# How to I iterate through all triangles in an ofMesh

I want to do intersection testing on all triangles of an ofMesh but the documentation says that ofMesh::getFaces() is not implemented. If I understand correctly, ofMesh::getUniqueFaces() only returns faces that don’t share a vertex/edge - so that doesn’t seem like the right method…(?)… suggestions ?

I would go for:

``````        intersectsPrimitive(const of3dPrimitive& primitive,  glm::vec3 & baricentricCoords, glm::vec3 & intNormal) {
// at the beginning, no intersection is found and the distance to the closest surface
// is set to an high value;
bool found = false;
float distanceToTheClosestSurface = numeric_limits<float>::max();

for (const ofMeshFace& face : primitive.getMesh().getUniqueFaces()) {
glm::vec3 baricentricCoords;
bool intersection = glm::intersectRayTriangle(
origin, direction,
glm::vec3(primitive.getGlobalTransformMatrix() * glm::vec4(face.getVertex(0), 1.f)),
glm::vec3(primitive.getGlobalTransformMatrix() * glm::vec4(face.getVertex(1), 1.f)),
glm::vec3(primitive.getGlobalTransformMatrix() * glm::vec4(face.getVertex(2), 1.f)),
baricentricCoords);
// when an intersection is found, it updates the distanceToTheClosestSurface value
// this value is used to order the new intersections, if a new intersection with a smaller baricenter.z
// value is found, this one will become the new intersection
if (intersection) {
if (baricentricCoords.z < distanceToTheClosestSurface) {
found = true;
distanceToTheClosestSurface = baricentricCoords.z;
intNormal = face.getFaceNormal();
}
}
}
return found;
};
``````

I have used this method in this addon, and it works quite well. https://github.com/edap/ofxRaycaster

1 Like

Thank You ! I have tried the glm::intersect methods and they seem to work nicely. I’ll look at your code.