frame3f mesh_frame(Mesh* mesh, int elementid, const vec2f& uv) {
auto f = mesh_triangle_face(mesh,elementid);
frame3f ff;
ff.x = normalize(mesh->pos[f.y]-mesh->pos[f.x]);
ff.y = normalize(mesh->pos[f.z]-mesh->pos[f.x]);
if(not mesh->norm.empty()) ff.z = normalize(interpolate_baricentric_triangle(mesh->norm,f,uv));
else if(elementid < mesh->triangle.size()) ff.z = triangle_normal(mesh->pos[f.x], mesh->pos[f.y], mesh->pos[f.z]);
else { auto f = mesh->quad[(elementid-mesh->triangle.size())/2]; ff.z = quad_normal(mesh->pos[f.x], mesh->pos[f.y], mesh->pos[f.z], mesh->pos[f.w]); }
ff.o = interpolate_baricentric_triangle(mesh->pos,f,uv);
ff = orthonormalize(ff);
return ff;
}
void shape_smooth_frames(Shape* shape) {
if(is<TriangleMesh>(shape)) {
auto mesh = cast<TriangleMesh>(shape);
mesh->norm.resize(mesh->pos.size(),zero3f);
for(auto f : mesh->triangle) for(auto vid : f) mesh->norm[vid] += triangle_normal(mesh->pos[f.x],mesh->pos[f.y],mesh->pos[f.z]);
for(auto &n : mesh->norm) n = normalize(n);
}
else if(is<Mesh>(shape)) {
auto mesh = cast<Mesh>(shape);
mesh->norm.resize(mesh->pos.size(),zero3f);
for(auto f : mesh->triangle) for(auto vid : f) mesh->norm[vid] += triangle_normal(mesh->pos[f.x],mesh->pos[f.y],mesh->pos[f.z]);
for(auto f : mesh->quad) for(auto vid : f) mesh->norm[vid] += quad_normal(mesh->pos[f.x],mesh->pos[f.y],mesh->pos[f.z],mesh->pos[f.w]);
for(auto &n : mesh->norm) n = normalize(n);
}
}
/*!
the distortion of a quad
*/
C_FUNC_DEF VERDICT_REAL v_quad_distortion( int num_nodes, VERDICT_REAL coordinates[][3] )
{
// To calculate distortion for linear and 2nd order quads
// distortion = {min(|J|)/actual area}*{parent area}
// parent area = 4 for a quad.
// min |J| is the minimum over nodes and gaussian integration points
// created by Ling Pan, CAT on 4/30/01
double element_area =0.0,distrt,thickness_gauss;
double cur_jacobian=0., sign_jacobian, jacobian ;
VerdictVector aa, bb, cc,normal_at_point, xin;
//use 2x2 gauss points for linear quads and 3x3 for 2nd order quads
int number_of_gauss_points=0;
if (num_nodes ==4)
//2x2 quadrature rule
number_of_gauss_points = 2;
else if (num_nodes ==8)
//3x3 quadrature rule
number_of_gauss_points = 3;
int total_number_of_gauss_points = number_of_gauss_points*number_of_gauss_points;
VerdictVector face_normal = quad_normal( coordinates );
double distortion = VERDICT_DBL_MAX;
VerdictVector first, second;
int i;
//Will work out the case for collapsed quad later
if ( is_collapsed_quad( coordinates ) == VERDICT_TRUE )
{
for ( i=0; i<3; i++ )
{
first.set( coordinates[i][0] - coordinates[(i+1)%3][0],
coordinates[i][1] - coordinates[(i+1)%3][1],
coordinates[i][2] - coordinates[(i+1)%3][2] );
second.set( coordinates[i][0] - coordinates[(i+2)%3][0],
coordinates[i][1] - coordinates[(i+2)%3][1],
coordinates[i][2] - coordinates[(i+2)%3][2] );
sign_jacobian = (face_normal % ( first * second )) > 0? 1.:-1.;
cur_jacobian = sign_jacobian*(first * second).length();
distortion = VERDICT_MIN(distortion, cur_jacobian);
}
element_area = (first*second).length()/2.0;
distortion /= element_area;
}
else
{
double shape_function[maxTotalNumberGaussPoints][maxNumberNodes];
double dndy1[maxTotalNumberGaussPoints][maxNumberNodes];
double dndy2[maxTotalNumberGaussPoints][maxNumberNodes];
double weight[maxTotalNumberGaussPoints];
//create an object of GaussIntegration
