]> git.sesse.net Git - nageru/blobdiff - flow.cpp
Make PersistentFBOSet handle depth.
[nageru] / flow.cpp
index 6a9d0eeb74ce551455e2392fb963e211759aaab3..cb747c91762b9692432966e27e2350a7c15e160d 100644 (file)
--- a/flow.cpp
+++ b/flow.cpp
@@ -15,6 +15,7 @@
 #include <stdio.h>
 #include <unistd.h>
 
+#include "gpu_timers.h"
 #include "util.h"
 
 #include <algorithm>
@@ -46,6 +47,7 @@ constexpr unsigned patch_size_pixels = 12;
 float vr_alpha = 1.0f, vr_delta = 0.25f, vr_gamma = 0.25f;
 
 bool enable_timing = true;
+bool detailed_timing = false;
 bool enable_variational_refinement = true;  // Just for debugging.
 bool enable_interpolation = false;
 
@@ -266,19 +268,19 @@ public:
        void render_to(const array<GLuint, num_elements> &textures);
 
        // Convenience wrappers.
-       void render_to(GLuint texture0, enable_if<num_elements == 1> * = nullptr) {
+       void render_to(GLuint texture0) {
                render_to({{texture0}});
        }
 
-       void render_to(GLuint texture0, GLuint texture1, enable_if<num_elements == 2> * = nullptr) {
+       void render_to(GLuint texture0, GLuint texture1) {
                render_to({{texture0, texture1}});
        }
 
-       void render_to(GLuint texture0, GLuint texture1, GLuint texture2, enable_if<num_elements == 3> * = nullptr) {
+       void render_to(GLuint texture0, GLuint texture1, GLuint texture2) {
                render_to({{texture0, texture1, texture2}});
        }
 
-       void render_to(GLuint texture0, GLuint texture1, GLuint texture2, GLuint texture3, enable_if<num_elements == 4> * = nullptr) {
+       void render_to(GLuint texture0, GLuint texture1, GLuint texture2, GLuint texture3) {
                render_to({{texture0, texture1, texture2, texture3}});
        }
 
@@ -309,6 +311,59 @@ void PersistentFBOSet<num_elements>::render_to(const array<GLuint, num_elements>
        glBindFramebuffer(GL_FRAMEBUFFER, fbo);
 }
 
+// Same, but with a depth texture.
+template<size_t num_elements>
+class PersistentFBOSetWithDepth {
+public:
+       void render_to(GLuint depth_tex, const array<GLuint, num_elements> &textures);
+
+       // Convenience wrappers.
+       void render_to(GLuint depth_tex, GLuint texture0) {
+               render_to(depth_tex, {{texture0}});
+       }
+
+       void render_to(GLuint depth_tex, GLuint texture0, GLuint texture1) {
+               render_to(depth_tex, {{texture0, texture1}});
+       }
+
+       void render_to(GLuint depth_tex, GLuint texture0, GLuint texture1, GLuint texture2) {
+               render_to(depth_tex, {{texture0, texture1, texture2}});
+       }
+
+       void render_to(GLuint depth_tex, GLuint texture0, GLuint texture1, GLuint texture2, GLuint texture3) {
+               render_to(depth_tex, {{texture0, texture1, texture2, texture3}});
+       }
+
+private:
+       // TODO: Delete these on destruction.
+       map<pair<GLuint, array<GLuint, num_elements>>, GLuint> fbos;
+};
+
+template<size_t num_elements>
+void PersistentFBOSetWithDepth<num_elements>::render_to(GLuint depth_tex, const array<GLuint, num_elements> &textures)
+{
+       auto key = make_pair(depth_tex, textures);
+
+       auto it = fbos.find(key);
+       if (it != fbos.end()) {
+               glBindFramebuffer(GL_FRAMEBUFFER, it->second);
+               return;
+       }
+
+       GLuint fbo;
+       glCreateFramebuffers(1, &fbo);
+       GLenum bufs[num_elements];
+       glNamedFramebufferTexture(fbo, GL_DEPTH_ATTACHMENT, depth_tex, 0);
+       for (size_t i = 0; i < num_elements; ++i) {
+               glNamedFramebufferTexture(fbo, GL_COLOR_ATTACHMENT0 + i, textures[i], 0);
+               bufs[i] = GL_COLOR_ATTACHMENT0 + i;
+       }
+       glNamedFramebufferDrawBuffers(fbo, num_elements, bufs);
+
+       fbos[key] = fbo;
+       glBindFramebuffer(GL_FRAMEBUFFER, fbo);
+}
+
 // Convert RGB to grayscale, using Rec. 709 coefficients.
 class GrayscaleConversion {
 public:
@@ -489,7 +544,7 @@ private:
        GLuint densify_program;
        GLuint densify_vao;
 
