#ifndef _EFFECT_H
#define _EFFECT_H 1
+// Effect is the base class for every effect. It basically represents a single
+// GLSL function, with an optional set of user-settable parameters.
+//
+// A note on naming: Since all effects run in the same GLSL namespace,
+// you can't use any name you want for global variables (e.g. uniforms).
+// The framework assigns a prefix to you which will be unique for each
+// effect instance; use the macro PREFIX() around your identifiers to
+// automatically prepend that prefix.
+
#include <map>
#include <string>
#include <vector>
class Effect {
public:
+ // Whether this effects expects its input (and output) to be in
+ // linear gamma, ie. without an applied gamma curve. Most effects
+ // will want this, although the ones that never actually look at
+ // the pixels, e.g. mirror, won't need to care, and can set this
+ // to false. If so, the input gamma will be undefined.
+ //
+ // Also see the note on needs_many_samples(), below.
virtual bool needs_linear_light() const { return true; }
+
+ // Whether this effect expects its input to be in the sRGB
+ // color space, ie. use the sRGB/Rec. 709 RGB primaries.
+ // (If not, it would typically come in as some slightly different
+ // set of RGB primaries; you would currently not get YCbCr
+ // or something similar).
+ //
+ // Again, most effects will want this.
virtual bool needs_srgb_primaries() const { return true; }
+
+ // Whether this effect expects to be sampling many times from
+ // its input. If this is true, the framework will not chain the
+ // input from other effects, but will store the results of the
+ // chain to a temporary (RGBA fp16) texture and let this effect
+ // sample directly from that.
+ //
+ // Note that if you do _not_ set this, and do not sample on
+ // whole pixels (ie. you request linear filtering), it is undefined
+ // whether that filtering happen in linear gamma or not.
+ // It _could_ be (for instance in the case where the input is sRGB
+ // and your GPU applies gamma expansion before filtering), but you
+ // have no such guarantee. For most uses, however, this will be fine.
virtual bool needs_many_samples() const { return false; }
+
+ // Whether this effect expects mipmaps or not. If you set this to
+ // true, you will be sampling with bilinear filtering; if not,
+ // you could be sampling with simple linear filtering and no mipmaps
+ // (although there is no guarantee; if a different effect in the chain
+ // needs mipmaps, you will also get them).
virtual bool needs_mipmaps() const { return false; }
+
+ // Requests that this effect adds itself to the given effect chain.
+ // For most effects, the default will be fine, but for effects that
+ // consist of multiple passes, it is often useful to replace this
+ // with something that adds completely different things to the chain.
virtual void add_self_to_effect_chain(std::vector<Effect *> *chain) {
chain->push_back(this);
}
+ // Outputs one GLSL uniform declaration for each registered parameter
+ // (see below), with the right prefix prepended to each uniform name.
+ // If you do not want this behavior, you can override this function.
virtual std::string output_convenience_uniforms() const;
+
+ // Returns the GLSL fragment shader string for this effect.
virtual std::string output_fragment_shader() = 0;
+ // Set all uniforms the shader needs in the current GL context.
+ // The default implementation sets one uniform per registered parameter.
+ //
+ // <sampler_num> is the first free texture sampler. If you want to use
+ // textures, you can bind a texture to GL_TEXTURE0 + <sampler_num>,
+ // and then increment the number (so that the next effect in the chain
+ // will use a different sampler).
+ //
+ // NOTE: Currently this is also abused a bit to set other GL state
+ // the effect might need.
virtual void set_uniforms(GLuint glsl_program_num, const std::string& prefix, unsigned *sampler_num);
- // Neither of these take ownership.
+ // Set a parameter; intended to be called from user code.
+ // Neither of these take ownership of the pointer.
virtual bool set_int(const std::string&, int value);
virtual bool set_float(const std::string &key, float value);
virtual bool set_vec2(const std::string &key, const float *values);
virtual bool set_vec3(const std::string &key, const float *values);
protected:
- // Neither of these take ownership.
+ // Register a parameter. Whenever set_*() is called with the same key,
+ // it will update the value in the given pointer (typically a pointer
+ // to some private member variable in your effect).
+ //
+ // Neither of these take ownership of the pointer.
+
+ // int is special since GLSL pre-1.30 doesn't have integer uniforms.
+ // Thus, ints that you register will _not_ be converted to GLSL uniforms.
void register_int(const std::string &key, int *value);
+
+ // These correspond directly to float/vec2/vec3 in GLSL.
void register_float(const std::string &key, float *value);
void register_vec2(const std::string &key, float *values);
void register_vec3(const std::string &key, float *values);
+
+ // This will register a 1D texture, which will be bound to a sampler
+ // when your GLSL code runs (so it corresponds 1:1 to a sampler2D uniform
+ // in GLSL).
+ //
+ // Note that if you change the contents of <values>, you will need to
+ // call invalidate_1d_texture() to have the picture re-uploaded on the
+ // next frame. This is in contrast to all the other parameters, which are
+ // set anew every frame.
void register_1d_texture(const std::string &key, float *values, size_t size);
void invalidate_1d_texture(const std::string &key);
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