Question

是否可以找到汽车中心的位置？我必须手动将车轮移动到汽车的中心，旋转并将其平移。

tireMatrix = Matrix.CreateTranslation(2.6f, -4.5f, 1.75f) *
                             Matrix.CreateRotationX(pitch) *
                             Matrix.CreateRotationZ(roll) *
                             Matrix.CreateTranslation(-2.7f, -4.7f, -1.75f);

手动移动确实有效，但我无法找到汽车的确切中心，必须有更好的方法。所有汽车零件都在同一个FBX文件中

Answer 1

我认为它有效，但我没有测试它。

matrix.X = box.Min.X+(box.Max.X-box.Min.X)/2;
matrix.Y = box.Min.Y+(box.Max.Y-box.Min.Y)/2;
matrix.Z = box.Min.Z+(box.Max.Z-box.Min.Z)/2;

要创建BoundingBox box，您可以使用this

Answer 2

没关系弄明白。我不得不使用ModelBone将车轮存储为汽车的骨头，存储车轮的初始变换，我可以在车轮上进行旋转而无需将它们转换到任何地方。对于将来的参考或者如果其他人可能想要做类似的事情，这里是代码

    Model carModel;
        Matrix carWorldMatrix;

        ModelBone fr_wheel;
        ModelBone fl_wheel;
        ModelBone bl_wheel;
        ModelBone br_wheel;
        //Matrices for storing the initial transform of each wheel 
        Matrix fr_transform;
        Matrix fl_transform;
        Matrix br_transform;
        Matrix bl_transform;

        Matrix[] transforms;

        float wheelRotation;
        float wheelSteerAngle;
        float carRotation;

public void Load(ContentManager content)
{
      carModel = content.Load<Model>("car");

      fr_wheel = carModel.Bones["fr_tire"];
      fl_wheel = carModel.Bones["fl_tire"];
      bl_wheel = carModel.Bones["bl_tire"];
      br_wheel = carModel.Bones["br_tire"];

      fr_transform = fr_wheel.Transform;
      fl_transform = fl_wheel.Transform;
      br_transform = br_wheel.Transform;
      bl_transform = bl_wheel.Transform;

      transforms = new Matrix[carModel.Bones.Count];
}

public void Update(GameTime gameTime)
{
     carModel.Root.Transform = carWorldMatrix;

     Matrix tireRotation = Matrix.CreateRotationX(wheelRotation) *
                           Matrix.CreateRotationY(wheelSteerAngle);

     fr_wheel.Transform = tireRotation * fr_transform;//this will apply the rotation to the     front right wheel

}

public void Draw(ref Camera camera)
{
     carModel.CopyAbsoluteBoneTransformsTo(transforms);

     foreach (ModelMesh mesh in carModel.Meshes)
     {
         foreach (BasicEffect effect in mesh.Effects)
         {
             effect.EnableDefaultLighting();
             effect.World = transforms[mesh.ParentBone.Index];
             effect.View = camera.viewMatrix;
             effect.Projection = camera.projectionMatrix;
         }
         mesh.Draw()
     }
}

如何找到网格的中心？

2 个答案: