Add textractor executable to dump model textures to file

CMakeLists.txt

@@ -89,3 +89,13 @@ add_custom_command(
     $<TARGET_FILE_DIR:tests>/Duck.glb
     COMMENT "Copying $<TARGET_FILE_DIR:tests>/Duck.glb"
 )
+
+add_executable(textractor src/textractor/main.cpp)
+target_link_libraries(textractor PRIVATE common glm::glm)
+add_custom_command(
+    TARGET textractor POST_BUILD
+    COMMAND ${CMAKE_COMMAND} -E copy
+    ${CMAKE_SOURCE_DIR}/assets/Duck.glb
+    $<TARGET_FILE_DIR:textractor>/Duck.glb
+    COMMENT "Copying $<TARGET_FILE_DIR:textractor>/Duck.glb"
+)

src/textractor/main.cpp

@@ -0,0 +1,42 @@
+#include <common/gltf_model.hpp>
+#include <common/texture.hpp>
+
+#include <cassert>
+#include <fstream>
+
+int main()
+{
+    const pt::GltfModel model("Duck.glb");
+
+    const auto baseColorTextures = model.baseColorTextures();
+    for (std::size_t i = 0; i < baseColorTextures.size(); ++i)
+    {
+        const pt::Texture& texture = baseColorTextures[i];
+        const auto         dimensions = texture.dimensions();
+        const auto         pixels = texture.pixels();
+
+        const std::string filename = "base_color_texture_" + std::to_string(i) + ".ppm";
+        std::ofstream     file(filename, std::ios::out | std::ios::binary);
+        assert(file.is_open());
+        // Outputs binary PPM image format, https://netpbm.sourceforge.net/doc/ppm.html
+        file << "P6\n";
+        file << dimensions.width << ' ' << dimensions.height << '\n';
+        file << "255\n";
+        for (std::uint32_t i = 0; i < dimensions.height; ++i)
+        {
+            for (std::uint32_t j = 0; j < dimensions.width; ++j)
+            {
+                const std::size_t idx = i * dimensions.width + j;
+                const auto        pixel = pixels[idx];
+
+                const auto r = static_cast<std::uint8_t>(pixel.r * 255.0f);
+                const auto g = static_cast<std::uint8_t>(pixel.g * 255.0f);
+                const auto b = static_cast<std::uint8_t>(pixel.b * 255.0f);
+
+                file << r << g << b;
+            }
+        }
+    }
+
+    return 0;
+}