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.
28 // Can alias on a float[2].
31 Point2D(float x, float y)
37 // Can alias on a float[3].
40 RGBTriplet(float r, float g, float b)
46 // Can alias on a float[4].
49 RGBATuple(float r, float g, float b, float a)
50 : r(r), g(g), b(b), a(a) {}
55 // Represents a registered uniform.
58 std::string name; // Without prefix.
59 const T *value; // Owner by the effect.
60 size_t num_values; // Number of elements; for arrays only. _Not_ the vector length.
61 std::string prefix; // Filled in only after phases have been constructed.
62 GLint location; // Filled in only after phases have been constructed. -1 if no location.
69 // An identifier for this type of effect, mostly used for debug output
70 // (but some special names, like "ColorspaceConversionEffect", holds special
71 // meaning). Same as the class name is fine.
72 virtual std::string effect_type_id() const = 0;
74 // Whether this effects expects its input (and output) to be in
75 // linear gamma, ie. without an applied gamma curve. Most effects
76 // will want this, although the ones that never actually look at
77 // the pixels, e.g. mirror, won't need to care, and can set this
78 // to false. If so, the input gamma will be undefined.
80 // Also see the note on needs_texture_bounce(), below.
81 virtual bool needs_linear_light() const { return true; }
83 // Whether this effect expects its input to be in the sRGB
84 // color space, ie. use the sRGB/Rec. 709 RGB primaries.
85 // (If not, it would typically come in as some slightly different
86 // set of RGB primaries; you would currently not get YCbCr
87 // or something similar).
89 // Again, most effects will want this, but you can set it to false
90 // if you process each channel independently, equally _and_
91 // in a linear fashion.
92 virtual bool needs_srgb_primaries() const { return true; }
94 // How this effect handles alpha, ie. what it outputs in its
95 // alpha channel. The choices are basically blank (alpha is always 1.0),
96 // premultiplied and postmultiplied.
98 // Premultiplied alpha is when the alpha value has been be multiplied
99 // into the three color components, so e.g. 100% red at 50% alpha
100 // would be (0.5, 0.0, 0.0, 0.5) instead of (1.0, 0.0, 0.0, 0.5)
101 // as it is stored in most image formats (postmultiplied alpha).
102 // The multiplication is taken to have happened in linear light.
103 // This is the most natural format for processing, and the default in
104 // most of Movit (just like linear light is).
106 // If you set INPUT_AND_OUTPUT_PREMULTIPLIED_ALPHA or
107 // INPUT_PREMULTIPLIED_ALPHA_KEEP_BLANK, all of your inputs
108 // (if any) are guaranteed to also be in premultiplied alpha.
109 // Otherwise, you can get postmultiplied or premultiplied alpha;
110 // you won't know. If you have multiple inputs, you will get the same
111 // (pre- or postmultiplied) for all inputs, although most likely,
112 // you will want to combine them in a premultiplied fashion anyway
115 // Always outputs blank alpha (ie. alpha=1.0). Only appropriate
116 // for inputs that do not output an alpha channel.
117 // Blank alpha is special in that it can be treated as both
118 // pre- and postmultiplied.
121 // Always outputs postmultiplied alpha. Only appropriate for inputs.
122 OUTPUT_POSTMULTIPLIED_ALPHA,
124 // Always outputs premultiplied alpha. As noted above,
125 // you will then also get all inputs in premultiplied alpha.
126 // If you set this, you should also set needs_linear_light().
127 INPUT_AND_OUTPUT_PREMULTIPLIED_ALPHA,
129 // Like INPUT_AND_OUTPUT_PREMULTIPLIED_ALPHA, but also guarantees
130 // that if you get blank alpha in, you also keep blank alpha out.
131 // This is a somewhat weaker guarantee than DONT_CARE_ALPHA_TYPE,
132 // but is still useful in many situations, and appropriate when
133 // e.g. you don't touch alpha at all.
135 // Does not make sense for inputs.
