Load arbitrary images through SDL_image, instead of requiring raw grayscale ones.

diff --git a/Makefile b/Makefile
index 609128bf52ccc788d0fe31b1077bdfb0a4e8b143..02ba83358eac66296438c0c732cc59bfa108d744 100644 (file)
--- a/Makefile
+++ b/Makefile
@@ -32,7 +32,7 @@ mainwindow.o: ui_mainwindow.h
 futatabi: $(OBJS) $(CEF_LIBS)
        $(CXX) -o $@ $^ $(LDFLAGS) $(LDLIBS)
 flow: flow.o
-       $(CXX) -o $@ $^ -lepoxy -lSDL2
+       $(CXX) -o $@ $^ -lepoxy -lSDL2 -lSDL2_image
 eval: eval.o util.o
        $(CXX) -o $@ $^
 vis: vis.o util.o

diff --git a/flow.cpp b/flow.cpp
index 15161988eb77ddab0c9eaf070385763f40038584..79b191623f1b03f2512b1a4d428ba115ab9cc6eb 100644 (file)
--- a/flow.cpp
+++ b/flow.cpp
@@ -1,8 +1,5 @@
 #define NO_SDL_GLEXT 1
 
-#define WIDTH 1280
-#define HEIGHT 720
-
 #include <epoxy/gl.h>
 
 #include <SDL2/SDL.h>
@@ -115,26 +112,41 @@ GLuint compile_shader(const string &shader_src, GLenum type)
        return obj;
 }
 
-
-GLuint load_texture(const char *filename, unsigned width, unsigned height)
+GLuint load_texture(const char *filename, unsigned *width_ret, unsigned *height_ret)
 {
-       FILE *fp = fopen(filename, "rb");
-       if (fp == nullptr) {
-               perror(filename);
+       SDL_Surface *surf = IMG_Load(filename);
+       if (surf == nullptr) {
+               fprintf(stderr, "IMG_Load(%s): %s\n", filename, IMG_GetError());
                exit(1);
        }
-       unique_ptr<uint8_t[]> pix(new uint8_t[width * height]);
-       if (fread(pix.get(), width * height, 1, fp) != 1) {
-               fprintf(stderr, "Short read from %s\n", filename);
+
+       // For whatever reason, SDL doesn't support converting to YUV surfaces
+       // nor grayscale, so we'll do it (slowly) ourselves.
+       SDL_Surface *rgb_surf = SDL_ConvertSurfaceFormat(surf, SDL_PIXELFORMAT_RGBA8888, /*flags=*/0);
+       if (rgb_surf == nullptr) {
+               fprintf(stderr, "SDL_ConvertSurfaceFormat(%s): %s\n", filename, SDL_GetError());
                exit(1);
        }
-       fclose(fp);
 
-       // Convert to bottom-left origin.
-       for (unsigned y = 0; y < height / 2; ++y) {
+       SDL_FreeSurface(surf);
+
+       unsigned width = rgb_surf->w, height = rgb_surf->h;
+       const uint8_t *sptr = (uint8_t *)rgb_surf->pixels;
+       unique_ptr<uint8_t[]> pix(new uint8_t[width * height]);
+
+       // Extract the Y component, and convert to bottom-left origin.
+       for (unsigned y = 0; y < height; ++y) {
                unsigned y2 = height - 1 - y;
-               swap_ranges(&pix[y * width], &pix[y * width + width], &pix[y2 * width]);
+               for (unsigned x = 0; x < width; ++x) {
+                       uint8_t r = sptr[(y2 * width + x) * 4 + 3];
+                       uint8_t g = sptr[(y2 * width + x) * 4 + 2];
+                       uint8_t b = sptr[(y2 * width + x) * 4 + 1];
+
+                       // Rec. 709.
+                       pix[y * width + x] = lrintf(r * 0.2126f + g * 0.7152f + b * 0.0722f);
+               }
        }
+       SDL_FreeSurface(rgb_surf);
 
        int levels = 1;
        for (int w = width, h = height; w > 1 || h > 1; ) {
@@ -149,6 +161,9 @@ GLuint load_texture(const char *filename, unsigned width, unsigned height)
        glTextureSubImage2D(tex, 0, 0, 0, width, height, GL_RED, GL_UNSIGNED_BYTE, pix.get());
        glGenerateTextureMipmap(tex);
 
+       *width_ret = width;
+       *height_ret = height;
+
        return tex;
 }
 
@@ -907,8 +922,15 @@ int main(void)
        assert(context != nullptr);
 
        // Load pictures.
-       GLuint tex0 = load_texture("test1499.pgm", WIDTH, HEIGHT);
-       GLuint tex1 = load_texture("test1500.pgm", WIDTH, HEIGHT);
+       unsigned width1, height1, width2, height2;
+       GLuint tex0 = load_texture("test1499.png", &width1, &height1);
+       GLuint tex1 = load_texture("test1500.png", &width2, &height2);
+
+       if (width1 != width2 || height1 != height2) {
+               fprintf(stderr, "Image dimensions don't match (%dx%d versus %dx%d)\n",
+                       width1, height1, width2, height2);
+               exit(1);
+       }
 
        // Make some samplers.
        glCreateSamplers(1, &nearest_sampler);
@@ -973,8 +995,8 @@ int main(void)
                snprintf(timer_name, sizeof(timer_name), "Level %d", level);
                ScopedTimer level_timer(timer_name, &total_timer);
 
-               int level_width = WIDTH >> level;
-               int level_height = HEIGHT >> level;
+               int level_width = width1 >> level;
+               int level_height = height1 >> level;
                float patch_spacing_pixels = patch_size_pixels * (1.0f - patch_overlap_ratio);
                int width_patches = 1 + lrintf((level_width - patch_size_pixels) / patch_spacing_pixels);
                int height_patches = 1 + lrintf((level_height - patch_size_pixels) / patch_spacing_pixels);
@@ -1125,8 +1147,8 @@ int main(void)
 
        timers.print();
 
-       int level_width = WIDTH >> finest_level;
-       int level_height = HEIGHT >> finest_level;
+       int level_width = width1 >> finest_level;
+       int level_height = height1 >> finest_level;
        unique_ptr<float[]> dense_flow(new float[level_width * level_height * 2]);
        glGetTextureImage(prev_level_flow_tex, 0, GL_RG, GL_FLOAT, level_width * level_height * 2 * sizeof(float), dense_flow.get());