X-Git-Url: https://git.sesse.net/?p=movit;a=blobdiff_plain;f=blur_effect.cpp;h=90d1b68653b9af51c009c1fae48a7e007998da8d;hp=7ca895a15f6b56b8dfee4e53a0f013610097d0de;hb=b09a4cb8dec09bcd1e42026d5b229b57e620e47c;hpb=75c27c449aabb27ed0b028b57b20d70005a6e447 diff --git a/blur_effect.cpp b/blur_effect.cpp index 7ca895a..90d1b68 100644 --- a/blur_effect.cpp +++ b/blur_effect.cpp @@ -1,56 +1,188 @@ -#define GL_GLEXT_PROTOTYPES 1 - #include -#include -#include +#include #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) + : radius(3.0f), + 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); + Effect::set_gl_state(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; - } - - glActiveTexture(GL_TEXTURE0); - glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_BASE_LEVEL, base_mipmap_level); - check_error(); - - set_uniform_float(glsl_program_num, prefix, "pixel_offset", pixel_size / 1280.0f); // FIXME - - // 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]; + // 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 { + 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)); + + 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() +{ }