136 INPUT_PREMULTIPLIED_ALPHA_KEEP_BLANK,
138 // Keeps the type of alpha (premultiplied, postmultiplied, blank)
139 // unchanged from input to output. Usually appropriate if you
140 // process all color channels in a linear fashion, do not change
141 // alpha, and do not produce any new pixels that have alpha != 1.0.
143 // Does not make sense for inputs.
144 DONT_CARE_ALPHA_TYPE,
146 virtual AlphaHandling alpha_handling() const { return INPUT_AND_OUTPUT_PREMULTIPLIED_ALPHA; }
148 // Whether this effect expects its input to come directly from
149 // a texture. If this is true, the framework will not chain the
150 // input from other effects, but will store the results of the
151 // chain to a temporary (RGBA fp16) texture and let this effect
152 // sample directly from that.
154 // There are two good reasons why you might want to set this:
156 // 1. You are sampling more than once from the input,
157 // in which case computing all the previous steps might
158 // be more expensive than going to a memory intermediate.
159 // 2. You rely on previous effects, possibly including gamma
160 // expansion, to happen pre-filtering instead of post-filtering.
161 // (This is only relevant if you actually need the filtering; if
162 // you sample 1:1 between pixels and texels, it makes no difference.)
164 // Note that in some cases, you might get post-filtered gamma expansion
165 // even when setting this option. More specifically, if you are the
166 // first effect in the chain, and the GPU is doing sRGB gamma
167 // expansion, it is undefined (from OpenGL's side) whether expansion
168 // happens pre- or post-filtering. For most uses, however,
169 // either will be fine.
170 virtual bool needs_texture_bounce() const { return false; }
172 // Whether this effect expects mipmaps or not.
173 enum MipmapRequirements {
174 // If chosen, you will be sampling with bilinear filtering,
175 // ie. the closest mipmap will be chosen, and then there will be
176 // bilinear interpolation inside it (GL_LINEAR_MIPMAP_NEAREST).
179 // Whether the effect doesn't really care whether input textures
180 // are with or without mipmaps. You could get the same effect
181 // as NEEDS_MIPMAPS or CANNOT_ACCEPT_MIPMAPS; normally, you won't
182 // get them, but if a different effect in the same phase needs mipmaps,
183 // you will also get them.
184 DOES_NOT_NEED_MIPMAPS,
186 // The opposite of NEEDS_MIPMAPS; you will always be sampling from
187 // the most detailed mip level (GL_LINEAR). Effects with NEEDS_MIPMAPS
188 // and CANNOT_ACCEPT_MIPMAPS can not coexist within the same phase;
189 // such phases will be split.
191 // This is the only choice that makes sense for a compute shader,
192 // given that it doesn't have screen-space derivatives and thus
193 // always will sample the most detailed mip level.
194 CANNOT_ACCEPT_MIPMAPS,
196 virtual MipmapRequirements needs_mipmaps() const {
197 if (is_compute_shader()) {
198 return CANNOT_ACCEPT_MIPMAPS;
200 return DOES_NOT_NEED_MIPMAPS;
204 // Whether there is a direct correspondence between input and output
205 // texels. Specifically, the effect must not:
207 // 1. Try to sample in the border (ie., outside the 0.0 to 1.0 area).
208 // 2. Try to sample between texels.
209 // 3. Sample with an x- or y-derivative different from -1 or 1.
210 // (This also means needs_mipmaps() and one_to_one_sampling()
211 // together would make no sense.)
213 // The most common case for this would be an effect that has an exact
214 // 1:1-correspondence between input and output texels, e.g. SaturationEffect.
215 // However, more creative things, like mirroring/flipping or padding,
216 // would also be allowed.
218 // The primary gain from setting this is that you can sample directly
219 // from an effect that changes output size (see changes_output_size() below),
220 // without going through a bounce texture. It won't work for effects that
221 // set sets_virtual_output_size(), though.
223 // Does not make a lot of sense together with needs_texture_bounce().
224 // Cannot be set for compute shaders.
