9 #include <SDL2/SDL_error.h>
10 #include <SDL2/SDL_events.h>
11 #include <SDL2/SDL_image.h>
12 #include <SDL2/SDL_keyboard.h>
13 #include <SDL2/SDL_mouse.h>
14 #include <SDL2/SDL_video.h>
25 #define BUFFER_OFFSET(i) ((char *)nullptr + (i))
29 // Operating point 3 (10 Hz on CPU, excluding preprocessing).
30 constexpr float patch_overlap_ratio = 0.75f;
31 constexpr unsigned coarsest_level = 5;
32 constexpr unsigned finest_level = 1;
33 constexpr unsigned patch_size_pixels = 12;
35 // Some global OpenGL objects.
36 GLuint nearest_sampler, linear_sampler;
39 string read_file(const string &filename)
41 FILE *fp = fopen(filename.c_str(), "r");
43 perror(filename.c_str());
47 int ret = fseek(fp, 0, SEEK_END);
49 perror("fseek(SEEK_END)");
55 ret = fseek(fp, 0, SEEK_SET);
57 perror("fseek(SEEK_SET)");
63 ret = fread(&str[0], size, 1, fp);
69 fprintf(stderr, "Short read when trying to read %d bytes from %s\n",
70 size, filename.c_str());
79 GLuint compile_shader(const string &shader_src, GLenum type)
81 GLuint obj = glCreateShader(type);
82 const GLchar* source[] = { shader_src.data() };
83 const GLint length[] = { (GLint)shader_src.size() };
84 glShaderSource(obj, 1, source, length);
87 GLchar info_log[4096];
88 GLsizei log_length = sizeof(info_log) - 1;
89 glGetShaderInfoLog(obj, log_length, &log_length, info_log);
90 info_log[log_length] = 0;
91 if (strlen(info_log) > 0) {
92 fprintf(stderr, "Shader compile log: %s\n", info_log);
96 glGetShaderiv(obj, GL_COMPILE_STATUS, &status);
97 if (status == GL_FALSE) {
98 // Add some line numbers to easier identify compile errors.
99 string src_with_lines = "/* 1 */ ";
101 for (char ch : shader_src) {
102 src_with_lines.push_back(ch);
105 snprintf(buf, sizeof(buf), "/* %3zu */ ", ++lineno);
106 src_with_lines += buf;
110 fprintf(stderr, "Failed to compile shader:\n%s\n", src_with_lines.c_str());
118 GLuint load_texture(const char *filename, unsigned width, unsigned height)
120 FILE *fp = fopen(filename, "rb");
125 unique_ptr<uint8_t[]> pix(new uint8_t[width * height]);
126 if (fread(pix.get(), width * height, 1, fp) != 1) {
127 fprintf(stderr, "Short read from %s\n", filename);
132 // Convert to bottom-left origin.
133 for (unsigned y = 0; y < height / 2; ++y) {
134 unsigned y2 = height - 1 - y;
135 swap_ranges(&pix[y * width], &pix[y * width + width], &pix[y2 * width]);
139 for (int w = width, h = height; w > 1 || h > 1; ) {
146 glCreateTextures(GL_TEXTURE_2D, 1, &tex);
147 glTextureStorage2D(tex, levels, GL_R8, width, height);
148 glTextureSubImage2D(tex, 0, 0, 0, width, height, GL_RED, GL_UNSIGNED_BYTE, pix.get());
149 glGenerateTextureMipmap(tex);
154 GLuint link_program(GLuint vs_obj, GLuint fs_obj)
156 GLuint program = glCreateProgram();
157 glAttachShader(program, vs_obj);
158 glAttachShader(program, fs_obj);
159 glLinkProgram(program);
161 glGetProgramiv(program, GL_LINK_STATUS, &success);
162 if (success == GL_FALSE) {
163 GLchar error_log[1024] = {0};
164 glGetProgramInfoLog(program, 1024, nullptr, error_log);
165 fprintf(stderr, "Error linking program: %s\n", error_log);
171 GLuint generate_vbo(GLint size, GLsizeiptr data_size, const GLvoid *data)
174 glCreateBuffers(1, &vbo);
175 glBufferData(GL_ARRAY_BUFFER, data_size, data, GL_STATIC_DRAW);
176 glNamedBufferData(vbo, data_size, data, GL_STATIC_DRAW);
180 GLuint fill_vertex_attribute(GLuint vao, GLuint glsl_program_num, const string &attribute_name, GLint size, GLenum type, GLsizeiptr data_size, const GLvoid *data)
182 int attrib = glGetAttribLocation(glsl_program_num, attribute_name.c_str());
187 GLuint vbo = generate_vbo(size, data_size, data);
189 glBindBuffer(GL_ARRAY_BUFFER, vbo);
190 glEnableVertexArrayAttrib(vao, attrib);
191 glVertexAttribPointer(attrib, size, type, GL_FALSE, 0, BUFFER_OFFSET(0));
192 glBindBuffer(GL_ARRAY_BUFFER, 0);
197 void bind_sampler(GLuint program, GLint location, GLuint texture_unit, GLuint tex, GLuint sampler)
199 if (location == -1) {
203 glBindTextureUnit(texture_unit, tex);
204 glBindSampler(texture_unit, sampler);
205 glProgramUniform1i(program, location, texture_unit);
208 // Compute gradients in every point, used for the motion search.
