如何为简单的顶点对象添加透明度？

Posted 2023-03-30

【中文标题】如何为简单的顶点对象添加透明度？

【英文标题】：How I can add transparency to simple vertex objects?

【发布时间】：2021-02-24 11:32:50

【问题描述】：

如何在 Direct3D 中为简单的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, 0, 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(0,0,DeclarationType.Float3,DeclarationMethod.Default,DeclarationUsage.PositionTransformed,0),
                    new VertexElement(0,12,DeclarationType.Color,DeclarationMethod.Default,DeclarationUsage.Color,0),
                    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 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, 100);

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


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, 100, 0, 0);

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

using (var decl = new VertexDeclaration(_device, ColoredVertex.Format))

    _device.VertexFormat = VertexFormat.Diffuse;
    _device.VertexDeclaration = decl;
    _device.DrawUserPrimitives<ColoredVertex>(PrimitiveType.TriangleList, 1, triangleN2);



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

【问题讨论】：

您使用的是旧版托管 DX 1.1 程序集吗？如果是这样，你应该转移到别的地方。见this blog post。

我使用 SlimDX。没有那么传统）

【参考方案1】：

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);