5 #include "blur_effect.h"
6 #include "effect_chain.h"
9 // Must match blur_effect.frag.
12 BlurEffect::BlurEffect()
17 // The first blur pass will forward resolution information to us.
18 hpass = new SingleBlurPassEffect(this);
19 CHECK(hpass->set_int("direction", SingleBlurPassEffect::HORIZONTAL));
20 vpass = new SingleBlurPassEffect(NULL);
21 CHECK(vpass->set_int("direction", SingleBlurPassEffect::VERTICAL));
26 void BlurEffect::rewrite_graph(EffectChain *graph, Node *self)
28 Node *hpass_node = graph->add_node(hpass);
29 Node *vpass_node = graph->add_node(vpass);
30 graph->connect_nodes(hpass_node, vpass_node);
31 graph->replace_receiver(self, hpass_node);
32 graph->replace_sender(self, vpass_node);
33 self->disabled = true;
36 // We get this information forwarded from the first blur pass,
37 // since we are not part of the chain ourselves.
38 void BlurEffect::inform_input_size(unsigned input_num, unsigned width, unsigned height)
40 assert(input_num == 0);
44 input_height = height;
48 void BlurEffect::update_radius()
50 // We only have 16 taps to work with on each side, and we want that to
51 // reach out to about 2.5*sigma. Bump up the mipmap levels (giving us
52 // box blurs) until we have what we need.
53 unsigned mipmap_width = input_width, mipmap_height = input_height;
54 float adjusted_radius = radius;
55 while ((mipmap_width > 1 || mipmap_height > 1) && adjusted_radius * 1.5f > NUM_TAPS / 2) {
56 // Find the next mipmap size (round down, minimum 1 pixel).
57 mipmap_width = std::max(mipmap_width / 2, 1u);
58 mipmap_height = std::max(mipmap_height / 2, 1u);
60 // Approximate when mipmap sizes are odd, but good enough.
61 adjusted_radius = radius * float(mipmap_width) / float(input_width);
64 bool ok = hpass->set_float("radius", adjusted_radius);
65 ok |= hpass->set_int("width", mipmap_width);
66 ok |= hpass->set_int("height", mipmap_height);
67 ok |= hpass->set_int("virtual_width", mipmap_width);
68 ok |= hpass->set_int("virtual_height", mipmap_height);
70 ok |= vpass->set_float("radius", adjusted_radius);
71 ok |= vpass->set_int("width", mipmap_width);
72 ok |= vpass->set_int("height", mipmap_height);
73 ok |= vpass->set_int("virtual_width", input_width);
74 ok |= vpass->set_int("virtual_height", input_height);
79 bool BlurEffect::set_float(const std::string &key, float value) {
80 if (key == "radius") {
88 SingleBlurPassEffect::SingleBlurPassEffect(BlurEffect *parent)
91 direction(HORIZONTAL),
95 register_float("radius", &radius);
96 register_int("direction", (int *)&direction);
97 register_int("width", &width);
98 register_int("height", &height);
99 register_int("virtual_width", &virtual_width);
100 register_int("virtual_height", &virtual_height);
103 std::string SingleBlurPassEffect::output_fragment_shader()
105 return read_file("blur_effect.frag");
108 void SingleBlurPassEffect::set_gl_state(GLuint glsl_program_num, const std::string &prefix, unsigned *sampler_num)
110 Effect::set_gl_state(glsl_program_num, prefix, sampler_num);
112 // Compute the weights; they will be symmetrical, so we only compute
114 float weight[NUM_TAPS + 1];
117 for (unsigned i = 1; i < NUM_TAPS + 1; ++i) {
122 for (unsigned i = 0; i < NUM_TAPS + 1; ++i) {
123 // Gaussian blur is a common, but maybe not the prettiest choice;
124 // it can feel a bit too blurry in the fine detail and too little
125 // long-tail. This is a simple logistic distribution, which has
126 // a narrower peak but longer tails.
128 // We interpret the radius as sigma, similar to Gaussian blur.
129 // Wikipedia says that sigma² = pi² s² / 3, which yields:
130 const float s = (sqrt(3.0) / M_PI) * radius;
131 float z = i / (2.0 * s);
133 weight[i] = 1.0f / (cosh(z) * cosh(z));
138 sum += 2.0f * weight[i];
141 for (unsigned i = 0; i < NUM_TAPS + 1; ++i) {
146 // Since the GPU gives us bilinear sampling for free, we can get two
147 // samples for the price of one (for every but the center sample,
148 // in which case this trick doesn't buy us anything). Simply sample
149 // between the two pixel centers, and we can do with fewer weights.
150 // (This is right even in the vertical pass where we don't actually
151 // sample between the pixels, because we have linear interpolation
154 // We pack the parameters into a float4: The relative sample coordinates
155 // in (x,y), and the weight in z. w is unused.
156 float samples[4 * (NUM_TAPS / 2 + 1)];
159 samples[4 * 0 + 0] = 0.0f;
160 samples[4 * 0 + 1] = 0.0f;
161 samples[4 * 0 + 2] = weight[0];
162 samples[4 * 0 + 3] = 0.0f;
164 // All other samples.
165 for (unsigned i = 1; i < NUM_TAPS / 2 + 1; ++i) {
166 unsigned base_pos = i * 2 - 1;
167 float w1 = weight[base_pos];
168 float w2 = weight[base_pos + 1];
170 float offset, total_weight;
171 combine_two_samples(w1, w2, &offset, &total_weight, NULL);
173 float x = 0.0f, y = 0.0f;
175 if (direction == HORIZONTAL) {
176 x = (base_pos + offset) / (float)width;
177 } else if (direction == VERTICAL) {
178 y = (base_pos + offset) / (float)height;
183 samples[4 * i + 0] = x;
184 samples[4 * i + 1] = y;
185 samples[4 * i + 2] = total_weight;
186 samples[4 * i + 3] = 0.0f;
189 set_uniform_vec4_array(glsl_program_num, prefix, "samples", samples, NUM_TAPS / 2 + 1);
192 void SingleBlurPassEffect::clear_gl_state()