// Load a mesh using the assimp library, and calculate its mesh saliency
bool load_mesh (const char* file_name, GLuint* vao, int* point_count) {
const aiScene* scene = aiImportFile (file_name, aiProcess_Triangulate);
if (!scene) {
fprintf (stderr, "ERROR: reading mesh %s\n", file_name);
return false;
}
// Get first mesh in file only
const aiMesh* mesh = scene->mMeshes[0];
printf (" %i vertices in mesh[0]\n", mesh->mNumVertices);
printf (" %i faces in mesh[0]\n", mesh->mNumFaces);
// Pass back number of vertex points in mesh
*point_count = mesh->mNumVertices;
vertexCnt = *point_count;
// Generate a VAO, using the pass-by-reference parameter that we give to the function
glGenVertexArrays (1, vao);
glBindVertexArray (*vao);
points = NULL; // array of vertex points
if (!mesh->HasPositions()) {
fprintf(stderr, "ERROR: mesh %s don't have vertex data!\n", file_name);
return false;
}
float xMin = oo, yMin = oo, zMin = oo;
float xMax = -oo, yMax = -oo, zMax = -oo;
// Get the mesh's vertecies
points = (GLfloat*)malloc (vertexCnt * 3 * sizeof (GLfloat));
for (int i = 0; i < vertexCnt; i++) {
const aiVector3D* vp = &(mesh->mVertices[i]);
points[i * 3] = (GLfloat)vp->x;
points[i * 3 + 1] = (GLfloat)vp->y;
points[i * 3 + 2] = (GLfloat)vp->z;
xMin = fMin(xMin, vp->x), xMax = fMax(xMax, vp->x);
yMin = fMin(yMin, vp->y), yMax = fMax(yMax, vp->y);
zMin = fMin(zMin, vp->z), zMax = fMax(zMax, vp->z);
}
// Calculate the mesh's normal
normals = (GLfloat*)malloc(vertexCnt * 3 * sizeof(GLfloat));
for(int i = 0; i < mesh->mNumFaces; i++) {
int idx[3];
for(int k = 0; k < 3; k++)
idx[k] = mesh->mFaces[i].mIndices[k];
// get all vertecies' location
const aiVector3D* v1 = &(mesh->mVertices[idx[0]]);
const aiVector3D* v2 = &(mesh->mVertices[idx[1]]);
const aiVector3D* v3 = &(mesh->mVertices[idx[2]]);
// vectors
vec3 faceVec1 = vec3(v2->x - v1->x, v2->y - v1->y, v2->z - v1->z);
vec3 faceVec2 = vec3(v3->x - v2->x, v3->y - v2->y, v3->z - v2->z);
vec3 crossProd = cross(faceVec1, faceVec2);
for(int k = 0; k < 3; k++) {
normals[idx[k]*3+0] += (GLfloat)crossProd.v[0],
normals[idx[k]*3+1] += (GLfloat)crossProd.v[1],
normals[idx[k]*3+2] += (GLfloat)crossProd.v[2];
}
}
for(int i = 0; i < vertexCnt; i++) {
float norm = 0.0f;
for(int k = 0; k < 3; k++)
norm += normals[i*3+k]*normals[i*3+k];
for(int k = 0; k < 3; k++)
normals[i*3+k] /= sqrt(norm);
}
// Calculate each vertecies' shape operator
mat3* shapeOperators = NULL;
float* vertexArea = NULL;
shapeOperators = (mat3*)malloc(vertexCnt * sizeof(mat3));
vertexArea = (float*)malloc(vertexCnt * sizeof(float));
for(int i = 0; i < vertexCnt ; i++) {
vertexArea[i] = 0.0f;
for(int j = 0; j < 9; j++)
shapeOperators[i].m[j] = 0.0f;
}
for(int k = 0; k < mesh->mNumFaces; k++) {
// Calculate the face's area
aiVector3D* aiVec[3];
for(int idx = 0; idx < 3; idx++)
aiVec[idx] = &(mesh->mVertices[mesh->mFaces[k].mIndices[idx]]);
vec3 faceVec1 = vec3(aiVec[1]->x - aiVec[0]->x,
aiVec[1]->y - aiVec[0]->y,
aiVec[1]->z - aiVec[0]->z);
vec3 faceVec2 = vec3(aiVec[2]->x - aiVec[1]->x,
aiVec[2]->y - aiVec[1]->y,
aiVec[2]->z - aiVec[1]->z);
vec3 vecArea = cross(faceVec1, faceVec2);
float faceArea = sqrt(vecArea.v[0]*vecArea.v[0] + vecArea.v[1]*vecArea.v[1] + vecArea.v[2]*vecArea.v[2]);
for(int idx = 0; idx < 3; idx++) {
int i = mesh->mFaces[k].mIndices[idx];
int j = mesh->mFaces[k].mIndices[(idx+1)%3];
// Get vertex i and j's normal vectors.
