-#define GL_GLEXT_PROTOTYPES 1
-
#include <math.h>
-#include <GL/gl.h>
-#include <GL/glext.h>
#include <assert.h>
#include "blur_effect.h"
+#include "effect_chain.h"
#include "util.h"
+#include "opengl.h"
+// Must match blur_effect.frag.
+#define NUM_TAPS 16
+
BlurEffect::BlurEffect()
: radius(3.0f),
- direction(HORIZONTAL)
+ input_width(1280),
+ input_height(720)
+{
+ // The first blur pass will forward resolution information to us.
+ hpass = new SingleBlurPassEffect(this);
+ hpass->set_int("direction", SingleBlurPassEffect::HORIZONTAL);
+ vpass = new SingleBlurPassEffect(NULL);
+ vpass->set_int("direction", SingleBlurPassEffect::VERTICAL);
+
+ update_radius();
+}
+
+void BlurEffect::rewrite_graph(EffectChain *graph, Node *self)
+{
+ Node *hpass_node = graph->add_node(hpass);
+ Node *vpass_node = graph->add_node(vpass);
+ graph->connect_nodes(hpass_node, vpass_node);
+ graph->replace_receiver(self, hpass_node);
+ graph->replace_sender(self, vpass_node);
+ self->disabled = true;
+}
+
+// We get this information forwarded from the first blur pass,
+// since we are not part of the chain ourselves.
+void BlurEffect::inform_input_size(unsigned input_num, unsigned width, unsigned height)
+{
+ assert(input_num == 0);
+ assert(width != 0);
+ assert(height != 0);
+ input_width = width;
+ input_height = height;
+ update_radius();
+}
+
+void BlurEffect::update_radius()
+{
+ // We only have 16 taps to work with on each side, and we want that to
+ // reach out to about 2.5*sigma. Bump up the mipmap levels (giving us
+ // box blurs) until we have what we need.
+ unsigned mipmap_width = input_width, mipmap_height = input_height;
+ float adjusted_radius = radius;
+ while ((mipmap_width > 1 || mipmap_height > 1) && adjusted_radius * 1.5f > NUM_TAPS / 2) {
+ // Find the next mipmap size (round down, minimum 1 pixel).
+ mipmap_width = std::max(mipmap_width / 2, 1u);
+ mipmap_height = std::max(mipmap_height / 2, 1u);
+
+ // Approximate when mipmap sizes are odd, but good enough.
+ adjusted_radius = radius * float(mipmap_width) / float(input_width);
+ }
+
+ bool ok = hpass->set_float("radius", adjusted_radius);
+ ok |= hpass->set_int("width", mipmap_width);
+ ok |= hpass->set_int("height", mipmap_height);
+
+ ok |= vpass->set_float("radius", adjusted_radius);
+ ok |= vpass->set_int("width", mipmap_width);
+ ok |= vpass->set_int("height", mipmap_height);
+
+ assert(ok);
+}
+
+bool BlurEffect::set_float(const std::string &key, float value) {
+ if (key == "radius") {
+ radius = value;
+ update_radius();
+ return true;
+ }
+ return false;
+}
+
+SingleBlurPassEffect::SingleBlurPassEffect(BlurEffect *parent)
+ : parent(parent),
+ radius(3.0f),
+ direction(HORIZONTAL),
+ width(1280),
+ height(720)
{
- register_float("radius", (float *)&radius);
+ register_float("radius", &radius);
register_int("direction", (int *)&direction);
+ register_int("width", &width);
+ register_int("height", &height);
}
-std::string BlurEffect::output_fragment_shader()
+std::string SingleBlurPassEffect::output_fragment_shader()
{
return read_file("blur_effect.frag");
}
-void BlurEffect::set_uniforms(GLuint glsl_program_num, const std::string &prefix, unsigned *sampler_num)
+void SingleBlurPassEffect::set_gl_state(GLuint glsl_program_num, const std::string &prefix, unsigned *sampler_num)
{
- Effect::set_uniforms(glsl_program_num, prefix, sampler_num);
-
- // We only have 15 taps to work with, and we want that to reach out to about 2.5*sigma.
- // Bump up the mipmap levels (giving us box blurs) until we have what we need.
- unsigned base_mipmap_level = 0;
- float adjusted_radius = radius;
- float pixel_size = 1.0f;
- while (adjusted_radius * 2.5f > 7.0f) {
- ++base_mipmap_level;
- adjusted_radius *= 0.5f;
- pixel_size *= 2.0f;
- }
-
- // In the second pass, we do the same, but don't sample from a mipmap;
- // that would re-blur the other direction in an ugly fashion, and we already
- // have the vertical box blur we need from that pass.
