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