209 // The DIS paper doesn't actually mention how these are computed,
210 // but seemingly, a 3x3 Sobel operator is used here (at least in
211 // later versions of the code), while a [1 -8 0 8 -1] kernel is
212 // used for all the derivatives in the variational refinement part
213 // (which borrows code from DeepFlow). This is inconsistent,
214 // but I guess we're better off with staying with the original
215 // decisions until we actually know having different ones would be better.
219 void exec(GLint tex0_view, GLint grad0_tex, int level_width, int level_height);
224 GLuint sobel_program;
227 GLuint uniform_tex, uniform_image_size, uniform_inv_image_size;
232 sobel_vs_obj = compile_shader(read_file("vs.vert"), GL_VERTEX_SHADER);
233 sobel_fs_obj = compile_shader(read_file("sobel.frag"), GL_FRAGMENT_SHADER);
234 sobel_program = link_program(sobel_vs_obj, sobel_fs_obj);
236 // Set up the VAO containing all the required position/texcoord data.
237 glCreateVertexArrays(1, &sobel_vao);
238 glBindVertexArray(sobel_vao);
240 GLint position_attrib = glGetAttribLocation(sobel_program, "position");
241 glEnableVertexArrayAttrib(sobel_vao, position_attrib);
242 glVertexAttribPointer(position_attrib, 2, GL_FLOAT, GL_FALSE, 0, BUFFER_OFFSET(0));
244 uniform_tex = glGetUniformLocation(sobel_program, "tex");
245 uniform_inv_image_size = glGetUniformLocation(sobel_program, "inv_image_size");
248 void Sobel::exec(GLint tex0_view, GLint grad0_tex, int level_width, int level_height)
250 glUseProgram(sobel_program);
251 glBindTextureUnit(0, tex0_view);
252 glBindSampler(0, nearest_sampler);
253 glProgramUniform1i(sobel_program, uniform_tex, 0);
254 glProgramUniform2f(sobel_program, uniform_inv_image_size, 1.0f / level_width, 1.0f / level_height);
256 GLuint grad0_fbo; // TODO: cleanup
257 glCreateFramebuffers(1, &grad0_fbo);
258 glNamedFramebufferTexture(grad0_fbo, GL_COLOR_ATTACHMENT0, grad0_tex, 0);
260 glViewport(0, 0, level_width, level_height);
261 glBindFramebuffer(GL_FRAMEBUFFER, grad0_fbo);
262 glBindVertexArray(sobel_vao);
263 glUseProgram(sobel_program);
265 glDrawArrays(GL_TRIANGLE_STRIP, 0, 4);
268 // Motion search to find the initial flow. See motion_search.frag for documentation.
272 void exec(GLuint tex0_view, GLuint tex1_view, GLuint grad0_tex, GLuint flow_tex, GLuint flow_out_tex, int level_width, int level_height, int width_patches, int height_patches);
275 GLuint motion_vs_obj;
276 GLuint motion_fs_obj;
277 GLuint motion_search_program;
278 GLuint motion_search_vao;
280 GLuint uniform_image_size, uniform_inv_image_size;
281 GLuint uniform_image0_tex, uniform_image1_tex, uniform_grad0_tex, uniform_flow_tex;
284 MotionSearch::MotionSearch()
286 motion_vs_obj = compile_shader(read_file("motion_search.vert"), GL_VERTEX_SHADER);
287 motion_fs_obj = compile_shader(read_file("motion_search.frag"), GL_FRAGMENT_SHADER);
288 motion_search_program = link_program(motion_vs_obj, motion_fs_obj);
290 // Set up the VAO containing all the required position/texcoord data.
