Question

image of the problem

我在这里使用了Microsoft的BasicEffect教程here和代码示例：go.microsoft.com/fwlink/?LinkId=198921并且一切正常。接下来我改变了所有东西以使用vertexPositionNormalTexture，添加了一些小方法来帮助纹理，并且能够很好地渲染纹理立方体。我也让立方体旋转了一下。接下来我想尝试使用vertexPositionNormalTexture。不幸的是，我得到的这个图像而不是立方体。这是我的一些代码，包含重大修改。

绘制方法

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

            RasterizerState rasterizerState1 = new RasterizerState();
            //backface culling
            rasterizerState1.CullMode = CullMode.None;
            //turn off texture blurring
            graphics.GraphicsDevice.SamplerStates[0] = SamplerState.PointClamp;


            graphics.GraphicsDevice.RasterizerState = rasterizerState1;
            foreach (EffectPass pass in basicEffect.CurrentTechnique.Passes)
            {
                pass.Apply();
                graphics.GraphicsDevice.DrawPrimitives(
                    PrimitiveType.TriangleList, 
                    0, 
                    12
                );
            } 

            base.Draw(gameTime);
        }

设置顶点的方法的一部分

private void InitializeCube()
    {

        Vector3 topLeftFront = new Vector3(-1.0f, 1.0f, 1.0f);
        Vector3 bottomLeftFront = new Vector3(-1.0f, -1.0f, 1.0f);
        Vector3 topRightFront = new Vector3(1.0f, 1.0f, 1.0f);
        Vector3 bottomRightFront = new Vector3(1.0f, -1.0f, 1.0f);
        Vector3 topLeftBack = new Vector3(-1.0f, 1.0f, -1.0f);
        Vector3 topRightBack = new Vector3(1.0f, 1.0f, -1.0f);
        Vector3 bottomLeftBack = new Vector3(-1.0f, -1.0f, -1.0f);
        Vector3 bottomRightBack = new Vector3(1.0f, -1.0f, -1.0f);

        Vector2 textureTopLeft = new Vector2(0.0f, 0.0f);
        Vector2 textureTopRight = new Vector2(.25f, 0.0f);
        Vector2 textureBottomLeft = new Vector2(0.0f, .25f);
        Vector2 textureBottomRight = new Vector2(.25f, .25f);

        Color frontColor = new Color(255, 255, 255);
        Color backColor = new Color(255, 0, 0);
        Color topColor = new Color(0, 255, 0);
        Color bottomColor = new Color(0, 0, 255);
        Color leftColor = new Color(0, 255, 255);
        Color rightColor = new Color(0, 0, 0);

        // Front face.
        cubeVertices[0] =
            new VertexPositionColorTexture(
            topLeftFront, frontColor, GetTexPos(2));
        cubeVertices[1] =
            new VertexPositionColorTexture(
            bottomLeftFront, frontColor, GetTexPos(2) + textureBottomLeft);
        cubeVertices[2] =
            new VertexPositionColorTexture(
            topRightFront, frontColor, GetTexPos(2) + textureTopRight);
        cubeVertices[3] =
            new VertexPositionColorTexture(
            bottomLeftFront, frontColor, GetTexPos(2) + textureBottomLeft);
        cubeVertices[4] =
            new VertexPositionColorTexture(
            bottomRightFront, frontColor, GetTexPos(2) + textureBottomRight);
        cubeVertices[5] =
            new VertexPositionColorTexture(
            topRightFront, frontColor, GetTexPos(2) + textureTopRight);

初始化basicEffect

private void InitializeEffect()
    {
        basicEffect = new BasicEffect(graphics.GraphicsDevice);


        basicEffect.World = worldMatrix;
        basicEffect.View = viewMatrix;
        basicEffect.Projection = projectionMatrix;

        //basicEffect.EnableDefaultLighting
    }

LoadContent

protected override void LoadContent()
    {
        canyonTexture = Content.Load<Texture2D>("CanyonTexture");
        textureSheetWidth = canyonTexture.Width / 16;
        InitializeTransform();
        InitializeEffect();
        basicEffect.TextureEnabled = true;
        basicEffect.VertexColorEnabled = true;
        basicEffect.Texture = canyonTexture;

        InitializeCube();

    }

设置VertexBuffer

private void CreateVertexBuffer()
    {
        vertexDeclaration = new VertexDeclaration(new VertexElement[]
            {
                new VertexElement(0, VertexElementFormat.Vector3, VertexElementUsage.Position, 0),
                new VertexElement(12, VertexElementFormat.Color, VertexElementUsage.Color, 0),
                new VertexElement(24, VertexElementFormat.Vector2, VertexElementUsage.TextureCoordinate, 0)
            });

        vertexBuffer = new VertexBuffer(
            graphics.GraphicsDevice,
            vertexDeclaration,
            number_of_vertices,
            BufferUsage.None
            );


        cubeVertices = new VertexPositionColorTexture[number_of_vertices];
        InitializeCube();


        vertexBuffer.SetData<VertexPositionColorTexture>(cubeVertices);

        graphics.GraphicsDevice.SetVertexBuffer(vertexBuffer);
    }


    protected override void Initialize()
    {
        // TODO: Add your initialization logic here
        CreateVertexBuffer();

        base.Initialize();
    }

Answer 1

基本上你的顶点声明是错误的。

Color只有四个字节宽。因此，随后的纹理坐标元素的偏移量应为16，而不是24。

但是，您甚至不需要在XNA 4.0中为此创建顶点声明。只需将VertexPositionColorTexture.VertexDeclaration或typeof(VertexPositionColorTexture)传递给VertexBuffer的构造函数。

有blog post here解释了这一切是如何运作的。

将VertexPositionColorTexture与BasicEffect一起使用时的三角形

1 个答案: