水波纹特效

      具体算法见 http://www.cnblogs.com/worldreason/archive/2008/05/09/1189648.html

下面直接上代码：

HLSL：

sampler2D Background : register(s0); //水波背景图片

float dx; //水波网格每个格子的大小 =1/(water.Width-1)
float dy; // =1/(water.Height-1)

texture Height; //水波网格的高度数据
sampler HeightSampler = sampler_state
{
    Texture = (Height);
    MipFilter = LINEAR;
    MinFilter = LINEAR;
    MagFilter = LINEAR;
};

float4 PS(float2 uv : TEXCOORD0) : COLOR0
{
    float xoff = tex2D(HeightSampler, float2(saturate(uv.x + dx), uv.y)).x - tex2D(HeightSampler, float2(saturate(uv.x - dx), uv.y)).x;
    float yoff = tex2D(HeightSampler, float2(uv.x, saturate(uv.y + dy))).x - tex2D(HeightSampler, float2(uv.x, saturate(uv.y - dy))).x;
    uv.x = saturate(uv.x + xoff / 20);
    uv.y = saturate(uv.y + yoff / 20);
    float4 color = tex2D(Background, uv);
    color.rgb += (xoff + yoff) / 2;
    return color;
}

technique simple
{
    pass Water
    {
        PixelShader = compile ps_2_0 PS();
    }
}

如果在WPF里使用，对应的HLSL需要做下修改：

float dx : register(C0);
float dy : register(C1);

sampler2D Background : register(S0);
sampler2D Height : register(S1);

float4 main(float2 uv : TEXCOORD) : COLOR
{
    float xoff = tex2D(HeightSampler, float2(saturate(uv.x + dx), uv.y)).x - tex2D(HeightSampler, float2(saturate(uv.x - dx), uv.y)).x;
    float yoff = tex2D(HeightSampler, float2(uv.x, saturate(uv.y + dy))).x - tex2D(HeightSampler, float2(uv.x, saturate(uv.y - dy))).x;
    uv.x = saturate(uv.x + xoff / 20);
    uv.y = saturate(uv.y + yoff / 20);
    float4 color = tex2D(BackgroundSampler, uv);
    color.rgb += (xoff + yoff) / 2;
    return color;
}

源代码下载  包含C++ & Win32、WinForm & SlimDX、WPF三个版本