-       GLuint uniform_patch_size, uniform_patch_spacing;
+       GLuint uniform_patch_size;
        GLuint uniform_image0_tex, uniform_image1_tex, uniform_flow_tex;
 };
 
@@ -509,7 +564,6 @@ Densify::Densify()
        glVertexAttribPointer(position_attrib, 2, GL_FLOAT, GL_FALSE, 0, BUFFER_OFFSET(0));
 
        uniform_patch_size = glGetUniformLocation(densify_program, "patch_size");
-       uniform_patch_spacing = glGetUniformLocation(densify_program, "patch_spacing");
        uniform_image0_tex = glGetUniformLocation(densify_program, "image0_tex");
        uniform_image1_tex = glGetUniformLocation(densify_program, "image1_tex");
        uniform_flow_tex = glGetUniformLocation(densify_program, "flow_tex");
@@ -527,14 +581,6 @@ void Densify::exec(GLuint tex0_view, GLuint tex1_view, GLuint flow_tex, GLuint d
                float(patch_size_pixels) / level_width,
                float(patch_size_pixels) / level_height);
 
-       float patch_spacing_x = float(level_width - patch_size_pixels) / (width_patches - 1);
-       float patch_spacing_y = float(level_height - patch_size_pixels) / (height_patches - 1);
-       if (width_patches == 1) patch_spacing_x = 0.0f;  // Avoid infinities.
-       if (height_patches == 1) patch_spacing_y = 0.0f;
-       glProgramUniform2f(densify_program, uniform_patch_spacing,
-               patch_spacing_x / level_width,
-               patch_spacing_y / level_height);
-
        glViewport(0, 0, level_width, level_height);
        glEnable(GL_BLEND);
        glBlendFunc(GL_ONE, GL_ONE);
@@ -808,7 +854,7 @@ void SetupEquations::exec(GLuint I_x_y_tex, GLuint I_t_tex, GLuint diff_flow_tex
 class SOR {
 public:
        SOR();
-       void exec(GLuint diff_flow_tex, GLuint equation_tex, GLuint smoothness_x_tex, GLuint smoothness_y_tex, int level_width, int level_height, int num_iterations);
+       void exec(GLuint diff_flow_tex, GLuint equation_tex, GLuint smoothness_x_tex, GLuint smoothness_y_tex, int level_width, int level_height, int num_iterations, ScopedTimer *sor_timer);
 
 private:
        PersistentFBOSet<1> fbos;
@@ -846,7 +892,7 @@ SOR::SOR()
        uniform_phase = glGetUniformLocation(sor_program, "phase");
 }
 
-void SOR::exec(GLuint diff_flow_tex, GLuint equation_tex, GLuint smoothness_x_tex, GLuint smoothness_y_tex, int level_width, int level_height, int num_iterations)
+void SOR::exec(GLuint diff_flow_tex, GLuint equation_tex, GLuint smoothness_x_tex, GLuint smoothness_y_tex, int level_width, int level_height, int num_iterations, ScopedTimer *sor_timer)
 {
        glUseProgram(sor_program);
 
@@ -865,14 +911,20 @@ void SOR::exec(GLuint diff_flow_tex, GLuint equation_tex, GLuint smoothness_x_te
        fbos.render_to(diff_flow_tex);
 
        for (int i = 0; i < num_iterations; ++i) {
-               glProgramUniform1i(sor_program, uniform_phase, 0);
-               glDrawArrays(GL_TRIANGLE_STRIP, 0, 4);
-               glTextureBarrier();
-               glProgramUniform1i(sor_program, uniform_phase, 1);
-               glDrawArrays(GL_TRIANGLE_STRIP, 0, 4);
-               if (i != num_iterations - 1) {
+               {
+                       ScopedTimer timer("Red pass", sor_timer);
+                       glProgramUniform1i(sor_program, uniform_phase, 0);
+                       glDrawArrays(GL_TRIANGLE_STRIP, 0, 4);
                        glTextureBarrier();
                }
+               {
+                       ScopedTimer timer("Black pass", sor_timer);
+                       glProgramUniform1i(sor_program, uniform_phase, 1);
+                       glDrawArrays(GL_TRIANGLE_STRIP, 0, 4);
+                       if (i != num_iterations - 1) {
+                               glTextureBarrier();
+                       }
+               }
        }
 }
 
@@ -980,90 +1032,6 @@ void ResizeFlow::exec(GLuint flow_tex, GLuint out_tex, int input_width, int inpu
        glDrawArrays(GL_TRIANGLE_STRIP, 0, 4);
 }
 
