void compute_color_vr(int current_ijk[3], int color_mapping_style, double *interval_point, int transfer_function_style, double opa_value, int num_of_features, double *fea_point, double view_point_d[3], int interval_mapping_num, int color_system_type, int num_of_lights, double *light_point, double k_ads[3], int r_level[3], double orig_xyz[3], double r_dxyz[3], double *var, double *grad_var, double accum_rgba[4], double mincolor, double maxcolor, double grad_minmax[2], double feap_minmax[2], double feai_minmax[2], double dis_minmax[2], double *opa_table, double in_point[3], double out_point[3], double tav_length, int time_step, int print_flag)