291 glCreateVertexArrays(1, &motion_search_vao);
292 glBindVertexArray(motion_search_vao);
293 glBindBuffer(GL_ARRAY_BUFFER, vertex_vbo);
295 GLint position_attrib = glGetAttribLocation(motion_search_program, "position");
296 glEnableVertexArrayAttrib(motion_search_vao, position_attrib);
297 glVertexAttribPointer(position_attrib, 2, GL_FLOAT, GL_FALSE, 0, BUFFER_OFFSET(0));
299 uniform_image_size = glGetUniformLocation(motion_search_program, "image_size");
300 uniform_inv_image_size = glGetUniformLocation(motion_search_program, "inv_image_size");
301 uniform_image0_tex = glGetUniformLocation(motion_search_program, "image0_tex");
302 uniform_image1_tex = glGetUniformLocation(motion_search_program, "image1_tex");
303 uniform_grad0_tex = glGetUniformLocation(motion_search_program, "grad0_tex");
304 uniform_flow_tex = glGetUniformLocation(motion_search_program, "flow_tex");
307 void MotionSearch::exec(GLuint tex0_view, GLuint tex1_view, GLuint grad0_tex, GLuint flow_tex, GLuint flow_out_tex, int level_width, int level_height, int width_patches, int height_patches)
309 glUseProgram(motion_search_program);
311 bind_sampler(motion_search_program, uniform_image0_tex, 0, tex0_view, nearest_sampler);
312 bind_sampler(motion_search_program, uniform_image1_tex, 1, tex1_view, linear_sampler);
313 bind_sampler(motion_search_program, uniform_grad0_tex, 2, grad0_tex, nearest_sampler);
314 bind_sampler(motion_search_program, uniform_flow_tex, 3, flow_tex, linear_sampler);
316 glProgramUniform2f(motion_search_program, uniform_image_size, level_width, level_height);
317 glProgramUniform2f(motion_search_program, uniform_inv_image_size, 1.0f / level_width, 1.0f / level_height);
319 GLuint flow_fbo; // TODO: cleanup
320 glCreateFramebuffers(1, &flow_fbo);
321 glNamedFramebufferTexture(flow_fbo, GL_COLOR_ATTACHMENT0, flow_out_tex, 0);
323 glViewport(0, 0, width_patches, height_patches);
324 glBindFramebuffer(GL_FRAMEBUFFER, flow_fbo);
325 glBindVertexArray(motion_search_vao);
326 glUseProgram(motion_search_program);
327 glDrawArrays(GL_TRIANGLE_STRIP, 0, 4);
330 // Do “densification”, ie., upsampling of the flow patches to the flow field
331 // (the same size as the image at this level). We draw one quad per patch
332 // over its entire covered area (using instancing in the vertex shader),
333 // and then weight the contributions in the pixel shader by post-warp difference.
334 // This is equation (3) in the paper.
336 // We accumulate the flow vectors in the R/G channels (for u/v) and the total
337 // weight in the B channel. Dividing R and G by B gives the normalized values.
341 void exec(GLuint tex0_view, GLuint tex1_view, GLuint flow_tex, GLuint dense_flow_tex, int level_width, int level_height, int width_patches, int height_patches);
344 GLuint densify_vs_obj;
345 GLuint densify_fs_obj;
346 GLuint densify_program;
349 GLuint uniform_width_patches, uniform_patch_size, uniform_patch_spacing;
350 GLuint uniform_image0_tex, uniform_image1_tex, uniform_flow_tex;
355 densify_vs_obj = compile_shader(read_file("densify.vert"), GL_VERTEX_SHADER);
356 densify_fs_obj = compile_shader(read_file("densify.frag"), GL_FRAGMENT_SHADER);
357 densify_program = link_program(densify_vs_obj, densify_fs_obj);
359 // Set up the VAO containing all the required position/texcoord data.
