source: GTP-Internal/trunk/App/Demos/Illum/Ocean/waves.h @ 1777

#ifndef WAVE_FX
        #define float2 D3DXVECTOR2
        #define float3 D3DXVECTOR3
#endif

struct Wave
{
        float           wavelength;
        float           amplitude;
        float2          direction;
        float           deformation;
};

#define NWAVES 4
Wave wave[NWAVES] = { {1.0f, 1.1f, float2(0.98,0.17), 1.3f },
                                                {1.5f, 2.1f, float2(0.98,-0.17), 1.3f },
                                                {2.5f, 1.1f, float2(0.934,0.342), 1.2f },
                                                {3.5f, 2.1f, float2(0.934,-0.342), 1.0f }
 };

//return the position difference 
float3 evaluateWave(Wave w, float phase)
{

        float2 offset;
        #ifdef WAVE_FX
                sincos(phase, offset.x, offset.y);
        #else
                offset.x = sin(phase);
                offset.y = cos(phase);
        #endif
        float2 tempPos = float2(0,0);
        #ifdef WAVE_FX
                tempPos.xy +=  offset * w.amplitude * float2(-1, 1);
        #else
                tempPos.x -=  offset.x * w.amplitude;
                tempPos.y +=  offset.y * w.amplitude;
        #endif
        tempPos.x -= tempPos.y * w.deformation;

        return float3(w.direction.x * tempPos.x, tempPos.y, w.direction.y * tempPos.x);
}

float3 evaluateWaveDerivative(Wave w, float phase)
{
        float2 offset;
        #ifdef WAVE_FX
                sincos(phase, offset.x, offset.y);
        #else
                offset.x = sin(phase);
                offset.y = cos(phase);
        #endif
        
        float dxdp = - offset.y * w.amplitude * w.direction.x;
        float dydp = - offset.x * w.amplitude;
        float dzdp = - offset.y * w.amplitude * w.direction.y;
        
        return float3(dxdp - dydp * w.deformation, dydp, dzdp);
}

#ifndef WAVE_FX
        #undef float2
        #undef float3
#endif