source: GTP/trunk/App/Demos/Illum/pathmap/WoodMaterial.hpp @ 2197

#pragma once
#include "material.hpp"

/*!
\brief A procedural material.
*/
class WoodMaterial :
        public Material
{
        Vector kinks[20];
public:

        WoodMaterial()
                :Material(Vector(0.7f, 0.5f, 0.3f), Vector(0.2f, 0.2f, 0.2f), 4.0f)
        {
                for(int k=0; k<20; k++)
                        kinks[k] = Vector(20.0f - 40.0f * rand() / RAND_MAX, -15.5f - 4.0f * rand() / RAND_MAX, 15.0f - 20.0f * rand() / RAND_MAX);
        }

        Vector getProceduralDiffuseBrdf(const Vector& atPoint) const
        {
                float x2 = atPoint.x * atPoint.x;
                float y2 = atPoint.y * atPoint.y;
                float d = sqrtf(x2 + y2) * 6.0f;
                for(int k=0; k < 20; k++)
                {
                        Vector diff; diff.setDifference(kinks[k], atPoint);
                        d *= 1.0f - (1.0f / (diff.norm2() + 1.0f));
                }
                d *= 0.5f;
                float c = 1.0f - (1.0f + cosf(d)) / 2.0f;
                c *= c; //c *= c;
                c = 1.0f - c;
                c *= 0.25f;
                return Vector(0.35f + c, 0.15f + c, c);
        }

        void proceduralScatteringProbability (const Vector& atPoint, const Vector& in, Vector& out, const Vector& normal, Vector& result) const
        {
                float nDotOut = normal * out;
                float nDotIn = - (normal * in);
                if ( nDotOut < 0) {
                        result = Vector::RGBBLACK;
                        return;
                }
                // add diffuse part
                result = getProceduralDiffuseBrdf(atPoint);
                // add specular using max Phong shading
                Vector idealReflected;
                idealReflected.setIdealReflectedDirection (in, normal);
                float dotProduct = idealReflected* out;
            if(dotProduct > 0)
                {
                        float scale = (float)pow (dotProduct, ns) * (ns + 2.0f) * 0.5f / 3.14159265358979323846f ;
                        if(nDotOut > nDotIn)
                                scale /= nDotOut;
                        else
                                scale /= nDotIn;
                        result += ks * scale;
                }
                result *= nDotOut;
        }
};