360 glCreateVertexArrays(1, &densify_vao);
361 glBindVertexArray(densify_vao);
362 glBindBuffer(GL_ARRAY_BUFFER, vertex_vbo);
364 GLint position_attrib = glGetAttribLocation(densify_program, "position");
365 glEnableVertexArrayAttrib(densify_vao, position_attrib);
366 glVertexAttribPointer(position_attrib, 2, GL_FLOAT, GL_FALSE, 0, BUFFER_OFFSET(0));
368 uniform_width_patches = glGetUniformLocation(densify_program, "width_patches");
369 uniform_patch_size = glGetUniformLocation(densify_program, "patch_size");
370 uniform_patch_spacing = glGetUniformLocation(densify_program, "patch_spacing");
371 uniform_image0_tex = glGetUniformLocation(densify_program, "image0_tex");
372 uniform_image1_tex = glGetUniformLocation(densify_program, "image1_tex");
373 uniform_flow_tex = glGetUniformLocation(densify_program, "flow_tex");
376 void Densify::exec(GLuint tex0_view, GLuint tex1_view, GLuint flow_tex, GLuint dense_flow_tex, int level_width, int level_height, int width_patches, int height_patches)
378 glUseProgram(densify_program);
380 bind_sampler(densify_program, uniform_image0_tex, 0, tex0_view, nearest_sampler);
381 bind_sampler(densify_program, uniform_image1_tex, 1, tex1_view, linear_sampler);
382 bind_sampler(densify_program, uniform_flow_tex, 2, flow_tex, nearest_sampler);
384 glProgramUniform1i(densify_program, uniform_width_patches, width_patches);
385 glProgramUniform2f(densify_program, uniform_patch_size,
386 float(patch_size_pixels) / level_width,
387 float(patch_size_pixels) / level_height);
389 float patch_spacing_x = float(level_width - patch_size_pixels) / (width_patches - 1);
390 float patch_spacing_y = float(level_height - patch_size_pixels) / (height_patches - 1);
391 glProgramUniform2f(densify_program, uniform_patch_spacing,
392 patch_spacing_x / level_width,
393 patch_spacing_y / level_height);
395 GLuint dense_flow_fbo; // TODO: cleanup
396 glCreateFramebuffers(1, &dense_flow_fbo);
397 glNamedFramebufferTexture(dense_flow_fbo, GL_COLOR_ATTACHMENT0, dense_flow_tex, 0);
399 glViewport(0, 0, level_width, level_height);
401 glBlendFunc(GL_ONE, GL_ONE);
402 glBindVertexArray(densify_vao);
403 glBindFramebuffer(GL_FRAMEBUFFER, dense_flow_fbo);
404 glDrawArraysInstanced(GL_TRIANGLE_STRIP, 0, 4, width_patches * height_patches);
407 // Warp I_1 to I_w, and then compute the mean (I) and difference (I_t) of
408 // I_0 and I_w. The prewarping is what enables us to solve the variational
409 // flow for du,dv instead of u,v.
411 // See variational_refinement.txt for more information.
415 void exec(GLuint tex0_view, GLuint tex1_view, GLuint flow_tex, GLuint I_tex, GLuint I_t_tex, int level_width, int level_height);
418 GLuint prewarp_vs_obj;
419 GLuint prewarp_fs_obj;
420 GLuint prewarp_program;
423 GLuint uniform_image0_tex, uniform_image1_tex, uniform_flow_tex;
428 prewarp_vs_obj = compile_shader(read_file("vs.vert"), GL_VERTEX_SHADER);
429 prewarp_fs_obj = compile_shader(read_file("prewarp.frag"), GL_FRAGMENT_SHADER);
430 prewarp_program = link_program(prewarp_vs_obj, prewarp_fs_obj);
432 // Set up the VAO containing all the required position/texcoord data.
