osg 用tif图像创建HeightFieldLayer

在 OpenSceneGraph (OSG) 中，可以使用 TIF 图像创建 HeightFieldLayer。以下是大致的步骤：

1. 加载 TIF 图像文件并获取其像素数据。

osg::ref_ptr<osg::Image> image = osgDB::readImageFile("heightmap.tif");
if (!image.valid())
{
    osg::notify(osg::FATAL) << "Failed to load image file!" << std::endl;
    return nullptr;
}

float* heightData = new float[image->s() * image->t()];
for (int i = 0; i < image->s(); ++i)
{
    for (int j = 0; j < image->t(); ++j)
    {
        heightData[i * image->t() + j] = image->getColor(i, j).r();
    }
}

2. 创建 HeightFieldLayer 对象并设置其高度数据。

osg::ref_ptr<osg::HeightField> heightField = new osg::HeightField();
heightField->allocate(image->s(), image->t());
heightField->setHeightList(heightData);

osg::ref_ptr<osg::HeightFieldLayer> heightFieldLayer = new osg::HeightFieldLayer();
heightFieldLayer->setHeightField(heightField.get());

3. 可以根据需要设置 HeightFieldLayer 的其他属性，例如纹理。

osg::ref_ptr<osg::Texture2D> texture = new osg::Texture2D();
texture->setImage(image.get());

osg::ref_ptr<osg::TextureLayer> textureLayer = new osg::TextureLayer();
textureLayer->setTexture(texture.get());

heightFieldLayer->setTextureLayer(textureLayer.get());

4. 将 HeightFieldLayer 添加到场景图中。

osg::ref_ptr<osg::Group> root = new osg::Group();
root->addChild(heightFieldLayer.get());