vec3 Ni = vec3(normals[i*3], normals[i*3+1], normals[i*3+2]);
vec3 Nj = vec3(normals[j*3], normals[j*3+1], normals[j*3+2]);
// Get vertex i and j's location.
const aiVector3D* aiVi = &(mesh->mVertices[i]);
const aiVector3D* aiVj = &(mesh->mVertices[j]);
vec3 Vi = vec3(aiVi->x, aiVi->y, aiVi->z);
vec3 Vj = vec3(aiVj->x, aiVj->y, aiVj->z);
// For vertex i, update the relative part of its shape operator
vec3 Tij = (identity_mat3() - wedge(Ni, Ni))*(Vi-Vj);
Tij = normalise(Tij);
float kappa_ij = 2*dot(Ni, Vj-Vi);
kappa_ij /= get_squared_dist(Vi, Vj);
// Maintain vi's shape operator
shapeOperators[i] = shapeOperators[i] + (wedge(Tij, Tij) * (kappa_ij * faceArea));
vertexArea[i] += faceArea;
// For vertex j, update the relative part of its shape operator
vec3 Tji = (identity_mat3() - wedge(Nj, Nj))*(Vj-Vi);
Tji = normalise(Tji);
float kappa_ji = 2*dot(Nj, Vi-Vj);
kappa_ji /= get_squared_dist(Vi, Vj);
// Maintain vj's shape operator
shapeOperators[j] = shapeOperators[j] + (wedge(Tji, Tji) * (kappa_ji * faceArea));
vertexArea[j] += faceArea;
}
}
for(int i = 0; i < vertexCnt; i++) {
shapeOperators[i] = shapeOperators[i] * (1.0f/vertexArea[i]);// * 10000000.0f;
//print(shapeOperators[i]);
}
free(vertexArea);
// Diagonalize the shape operator, and get the mean curvature
meanCurvature = (float*)malloc(vertexCnt * sizeof(float));
for(int k = 0; k < vertexCnt; k++) {
vec3 E1 = vec3(1.0f, 0.0f, 0.0f);
vec3 Nk = vec3(normals[k*3], normals[k*3+1], normals[k*3+2]);
bool isMinus = get_squared_dist(E1, Nk) > get_squared_dist(E1 * (-1.0f), Nk);
vec3 Wk;
// Diagnoalization by the Householder transform
if (!isMinus)
Wk = E1 + Nk;
else
Wk = E1 - Nk;
Wk = normalise(Wk);
mat3 Qk = identity_mat3() - (wedge(Wk, Wk) * 2.0f);
mat3 Mk = transpose(Qk) * shapeOperators[k] * Qk;
// Calculate the mean curvature by M_k's trace;
meanCurvature[k] = (GLfloat)(Mk.m[4] + Mk.m[8]);
}
free(shapeOperators);
// Calculate the incident matrix ( as linked list )
int* first = NULL;
int* next = NULL;
int* incidentVertex = NULL;
first = (int*)malloc(vertexCnt * sizeof(int));
for(int i = 0; i < vertexCnt; i++)
first[i] = -1;
next = (int*)malloc(mesh->mNumFaces * 6 * sizeof(int));
incidentVertex = (int*)malloc(mesh->mNumFaces * 6 * sizeof(int));
int edgeCnt = 0;
for(int k = 0; k < mesh->mNumFaces; k++) {
int idx[3];
for(int i = 0; i < 3; i++)
idx[i] = mesh->mFaces[k].mIndices[i];
for(int i = 0; i < 3; i++) {
int j1 = idx[(i+1)%3], j2 = idx[(i+2)%3];
incidentVertex[++edgeCnt] = j1;
next[edgeCnt] = first[idx[i]]; first[idx[i]] = edgeCnt;
incidentVertex[++edgeCnt] = j2;
next[edgeCnt] = first[idx[i]]; first[idx[i]] = edgeCnt;
}
}
printf("BFS 1\n");
// Calculate the mesh saliency by BFS
float diagonalLength = sqrt((xMax-xMin)*(xMax-xMin) + (yMax-yMin)*(yMax-yMin) + (zMax-zMin)*(zMax-zMin));
float sigma = 0.003 * diagonalLength;
float* saliency[7];
float maxSaliency[7];
for(int i = 2; i <= 6; i++) {
saliency[i] = NULL;;
saliency[i] = (float*)malloc(vertexCnt * sizeof(float));
maxSaliency[i] = -oo;
}
// Labeled the vertecies whether covered or not.