433 glCreateVertexArrays(1, &prewarp_vao);
434 glBindVertexArray(prewarp_vao);
435 glBindBuffer(GL_ARRAY_BUFFER, vertex_vbo);
437 GLint position_attrib = glGetAttribLocation(prewarp_program, "position");
438 glEnableVertexArrayAttrib(prewarp_vao, position_attrib);
439 glVertexAttribPointer(position_attrib, 2, GL_FLOAT, GL_FALSE, 0, BUFFER_OFFSET(0));
441 uniform_image0_tex = glGetUniformLocation(prewarp_program, "image0_tex");
442 uniform_image1_tex = glGetUniformLocation(prewarp_program, "image1_tex");
443 uniform_flow_tex = glGetUniformLocation(prewarp_program, "flow_tex");
446 void Prewarp::exec(GLuint tex0_view, GLuint tex1_view, GLuint flow_tex, GLuint I_tex, GLuint I_t_tex, int level_width, int level_height)
448 glUseProgram(prewarp_program);
450 bind_sampler(prewarp_program, uniform_image0_tex, 0, tex0_view, nearest_sampler);
451 bind_sampler(prewarp_program, uniform_image1_tex, 1, tex1_view, linear_sampler);
452 bind_sampler(prewarp_program, uniform_flow_tex, 2, flow_tex, nearest_sampler);
454 GLuint prewarp_fbo; // TODO: cleanup
455 glCreateFramebuffers(1, &prewarp_fbo);
456 GLenum bufs[] = { GL_COLOR_ATTACHMENT0, GL_COLOR_ATTACHMENT1 };
457 glNamedFramebufferDrawBuffers(prewarp_fbo, 2, bufs);
458 glNamedFramebufferTexture(prewarp_fbo, GL_COLOR_ATTACHMENT0, I_tex, 0);
459 glNamedFramebufferTexture(prewarp_fbo, GL_COLOR_ATTACHMENT1, I_t_tex, 0);
461 glViewport(0, 0, level_width, level_height);
463 glBindVertexArray(prewarp_vao);
464 glBindFramebuffer(GL_FRAMEBUFFER, prewarp_fbo);
465 glDrawArrays(GL_TRIANGLE_STRIP, 0, 4);
470 if (SDL_Init(SDL_INIT_EVERYTHING) == -1) {
471 fprintf(stderr, "SDL_Init failed: %s\n", SDL_GetError());
474 SDL_GL_SetAttribute(SDL_GL_ALPHA_SIZE, 8);
475 SDL_GL_SetAttribute(SDL_GL_DEPTH_SIZE, 0);
476 SDL_GL_SetAttribute(SDL_GL_STENCIL_SIZE, 0);
477 SDL_GL_SetAttribute(SDL_GL_DOUBLEBUFFER, 1);
479 SDL_GL_SetAttribute(SDL_GL_CONTEXT_PROFILE_MASK, SDL_GL_CONTEXT_PROFILE_CORE);
480 SDL_GL_SetAttribute(SDL_GL_CONTEXT_MAJOR_VERSION, 4);
481 SDL_GL_SetAttribute(SDL_GL_CONTEXT_MINOR_VERSION, 5);
482 // SDL_GL_SetAttribute(SDL_GL_CONTEXT_FLAGS, SDL_GL_CONTEXT_DEBUG_FLAG);
483 SDL_Window *window = SDL_CreateWindow("OpenGL window",
484 SDL_WINDOWPOS_UNDEFINED,
485 SDL_WINDOWPOS_UNDEFINED,
488 SDL_GLContext context = SDL_GL_CreateContext(window);
489 assert(context != nullptr);
492 GLuint tex0 = load_texture("test1499.pgm", WIDTH, HEIGHT);
493 GLuint tex1 = load_texture("test1500.pgm", WIDTH, HEIGHT);
495 // Make some samplers.
496 glCreateSamplers(1, &nearest_sampler);
497 glSamplerParameteri(nearest_sampler, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
498 glSamplerParameteri(nearest_sampler, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
499 glSamplerParameteri(nearest_sampler, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
500 glSamplerParameteri(nearest_sampler, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
502 glCreateSamplers(1, &linear_sampler);
503 glSamplerParameteri(linear_sampler, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
504 glSamplerParameteri(linear_sampler, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
505 glSamplerParameteri(linear_sampler, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
506 glSamplerParameteri(linear_sampler, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
514 glCreateBuffers(1, &vertex_vbo);
515 glNamedBufferData(vertex_vbo, sizeof(vertices), vertices, GL_STATIC_DRAW);
516 glBindBuffer(GL_ARRAY_BUFFER, vertex_vbo);
518 // Initial flow is zero, 1x1.
519 GLuint initial_flow_tex;
520 glCreateTextures(GL_TEXTURE_2D, 1, &initial_flow_tex);
521 glTextureStorage2D(initial_flow_tex, 1, GL_RGB32F, 1, 1);
523 GLuint prev_level_flow_tex = initial_flow_tex;
526 MotionSearch motion_search;
531 glGenQueries(1, &query);
532 glBeginQuery(GL_TIME_ELAPSED, query);
534 for (int level = coarsest_level; level >= int(finest_level); --level) {
535 int level_width = WIDTH >> level;
536 int level_height = HEIGHT >> level;
537 float patch_spacing_pixels = patch_size_pixels * (1.0f - patch_overlap_ratio);
538 int width_patches = 1 + lrintf((level_width - patch_size_pixels) / patch_spacing_pixels);
539 int height_patches = 1 + lrintf((level_height - patch_size_pixels) / patch_spacing_pixels);
541 // Make sure we always read from the correct level; the chosen
542 // mipmapping could otherwise be rather unpredictable, especially
543 // during motion search.