-class GPUTimers {
-public:
-       void print();
-       pair<GLuint, GLuint> begin_timer(const string &name, int level);
-
-private:
-       struct Timer {
-               string name;
-               int level;
-               pair<GLuint, GLuint> query;
-       };
-       vector<Timer> timers;
-};
-
-pair<GLuint, GLuint> GPUTimers::begin_timer(const string &name, int level)
-{
-       if (!enable_timing) {
-               return make_pair(0, 0);
-       }
-
-       GLuint queries[2];
-       glGenQueries(2, queries);
-       glQueryCounter(queries[0], GL_TIMESTAMP);
-
-       Timer timer;
-       timer.name = name;
-       timer.level = level;
-       timer.query.first = queries[0];
-       timer.query.second = queries[1];
-       timers.push_back(timer);
-       return timer.query;
-}
-
-void GPUTimers::print()
-{
-       for (const Timer &timer : timers) {
-               // NOTE: This makes the CPU wait for the GPU.
-               GLuint64 time_start, time_end;
-               glGetQueryObjectui64v(timer.query.first, GL_QUERY_RESULT, &time_start);
-               glGetQueryObjectui64v(timer.query.second, GL_QUERY_RESULT, &time_end);
-               //fprintf(stderr, "GPU time used = %.1f ms\n", time_elapsed / 1e6);
-               for (int i = 0; i < timer.level * 2; ++i) {
-                       fprintf(stderr, " ");
-               }
-               fprintf(stderr, "%-30s %4.1f ms\n", timer.name.c_str(), GLint64(time_end - time_start) / 1e6);
-       }
-}
-
-// A simple RAII class for timing until the end of the scope.
-class ScopedTimer {
-public:
-       ScopedTimer(const string &name, GPUTimers *timers)
-               : timers(timers), level(0)
-       {
-               query = timers->begin_timer(name, level);
-       }
-
-       ScopedTimer(const string &name, ScopedTimer *parent_timer)
-               : timers(parent_timer->timers),
-                 level(parent_timer->level + 1)
-       {
-               query = timers->begin_timer(name, level);
-       }
-
-       ~ScopedTimer()
-       {
-               end();
-       }
-
-       void end()
-       {
-               if (enable_timing && !ended) {
-                       glQueryCounter(query.second, GL_TIMESTAMP);
-                       ended = true;
-               }
-       }
-
-private:
-       GPUTimers *timers;
-       int level;
-       pair<GLuint, GLuint> query;
-       bool ended = false;
-};
-
 class TexturePool {
 public:
        GLuint get_texture(GLenum format, GLuint width, GLuint height);
@@ -1158,7 +1126,7 @@ GLuint DISComputeFlow::exec(GLuint tex0, GLuint tex1, ResizeStrategy resize_stra
        ScopedTimer total_timer("Total", &timers);
        for (int level = coarsest_level; level >= int(finest_level); --level) {
                char timer_name[256];
-               snprintf(timer_name, sizeof(timer_name), "Level %d", level);
+               snprintf(timer_name, sizeof(timer_name), "Level %d (%d x %d)", level, width >> level, height >> level);
                ScopedTimer level_timer(timer_name, &total_timer);
 
                int level_width = width >> level;
@@ -1282,7 +1250,7 @@ GLuint DISComputeFlow::exec(GLuint tex0, GLuint tex1, ResizeStrategy resize_stra
                        // Note that these are to/from the same texture.
                        {
                                ScopedTimer timer("SOR", &varref_timer);
-                               sor.exec(du_dv_tex, equation_tex, smoothness_x_tex, smoothness_y_tex, level_width, level_height, 5);
+                               sor.exec(du_dv_tex, equation_tex, smoothness_x_tex, smoothness_y_tex, level_width, level_height, 5, &timer);
                        }
                }
 
@@ -1337,7 +1305,7 @@ public:
        void exec(GLuint tex0, GLuint tex1, GLuint forward_flow_tex, GLuint backward_flow_tex, GLuint flow_tex, GLuint depth_tex, int width, int height, float alpha);
 
 private:
-       PersistentFBOSet<2> fbos;
+       PersistentFBOSetWithDepth<1> fbos;
 
        GLuint splat_vs_obj;
        GLuint splat_fs_obj;
@@ -1381,7 +1349,9 @@ void Splat::exec(GLuint tex0, GLuint tex1, GLuint forward_flow_tex, GLuint backw
        bind_sampler(splat_program, uniform_image1_tex, 1, tex1, linear_sampler);
 
        // FIXME: This is set to 1.0 right now so not to trigger Haswell's “PMA stall”.
-       // Move to 2.0 later.
+       // Move to 2.0 later, or even 4.0.
+       // (Since we have hole filling, it's not critical, but larger values seem to do
+       // better than hole filling for large motion, blurs etc.)
        float splat_size = 1.0f;  // 4x4 splat means 16x overdraw, 2x2 splat means 4x overdraw.
        glProgramUniform2f(splat_program, uniform_splat_size, splat_size / width, splat_size / height);
        glProgramUniform1f(splat_program, uniform_alpha, alpha);
@@ -1393,12 +1363,7 @@ void Splat::exec(GLuint tex0, GLuint tex1, GLuint forward_flow_tex, GLuint backw
        glDepthFunc(GL_LESS);  // We store the difference between I_0 and I_1, where less difference is good. (Default 1.0 is effectively +inf, which always loses.)
        glBindVertexArray(splat_vao);
 