225 virtual bool one_to_one_sampling() const { return strong_one_to_one_sampling(); }
227 // Similar in use to one_to_one_sampling(), but even stricter:
228 // The effect must not use texture coordinate in any way beyond
229 // giving it unmodified to its (single) input. This allows it to
230 // also be used after a compute shader, in the same phase.
232 // An effect that it strong one-to-one must also be one-to-one.
233 virtual bool strong_one_to_one_sampling() const { return false; }
235 // Whether this effect wants to output to a different size than
236 // its input(s) (see inform_input_size(), below). See also
237 // sets_virtual_output_size() below.
238 virtual bool changes_output_size() const { return false; }
240 // Whether your get_output_size() function (see below) intends to ever set
241 // virtual_width different from width, or similar for height.
242 // It does not make sense to set this to true if changes_output_size() is false.
243 virtual bool sets_virtual_output_size() const { return changes_output_size(); }
245 // Whether this effect is effectively sampling from a a single texture.
246 // If so, it will override needs_texture_bounce(); however, there are also
247 // two demands it needs to fulfill:
249 // 1. It needs to be an Input, ie. num_inputs() == 0.
250 // 2. It needs to allocate exactly one sampler in set_gl_state(),
251 // and allow dependent effects to change that sampler state.
252 virtual bool is_single_texture() const { return false; }
254 // If set, this effect should never be bounced to an output, even if a
255 // dependent effect demands texture bounce.
257 // Note that setting this can invoke undefined behavior, up to and including crashing,
258 // so you should only use it if you have deep understanding of your entire chain
259 // and Movit's processing of it. The most likely use case is if you have an input
260 // that's cheap to compute but not a single texture (e.g. YCbCrInput), and want
261 // to run a ResampleEffect directly from it. Normally, this would require a bounce,
262 // but it's faster not to. (However, also note that in this case, effective texel
263 // subpixel precision will be too optimistic, since chroma is already subsampled.)
265 // Has no effect if is_single_texture() is set.
266 virtual bool override_disable_bounce() const { return false; }
268 // If changes_output_size() is true, you must implement this to tell
269 // the framework what output size you want. Also, you can set a
270 // virtual width/height, which is the size the next effect (if any)
271 // will _think_ your data is in. This is primarily useful if you are
272 // relying on getting OpenGL's bilinear resizing for free; otherwise,
273 // your virtual_width/virtual_height should be the same as width/height.
275 // Note that it is explicitly allowed to change width and height
276 // from frame to frame; EffectChain will reallocate textures as needed.
277 virtual void get_output_size(unsigned *width, unsigned *height,
278 unsigned *virtual_width, unsigned *virtual_height) const {
282 // Whether this effect uses a compute shader instead of a regular fragment shader.
283 // Compute shaders are more flexible in that they can have multiple outputs
284 // for each invocation and also communicate between instances (by using shared
285 // memory within each group), but are not universally supported. The typical
286 // pattern would be to check movit_compute_shaders_supported and rewrite the
287 // graph to use a compute shader effect instead of a regular effect if it is
288 // available, in order to get better performance. Since compute shaders can reuse
289 // loads (again typically through shared memory), using needs_texture_bounce()
290 // is usually not needed, although it is allowed; the best candidates for compute
291 // shaders are typically those that sample many times from their input
292 // but can reuse those loads across neighboring instances.
294 // Compute shaders commonly work with unnormalized texture coordinates
295 // (where coordinates are integers [0..W) and [0..H)), whereas the rest
296 // of Movit, including any inputs you may want to sample from, works
297 // with normalized coordinates ([0..1)). Movit gives you uniforms
298 // PREFIX(inv_output_size) and PREFIX(output_texcoord_adjust) that you
299 // can use to transform unnormalized to normalized, as well as a macro
300 // NORMALIZE_TEXTURE_COORDS(vec2) that does it for you.
302 // Since compute shaders have flexible output, it is difficult to chain other
303 // effects after them in the same phase, and thus, they will always be last.