544 // TODO: create these beforehand, and stop leaking them.
545 GLuint tex0_view, tex1_view;
546 glGenTextures(1, &tex0_view);
547 glTextureView(tex0_view, GL_TEXTURE_2D, tex0, GL_R8, level, 1, 0, 1);
548 glGenTextures(1, &tex1_view);
549 glTextureView(tex1_view, GL_TEXTURE_2D, tex1, GL_R8, level, 1, 0, 1);
551 // Create a new texture; we could be fancy and render use a multi-level
554 glCreateTextures(GL_TEXTURE_2D, 1, &grad0_tex);
555 glTextureStorage2D(grad0_tex, 1, GL_RG16F, level_width, level_height);
557 // Find the derivative.
558 sobel.exec(tex0_view, grad0_tex, level_width, level_height);
560 // Motion search to find the initial flow. We use the flow from the previous
561 // level (sampled bilinearly; no fancy tricks) as a guide, then search from there.
563 // Create an output flow texture.
565 glCreateTextures(GL_TEXTURE_2D, 1, &flow_out_tex);
566 glTextureStorage2D(flow_out_tex, 1, GL_RGB16F, width_patches, height_patches);
569 motion_search.exec(tex0_view, tex1_view, grad0_tex, prev_level_flow_tex, flow_out_tex, level_width, level_height, width_patches, height_patches);
573 // Set up an output texture (initially zero).
574 GLuint dense_flow_tex;
575 glCreateTextures(GL_TEXTURE_2D, 1, &dense_flow_tex);
576 glTextureStorage2D(dense_flow_tex, 1, GL_RGB16F, level_width, level_height);
579 densify.exec(tex0_view, tex1_view, flow_out_tex, dense_flow_tex, level_width, level_height, width_patches, height_patches);
581 // Everything below here in the loop belongs to variational refinement.
582 // It is not done yet.
584 // Prewarping; create I and I_t.
585 GLuint I_tex, I_t_tex;
586 glCreateTextures(GL_TEXTURE_2D, 1, &I_tex);
587 glCreateTextures(GL_TEXTURE_2D, 1, &I_t_tex);
588 glTextureStorage2D(I_tex, 1, GL_R16F, level_width, level_height);
589 glTextureStorage2D(I_t_tex, 1, GL_R16F, level_width, level_height);
590 prewarp.exec(tex0_view, tex1_view, dense_flow_tex, I_tex, I_t_tex, level_width, level_height);
592 prev_level_flow_tex = dense_flow_tex;
594 glEndQuery(GL_TIME_ELAPSED);
598 glGetQueryObjectiv(query, GL_QUERY_RESULT_AVAILABLE, &available);
600 } while (!available);
601 GLuint64 time_elapsed;
602 glGetQueryObjectui64v(query, GL_QUERY_RESULT, &time_elapsed);
603 fprintf(stderr, "GPU time used = %.1f ms\n", time_elapsed / 1e6);
605 int level_width = WIDTH >> finest_level;
606 int level_height = HEIGHT >> finest_level;
607 unique_ptr<float[]> dense_flow(new float[level_width * level_height * 3]);
608 glGetTextureImage(prev_level_flow_tex, 0, GL_RGB, GL_FLOAT, level_width * level_height * 3 * sizeof(float), dense_flow.get());
610 FILE *fp = fopen("flow.ppm", "wb");
611 FILE *flowfp = fopen("flow.flo", "wb");
612 fprintf(fp, "P6\n%d %d\n255\n", level_width, level_height);
613 fprintf(flowfp, "FEIH");
614 fwrite(&level_width, 4, 1, flowfp);
615 fwrite(&level_height, 4, 1, flowfp);
616 for (unsigned y = 0; y < unsigned(level_height); ++y) {
617 int yy = level_height - y - 1;
618 for (unsigned x = 0; x < unsigned(level_width); ++x) {
619 float du = dense_flow[(yy * level_width + x) * 3 + 0];
620 float dv = dense_flow[(yy * level_width + x) * 3 + 1];
621 float w = dense_flow[(yy * level_width + x) * 3 + 2];
623 du = (du / w) * level_width;
624 dv = (-dv / w) * level_height;
626 fwrite(&du, 4, 1, flowfp);
627 fwrite(&dv, 4, 1, flowfp);
630 flow2rgb(du, dv, &r, &g, &b);
639 fprintf(stderr, "err = %d\n", glGetError());