If statement HLSL'中的条件运算符；s通行证

据

HLSL支持条件运算符（从版本2.0开始？我使用的是4_0）

我需要在每次绘制调用之前设置混合状态。在FX文件中，我正在执行以下操作：

BlendState BlendNone
{
    AlphaToCoverageEnable = FALSE;
    BlendEnable[0] = FALSE;
};
BlendState BlendSrcAlphaOne
{
    BlendEnable[0] = TRUE;
    SrcBlend = SRC_ALPHA;
    DestBlend = INV_SRC_ALPHA;
    BlendOp = ADD;
    RenderTargetWriteMask[0] = 0x0F;
};
BlendState BlendSrcAlphaOneMinusSrcAlpha
{
    BlendEnable[0] = TRUE;
    SrcBlend = SRC_ALPHA;
    DestBlend = ONE;
    BlendOp = ADD;
    RenderTargetWriteMask[0] = 0x0F;
};
int g_Blend;

technique10 Render
{
    pass P0
    {
        SetVertexShader( CompileShader( vs_4_0, VS() ) );
        SetGeometryShader( CompileShader( gs_4_0, GS() ) );
        SetPixelShader( CompileShader( ps_4_0, PS() ) );

        SetRasterizerState(rsCullNone);
        SetDepthStencilState( EnableDepth, 0 );

        if (g_Blend == 0)
        {
            SetBlendState( BlendNone, float4( 0.0f, 0.0f, 0.0f, 0.0f ), 0xFFFFFFFF );
        }
        else if (g_Blend == 1)
        {
            SetBlendState( BlendSrcAlphaOne, float4( 0.0f, 0.0f, 0.0f, 0.0f ), 0xFFFFFFFF );
        }
        else if (g_Blend == 2)
        {
            SetBlendState( BlendSrcAlphaOneMinusSrcAlpha, float4( 0.0f, 0.0f, 0.0f, 0.0f ), 0xFFFFFFFF );
        }
    }
}

这不会编译时出错： 错误X3000:语法错误：意外标记“if”

如果我将整个块移动到一个单独的函数中，如：

void setBlend()
{
        if (g_Blend == 0)
        {
            SetBlendState( BlendNone, float4( 0.0f, 0.0f, 0.0f, 0.0f ), 0xFFFFFFFF );
        }
        else if (g_Blend == 1)
        {
            SetBlendState( BlendSrcAlphaOne, float4( 0.0f, 0.0f, 0.0f, 0.0f ), 0xFFFFFFFF );
        }
        else if (g_Blend == 2)
        {
            SetBlendState( BlendSrcAlphaOneMinusSrcAlpha, float4( 0.0f, 0.0f, 0.0f, 0.0f ), 0xFFFFFFFF );
        }
}

technique10 Render
{
    pass P0
    {
        SetVertexShader( CompileShader( vs_4_0, VS() ) );
        SetGeometryShader( CompileShader( gs_4_0, GS() ) );
        SetPixelShader( CompileShader( ps_4_0, PS() ) );

        SetRasterizerState(rsCullNone);
        SetDepthStencilState( EnableDepth, 0 );

        setBlend();
    }
}

它没有编译时出错： 错误X3000:此FX API在您的程序（SetBlendState）的此部分中不可用

---

那么，在经过多次尝试和阅读后，HLSL中是否支持if？

正常

这包括：

BlendState blendStates[3]
{
    {
        AlphaToCoverageEnable = FALSE;
        BlendEnable[0] = FALSE;
    },
    {
        BlendEnable[0] = TRUE;
        SrcBlend = SRC_ALPHA;
        DestBlend = INV_SRC_ALPHA;
        BlendOp = ADD;
        RenderTargetWriteMask[0] = 0x0F;
    },
    {
        BlendEnable[0] = TRUE;
        SrcBlend = SRC_ALPHA;
        DestBlend = ONE;
        BlendOp = ADD;
        RenderTargetWriteMask[0] = 0x0F;
    }
};
int g_Blend;

technique10 Render
{
    pass P0
    {
        SetVertexShader( CompileShader( vs_4_0, VS() ) );
        SetGeometryShader( CompileShader( gs_4_0, GS() ) );
        SetPixelShader( CompileShader( ps_4_0, PS() ) );

        SetRasterizerState(rsCullNone);
        SetDepthStencilState( EnableDepth, 0 );

        SetBlendState( blendStates[g_Blend], float4( 0.0f, 0.0f, 0.0f, 0.0f ), 0xFFFFFFFF );
    }
}

SetBlendState严格来说不是函数调用，并且不允许在过程{}中使用条件运算符。但是，它可以通过索引传递状态对象数组，而不仅仅是状态对象