source: GTP/trunk/App/Demos/Vis/FriendlyCulling/src/shaders/common.h @ 3232

/************************************/
/*     Common shader functions      */
/************************************/

/** Interpolate bilinearly between 2 vectors
*/
inline float3 Interpol(float2 w, float3 bl, float3 br, float3 tl, float3 tr)
{
        float3 x1 = lerp(bl, tl, w.y);
        float3 x2 = lerp(br, tr, w.y); 
        float3 v = lerp(x1, x2, w.x); 

        return v;
}


/** reconstruct world space position
*/
inline float3 ReconstructSamplePos(uniform sampler2D tex,
                                                                   float2 texcoord, 
                                                                   float3 bl, float3 br, float3 tl, float3 tr)
{
        const float eyeSpaceDepth = tex2Dlod(tex, float4(texcoord, 0, 0)).w;
        
        float3 viewVec = Interpol(texcoord, bl, br, tl, tr);
        float3 samplePos = -viewVec * eyeSpaceDepth;

        return samplePos;
}


inline float SqrLen(float3 v)
{
        return v.x * v.x + v.y * v.y + v.z * v.z;
}


inline float2 myreflect(float2 pt, float2 n)
{
        // distance to plane
        float d = dot(n, pt);
        // reflect around plane
        float2 rpt = pt - d * 2.0f * n;

        return rpt;
}


inline float2 myrotate(float2 pt, float angle)
{
        float2 rpt;

        rpt.x = pt.x * cos(angle) - pt.y * sin(angle);
        rpt.y = pt.y * cos(angle) + pt.x * sin(angle);

        //normalize(rpt);
        return rpt;
}