304 // (This limitation may be lifted for the special case of one-to-one effects
305 // in the future.) Furthermore, they cannot write to the framebuffer, just to
306 // textures, so Movit may have to insert an extra phase just to do the output
307 // from a texture to the screen in some cases. However, this is transparent
308 // to both the effect and the user.
309 virtual bool is_compute_shader() const { return false; }
311 // For a compute shader (see the previous member function), what dimensions
312 // it should be invoked over. Called every frame, before uniforms are set
313 // (so you are allowed to update uniforms based from this call).
314 virtual void get_compute_dimensions(unsigned output_width, unsigned output_height,
315 unsigned *x, unsigned *y, unsigned *z) const {
321 // Tells the effect the resolution of each of its input.
322 // This will be called every frame, and always before get_output_size(),
323 // so you can change your output size based on the input if so desired.
325 // Note that in some cases, an input might not have a single well-defined
326 // resolution (for instance if you fade between two inputs with
327 // different resolutions). In this case, you will get width=0 and height=0
328 // for that input. If you cannot handle that, you will need to set
329 // needs_texture_bounce() to true, which will force a render to a single
330 // given resolution before you get the input.
331 virtual void inform_input_size(unsigned input_num, unsigned width, unsigned height) {}
333 // How many inputs this effect will take (a fixed number).
334 // If you have only one input, it will be called INPUT() in GLSL;
335 // if you have several, they will be INPUT1(), INPUT2(), and so on.
336 virtual unsigned num_inputs() const { return 1; }
338 // Inform the effect that it has been just added to the EffectChain.
339 // The primary use for this is to store the ResourcePool uesd by
340 // the chain; for modifications to it, rewrite_graph() below
341 // is probably a better fit.
342 virtual void inform_added(EffectChain *chain) {}
344 // Let the effect rewrite the effect chain as it sees fit.
345 // Most effects won't need to do this, but this is very useful
346 // if you have an effect that consists of multiple sub-effects
347 // (for instance, two passes). The effect is given to its own
348 // pointer, and it can add new ones (by using add_node()
349 // and connect_node()) as it sees fit. This is called at
350 // EffectChain::finalize() time, when the entire graph is known,
351 // in the order that the effects were originally added.
353 // Note that if the effect wants to take itself entirely out
354 // of the chain, it must set “disabled” to true and then disconnect
355 // itself from all other effects.
356 virtual void rewrite_graph(EffectChain *graph, Node *self) {}
358 // Returns the GLSL fragment shader string for this effect.
359 virtual std::string output_fragment_shader() = 0;
361 // Set all OpenGL state that this effect needs before rendering.
362 // The default implementation sets one uniform per registered parameter,
363 // but no other state.
365 // <sampler_num> is the first free texture sampler. If you want to use
366 // textures, you can bind a texture to GL_TEXTURE0 + <sampler_num>,
367 // and then increment the number (so that the next effect in the chain
368 // will use a different sampler).
369 virtual void set_gl_state(GLuint glsl_program_num, const std::string& prefix, unsigned *sampler_num);
371 // If you set any special OpenGL state in set_gl_state(), you can clear it
372 // after rendering here. The default implementation does nothing.
373 virtual void clear_gl_state();
375 // Set a parameter; intended to be called from user code.
376 // Neither of these take ownership of the pointer.
377 virtual bool set_int(const std::string &key, int value) MUST_CHECK_RESULT;
378 virtual bool set_ivec2(const std::string &key, const int *values) MUST_CHECK_RESULT;
379 virtual bool set_float(const std::string &key, float value) MUST_CHECK_RESULT;
380 virtual bool set_vec2(const std::string &key, const float *values) MUST_CHECK_RESULT;
381 virtual bool set_vec3(const std::string &key, const float *values) MUST_CHECK_RESULT;
382 virtual bool set_vec4(const std::string &key, const float *values) MUST_CHECK_RESULT;
385 // Register a parameter. Whenever set_*() is called with the same key,
386 // it will update the value in the given pointer (typically a pointer
387 // to some private member variable in your effect). It will also
388 // register a uniform of the same name (plus an arbitrary prefix
389 // which you can access using the PREFIX macro) that you can access.
