Specular per-pixel lighting

#if SUPPORT_SPECULAR_REFLECTION
            auto normal = polygon.plane.Normal();
            if(polygon.normalmap >= 0)
            {
                // Load sample from normalmap
                #if TEXTUREMODE==2
                xyz<float> rgb = BilinearTextureFetch<32>(polygon.normalmap, {u,v}, {u0,v0});
                #else
                unsigned c = texturedata[polygon.normalmap][ (u % txth) * txtw + (v % txtw) ];
                xyz<float> rgb = dergb(c);
                #endif
                // Convert it into a vector of 3 floats
                auto perturb = rgb * (1 / 127.5f) - 1.f;
                // Tweak the normal by that vector
                normal = normal            * perturb[2]
                       - polygon.tangent   * perturb[1]
                       + polygon.bitangent * perturb[0];
            }
            xyz<float> point = xyz<float>(prop(5), prop(6), prop(7)); // 3D location of this pixel in space
            auto addlight = [&] (const Light& l)
            {
                constexpr float fade_distance = 655360, fade_power = 2;
                xyz<float> light_to_point = (l.v - point);
                xyz<float> V = (observer - point).Normalized(); // point to camera
                float v = V.DotProduct(normal);
                float factor = light_to_point.Normalized().DotProduct( normal * (v+v) - V );
                if(factor > 0)
                {
                    // Do phong/roughness adjustment
                    factor = std::pow(factor, 12.0f);
                    // Do distance fading to compensate for the point-light
                    factor /= 1 + std::pow(light_to_point.Length()*2 / fade_distance, fade_power);
                    pix += l.rgb * factor;
                }
            };
            for(const auto& l: level.lights) addlight(l);
            /*for(const auto& d: level.decorations)
                for(const auto& l: d.object->lights) addlight(l);*/
#endif