source: GTP-Internal/trunk/App/Demos/Illum/Ocean/terrain.fx @ 1777

texture2D elevationTexture;
sampler2D elevationSampler = sampler_state
{
        texture = <elevationTexture>;
        MipFilter = Linear;
        MagFilter = Linear;
        MinFilter = Linear;
        AddressU = CLAMP;
        AddressV = CLAMP;
}; 

texture2D terrainTexture;
sampler2D terrainSampler = sampler_state
{
        texture = <terrainTexture>;
        MipFilter = Linear;
        MagFilter = Linear;
        MinFilter = Linear;
        AddressU = WRAP;
        AddressV = WRAP;
}; 

float3 eyeDirection;
float fp;
float bp;

struct vsTerrainInput
{
        float4  pos             : POSITION;
};

float getTerrainHeight(float3 pos)
{
        float2 d = sin(pos.xz / 100.0);
        for(int ni=0; ni<4; ni++)
                d = float2(d.x*d.x - d.y * d.y + 0.45, 2 * d.x * d.y + 0.3);
        return 1/(dot(d, d) + 1) * 20.1 - 10.0;
}

struct vsTerrainOutput
{
        float4 pos                      : POSITION;
        float3 normal           : NORMAL;
        float3 worldPos         : TEXCOORD0;
        float3 tangent          : TEXCOORD1;
        float3 binormal         : TEXCOORD2;
        float3 eyeRayDir        : TEXCOORD4;
        
        float2 bumpCoord        : TEXCOORD3;
};

vsTerrainOutput vsTerrain(vsTerrainInput input)
{
        vsTerrainOutput output = (vsTerrainOutput)0;
        output.bumpCoord.xy = input.pos.xz*0.006;
        
//      input.pos.y = tex2Dlod(elevationSampler, float4(input.pos.xz, 0, 1)) - 0.5;
        input.pos.y = cos(input.pos.x * 12.0) - 0.01;
        
        input.pos.xyz *= float3(1000.0, 10.0, 1000.0);
        
        output.worldPos = input.pos.xyz;

        float3 du = float3(1, 0, 0);
        float3 dv = float3(0, 0, 1);
        
        output.pos = mul(float4(input.pos.xyz, 1), viewProjMatrix);

        output.binormal = normalize(du) * 0.3;
        output.tangent  = normalize(dv) * 0.3;
        output.normal   = normalize(cross(dv,du));
        
        return output;
}

float4 psTerrain(vsTerrainOutput input) : COLOR0
{
/*      input.worldPos.y = 0;
        input.eyeRayDir = normalize(input.eyeRayDir);
        for(int r=0; r<15; r++)
                input.worldPos -= input.eyeRayDir * (getTerrainHeight(input.worldPos) - input.worldPos.y);

        input.worldPos.y = getTerrainHeight(input.worldPos);
        depth = (dot(input.worldPos - eyePosition, eyeDirection) - fp)/(bp-fp);*/
        
        half4 t0 = tex2D(terrainSampler, input.bumpCoord) * 2 - 1;
        half3 N = t0.xzy;
        
        half3x3 m;
        m[0] = input.tangent;
        m[2] = input.binormal;
        m[1] = input.normal;
        
        half3 normalWorld = mul(m, N);
        normalWorld = normalize(normalWorld);
        
        float3 viewDir = -normalize(eyePosition - input.worldPos);

        return float4(1, (input.worldPos.y + 5) / 20, 0, 1);
}

technique terrain
{
        pass P0
        {
                VertexShader = compile vs_3_0 vsTerrain();
                PixelShader = compile ps_3_0 psTerrain();
        }       
};