usdgeom-mesh-topology#

Code

VG.014

Validator

latest+

Compatibility

core usd

Tags

✅

Summary#

Mesh topology must be valid

Description#

Mesh topology must be valid for proper rendering and simulation. Invalid topology includes incorrect face winding, degenerate faces, and invalid vertex indices.

Why is it required?#

  • Rendering artifacts

  • Simulation failures

  • Invalid collision detection

Examples#

#usda 1.0

# Invalid: Degenerate faces and invalid indices
def Mesh "BadTopology" {
    int[] faceVertexCounts = [4, 3]
    int[] faceVertexIndices = [
        0, 0, 0, 0,  # Degenerate face (all vertices same)
        0, 1, 99     # Invalid index (99 > number of points)
    ]
    point3f[] points = [(0,0,0), (1,0,0)]
}

# Valid: Proper topology
def Mesh "GoodTopology" {
    int[] faceVertexCounts = [4, 3]
    int[] faceVertexIndices = [
        0, 1, 2, 3,  # Proper quad
        0, 1, 2      # Proper triangle
    ]
    point3f[] points = [(0,0,0), (1,0,0), (1,1,0), (0,1,0)]
}

How to comply#

  • Fix topology in source application

  • Verify vertex indices

  • Check face winding order

For More Information#