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.
19 // Can alias on a float[2].
21 Point2D(float x, float y)
27 // Can alias on a float[3].
29 RGBTriplet(float r, float g, float b)
35 // Convenience functions that deal with prepending the prefix.
36 GLint get_uniform_location(GLuint glsl_program_num, const std::string &prefix, const std::string &key);
37 void set_uniform_int(GLuint glsl_program_num, const std::string &prefix, const std::string &key, int value);
38 void set_uniform_float(GLuint glsl_program_num, const std::string &prefix, const std::string &key, float value);
39 void set_uniform_float_array(GLuint glsl_program_num, const std::string &prefix, const std::string &key, const float *values, size_t num_values);
40 void set_uniform_vec2(GLuint glsl_program_num, const std::string &prefix, const std::string &key, const float *values);
41 void set_uniform_vec3(GLuint glsl_program_num, const std::string &prefix, const std::string &key, const float *values);
42 void set_uniform_vec4_array(GLuint glsl_program_num, const std::string &prefix, const std::string &key, const float *values, size_t num_values);
46 // Whether this effects expects its input (and output) to be in
47 // linear gamma, ie. without an applied gamma curve. Most effects
48 // will want this, although the ones that never actually look at
49 // the pixels, e.g. mirror, won't need to care, and can set this
50 // to false. If so, the input gamma will be undefined.
52 // Also see the note on needs_texture_bounce(), below.
53 virtual bool needs_linear_light() const { return true; }
55 // Whether this effect expects its input to be in the sRGB
56 // color space, ie. use the sRGB/Rec. 709 RGB primaries.
57 // (If not, it would typically come in as some slightly different
58 // set of RGB primaries; you would currently not get YCbCr
59 // or something similar).
61 // Again, most effects will want this.
62 virtual bool needs_srgb_primaries() const { return true; }
64 // Whether this effect expects its input to come directly from
65 // a texture. If this is true, the framework will not chain the
66 // input from other effects, but will store the results of the
67 // chain to a temporary (RGBA fp16) texture and let this effect
68 // sample directly from that.
70 // There are two good reasons why you might want to set this:
72 // 1. You are sampling more than once from the input,
73 // in which case computing all the previous steps might
74 // be more expensive than going to a memory intermediate.
75 // 2. You rely on previous effects, possibly including gamma
76 // expansion, to happen pre-filtering instead of post-filtering.
77 // (This is only relevant if you actually need the filtering; if
78 // you sample on whole input pixels only, it makes no difference.)
80 // Note that in some cases, you might get post-filtered gamma expansion
81 // even when setting this option. More specifically, if you are the
82 // first effect in the chain, and the GPU is doing sRGB gamma
83 // expansion, it is undefined (from OpenGL's side) whether expansion
84 // happens pre- or post-filtering. For most uses, however,
85 // either will be fine.
86 virtual bool needs_texture_bounce() const { return false; }
88 // Whether this effect expects mipmaps or not. If you set this to
89 // true, you will be sampling with bilinear filtering; if not,
90 // you could be sampling with simple linear filtering and no mipmaps
91 // (although there is no guarantee; if a different effect in the chain
92 // needs mipmaps, you will also get them).
93 virtual bool needs_mipmaps() const { return false; }
95 // Requests that this effect adds itself to the given effect chain.
96 // For most effects, the default will be fine, but for effects that
97 // consist of multiple passes, it is often useful to replace this
98 // with something that adds completely different things to the chain.
99 virtual void add_self_to_effect_chain(std::vector<Effect *> *chain) {
100 chain->push_back(this);
103 // Outputs one GLSL uniform declaration for each registered parameter
104 // (see below), with the right prefix prepended to each uniform name.
105 // If you do not want this behavior, you can override this function.
106 virtual std::string output_convenience_uniforms() const;
108 // Returns the GLSL fragment shader string for this effect.
109 virtual std::string output_fragment_shader() = 0;
111 // Set all uniforms the shader needs in the current GL context.
112 // The default implementation sets one uniform per registered parameter.
114 // <sampler_num> is the first free texture sampler. If you want to use
115 // textures, you can bind a texture to GL_TEXTURE0 + <sampler_num>,
116 // and then increment the number (so that the next effect in the chain
117 // will use a different sampler).
119 // NOTE: Currently this is also abused a bit to set other GL state
120 // the effect might need.
121 virtual void set_uniforms(GLuint glsl_program_num, const std::string& prefix, unsigned *sampler_num);
123 // Set a parameter; intended to be called from user code.
124 // Neither of these take ownership of the pointer.
125 virtual bool set_int(const std::string&, int value);
126 virtual bool set_float(const std::string &key, float value);
127 virtual bool set_vec2(const std::string &key, const float *values);
128 virtual bool set_vec3(const std::string &key, const float *values);
131 // Register a parameter. Whenever set_*() is called with the same key,
132 // it will update the value in the given pointer (typically a pointer
133 // to some private member variable in your effect).
135 // Neither of these take ownership of the pointer.
137 // int is special since GLSL pre-1.30 doesn't have integer uniforms.
138 // Thus, ints that you register will _not_ be converted to GLSL uniforms.
139 void register_int(const std::string &key, int *value);
141 // These correspond directly to float/vec2/vec3 in GLSL.
142 void register_float(const std::string &key, float *value);
143 void register_vec2(const std::string &key, float *values);
144 void register_vec3(const std::string &key, float *values);
146 // This will register a 1D texture, which will be bound to a sampler
147 // when your GLSL code runs (so it corresponds 1:1 to a sampler2D uniform
150 // Note that if you change the contents of <values>, you will need to
151 // call invalidate_1d_texture() to have the picture re-uploaded on the
152 // next frame. This is in contrast to all the other parameters, which are
153 // set anew every frame.
154 void register_1d_texture(const std::string &key, float *values, size_t size);
155 void invalidate_1d_texture(const std::string &key);
165 std::map<std::string, int *> params_int;
166 std::map<std::string, float *> params_float;
167 std::map<std::string, float *> params_vec2;
168 std::map<std::string, float *> params_vec3;
169 std::map<std::string, Texture1D> params_tex_1d;
172 #endif // !defined(_EFFECT_H)