Rename needs_many_samples() to needs_texture_bounce(), and update the comment.

diff --git a/blur_effect.h b/blur_effect.h
index 0c7dccc826b9ae9ccb4be6b352aa1e288fb787e9..3f86e1797529d6aadc06ba08611abfde5083a269 100644 (file)
--- a/blur_effect.h
+++ b/blur_effect.h
@@ -24,7 +24,7 @@ public:
                assert(false);
        }
 
-       virtual bool needs_many_samples() const { return true; }
+       virtual bool needs_texture_bounce() const { return true; }
        virtual bool needs_mipmaps() const { return true; }
        virtual void add_self_to_effect_chain(std::vector<Effect *> *chain);
        virtual bool set_float(const std::string &key, float value);
@@ -38,7 +38,7 @@ public:
        SingleBlurPassEffect();
        std::string output_fragment_shader();
 
-       virtual bool needs_many_samples() const { return true; }
+       virtual bool needs_texture_bounce() const { return true; }
        virtual bool needs_mipmaps() const { return true; }
 
        void set_uniforms(GLuint glsl_program_num, const std::string &prefix, unsigned *sampler_num);

diff --git a/effect.h b/effect.h
index f495867a42029128eaa7140747508fa76ebce696..4191d4ddfb6714ec284719acae8c0e4b0f89b4bf 100644 (file)
--- a/effect.h
+++ b/effect.h
@@ -49,7 +49,7 @@ public:
        // 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.
+       // Also see the note on needs_texture_bounce(), below.
        virtual bool needs_linear_light() const { return true; }
 
        // Whether this effect expects its input to be in the sRGB
@@ -61,19 +61,29 @@ public:
        // 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
+       // Whether this effect expects its input to come directly from
+       // a texture. 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; }
+       // There are two good reasons why you might want to set this:
+       //
+       //  1. You are sampling more than once from the input,
+       //     in which case computing all the previous steps might
+       //     be more expensive than going to a memory intermediate.
+       //  2. You rely on previous effects, possibly including gamma
+       //     expansion, to happen pre-filtering instead of post-filtering.
+       //     (This is only relevant if you actually need the filtering; if
+       //     you sample on whole input pixels only, it makes no difference.)
+       //
+       // Note that in some cases, you might get post-filtered gamma expansion
+       // even when setting this option. More specifically, if you are the
+       // first effect in the chain, and the GPU is doing sRGB gamma
+       // expansion, it is undefined (from OpenGL's side) whether expansion
+       // happens pre- or post-filtering. For most uses, however,
+       // either will be fine.
+       virtual bool needs_texture_bounce() 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,

diff --git a/effect_chain.cpp b/effect_chain.cpp
index e728963759a7f85c85c86f29e304a72c7d8f315b..fcf94f8505299c0ec12156c8ab427b06e9fa73c0 100644 (file)
--- a/effect_chain.cpp
+++ b/effect_chain.cpp
@@ -208,7 +208,7 @@ void EffectChain::finalize()
        // and of course at the end.
        unsigned start = 0;
        for (unsigned i = 0; i < effects.size(); ++i) {
-               if (effects[i]->needs_many_samples() && i != start) {
+               if (effects[i]->needs_texture_bounce() && i != start) {
                        phases.push_back(compile_glsl_program(start, i));
                        start = i;
                }

diff --git a/main.cpp b/main.cpp
index abc0a384b2c13ef00170232a6b559a3306742c76..b41c9ed0789f219d8eba163457e0abe61098cda9 100644 (file)
--- a/main.cpp
+++ b/main.cpp
@@ -150,7 +150,7 @@ int main(int argc, char **argv)
        glPixelStorei(GL_PACK_ALIGNMENT, 1);
 
        unsigned img_w, img_h;
-       unsigned char *src_img = load_image("blg_wheels_woman_1.jpg", &img_w, &img_h);
+       unsigned char *src_img = load_image("test.jpg", &img_w, &img_h);
 
        EffectChain chain(WIDTH, HEIGHT);