bool* used = NULL;
used = (bool*)malloc(vertexCnt * sizeof(bool));
for(int k = 0; k < vertexCnt; k++) {
if(k%1000 == 0)
printf("#%d#\n", k);
// Initialize the saliency and its local counter.
for(int i = 2; i <= 6; i++)
saliency[i][k] = 0.0f;
// Initialize the saliency's Gaussian filter.
float gaussianSigma1[7], gaussianSigma2[7], sumSigma1[7], sumSigma2[7];
for(int i = 2; i <= 6; i++)
gaussianSigma1[i] = gaussianSigma2[i] = 0.0f,
sumSigma1[i] = sumSigma2[i] = 0.0f;
// Get the current vertex's information.
aiVector3D* aiVec = &(mesh->mVertices[k]);
vec3 vVec = vec3(aiVec->x, aiVec->y, aiVec->z);
// Initialize the queue to find neighbourhood.
for(int i = 0; i < vertexCnt; i++)
used[i] = false;
queue<int> Q;
Q.push(k);
used[k] = true;
// Frsit BFS
while(!Q.empty()) {
// Get the front element in the queue.
int idx = Q.front(); Q.pop();
aiVec = &(mesh->mVertices[idx]);
vec3 idxVec = vec3(aiVec->x, aiVec->y, aiVec->z);
// Put the next level vertecies into the queue.
for(int e = first[idx]; e != -1; e = next[e]) {
int idxNext = incidentVertex[e];
// Expand the next level vertecies.
if(!used[idxNext]) {
aiVec = &(mesh->mVertices[idxNext]);
vec3 idxNextVec = vec3(aiVec->x, aiVec->y, aiVec->z);
if(get_squared_dist(vVec, idxNextVec) <= 36*sigma*sigma)
Q.push(incidentVertex[e]),
used[incidentVertex[e]] = 1;
}
}
// Update Gaussian filter
float dist = get_squared_dist(vVec, idxVec);
for(int i = 2; i <= 6; i++) {
float sigmaHere = i*i*sigma*sigma;
if(dist <= sigmaHere) {
float factor = exp(-dist/(2*sigmaHere));
gaussianSigma1[i] += meanCurvature[idx] * factor;
sumSigma1[i] += factor;
}
if(dist <= 2*sigmaHere) {
float factor = exp(-dist/(8*sigma*sigma));
gaussianSigma2[i] += meanCurvature[idx] * factor;
sumSigma2[i] += factor;
}
}
}
for(int i = 2; i <= 6; i++) {
saliency[i][k] = fabs(gaussianSigma1[i]/sumSigma1[i]
- gaussianSigma2[i]/sumSigma2[i]);
maxSaliency[i] = fMax(maxSaliency[i], saliency[i][k]);
}
}
printf("BFS 2\n");
// Second BFS and get the non-linear normailization of suppressian's saliency.
smoothSaliency = (float*)malloc(vertexCnt * sizeof(float));
for(int k = 0; k < vertexCnt; k++) {
if(k%1000 == 0)
printf("[%d]\n", k);
smoothSaliency[k] = 0.0f;
float localMaxSaliency[7];//, localCntSaliency[7];
for(int i = 2; i <= 6; i++)
localMaxSaliency[i] = -oo;
// Get the current vertex's information.
aiVector3D* aiVec = &(mesh->mVertices[k]);
vec3 vVec = vec3(aiVec->x, aiVec->y, aiVec->z);
// Initialize the queue to find neighbourhood.
for(int i = 0; i < vertexCnt; i++)
used[i] = false;
queue<int> Q;
Q.push(k);
used[k] = true;
while(!Q.empty()) {
// Get the front element in the queue.
int idx = Q.front(); Q.pop();
//aiVec = &(mesh->mVertices[idx]);
//vec3 idxVec = vec3(aiVec->x, aiVec->y, aiVec->z);
// Put the next level vertecies into the queue.
