Hey all, i ve been working on this small project in XNA the goal is pretty basic i have a 3D model which pops up somewhere on the screen, the object is suppose to rotate on it s y axis,

The problem is: what happens instead is that the models rotate around themselves and also start to orbit the middle point between themselves and the 0,0,0 point in the screen, so it looks like the middle model is rotating normally while the other 2 act in the afore mentioned way (included img s of the rotating models below).

“某些”细节

我的架构就是这样,即有3个模型(这些模型吸收了狩猎、Position、Size @ ctor)。

private void initDradles()
    {
        m_Dradles[0] = new DradlePositionColor(this, new Vector3(15, 0, 0), 8);
        m_Dradles[1] = new DradlePositionColor(this, new Vector3(0, 0, 0), 8);
        m_Dradles[2] = new DradlePositionColor(this, new Vector3(-15, 0, 0), 8);
        this.Components.Add(m_Dradles[0]);
        this.Components.Add(m_Dradles[1]);
        this.Components.Add(m_Dradles[2]);
    }

这些模型首先以图1所示方式出现在屏幕上。

他们都拥有同样的基本影响,但有一个不同的世界矩阵。

模型的基本效果生成和分配

protected override void Initialize()
    {
        float k_NearPlaneDistance = 0.5f;
        float k_FarPlaneDistance = 1000.0f;
        float k_ViewAngle = MathHelper.PiOver4;

        // we are storing the field-of-view data in a matrix:
        m_ProjectionFieldOfView = Matrix.CreatePerspectiveFieldOfView(
            k_ViewAngle,
            GraphicsDevice.Viewport.AspectRatio,
            k_NearPlaneDistance,
            k_FarPlaneDistance);

        // we want to shoot the center of the world:
        Vector3 targetPosition = new Vector3(0, 0, 0);//Vector3.Zero;
        // we are standing 100 units in front of our target:
        Vector3 pointOfViewPosition = new Vector3(0, 0, 130);
        // we are not standing on our head:
        Vector3 pointOfViewUpDirection = new Vector3(0, 1, 0);

        // we are storing the point-of-view data in a matrix:
        m_PointOfView = Matrix.CreateLookAt(
            pointOfViewPosition, targetPosition, pointOfViewUpDirection);

        base.Initialize();
    }

    protected override void LoadContent()
    {
        // we are working with the out-of-the box shader that comes with XNA:
        m_BasicEffect = new BasicEffect(this.GraphicsDevice, null);
        m_BasicEffect.View = m_PointOfView;
        m_BasicEffect.Projection = m_ProjectionFieldOfView;
        m_BasicEffect.VertexColorEnabled = true;

        // we are working with colored vertices
        GraphicsDevice.VertexDeclaration = new VertexDeclaration(
            GraphicsDevice, VertexPositionColor.VertexElements);

        // we did not use certain clockwise ordering in our vertex buffer
        // and we don t want antthing to be culled away..
        this.GraphicsDevice.RenderState.CullMode = CullMode.None;

        foreach (var dradle in m_Dradles)
        {
            dradle.BasicEffect = m_BasicEffect;
        }

        base.LoadContent();
    }

在每种模式中,该守则采用更新方法:

private void BuildWorldMatrix()
    {
        m_WorldMatrix = Matrix.Identity;
        m_WorldMatrix *= Matrix.CreateScale(m_Scales);
        m_WorldMatrix *= Matrix.CreateRotationX(m_Rotations.X);
        m_WorldMatrix *= Matrix.CreateRotationY(m_Rotations.Y);
        m_WorldMatrix *= Matrix.CreateRotationZ(m_Rotations.Z);
        m_WorldMatrix *= Matrix.CreateTranslation(m_Position);
            ///*I*/ Matrix.Identity *
            ///*S*/ Matrix.CreateScale(m_Scales) *
            ///*R*/ Matrix.CreateRotationX(m_Rotations.X) *
            //        Matrix.CreateRotationY(m_Rotations.Y) *
            //        Matrix.CreateRotationZ(m_Rotations.Z) *
            ///* No Orbit */
            ///*T*/ Matrix.CreateTranslation(m_Position);
    }

    public override void Update(GameTime gameTime)
    {
        m_Rotations.Y += (float)gameTime.ElapsedGameTime.TotalSeconds;
        BuildWorldMatrix();

        base.Update(gameTime);
    }

以及这一代法

public override void Draw(GameTime gameTime)
    {
        m_BasicEffect.World = m_WorldMatrix;
        m_BasicEffect.Begin();
        foreach (EffectPass pass in m_BasicEffect.CurrentTechnique.Passes)
        {
            pass.Begin();
            Render();
            pass.End();
        }
        m_BasicEffect.End();

        base.Draw(gameTime);
    }

    public override void Render()
    {
        renderVerticesBox(m_BodyVertices);
        renderVerticesBox(m_HandleVertices);
        Game.GraphicsDevice.DrawUserPrimitives<VertexPositionColor>(
            PrimitiveType.TriangleFan, m_PyramidVertices, 0, 4);
    }

    private void renderVerticesBox(VertexPositionColor[] m_Vertices)
    {
        Game.GraphicsDevice.DrawUserPrimitives<VertexPositionColor>(
            PrimitiveType.TriangleStrip, m_Vertices, 0, 8);

        Game.GraphicsDevice.DrawUserPrimitives<VertexPositionColor>(
            PrimitiveType.TriangleStrip, m_Vertices, 10, 2);

        Game.GraphicsDevice.DrawUserPrimitives<VertexPositionColor>(
            PrimitiveType.TriangleStrip, m_Vertices, 14, 2);
    }

image when rotating alt text http://www.freeimagehosting.net/uploads/b0aa83d0d6.png

形象的开始

alt text http://www.freeimagehosting.net/uploads/ee9e5c379c.png