ray_pyembree.intersects_any and ray_pyembree.intersects_id produce incorrect results

[YuanWenqing]

I'm trying to test whether a bigger mesh is blocked by a small mesh and I found that ray test results are weird in some cases.

I compared results of intersects_any and intersects_id in both of ray_pyembree and ray_triangle. Results by ray_pyembree does not match while results by ray_triangle do match as expected. Meanwhile in some case ray_pyembree.intersects_any also gives incorrect result.

I don't know whether this bug is from pyembree or trimesh.ray.ray_pyembree. But it seems that all rays mis-checked by ray_pyembree pass through some vertices or edges of the small mesh. So I guess the bug may be a precision issue.

I tried this code below to reproduce my issue. Every ray passes through some vertices or edges of the small mesh and still some rays are mis-checked in intersects_id.

ray=trimesh.ray.ray_pyembree
# ray=trimesh.ray.ray_triangle

small=trimesh.creation.box(extents=np.full(3,40)).subdivide_to_size(20)
big=trimesh.creation.box(extents=np.full(3,60)).subdivide_to_size(20)
print('small:',small)
print('big:',big)
small.export('/tmp/small.obj')
big.export('/tmp/big.obj')

origin=np.zeros(3)
intersector = ray.RayMeshIntersector(small)
ray_origins=np.tile(origin, (len(big.vertices),1))
ray_directions=big.vertices-origin
intersected=intersector.intersects_any(ray_origins,ray_directions)
ray_idx=intersector.intersects_id(ray_origins,ray_directions,multiple_hits=False)[1]

reserved=np.reshape(np.in1d(big.faces.ravel(),ray_idx),(-1,3)).all(axis=1)
filtered1=trimesh.Trimesh(big.vertices,big.faces[reserved])
filtered1.export('/tmp/filtered1.obj')

reserved=np.all(intersected[big.faces],axis=1)
filtered2=trimesh.Trimesh(big.vertices,big.faces[reserved])
filtered2.export('/tmp/filtered2.obj')

print('intersects_any:',intersected.shape)
print('intersects_id:',ray_idx.shape)

Results:

small: <trimesh.Trimesh(vertices.shape=(98, 3), faces.shape=(192, 3))>
big: <trimesh.Trimesh(vertices.shape=(386, 3), faces.shape=(768, 3))>
intersects_any: (386,)
intersects_id: (373,)

Visual small mesh, big mesh, filtered1 mesh(by intersects_id) and rays:

Visual small mesh, big mesh, filtered2 mesh(intersects_any) and rays:

[mikedh]

Hey, yeah unfortunately embree doesn't make particularly strong promises:
RenderKit/embree#188
RenderKit/embree#174
RenderKit/embree#181

I'm hoping at some point to get some of the variants/forks of #1108 merged, and the upstream embree-3 package set up with cibuildwheel.