-       // FIXME: Get this into FBOSet, so we can reuse FBOs across frames.
-       GLuint fbo;
-       glCreateFramebuffers(1, &fbo);
-       glNamedFramebufferTexture(fbo, GL_COLOR_ATTACHMENT0, flow_tex, 0);
-       glNamedFramebufferTexture(fbo, GL_DEPTH_ATTACHMENT, depth_tex, 0);
-       glBindFramebuffer(GL_FRAMEBUFFER, fbo);
+       fbos.render_to(depth_tex, flow_tex);
 
        // Do forward splatting.
        bind_sampler(splat_program, uniform_flow_tex, 2, forward_flow_tex, nearest_sampler);
@@ -1411,8 +1376,182 @@ void Splat::exec(GLuint tex0, GLuint tex1, GLuint forward_flow_tex, GLuint backw
        glDrawArraysInstanced(GL_TRIANGLE_STRIP, 0, 4, width * height);
 
        glDisable(GL_DEPTH_TEST);
+}
+
+// Doing good and fast hole-filling on a GPU is nontrivial. We choose an option
+// that's fairly simple (given that most holes are really small) and also hopefully
+// cheap should the holes not be so small. Conceptually, we look for the first
+// non-hole to the left of us (ie., shoot a ray until we hit something), then
+// the first non-hole to the right of us, then up and down, and then average them
+// all together. It's going to create “stars” if the holes are big, but OK, that's
+// a tradeoff.
+//
+// Our implementation here is efficient assuming that the hierarchical Z-buffer is
+// on even for shaders that do discard (this typically kills early Z, but hopefully
+// not hierarchical Z); we set up Z so that only holes are written to, which means
+// that as soon as a hole is filled, the rasterizer should just skip it. Most of the
+// fullscreen quads should just be discarded outright, really.
+class HoleFill {
+public:
+       HoleFill();
+
+       // Output will be in flow_tex, temp_tex[0, 1, 2], representing the filling
+       // from the down, left, right and up, respectively. Use HoleBlend to merge
+       // them into one.
+       void exec(GLuint flow_tex, GLuint depth_tex, GLuint temp_tex[3], int width, int height);
+
+private:
+       PersistentFBOSetWithDepth<1> fbos;
+
+       GLuint fill_vs_obj;
+       GLuint fill_fs_obj;
+       GLuint fill_program;
+       GLuint fill_vao;
+
+       GLuint uniform_tex;
+       GLuint uniform_z, uniform_sample_offset;
+};
+
+HoleFill::HoleFill()
+{
+       fill_vs_obj = compile_shader(read_file("hole_fill.vert"), GL_VERTEX_SHADER);
+       fill_fs_obj = compile_shader(read_file("hole_fill.frag"), GL_FRAGMENT_SHADER);
+       fill_program = link_program(fill_vs_obj, fill_fs_obj);
+
+       // Set up the VAO containing all the required position/texcoord data.
+       glCreateVertexArrays(1, &fill_vao);
+       glBindVertexArray(fill_vao);
+       glBindBuffer(GL_ARRAY_BUFFER, vertex_vbo);
+
+       GLint position_attrib = glGetAttribLocation(fill_program, "position");
+       glEnableVertexArrayAttrib(fill_vao, position_attrib);
+       glVertexAttribPointer(position_attrib, 2, GL_FLOAT, GL_FALSE, 0, BUFFER_OFFSET(0));
+
+       uniform_tex = glGetUniformLocation(fill_program, "tex");
+       uniform_z = glGetUniformLocation(fill_program, "z");
+       uniform_sample_offset = glGetUniformLocation(fill_program, "sample_offset");
+}
+
+void HoleFill::exec(GLuint flow_tex, GLuint depth_tex, GLuint temp_tex[3], int width, int height)
+{
+       glUseProgram(fill_program);
+
+       bind_sampler(fill_program, uniform_tex, 0, flow_tex, nearest_sampler);
+
+       glProgramUniform1f(fill_program, uniform_z, 1.0f - 1.0f / 1024.0f);
+
+       glViewport(0, 0, width, height);
+       glDisable(GL_BLEND);
+       glEnable(GL_DEPTH_TEST);
+       glDepthFunc(GL_LESS);  // Only update the values > 0.999f (ie., only invalid pixels).
+       glBindVertexArray(fill_vao);
+
+       fbos.render_to(depth_tex, flow_tex);  // NOTE: Reading and writing to the same texture.
+
+       // Fill holes from the left, by shifting 1, 2, 4, 8, etc. pixels to the right.
+       for (int offs = 1; offs < width; offs *= 2) {
+               glProgramUniform2f(fill_program, uniform_sample_offset, -offs / float(width), 0.0f);
+               glDrawArrays(GL_TRIANGLE_STRIP, 0, 4);
+               glTextureBarrier();
+       }
+       glCopyImageSubData(flow_tex, GL_TEXTURE_2D, 0, 0, 0, 0, temp_tex[0], GL_TEXTURE_2D, 0, 0, 0, 0, width, height, 1);
+
+       // Similar to the right; adjust Z a bit down, so that we re-fill the pixels that
+       // were overwritten in the last algorithm.
+       glProgramUniform1f(fill_program, uniform_z, 1.0f - 2.0f / 1024.0f);
+       for (int offs = 1; offs < width; offs *= 2) {
+               glProgramUniform2f(fill_program, uniform_sample_offset, offs / float(width), 0.0f);
+               glDrawArrays(GL_TRIANGLE_STRIP, 0, 4);
+               glTextureBarrier();
+       }
+       glCopyImageSubData(flow_tex, GL_TEXTURE_2D, 0, 0, 0, 0, temp_tex[1], GL_TEXTURE_2D, 0, 0, 0, 0, width, height, 1);
+
+       // Up.
+       glProgramUniform1f(fill_program, uniform_z, 1.0f - 3.0f / 1024.0f);
+       for (int offs = 1; offs < height; offs *= 2) {
+               glProgramUniform2f(fill_program, uniform_sample_offset, 0.0f, -offs / float(height));
+               glDrawArrays(GL_TRIANGLE_STRIP, 0, 4);
+               glTextureBarrier();
+       }
+       glCopyImageSubData(flow_tex, GL_TEXTURE_2D, 0, 0, 0, 0, temp_tex[2], GL_TEXTURE_2D, 0, 0, 0, 0, width, height, 1);
+
+       // Down.
+       glProgramUniform1f(fill_program, uniform_z, 1.0f - 4.0f / 1024.0f);
+       for (int offs = 1; offs < height; offs *= 2) {
+               glProgramUniform2f(fill_program, uniform_sample_offset, 0.0f, offs / float(height));
+               glDrawArrays(GL_TRIANGLE_STRIP, 0, 4);
+               glTextureBarrier();
+       }
+
+       glDisable(GL_DEPTH_TEST);
+}
 