GaussIntegration::initialize(number_of_gauss_points,num_nodes );
GaussIntegration::calculate_shape_function_2d_quad();
GaussIntegration::get_shape_func(shape_function[0], dndy1[0], dndy2[0], weight);
// calculate element area
int ife,ja;
for ( ife=0;ife<total_number_of_gauss_points; ife++)
{
aa.set(0.0,0.0,0.0);
bb.set(0.0,0.0,0.0);
for (ja=0;ja<num_nodes;ja++)
{
xin.set(coordinates[ja][0], coordinates[ja][1], coordinates[ja][2]);
aa += dndy1[ife][ja]*xin;
bb += dndy2[ife][ja]*xin;
}
normal_at_point = aa*bb;
jacobian = normal_at_point.length();
element_area += weight[ife]*jacobian;
}
double dndy1_at_node[maxNumberNodes][maxNumberNodes];
double dndy2_at_node[maxNumberNodes][maxNumberNodes];
GaussIntegration::calculate_derivative_at_nodes( dndy1_at_node, dndy2_at_node);
VerdictVector normal_at_nodes[9];
//evaluate normal at nodes and distortion values at nodes
int jai;
for (ja =0; ja<num_nodes; ja++)
{
aa.set(0.0,0.0,0.0);
bb.set(0.0,0.0,0.0);
for (jai =0; jai<num_nodes; jai++)
{
xin.set(coordinates[jai][0], coordinates[jai][1], coordinates[jai][2]);
aa += dndy1_at_node[ja][jai]*xin;
bb += dndy2_at_node[ja][jai]*xin;
}
normal_at_nodes[ja] = aa*bb;
normal_at_nodes[ja].normalize();
}
//determine if element is flat
bool flat_element =true;
double dot_product;
for ( ja=0; ja<num_nodes;ja++)
{
dot_product = normal_at_nodes[0]%normal_at_nodes[ja];
if (fabs(dot_product) <0.99)
{
flat_element = false;
break;
}
}
// take into consideration of the thickness of the element
double thickness;
//get_quad_thickness(face, element_area, thickness );
thickness = 0.001*sqrt(element_area);
//set thickness gauss point location
double zl = 0.5773502691896;
if (flat_element) zl =0.0;
int no_gauss_pts_z = (flat_element)? 1 : 2;
double thickness_z;
int igz;
//loop on Gauss points
for (ife=0;ife<total_number_of_gauss_points;ife++)
{
//loop on the thickness direction gauss points
for ( igz=0;igz<no_gauss_pts_z;igz++)
{
zl = -zl;
thickness_z = zl*thickness/2.0;
aa.set(0.0,0.0,0.0);
bb.set(0.0,0.0,0.0);
cc.set(0.0,0.0,0.0);
for (ja=0;ja<num_nodes;ja++)
{
xin.set(coordinates[ja][0], coordinates[ja][1], coordinates[ja][2]);
xin += thickness_z*normal_at_nodes[ja];
aa += dndy1[ife][ja]*xin;
bb += dndy2[ife][ja]*xin;
thickness_gauss = shape_function[ife][ja]*thickness/2.0;
cc += thickness_gauss*normal_at_nodes[ja];
}
normal_at_point = aa*bb;
jacobian = normal_at_point.length();
distrt = cc%normal_at_point;
if (distrt < distortion) distortion = distrt;
}
}
//loop through nodal points
for ( ja =0; ja<num_nodes; ja++)
{
for ( igz=0;igz<no_gauss_pts_z;igz++)
{
zl = -zl;
thickness_z = zl*thickness/2.0;
aa.set(0.0,0.0,0.0);
bb.set(0.0,0.0,0.0);
cc.set(0.0,0.0,0.0);
for ( jai =0; jai<num_nodes; jai++)
{
xin.set(coordinates[jai][0], coordinates[jai][1], coordinates[jai][2]);
xin += thickness_z*normal_at_nodes[ja];
aa += dndy1_at_node[ja][jai]*xin;
bb += dndy2_at_node[ja][jai]*xin;
if (jai == ja)
thickness_gauss = thickness/2.0;
else
thickness_gauss = 0.;
cc += thickness_gauss*normal_at_nodes[jai];
}
}
normal_at_point = aa*bb;
double sign_jacobian = (face_normal % normal_at_point) > 0? 1.:-1.;
distrt = sign_jacobian * (cc%normal_at_point);
if (distrt < distortion) distortion = distrt;
}
if (element_area*thickness !=0)
distortion *=8./( element_area*thickness);
else
distortion *=8.;
}
return (VERDICT_REAL)distortion;
}
