From 47a989774797c3af5a37d377e13beabff06bd5b7 Mon Sep 17 00:00:00 2001
From: ccolin <contact@ccolin.fr>
Date: Thu, 1 Oct 2020 17:35:38 +0200
Subject: [PATCH] implements the computation of the surface area

---
 src/main.cpp | 24 ++++++++++++++++++++++++
 1 file changed, 24 insertions(+)

diff --git a/src/main.cpp b/src/main.cpp
index 0dfd3d5..7587b2f 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -54,6 +54,29 @@ bool check_edges_arent_lonely(const char *path) {
 }
 
 
+float face_area(MyMesh &mesh, const MyMesh::FaceHandle &face) {
+	MyMesh::Point p0, p1, p2;
+	auto fv_it = mesh.fv_iter(face);
+	p0 = mesh.point(*fv_it++);
+	p1 = mesh.point(*fv_it++);
+	p2 = mesh.point(*fv_it);
+	return ((p1 - p0) % (p2 - p0)).norm() / 2;
+}
+
+
+float total_area(MyMesh &mesh) {
+	if (!check_faces_are_triangles(mesh)) {
+		std::cerr << "Le calcul de l’aire ne peu se faire que sur un maillage triangulaire." << std::endl;
+		return -1;
+	}
+	float ret = 0;
+	for (const MyMesh::FaceHandle &face : mesh.faces()) {
+		ret += face_area(mesh, face);
+	}
+	return ret;
+}
+
+
 int main(int argc, char *argv[]) {
 	using namespace std;
 
@@ -75,5 +98,6 @@ int main(int argc, char *argv[]) {
 	cout << "Les arêtes sont sur une face : "
 		 << (check_edges_arent_lonely(argv[1]) ? "oui" : "non")
 		 << endl;
+	cout << "Aire totale : " << total_area(mesh) << endl;
 	return 0;
 }