-       glDeleteFramebuffers(1, &fbo);
+// Blend the four directions from HoleFill into one pixel, so that single-pixel
+// holes become the average of their four neighbors.
+class HoleBlend {
+public:
+       HoleBlend();
+
+       void exec(GLuint flow_tex, GLuint depth_tex, GLuint temp_tex[3], int width, int height);
+
+private:
+       PersistentFBOSetWithDepth<1> fbos;
+
+       GLuint blend_vs_obj;
+       GLuint blend_fs_obj;
+       GLuint blend_program;
+       GLuint blend_vao;
+
+       GLuint uniform_left_tex, uniform_right_tex, uniform_up_tex, uniform_down_tex;
+       GLuint uniform_z, uniform_sample_offset;
+};
+
+HoleBlend::HoleBlend()
+{
+       blend_vs_obj = compile_shader(read_file("hole_fill.vert"), GL_VERTEX_SHADER);  // Reuse the vertex shader from the fill.
+       blend_fs_obj = compile_shader(read_file("hole_blend.frag"), GL_FRAGMENT_SHADER);
+       blend_program = link_program(blend_vs_obj, blend_fs_obj);
+
+       // Set up the VAO containing all the required position/texcoord data.
+       glCreateVertexArrays(1, &blend_vao);
+       glBindVertexArray(blend_vao);
+       glBindBuffer(GL_ARRAY_BUFFER, vertex_vbo);
+
+       GLint position_attrib = glGetAttribLocation(blend_program, "position");
+       glEnableVertexArrayAttrib(blend_vao, position_attrib);
+       glVertexAttribPointer(position_attrib, 2, GL_FLOAT, GL_FALSE, 0, BUFFER_OFFSET(0));
+
+       uniform_left_tex = glGetUniformLocation(blend_program, "left_tex");
+       uniform_right_tex = glGetUniformLocation(blend_program, "right_tex");
+       uniform_up_tex = glGetUniformLocation(blend_program, "up_tex");
+       uniform_down_tex = glGetUniformLocation(blend_program, "down_tex");
+       uniform_z = glGetUniformLocation(blend_program, "z");
+       uniform_sample_offset = glGetUniformLocation(blend_program, "sample_offset");
+}
+
+void HoleBlend::exec(GLuint flow_tex, GLuint depth_tex, GLuint temp_tex[3], int width, int height)
+{
+       glUseProgram(blend_program);
+
+       bind_sampler(blend_program, uniform_left_tex, 0, temp_tex[0], nearest_sampler);
+       bind_sampler(blend_program, uniform_right_tex, 1, temp_tex[1], nearest_sampler);
+       bind_sampler(blend_program, uniform_up_tex, 2, temp_tex[2], nearest_sampler);
+       bind_sampler(blend_program, uniform_down_tex, 3, flow_tex, nearest_sampler);
+
+       glProgramUniform1f(blend_program, uniform_z, 1.0f - 4.0f / 1024.0f);
+       glProgramUniform2f(blend_program, uniform_sample_offset, 0.0f, 0.0f);
+
+       glViewport(0, 0, width, height);
+       glDisable(GL_BLEND);
+       glEnable(GL_DEPTH_TEST);
+       glDepthFunc(GL_LEQUAL);  // Skip over all of the pixels that were never holes to begin with.
+       glBindVertexArray(blend_vao);
+
+       fbos.render_to(depth_tex, flow_tex);  // NOTE: Reading and writing to the same texture.
+
+       glDrawArrays(GL_TRIANGLE_STRIP, 0, 4);
+
+       glDisable(GL_DEPTH_TEST);
 }
 
