如何为简单的顶点对象添加透明度？

问题描述

如何为 Direct3D 中的简单顶点对象添加透明度？

我使用了这里的信息但没有结果： https://docs.microsoft.com/ru-ru/windows/win32/direct3d9/vertex-alpha

我这样初始化设备：

PresentParameters presentParams = new PresentParameters();
presentParams.SwapEffect = SwapEffect.Discard;
presentParams.DeviceWindowHandle = this.Handle;
presentParams.BackBufferFormat = Format.A8R8G8B8;
presentParams.PresentFlags = PresentFlags.LockableBackBuffer;
presentParams.BackBufferWidth = this.ClientSize.Width;
presentParams.BackBufferHeight = this.ClientSize.Height;
presentParams.Windowed = true;

var device = new Device(_direct3d,DeviceType.Hardware,this.Handle,_createFlags,presentParams);device.SetRenderState(RenderState.Lighting,false);

// ..tried different variations of flags here with no result..
device.SetRenderState(RenderState.DiffuseMaterialSource,ColorSource.Color1);

var surface = device.GetBackBuffer(0,0);
device.Clear(ClearFlags.Target | ClearFlags.ZBuffer,Color.Black,1.0f,0);

顶点类声明：

[StructLayout(LayoutKind.Sequential)]
    public struct ColoredVertex : IEquatable<ColoredVertex>
    {
        public Vector3 Position { get; set; }
        public int Color { get; set; }

        public static VertexElement[] Format
        {
            get
            {
                return new VertexElement[] { 
                    new VertexElement(0,DeclarationType.Float3,DeclarationMethod.Default,DeclarationUsage.PositionTransformed,0),new VertexElement(0,12,DeclarationType.Color,DeclarationUsage.Color,VertexElement.VertexDeclarationEnd
                };
            }
        }

        public ColoredVertex(Vector3 position,int color)
            : this()
        {
            Position = position;
            Color = color;
        }

然后我画图元。 颜色包含第二个三角形的 alpha 值为 50，所以我希望三角形是透明的......但没有

_device.BeginScene();

var colorN1 = Color.FromArgb(255,100,100);

var triangleN1 = new ColoredVertex[] {
    new ColoredVertex(new Vector3(10f,10f,0.0f),colorN1.ToArgb()),new ColoredVertex(new Vector3(1000.0f,10.0f,new ColoredVertex(new Vector3(1000f,800f,};


using (var decl = new VertexDeclaration(_device,ColoredVertex.Format))
{
    _device.VertexFormat = VertexFormat.Diffuse; 
    _device.VertexDeclaration = decl;
    _device.DrawUserPrimitives<ColoredVertex>(PrimitiveType.TriangleList,1,triangleN1);
}

var colorN2 = Color.FromArgb(50,0);

var triangleN2 = new ColoredVertex[] {
    new ColoredVertex(new Vector3(100f,100f,1.0f),colorN2.ToArgb()),new ColoredVertex(new Vector3(800.0f,100.0f,new ColoredVertex(new Vector3(700f,900f,};

using (var decl = new VertexDeclaration(_device,ColoredVertex.Format))
{
    _device.VertexFormat = VertexFormat.Diffuse;
    _device.VertexDeclaration = decl;
    _device.DrawUserPrimitives<ColoredVertex>(PrimitiveType.TriangleList,triangleN2);
}


_device.EndScene();
_device.Present();

解决方法

这些 RenderState 标志发挥了作用：

_device.SetRenderState(RenderState.SourceBlend,Blend.SourceAlpha);
_device.SetRenderState(RenderState.DestinationBlend,Blend.InverseSourceAlpha);
_device.SetRenderState(RenderState.AlphaBlendEnable,true);