- //
- // TODO: We really need to present horizontal+vertical as a unit;
- // currently, there's really no guarantee vertical blur is the second pass.
- if (direction == VERTICAL) {
- base_mipmap_level = 0;
- }
+ Effect::set_gl_state(glsl_program_num, prefix, sampler_num);
- glActiveTexture(GL_TEXTURE0);
- glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_BASE_LEVEL, base_mipmap_level);
- check_error();
-
- // FIXME
- if (direction == HORIZONTAL) {
- float ps[] = { pixel_size / 1280.0f, 0.0f };
- set_uniform_vec2(glsl_program_num, prefix, "pixel_offset", ps);
- } else if (direction == VERTICAL) {
- float ps[] = { 0.0f, pixel_size / 720.0f };
- set_uniform_vec2(glsl_program_num, prefix, "pixel_offset", ps);
+ // Compute the weights; they will be symmetrical, so we only compute
+ // the right side.
+ float weight[NUM_TAPS + 1];
+ if (radius < 1e-3) {
+ weight[0] = 1.0f;
+ for (unsigned i = 1; i < NUM_TAPS + 1; ++i) {
+ weight[i] = 0.0f;
+ }
} else {
- assert(false);
- }
+ float sum = 0.0f;
+ for (unsigned i = 0; i < NUM_TAPS + 1; ++i) {
+ // Gaussian blur is a common, but maybe not the prettiest choice;
+ // it can feel a bit too blurry in the fine detail and too little
+ // long-tail. This is a simple logistic distribution, which has
+ // a narrower peak but longer tails.
+ //
+ // We interpret the radius as sigma, similar to Gaussian blur.
+ // Wikipedia says that sigma² = pi² s² / 3, which yields:
+ const float s = (sqrt(3.0) / M_PI) * radius;
+ float z = i / (2.0 * s);
+
+ weight[i] = 1.0f / (cosh(z) * cosh(z));
- // Simple Gaussian weights for now.
- float weight[15], total = 0.0f;
- for (unsigned i = 0; i < 15; ++i) {
- float z = (i - 7.0f) / adjusted_radius;
- weight[i] = exp(-(z*z));
- total += weight[i];
+ if (i == 0) {
+ sum += weight[i];
+ } else {
+ sum += 2.0f * weight[i];
+ }
+ }
+ for (unsigned i = 0; i < NUM_TAPS + 1; ++i) {
+ weight[i] /= sum;
+ }
}
- printf("[mip level %d] ", base_mipmap_level);
- for (unsigned i = 0; i < 15; ++i) {
- weight[i] /= total;
- printf("%f ", weight[i]);
+
+ // Since the GPU gives us bilinear sampling for free, we can get two
+ // samples for the price of one (for every but the center sample,
+ // in which case this trick doesn't buy us anything). Simply sample
+ // between the two pixel centers, and we can do with fewer weights.
+ // (This is right even in the vertical pass where we don't actually
+ // sample between the pixels, because we have linear interpolation
+ // there too.)
+ //
+ // We pack the parameters into a float4: The relative sample coordinates
+ // in (x,y), and the weight in z. w is unused.
+ float samples[4 * (NUM_TAPS / 2 + 1)];
+
+ // Center sample.
+ samples[4 * 0 + 0] = 0.0f;
+ samples[4 * 0 + 1] = 0.0f;
+ samples[4 * 0 + 2] = weight[0];
+ samples[4 * 0 + 3] = 0.0f;
+
+ // All other samples.
+ for (unsigned i = 1; i < NUM_TAPS / 2 + 1; ++i) {
+ unsigned base_pos = i * 2 - 1;
+ float w1 = weight[base_pos];
+ float w2 = weight[base_pos + 1];
+
+ float offset, total_weight;
+ combine_two_samples(w1, w2, &offset, &total_weight);
+
+ float x = 0.0f, y = 0.0f;
+
+ if (direction == HORIZONTAL) {
+ x = (base_pos + offset) / (float)width;
+ } else if (direction == VERTICAL) {
+ y = (base_pos + offset) / (float)height;
+ } else {
+ assert(false);
+ }
+
+ samples[4 * i + 0] = x;
+ samples[4 * i + 1] = y;
+ samples[4 * i + 2] = total_weight;
+ samples[4 * i + 3] = 0.0f;
}
- printf("\n");
- set_uniform_float_array(glsl_program_num, prefix, "weight", weight, 15);
+
+ set_uniform_vec4_array(glsl_program_num, prefix, "samples", samples, NUM_TAPS / 2 + 1);
+}
+
+void SingleBlurPassEffect::clear_gl_state()
+{
}
projects / movit / blobdiff