391 // Neither of these take ownership of the pointer.
393 // These correspond directly to int/float/vec2/vec3/vec4 in GLSL.
394 void register_int(const std::string &key, int *value);
395 void register_ivec2(const std::string &key, int *values);
396 void register_float(const std::string &key, float *value);
397 void register_vec2(const std::string &key, float *values);
398 void register_vec3(const std::string &key, float *values);
399 void register_vec4(const std::string &key, float *values);
401 // Register uniforms, such that they will automatically be set
402 // before the shader runs. This is more efficient than set_uniform_*
403 // in effect_util.h, because it doesn't need to do name lookups
404 // every time. Also, in the future, it will use uniform buffer objects
405 // (UBOs) if available to reduce the number of calls into the driver.
407 // May not be called after output_fragment_shader() has returned.
408 // The pointer must be valid for the entire lifetime of the Effect,
409 // since the value is pulled from it each execution. The value is
410 // guaranteed to be read after set_gl_state() for the effect has
411 // returned, so you can safely update its value from there.
413 // Note that this will also declare the uniform in the shader for you,
414 // so you should not do that yourself. (This is so it can be part of
415 // the right uniform block.) However, it is probably a good idea to
416 // have a commented-out declaration so that it is easier to see the
417 // type and thus understand the shader on its own.
419 // Calling register_* will automatically imply register_uniform_*,
420 // except for register_int as noted above.
421 void register_uniform_sampler2d(const std::string &key, const int *value);
422 void register_uniform_bool(const std::string &key, const bool *value);
423 void register_uniform_int(const std::string &key, const int *value);
424 void register_uniform_ivec2(const std::string &key, const int *values);
425 void register_uniform_float(const std::string &key, const float *value);
426 void register_uniform_vec2(const std::string &key, const float *values);
427 void register_uniform_vec3(const std::string &key, const float *values);
428 void register_uniform_vec4(const std::string &key, const float *values);
429 void register_uniform_float_array(const std::string &key, const float *values, size_t num_values);
430 void register_uniform_vec2_array(const std::string &key, const float *values, size_t num_values);
431 void register_uniform_vec3_array(const std::string &key, const float *values, size_t num_values);
432 void register_uniform_vec4_array(const std::string &key, const float *values, size_t num_values);
433 void register_uniform_mat3(const std::string &key, const Eigen::Matrix3d *matrix);
436 std::map<std::string, int *> params_int;
437 std::map<std::string, int *> params_ivec2;
438 std::map<std::string, float *> params_float;
439 std::map<std::string, float *> params_vec2;
440 std::map<std::string, float *> params_vec3;
441 std::map<std::string, float *> params_vec4;
443 // Picked out by EffectChain during finalization.
444 std::vector<Uniform<int>> uniforms_image2d;
445 std::vector<Uniform<int>> uniforms_sampler2d;
446 std::vector<Uniform<bool>> uniforms_bool;
447 std::vector<Uniform<int>> uniforms_int;
448 std::vector<Uniform<int>> uniforms_ivec2;
449 std::vector<Uniform<float>> uniforms_float;
450 std::vector<Uniform<float>> uniforms_vec2;
451 std::vector<Uniform<float>> uniforms_vec3;
452 std::vector<Uniform<float>> uniforms_vec4;
453 std::vector<Uniform<float>> uniforms_float_array;
454 std::vector<Uniform<float>> uniforms_vec2_array;
455 std::vector<Uniform<float>> uniforms_vec3_array;
456 std::vector<Uniform<float>> uniforms_vec4_array;
457 std::vector<Uniform<Eigen::Matrix3d>> uniforms_mat3;
458 friend class EffectChain;
463 #endif // !defined(_MOVIT_EFFECT_H)