According to the documentation, llDetectedTouchST and llDetectedTouchUV use the bottom-left corner of the surface as the origin (0,0). This behavior is correct when interacting with meshes uploaded using COLLADA. However, when the same geometry is uploaded as a GLTF/GLB mesh, the origin appears to be the top-left corner instead. As a result, the returned Y coordinate is inverted, producing negative or flipped values compared to the expected result. This issue is demonstrated in the attached video, which shows a single plane mesh containing a script that outputs llDetectedTouchST. The Y value becomes negative when touching the surface. The same behavior occurs with llDetectedTouchUV: https://gyazo.com/839b47c39612dd6d600eb54a083cbc50 Impact This is a significant problem because it causes these functions to behave differently depending on the mesh upload format. Scripts that rely on consistent UV/ST coordinates cannot work reliably across COLLADA and GLTF meshes. Steps to Reproduce Create a simple mesh in a 3D application (for example, a single plane or a cube). Export the mesh as GLTF or GLB. Upload the mesh to Second Life. Add a script that outputs llDetectedTouchST(0) and/or llDetectedTouchUV(0) to local chat on touch. Touch the mesh and observe that the Y coordinate is inverted compared to a COLLADA-uploaded mesh.