 class Blend {
@@ -1486,6 +1625,8 @@ private:
        int width, height, flow_level;
        TexturePool pool;
        Splat splat;
+       HoleFill hole_fill;
+       HoleBlend hole_blend;
        Blend blend;
 };
 
@@ -1512,22 +1653,36 @@ GLuint Interpolate::exec(GLuint tex0, GLuint tex1, GLuint forward_flow_tex, GLui
        GLuint depth_tex = pool.get_texture(GL_DEPTH_COMPONENT32F, flow_width, flow_height);  // Used for ranking flows.
        {
                ScopedTimer timer("Clear", &total_timer);
-               glClearTexImage(flow_tex, 0, GL_RG, GL_FLOAT, nullptr);
+               float invalid_flow[] = { 1000.0f, 1000.0f };
+               glClearTexImage(flow_tex, 0, GL_RG, GL_FLOAT, invalid_flow);
                float infinity = 1.0f;
                glClearTexImage(depth_tex, 0, GL_DEPTH_COMPONENT, GL_FLOAT, &infinity);
        }
 
-       //SDL_GL_SwapWindow(window);
        {
                ScopedTimer timer("Splat", &total_timer);
                splat.exec(tex0_view, tex1_view, forward_flow_tex, backward_flow_tex, flow_tex, depth_tex, flow_width, flow_height, alpha);
        }
-       //SDL_GL_SwapWindow(window);
-       pool.release_texture(depth_tex);
        glDeleteTextures(1, &tex0_view);
        glDeleteTextures(1, &tex1_view);
 
-       GLuint output_tex = pool.get_texture(GL_RGB8, width, height);
+       GLuint temp_tex[3];
+       temp_tex[0] = pool.get_texture(GL_RG16F, flow_width, flow_height);
+       temp_tex[1] = pool.get_texture(GL_RG16F, flow_width, flow_height);
+       temp_tex[2] = pool.get_texture(GL_RG16F, flow_width, flow_height);
+
+       {
+               ScopedTimer timer("Fill holes", &total_timer);
+               hole_fill.exec(flow_tex, depth_tex, temp_tex, flow_width, flow_height);
+               hole_blend.exec(flow_tex, depth_tex, temp_tex, flow_width, flow_height);
+       }
+
+       pool.release_texture(temp_tex[0]);
+       pool.release_texture(temp_tex[1]);
+       pool.release_texture(temp_tex[2]);
+       pool.release_texture(depth_tex);
+
+       GLuint output_tex = pool.get_texture(GL_RGBA8, width, height);
        {
                ScopedTimer timer("Blend", &total_timer);
                blend.exec(tex0, tex1, flow_tex, output_tex, width, height, alpha);
@@ -1579,6 +1734,11 @@ void flip_coordinate_system(float *dense_flow, unsigned width, unsigned height)
        }
 }
 
+// Not relevant for RGB.
+void flip_coordinate_system(uint8_t *dense_flow, unsigned width, unsigned height)
+{
+}
+
 void write_flow(const char *filename, const float *dense_flow, unsigned width, unsigned height)
 {
        FILE *flowfp = fopen(filename, "wb");
@@ -1592,6 +1752,12 @@ void write_flow(const char *filename, const float *dense_flow, unsigned width, u
        fclose(flowfp);
 }
 
