LodeNode Image Loading for Terrain

urho3d_image_lodenode.cpp

// Storage for our 16bit pixel.
union uimage_data
{
    uint16_t s;
    uint8_t b[2];
};

Image* LoadHeightmap(const String& heightmapFilePath)
{
    std::vector<unsigned char> pngData;
    std::vector<unsigned char> image;
    unsigned width = 0, height = 0;
    lodepng::State state;

    unsigned error = lodepng::load_file(pngData, heightmapFilePath.CString());
    if (!error) {
        error = lodepng::decode(image, width, height, pngData, LCT_GREY, 16);
    }

    if (error) {
        URHO3D_LOGERROR(String("Unable to load raw PNG file @ ") + heightmapFilePath);
        return nullptr;
    }

    // Map our data.
    Image* heightmap = new Image(context_);

    unsigned components = 2;
    unsigned dataLen = width * height * components;
    unsigned char* pixelData = new unsigned char[dataLen];
    heightmap->SetSize(width, height, components);
    
    // Check if our image is 16 bit or 8 bit
    if (state.info_png.color.bitdepth == 16) {
        unsigned imgDataIndex = 0;
        unsigned index = 0;
        unsigned sDataLen = static_cast<unsigned>(image.size() / 2);
        uimage_data* sData = new uimage_data[sDataLen];

        // Copy over the pixel data into our storage.
        for (index = 0; index < sDataLen; index += 2, imgDataIndex += 1) {
            sData[imgDataIndex].b[0] = image[index + 1];
            sData[imgDataIndex].b[1] = image[index];
        }

        // Update our pixel data for Urho3D.
        imgDataIndex = 0;
        for (index = 0; index < dataLen; index += components, imgDataIndex += 2) {
            pixelData[index] = sData[imgDataIndex].b[0];
            pixelData[index + 1] = sData[imgDataIndex].b[1];
        }

        delete [] sData;
    } else {
        std::copy(image.begin(), image.end(), pixelData);
    }

    heightmap->SetData(pixelData);
    return heightmap;
}