From bab1e5d9c93a065f97ebb5885bdd494213336e2a Mon Sep 17 00:00:00 2001
From: Aditya Rathore <adityaranigaon@icloud.com>
Date: Thu, 12 Dec 2024 20:50:33 +0530
Subject: [PATCH] Added pybind and python tests

---
 cpp/pybind/t/geometry/trianglemesh.cpp      |  5 +-
 python/test/t/geometry/test_trianglemesh.py | 60 +++++++++++++++++++++
 2 files changed, 64 insertions(+), 1 deletion(-)

diff --git a/cpp/pybind/t/geometry/trianglemesh.cpp b/cpp/pybind/t/geometry/trianglemesh.cpp
index 3f56bb52d8b..9c891430c91 100644
--- a/cpp/pybind/t/geometry/trianglemesh.cpp
+++ b/cpp/pybind/t/geometry/trianglemesh.cpp
@@ -734,11 +734,14 @@ This function always uses the CPU device.
 
         o3d.visualization.draw([{'name': 'difference', 'geometry': ans}])
 )");
-
+    triangle_mesh.def("compute_adjacency_list", &TriangleMesh::ComputeAdjacencyList,
+    "Return Mesh Adjacency Matrix in CSR format using Triangle indices attribute.");
+    
     triangle_mesh.def("get_axis_aligned_bounding_box",
                       &TriangleMesh::GetAxisAlignedBoundingBox,
                       "Create an axis-aligned bounding box from vertex "
                       "attribute 'positions'.");
+                      
     triangle_mesh.def("get_oriented_bounding_box",
                       &TriangleMesh::GetOrientedBoundingBox,
                       "Create an oriented bounding box from vertex attribute "
diff --git a/python/test/t/geometry/test_trianglemesh.py b/python/test/t/geometry/test_trianglemesh.py
index 88678e3f877..d99072d6181 100644
--- a/python/test/t/geometry/test_trianglemesh.py
+++ b/python/test/t/geometry/test_trianglemesh.py
@@ -241,6 +241,66 @@ def test_create_octahedron(device):
     assert octahedron_custom.vertex.positions.allclose(vertex_positions_custom)
     assert octahedron_custom.triangle.indices.allclose(triangle_indices_custom)
 
+@pytest.mark.parametrize("device", list_devices())
+def test_compute_adjacency_list(device):
+    # Test with custom parameters.
+    mesh = o3d.t.geometry.TriangleMesh.create_icosahedron(
+        2, o3c.float64, o3c.int32, device)
+    adjv, adjst = mesh.compute_adjacency_list()
+
+    # Check the number of edges at the end of row_index as per CRS format
+    assert adjst[-1] == len(adjv)
+
+    num_vertices = len(adjst)-1
+    # Create a adjacency matrix 
+    adjacencyMatrix = np.zeros((num_vertices, num_vertices))
+
+    for s in range(num_vertices):
+        start = adjst[s].item()
+        end = adjst[s+1].item()
+        for v in range(start, end):
+            t = adjv[v].item()
+            adjacencyMatrix[s,t] = 1
+    
+    # Number of edges
+    assert len(adjv) == adjacencyMatrix.sum()
+
+    # Adjacency Matrix should be symmetric
+    assert np.array_equal(adjacencyMatrix, adjacencyMatrix.T)
+    
+    #Triangle faces from computed adjacency matrix should match
+    actual_indices = [
+            [0, 1, 4],
+            [0, 1, 5],
+            [0, 4, 8],
+            [0, 5, 11],
+            [0, 8, 11],
+            [1, 4, 9],
+            [1, 5, 10],
+            [1, 9, 10],
+            [2, 3, 6],
+            [2, 3, 7],
+            [2, 6, 10],
+            [2, 7, 9],
+            [2, 9, 10],
+            [3, 6, 11],
+            [3, 7, 8],
+            [3, 8, 11],
+            [4, 7, 8],
+            [4, 7, 9],
+            [5, 6, 10],
+            [5, 6, 11]
+        ]
+    
+    computed_triangles = []
+    for i in range(num_vertices):
+        for j in range(i+1, num_vertices):
+            for k in range(j+1, num_vertices):
+                if (adjacencyMatrix[i,j] + adjacencyMatrix[j,k] + adjacencyMatrix[k,i] == 3):
+                    computed_triangles.append([i,j,k])
+
+    assert len(computed_triangles) == len(actual_indices)
+    assert np.array_equal(np.array(actual_indices,int), np.array(computed_triangles,int))
 
 @pytest.mark.parametrize("device", list_devices())
 def test_create_icosahedron(device):