+// Not relevant for RGB.
+void write_flow(const char *filename, const uint8_t *dense_flow, unsigned width, unsigned height)
+{
+       assert(false);
+}
+
 void write_ppm(const char *filename, const float *dense_flow, unsigned width, unsigned height)
 {
        FILE *fp = fopen(filename, "wb");
@@ -1612,15 +1778,49 @@ void write_ppm(const char *filename, const float *dense_flow, unsigned width, un
        fclose(fp);
 }
 
+void write_ppm(const char *filename, const uint8_t *rgba, unsigned width, unsigned height)
+{
+       unique_ptr<uint8_t[]> rgb_line(new uint8_t[width * 3 + 1]);
+
+       FILE *fp = fopen(filename, "wb");
+       fprintf(fp, "P6\n%d %d\n255\n", width, height);
+       for (unsigned y = 0; y < height; ++y) {
+               unsigned y2 = height - 1 - y;
+               for (size_t x = 0; x < width; ++x) {
+                       memcpy(&rgb_line[x * 3], &rgba[(y2 * width + x) * 4], 4);
+               }
+               fwrite(rgb_line.get(), width * 3, 1, fp);
+       }
+       fclose(fp);
+}
+
+struct FlowType {
+       using type = float;
+       static constexpr GLenum gl_format = GL_RG;
+       static constexpr GLenum gl_type = GL_FLOAT;
+       static constexpr int num_channels = 2;
+};
+
+struct RGBAType {
+       using type = uint8_t;
+       static constexpr GLenum gl_format = GL_RGBA;
+       static constexpr GLenum gl_type = GL_UNSIGNED_BYTE;
+       static constexpr int num_channels = 4;
+};
+
+template <class Type>
 void finish_one_read(GLuint width, GLuint height)
 {
+       using T = typename Type::type;
+       constexpr int bytes_per_pixel = Type::num_channels * sizeof(T);
+
        assert(!reads_in_progress.empty());
        ReadInProgress read = reads_in_progress.front();
        reads_in_progress.pop_front();
 
-       unique_ptr<float[]> flow(new float[width * height * 2]);
-       void *buf = glMapNamedBufferRange(read.pbo, 0, width * height * 2 * sizeof(float), GL_MAP_READ_BIT);  // Blocks if the read isn't done yet.
-       memcpy(flow.get(), buf, width * height * 2 * sizeof(float));
+       unique_ptr<T[]> flow(new typename Type::type[width * height * Type::num_channels]);
+       void *buf = glMapNamedBufferRange(read.pbo, 0, width * height * bytes_per_pixel, GL_MAP_READ_BIT);  // Blocks if the read isn't done yet.
+       memcpy(flow.get(), buf, width * height * bytes_per_pixel);  // TODO: Unneeded for RGBType, since flip_coordinate_system() does nothing.:
        glUnmapNamedBuffer(read.pbo);
        spare_pbos.push(read.pbo);
 
@@ -1634,16 +1834,20 @@ void finish_one_read(GLuint width, GLuint height)
        }
 }
 
+template <class Type>
 void schedule_read(GLuint tex, GLuint width, GLuint height, const char *filename0, const char *filename1, const char *flow_filename, const char *ppm_filename)
 {
+       using T = typename Type::type;
+       constexpr int bytes_per_pixel = Type::num_channels * sizeof(T);
+
        if (spare_pbos.empty()) {
-               finish_one_read(width, height);
+               finish_one_read<Type>(width, height);
        }
        assert(!spare_pbos.empty());
        reads_in_progress.emplace_back(ReadInProgress{ spare_pbos.top(), filename0, filename1, flow_filename, ppm_filename });
        glBindBuffer(GL_PIXEL_PACK_BUFFER, spare_pbos.top());
        spare_pbos.pop();
-       glGetTextureImage(tex, 0, GL_RG, GL_FLOAT, width * height * 2 * sizeof(float), nullptr);
+       glGetTextureImage(tex, 0, Type::gl_format, Type::gl_type, width * height * bytes_per_pixel, nullptr);
        glBindBuffer(GL_PIXEL_PACK_BUFFER, 0);
 }
 
@@ -1691,7 +1895,7 @@ void compute_flow_only(int argc, char **argv, int optind)
        DISComputeFlow compute_flow(width1, height1);
        GLuint final_tex = compute_flow.exec(tex0_gray, tex1_gray, DISComputeFlow::RESIZE_FLOW_TO_FULL_SIZE);
 
-       schedule_read(final_tex, width1, height1, filename0, filename1, flow_filename, "flow.ppm");
+       schedule_read<FlowType>(final_tex, width1, height1, filename0, filename1, flow_filename, "flow.ppm");
        compute_flow.release_texture(final_tex);
 
        // See if there are more flows on the command line (ie., more than three arguments),
@@ -1724,14 +1928,14 @@ void compute_flow_only(int argc, char **argv, int optind)
 
