pre- or postmultiplied) for all inputs, although most likely,
100 // you will want to combine them in a premultiplied fashion anyway
103 // Always outputs blank alpha (ie. alpha=1.0). Only appropriate
104 // for inputs that do not output an alpha channel.
105 // Blank alpha is special in that it can be treated as both
106 // pre- and postmultiplied.
109 // Always outputs postmultiplied alpha. Only appropriate for inputs.
110 OUTPUT_POSTMULTIPLIED_ALPHA,
112 // Always outputs premultiplied alpha. As noted above,
113 // you will then also get all inputs in premultiplied alpha.
114 // If you set this, you should also set needs_linear_light().
115 INPUT_AND_OUTPUT_PREMULTIPLIED_ALPHA,
117 // Like INPUT_AND_OUTPUT_PREMULTIPLIED_ALPHA, but also guarantees
118 // that if you get blank alpha in, you also keep blank alpha out.
119 // This is a somewhat weaker guarantee than DONT_CARE_ALPHA_TYPE,
120 // but is still useful in many situations, and appropriate when
121 // e.g. you don't touch alpha at all.
123 // Does not make sense for inputs.
124 INPUT_PREMULTIPLIED_ALPHA_KEEP_BLANK,
126 // Keeps the type of alpha (premultiplied, postmultiplied, blank)
127 // unchanged from input to output. Usually appropriate if you
128 // process all color channels in a linear fashion, do not change
129 // alpha, and do not produce any new pixels thare have alpha != 1.0.
131 // Does not make sense for inputs.
132 DONT_CARE_ALPHA_TYPE,
134 virtual AlphaHandling alpha_handling() const { return INPUT_AND_OUTPUT_PREMULTIPLIED_ALPHA; }
136 // Whether this effect expects its input to come directly from
137 // a texture. If this is true, the framework will not chain the
138 // input from other effects, but will store the results of the
139 // chain to a temporary (RGBA fp16) texture and let this effect
140 // sample directly from that.
142 // There are two good reasons why you might want to set this:
144 // 1. You are sampling more than once from the input,
145 // in which case computing all the previous steps might
146 // be more expensive than going to a memory intermediate.
147 // 2. You rely on previous effects, possibly including gamma
148 // expansion, to happen pre-filtering instead of post-filtering.
149 // (This is only relevant if you actually need the filtering; if
150 // you sample 1:1 between pixels and texels, it makes no difference.)
152 // Note that in some cases, you might get post-filtered gamma expansion
153 // even when setting this option. More specifically, if you are the
154 // first effect in the chain, and the GPU is doing sRGB gamma
155 // expansion, it is undefined (from OpenGL's side) whether expansion
156 // happens pre- or post-filtering. For most uses, however,
157 // either will be fine.
158 virtual bool needs_texture_bounce() const { return false; }
160 // Whether this effect expects mipmaps or not. If you set this to
161 // true, you will be sampling with bilinear filtering; if not,
162 // you could be sampling with simple linear filtering and no mipmaps
163 // (although there is no guarantee; if a different effect in the chain
164 // needs mipmaps, you will also get them).
165 virtual bool needs_mipmaps() const { return false; }
167 // Whether there is a direct correspondence between input and output
168 // texels. Specifically, the effect must not:
170 // 1. Try to sample in the border (ie., outside the 0.0 to 1.0 area).
171 // 2. Try to sample between texels.
172 // 3. Sample with an x- or y-derivative different from -1 or 1.
173 // (This also means needs_mipmaps() and one_to_one_sampling()
174 // together would make no sense.)
176 // The most common case for this would be an effect that has an exact
177 // 1:1-correspondence between input and output texels, e.g. SaturationEffect.
178 // However, more creative things, like mirroring/flipping or padding,
179 // would also be allowed.
181 // The primary gain from setting this is that you can sample directly
182 // from an effect that changes output size (see changes_output_size() below),
183 // without going through a bounce texture. It won't work for effects that
184 // set sets_virtual_output_size(), though.
186 // Does not make a lot of sense together with needs_texture_bounce().
187 virtual bool one_to_one_sampling() const { return false; }
189 // Whether this effect wants to output to a different size than
190 // its input(s) (see inform_input_size(), below). See also
191 // sets_virtual_output_size() below.
192 virtual bool changes_output_size() const { return false; }
194 // Whether your get_output_size() function (see below) intends to ever set
195 // virtual_width different from width, or similar for height.
196 // It does not make sense to set this to true if changes_output_size() is false.
197 virtual bool sets_virtual_output_size() const { return changes_output_size(); }
199 // Whether this effect is effectively sampling from a a single texture.
200 // If so, it will override needs_texture_bounce(); however, there are also
201 // two demands it needs to fulfill:
203 // 1. It needs to be an Input, ie. num_inputs() == 0.
204 // 2. It needs to allocate exactly one sampler in set_gl_state(),
205 // and allow dependent effects to change that sampler state.
