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 this effect wants to output to a different size than
165 // its input(s) (see inform_input_size(), below). If you set this to
166 // true, the output will be bounced to a texture (similarly to if the
167 // next effect set needs_texture_bounce()).
168 virtual bool changes_output_size() const { return false; }
170 // Whether this effect is effectively sampling from a a single texture.
171 // If so, it will override needs_texture_bounce(); however, there are also
172 // two demands it needs to fulfill:
174 // 1. It needs to be an Input, ie. num_inputs() == 0.
175 // 2. It needs to allocate exactly one sampler in set_gl_state(),
176 // and allow dependent effects to change that sampler state.
177 virtual bool is_single_texture() const { return false; }
179 // If changes_output_size() is true, you must implement this to tell
180 // the framework what output size you want. Also, you can set a
181 // virtual width/height, which is the size the next effect (if any)
182 // will _think_ your data is in. This is primarily useful if you are
183 // relying on getting OpenGL's bilinear resizing for free; otherwise,
184 // your virtual_width/virtual_height should be the same as width/height.
186 // Note that it is explicitly allowed to change width and height
187 // from frame to frame; EffectChain will reallocate textures as needed.
188 virtual void get_output_size(unsigned *width, unsigned *height,
189 unsigned *virtual_width, unsigned *virtual_height) const {
193 // Tells the effect the resolution of each of its input.
194 // This will be called every frame, and always before get_output_size(),
195 // so you can change your output size based on the input if so desired.
197 // Note that in some cases, an input might not have a single well-defined
198 // resolution (for instance if you fade between two inputs with
199 // different resolutions). In this case, you will get width=0 and height=0
200 // for that input. If you cannot handle that, you will need to set
201 // needs_texture_bounce() to true, which will force a render to a single
202 // given resolution before you get the input.
203 virtual void inform_input_size(unsigned input_num, unsigned width, unsigned height) {}
205 // How many inputs this effect will take (a fixed number).
206 // If you have only one input, it will be called INPUT() in GLSL;
207 // if you have several, they will be INPUT1(), INPUT2(), and so on.
208 virtual unsigned num_inputs() const { return 1; }
210 // Inform the effect that it has been just added to the EffectChain.
211 // The primary use for this is to store the ResourcePool uesd by
212 // the chain; for modifications to it, rewrite_graph() below
213 // is probably a better fit.
214 virtual void inform_added(EffectChain *chain) {}
216 // Let the effect rewrite the effect chain as it sees fit.
217 // Most effects won't need to do this, but this is very useful
218 // if you have an effect that consists of multiple sub-effects
219 // (for instance, two passes). The effect is given to its own
220 // pointer, and it can add new ones (by using add_node()
221 // and connect_node()) as it sees fit. This is called at
222 // EffectChain::finalize() time, when the entire graph is known,
223 // in the order that the effects were originally added.
225 // Note that if the effect wants to take itself entirely out
226 // of the chain, it must set “disabled” to true and then disconnect
227 // itself from all other effects.
228 virtual void rewrite_graph(EffectChain *graph, Node *self) {}
230 // Outputs one GLSL uniform declaration for each registered parameter
231 // (see below), with the right prefix prepended to each uniform name.
232 // If you do not want this behavior, you can override this function.
233 virtual std::string output_convenience_uniforms() const;
235 // Returns the GLSL fragment shader string for this effect.
236 virtual std::string output_fragment_shader() = 0;
238 // Set all OpenGL state that this effect needs before rendering.
239 // The default implementation sets one uniform per registered parameter,
240 // but no other state.
242 // <sampler_num> is the first free texture sampler. If you want to use
243 // textures, you can bind a texture to GL_TEXTURE0 + <sampler_num>,
244 // and then increment the number (so that the next effect in the chain
245 // will use a different sampler).
246 virtual void set_gl_state(GLuint glsl_program_num, const std::string& prefix, unsigned *sampler_num);
248 // If you set any special OpenGL state in set_gl_state(), you can clear it
249 // after rendering here. The default implementation does nothing.
250 virtual void clear_gl_state();
252 // Set a parameter; intended to be called from user code.
253 // Neither of these take ownership of the pointer.
254 virtual bool set_int(const std::string&, int value) MUST_CHECK_RESULT;
255 virtual bool set_float(const std::string &key, float value) MUST_CHECK_RESULT;
256 virtual bool set_vec2(const std::string &key, const float *values) MUST_CHECK_RESULT;
257 virtual bool set_vec3(const std::string &key, const float *values) MUST_CHECK_RESULT;
258 virtual bool set_vec4(const std::string &key, const float *values) MUST_CHECK_RESULT;
261 // Register a parameter. Whenever set_*() is called with the same key,
262 // it will update the value in the given pointer (typically a pointer
263 // to some private member variable in your effect).
265 // Neither of these take ownership of the pointer.
267 // int is special since GLSL pre-1.30 doesn't have integer uniforms.
268 // Thus, ints that you register will _not_ be converted to GLSL uniforms.
269 void register_int(const std::string &key, int *value);
271 // These correspond directly to float/vec2/vec3/vec4 in GLSL.
272 void register_float(const std::string &key, float *value);
273 void register_vec2(const std::string &key, float *values);
274 void register_vec3(const std::string &key, float *values);
275 void register_vec4(const std::string &key, float *values);
278 std::map<std::string, int *> params_int;
279 std::map<std::string, float *> params_float;
280 std::map<std::string, float *> params_vec2;
281 std::map<std::string, float *> params_vec3;
282 std::map<std::string, float *> params_vec4;
287 #endif // !defined(_MOVIT_EFFECT_H)