                GLuint final_tex = compute_flow.exec(tex0_gray, tex1_gray, DISComputeFlow::RESIZE_FLOW_TO_FULL_SIZE);
 
-               schedule_read(final_tex, width1, height1, filename0, filename1, flow_filename, "");
+               schedule_read<FlowType>(final_tex, width1, height1, filename0, filename1, flow_filename, "");
                compute_flow.release_texture(final_tex);
        }
        glDeleteTextures(1, &tex0_gray);
        glDeleteTextures(1, &tex1_gray);
 
        while (!reads_in_progress.empty()) {
-               finish_one_read(width1, height1);
+               finish_one_read<FlowType>(width1, height1);
        }
 }
 
@@ -1762,14 +1966,13 @@ void interpolate_image(int argc, char **argv, int optind)
        GLuint pbos[5];
        glCreateBuffers(5, pbos);
        for (int i = 0; i < 5; ++i) {
-               glNamedBufferData(pbos[i], width1 * height1 * 2 * sizeof(float), nullptr, GL_STREAM_READ);
+               glNamedBufferData(pbos[i], width1 * height1 * 4 * sizeof(uint8_t), nullptr, GL_STREAM_READ);
                spare_pbos.push(pbos[i]);
        }
 
        DISComputeFlow compute_flow(width1, height1);
        GrayscaleConversion gray;
        Interpolate interpolate(width1, height1, finest_level);
-       //Interpolate interpolate(width1, height1, 0);
 
        int levels = find_num_levels(width1, height1);
        GLuint tex0_gray, tex1_gray;
@@ -1788,26 +1991,19 @@ void interpolate_image(int argc, char **argv, int optind)
        GLuint backward_flow_tex = compute_flow.exec(tex1_gray, tex0_gray, DISComputeFlow::DO_NOT_RESIZE_FLOW);
 
        for (int frameno = 1; frameno < 60; ++frameno) {
+               char ppm_filename[256];
+               snprintf(ppm_filename, sizeof(ppm_filename), "interp%04d.ppm", frameno);
+
                float alpha = frameno / 60.0f;
                GLuint interpolated_tex = interpolate.exec(tex0, tex1, forward_flow_tex, backward_flow_tex, width1, height1, alpha);
 
-               unique_ptr<uint8_t[]> rgb(new uint8_t[width1 * height1 * 3]);
-               glGetTextureImage(interpolated_tex, 0, GL_RGB, GL_UNSIGNED_BYTE, width1 * height1 * 3, rgb.get());
-
-               char buf[256];
-               snprintf(buf, sizeof(buf), "interp%04d.ppm", frameno);
-               FILE *fp = fopen(buf, "wb");
-               fprintf(fp, "P6\n%d %d\n255\n", width1, height1);
-               for (unsigned y = 0; y < height1; ++y) {
-                       unsigned y2 = height1 - 1 - y;
-                       fwrite(rgb.get() + y2 * width1 * 3, width1 * 3, 1, fp);
-               }
-               fclose(fp);
+               schedule_read<RGBAType>(interpolated_tex, width1, height1, filename0, filename1, "", ppm_filename);
+               interpolate.release_texture(interpolated_tex);
        }
 
-       //schedule_read(interpolated_tex, width1, height1, filename0, filename1, "", "halfflow.ppm");
-       //interpolate.release_texture(interpolated_tex);
-       //finish_one_read(width1, height1);
+       while (!reads_in_progress.empty()) {
+               finish_one_read<RGBAType>(width1, height1);
+       }
 }
 
 int main(int argc, char **argv)
@@ -1817,6 +2013,7 @@ int main(int argc, char **argv)
                { "intensity-relative-weight", required_argument, 0, 'i' },  // delta.
                { "gradient-relative-weight", required_argument, 0, 'g' },  // gamma.
                { "disable-timing", no_argument, 0, 1000 },
+               { "detailed-timing", no_argument, 0, 1003 },
                { "ignore-variational-refinement", no_argument, 0, 1001 },  // Still calculates it, just doesn't apply it.
                { "interpolate", no_argument, 0, 1002 }
        };
@@ -1847,6 +2044,9 @@ int main(int argc, char **argv)
                case 1002:
                        enable_interpolation = true;
                        break;
+               case 1003:
+                       detailed_timing = true;
+                       break;
                default:
                        fprintf(stderr, "Unknown option '%s'\n", argv[option_index]);
                        exit(1);
@@ -1874,6 +2074,8 @@ int main(int argc, char **argv)
        SDL_GLContext context = SDL_GL_CreateContext(window);
        assert(context != nullptr);
 
+       glDisable(GL_DITHER);
+
        // FIXME: Should be part of DISComputeFlow (but needs to be initialized
        // before all the render passes).
        float vertices[] = {