绕自身轴旋转的3D基本图形

Question

绕自身轴旋转的3D基本图形

c#matrix3dxnatransformation

3

几天前，我一直在使用XNA开发某个项目。该应用程序的主要思路是创建一个平面着色瓷砖网格，每个瓷砖都可以单独翻转。我遇到的问题是无法确定如何围绕各自中心轴旋转瓷砖。

现在发生的情况是瓷砖围绕世界坐标系旋转，而不是围绕自身旋转。

每个瓷砖由一组顶点组成，在三维世界中创建了一个二维正方形。

我相信问题与我搞错了矩阵有关。

以下是每个单独瓷砖的代码：

public Tile(Vector3 position, int size, Matrix world)
    {
        this.position = position;
        this.size = size;
        this.world = world;

        vertices = new VertexPositionColor[6];

        for (int i = 0; i < vertices.Length; i++)
            vertices[i].Position = position;

        vertices[0].Position += new Vector3(0, 0, 0);
        vertices[0].Color = Color.Pink;
        vertices[1].Position += new Vector3(0, size, 0);
        vertices[1].Color = Color.Yellow;
        vertices[2].Position += new Vector3(0, size, size);
        vertices[2].Color = Color.Green;

        vertices[3].Position += new Vector3(0, size, size);
        vertices[3].Color = Color.Green;
        vertices[4].Position += new Vector3(0, 0f, size);
        vertices[4].Color = Color.Blue;
        vertices[5].Position += new Vector3(0, 0, 0);
        vertices[5].Color = Color.Blue;
    }

    public VertexPositionColor[] Vertices
    {
        get{ return Functions.TransformVertices((VertexPositionColor[])vertices.Clone(), GetMatrix()); }
    }

    private Matrix GetMatrix()
    {
        return Matrix.CreateRotationZ(rot);
    }


    private void TransformVertices(Matrix matrix)
    {
        for (int i = 0; i < vertices.Length; i++)
            vertices[i].Position = Vector3.Transform(vertices[i].Position, matrix);
    }

这里是绘制方法：

protected override void Draw( GameTime gameTime)
    {
        GraphicsDevice.Clear(Color.CornflowerBlue);

        RasterizerState rasterizerState = new RasterizerState();
        rasterizerState.CullMode = CullMode.None;
        GraphicsDevice.RasterizerState = rasterizerState;
        viewMatrix = Matrix.CreateLookAt(cameraPos, new Vector3(0, 0, 0), Vector3.Up);

        effect.CurrentTechnique = effect.Techniques["ColoredNoShading"];
        effect.Parameters["xView"].SetValue(viewMatrix);
        effect.Parameters["xProjection"].SetValue(projectionMatrix);

        Vector3 rotAxis = new Vector3(0, 0, 1);
        rotAxis.Normalize();
        worldMatrix = Matrix.Identity;
        effect.Parameters["xWorld"].SetValue(worldMatrix);

        foreach (EffectPass pass in effect.CurrentTechnique.Passes)
        {
            pass.Apply();

            foreach(Tile tile in tiles)
                GraphicsDevice.DrawUserPrimitives(PrimitiveType.TriangleList, tile.Vertices, 0, 2, VertexPositionColor.VertexDeclaration);
        }

        base.Draw(gameTime);
    }

如果有帮助的话，我可以将整个源代码发送给你。任何帮助都是无价之宝！

- Pijm0

1个回答

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- Paddyd · Accepted Answer

要围绕自身轴旋转 Tile：

(1) Transform the tile back to the origin.
(2) Perform rotation.
(3) Transform back to original position.