code.cpp

// -------------------------------------------------------------------------- // This code snipplet projects the incoming radiance on hemi(spherical) // harmonics and computes the translational gradient of the coefficient // vector. // // The code is invoked once for every ray used for hemisphere sampling when // a new radiance cache records is being created. // // // Identifiers are // float *H............... evaluated basis functions // float *dH_dt // float *dH_dp........... derivatives of the basis functions w.r.t theta // and phi // CVector3D raydir_loc... ray direction in the local frame // CVector3D raydir_glob.. ray direction in the global frame // float cos_theta, cos_phi, sin_theta, sin_phi // ................ ray direction w.r.t. the local frame // _sphBasis->EvalDerivCartVInt() // ................ evaluates the basis functions (SH or HSH) and // their derivatives up to 'desiredOrder' in a // given direction. // float r ............... distance to the hit point // float ir .............. 1/r // CVector3D U, V, N .... axes of the local coordinate frame // float cos_xi .......... angle between the ray direction and the surface // normal at the hit point // float *dx_gray, *dy_gray .. aux arrays // // Results of the computation are: // 'result'................ 3 vectors of projection coefficients, one vector // for each color channel // 'dx', 'dy' ............. 3 vectors of derivatives of the projection // coefficients, one vector for each color channel // sqrDesiredOrder ...... order^2 // // After processing all rays, the vectors 'result', 'dx' and 'dy' // have to be multiplies by 2*PI/N, where N is the number of cast rays. // ////////////////////////////////////////////////////////////////// // evaluate (H)SH coefficients + derivatives _sphBasis->EvalDerivCartVInt(desiredOrder, _localFrame ? raydir_loc : raydir_glob, &H, &dH_dt, &dH_dp); // transform the normal at the hit point to the local frame CVector3D nl = ToLocalFrame(outgoingHitInfo.GetNormal(),U,V,N); // derivatives of Omega w.r.t x and y float dOmega_dx = ( nl.x + 3.0f*raydir_loc.x*cos_xi ) / (r*cos_xi); float dOmega_dy = ( nl.y + 3.0f*raydir_loc.y*cos_xi ) / (r*cos_xi); // derivatives needed to evaluate dH/dx // using dH/dx = dH/dtheta*dtheta/dx + dH/dphi*dphi/dx float dTheta_dx = -cos_theta * cos_phi * ir; float dTheta_dy = -cos_theta * sin_phi * ir; float dPhi_dx = sin_phi / (r * sin_theta); float dPhi_dy = -cos_phi / (r * sin_theta); // L_i - independent computation... for(int i=0; iGetChannel(ch), dx_gray,Li[ch]); gvectf::madvsip(sqrDesiredOrder,dy->GetChannel(ch), dy_gray,Li[ch]); }