ValveSoftware
GetHiddenAreaMesh does not specify mesh format
The IVRSystem::GetHiddenAreaMesh method is documented to return a HiddenAreaMesh_t that simply contains a pointer to a list of vertices and an indicated number of triangles. Could you please post more information to the wiki as to what the format of that list of vertices is (i.e. is it 3-vectors or 4-vectors, is it a triangle list or a triangle strip, does it need to be transformed or projected, can it change during program execution, etc.)?
It's a list of 2d triangles. There should be 20 triangles reported. That's 60 vertices and 2 coordinates per vertex so 120 individual values in the format x1, y1, x2, y2, x3, y3 ... etc
As this issue is the only documentation I found on the subject, let me expand it a bit:
As of today (IVRSystem_017 with a HTC Vive), GetHiddenAreaMesh returns 78
vertices in the [0-1] range. (0,0) is bottom-left.
The rest can be inferred from the definition of HiddenAreaMesh_t.
The comments on GetHiddenAreaMesh does not match the definition but match the
functionality.
There's a C# example of converting the HmdVector2_t pVertexData into a Unity mesh.
https://github.com/ValveSoftware/openvr/blob/4c85abcb7f7f1f02adaf3812018c99fc593bc341/samples/unity_teleport_sample/Assets/SteamVR/Scripts/SteamVR_Utils.cs#L390
It's also worth checking out that Ogre3D has mentioned Valve's hidden area mesh in this blogpost: https://www.ogre3d.org/2019/09/22/improvements-in-vr-morph-animations-moving-to-github-and-ci