206 virtual bool is_single_texture() const { return false; }
208 // If changes_output_size() is true, you must implement this to tell
209 // the framework what output size you want. Also, you can set a
210 // virtual width/height, which is the size the next effect (if any)
211 // will _think_ your data is in. This is primarily useful if you are
212 // relying on getting OpenGL's bilinear resizing for free; otherwise,
213 // your virtual_width/virtual_height should be the same as width/height.
215 // Note that it is explicitly allowed to change width and height
216 // from frame to frame; EffectChain will reallocate textures as needed.
217 virtual void get_output_size(unsigned *width, unsigned *height,
218 unsigned *virtual_width, unsigned *virtual_height) const {
222 // Tells the effect the resolution of each of its input.
223 // This will be called every frame, and always before get_output_size(),
224 // so you can change your output size based on the input if so desired.
226 // Note that in some cases, an input might not have a single well-defined
227 // resolution (for instance if you fade between two inputs with
228 // different resolutions). In this case, you will get width=0 and height=0
229 // for that input. If you cannot handle that, you will need to set
230 // needs_texture_bounce() to true, which will force a render to a single
231 // given resolution before you get the input.
232 virtual void inform_input_size(unsigned input_num, unsigned width, unsigned height) {}
234 // How many inputs this effect will take (a fixed number).
235 // If you have only one input, it will be called INPUT() in GLSL;
236 // if you have several, they will be INPUT1(), INPUT2(), and so on.
237 virtual unsigned num_inputs() const { return 1; }
239 // Inform the effect that it has been just added to the EffectChain.
240 // The primary use for this is to store the ResourcePool uesd by
241 // the chain; for modifications to it, rewrite_graph() below
242 // is probably a better fit.
243 virtual void inform_added(EffectChain *chain) {}
245 // Let the effect rewrite the effect chain as it sees fit.
246 // Most effects won't need to do this, but this is very useful
247 // if you have an effect that consists of multiple sub-effects
248 // (for instance, two passes). The effect is given to its own
249 // pointer, and it can add new ones (by using add_node()
250 // and connect_node()) as it sees fit. This is called at
251 // EffectChain::finalize() time, when the entire graph is known,
252 // in the order that the effects were originally added.
254 // Note that if the effect wants to take itself entirely out
255 // of the chain, it must set “disabled” to true and then disconnect
256 // itself from all other effects.
257 virtual void rewrite_graph(EffectChain *graph, Node *self) {}
259 // Outputs one GLSL uniform declaration for each registered parameter
260 // (see below), with the right prefix prepended to each uniform name.
261 // If you do not want this behavior, you can override this function.
262 virtual std::string output_convenience_uniforms() const;
264 // Returns the GLSL fragment shader string for this effect.
265 virtual std::string output_fragment_shader() = 0;
267 // Set all OpenGL state that this effect needs before rendering.
268 // The default implementation sets one uniform per registered parameter,
269 // but no other state.
271 // <sampler_num> is the first free texture sampler. If you want to use
272 // textures, you can bind a texture to GL_TEXTURE0 + <sampler_num>,
273 // and then increment the number (so that the next effect in the chain
274 // will use a different sampler).
275 virtual void set_gl_state(GLuint glsl_program_num, const std::string& prefix, unsigned *sampler_num);
277 // If you set any special OpenGL state in set_gl_state(), you can clear it
278 // after rendering here. The default implementation does nothing.
279 virtual void clear_gl_state();
281 // Set a parameter; intended to be called from user code.
282 // Neither of these take ownership of the pointer.
283 virtual bool set_int(const std::string&, int value) MUST_CHECK_RESULT;
284 virtual bool set_float(const std::string &key, float value) MUST_CHECK_RESULT;
285 virtual bool set_vec2(const std::string &key, const float *values) MUST_CHECK_RESULT;
286 virtual bool set_vec3(const std::string &key, const float *values) MUST_CHECK_RESULT;
287 virtual bool set_vec4(const std::string &key, const float *values) MUST_CHECK_RESULT;
290 // Register a parameter. Whenever set_*() is called with the same key,
291 // it will update the value in the given pointer (typically a pointer
292 // to some private member variable in your effect).
294 // Neither of these take ownership of the pointer.
296 // int is special since GLSL pre-1.30 doesn't have integer uniforms.
297 // Thus, ints that you register will _not_ be converted to GLSL uniforms.
298 void register_int(const std::string &key, int *value);
300 // These correspond directly to float/vec2/vec3/vec4 in GLSL.
301 void register_float(const std::string &key, float *value);
302 void register_vec2(const std::string &key, float *values);
303 void register_vec3(const std::string &key, float *values);
304 void register_vec4(const std::string &key, float *values);
307 std::map<std::string, int *> params_int;
308 std::map<std::string, float *> params_float;
309 std::map<std::string, float *> params_vec2;
310 std::map<std::string, float *> params_vec3;
311 std::map<std::string, float *> params_vec4;
316 #endif // !defined(_MOVIT_EFFECT_H)