/* -*- mode: c++; c-basic-offset: 4; indent-tabs-mode: nil -*- */

float4 main(float3 pos : TEXCOORD0,
            uniform sampler3D vfield) : COLOR
{
    float3 velocity = tex3D(vfield, pos).yzw * 2 - float3(1, 1, 1);
    return float4(velocity, 1);
}