for(int e = first[idx]; e != -1; e = next[e]) {
int idxNext = incidentVertex[e];
// Expand the next level vertecies.
if(!used[idxNext]) {
aiVec = &(mesh->mVertices[idxNext]);
vec3 idxNextVec = vec3(aiVec->x, aiVec->y, aiVec->z);
if(get_squared_dist(vVec, idxNextVec) <= 36*sigma*sigma)
Q.push(incidentVertex[ e]),
used[incidentVertex[e]] = 1;
}
}
// Update Gaussian filter
for(int i = 2; i <= 6; i++)
localMaxSaliency[i] = fMax(localMaxSaliency[i], saliency[i][idx]);
}
// Calculate the weighted saliency
float saliencySum = 0.0f;
for(int i = 2; i <= 6; i++) {
float factor = (maxSaliency[i]-localMaxSaliency[i])*(maxSaliency[i]-localMaxSaliency[i]);
smoothSaliency[k] += (GLfloat)saliency[i][k] * factor;
saliencySum += factor;
}
smoothSaliency[k] /= (GLfloat)saliencySum;
}
// Clean up resources
free(first);
free(next);
free(incidentVertex);
for(int i = 2; i <= 6; i++)
free(saliency[i]);
// Copy all vertecies and normal vertors in mesh data into VBOs
/*
{
GLuint vbo;
glGenBuffers (1, &vbo);
glBindBuffer (GL_ARRAY_BUFFER, vbo);
glBufferData (
GL_ARRAY_BUFFER,
3 * vertexCnt * sizeof (GLfloat),
points,
GL_STATIC_DRAW
);
glVertexAttribPointer (0, 3, GL_FLOAT, GL_FALSE, 0, NULL);
glEnableVertexAttribArray (0);
free (points);
}
*/
// Copy all normal vectors in mesh data into VBOs
updateDisplayType(1);
aiReleaseImport (scene);
printf ("mesh loaded\n");
return true;
}
/*
* return the minimum on the projective line
*
*/
int lp_base_case(FLOAT halves[][2], /* halves --- half lines */
int m, /* m --- terminal marker */
FLOAT n_vec[2], /* n_vec --- numerator funciton */
FLOAT d_vec[2], /* d_vec --- denominator function */
FLOAT opt[2], /* opt --- optimum */
int next[],
int prev[]) /* next, prev ---
double linked list of indices */
{
FLOAT cw_vec[2], ccw_vec[2];
#ifdef CHECK
FLOAT d_cw;
int i;
#endif
int status, degen;
FLOAT ab;
/* find the feasible region of the line */
status = wedge(halves,m,next,prev,cw_vec,ccw_vec,°en);
if(status==INFEASIBLE) return(status);
/* no non-trivial constraints one the plane: return the unconstrained
** optimum */
if(status==UNBOUNDED) {
return(lp_no_constraints(1,n_vec,d_vec,opt));
}
ab = ABS(cross2(n_vec,d_vec));
if(ab < 2*EPS*EPS) {
if(dot2(n_vec,n_vec) < 2*EPS*EPS ||
dot2(d_vec,d_vec) > 2*EPS*EPS) {
/* numerator is zero or numerator and denominator are linearly dependent */
opt[0] = cw_vec[0];
opt[1] = cw_vec[1];
status = AMBIGUOUS;
} else {
/* numerator is non-zero and denominator is zero
** minimize linear functional on circle */
if(!degen && cross2(cw_vec,n_vec) <= 0.0 &&
cross2(n_vec,ccw_vec) <= 0.0 ) {
/* optimum is in interior of feasible region */
opt[0] = -n_vec[0];
opt[1] = -n_vec[1];
} else if(dot2(n_vec,cw_vec) > dot2(n_vec,ccw_vec) ) {
/* optimum is at counter-clockwise boundary */
opt[0] = ccw_vec[0];
opt[1] = ccw_vec[1];
} else {
/* optimum is at clockwise boundary */
opt[0] = cw_vec[0];
opt[1] = cw_vec[1];
}
status = MINIMUM;
}
} else {
/* niether numerator nor denominator is zero */
lp_min_lin_rat(degen,cw_vec,ccw_vec,n_vec,d_vec,opt);
status = MINIMUM;
}
#ifdef CHECK
for(i=0; i!=m; i=next[i]) {
d_cw = dot2(opt,halves[i]);
if(d_cw < -2*EPS) {
printf("error at base level\n");
exit(1);
}
}
#endif
return(status);
}
