Hello, I have a project where I need to compute line segment vs. mesh intersection, accounting for visibility. Each line segment should be transformed in 0, 1 or more segments where, assuming a projection direction (eg. z axis), including the part of the segment that is in front of the mesh and the parts that are not overlapping with the mesh, excluding both the part that is inside the mesh (assuming its watertight) and the part that is "behind" the mesh (along projection axis). Basically, I'm trying to "render" line segments into vector data (not raster), accounting for opaque meshes in the scene. I'm very new to Trimesh, is there an easy way to achieve this?
I assume ray-mesh intersection is where to start, but I would then have to somehow subtract the silhouette of the mesh from the segment part that is behind.
To be more specific, I'm trying to slide a box collider over a scene and find which meshes or are within it. Here is my sample code
import numpy as np
import trimesh
debug_material = trimesh.visual.material.PBRMaterial(baseColorFactor=np.array((255,0,0,80), dtype=np.uint), alphaMode='BLEND')
scene = trimesh.load_mesh('./data/simple.glb')
scene_bounds = scene.bounding_box
max_bounds = scene_bounds.extents.min()
box_count = 2
grid_width = int(max_bounds/box_count)
grid = scene_bounds.sample_grid(step=grid_width)
cm, _ = trimesh.collision.scene_to_collision(scene)
# Sliding box collider
box = trimesh.primitives.Box()
box.apply_scale(grid_width)
cm.add_object('selection', box)
# List of unique objects that were hit
was_hit = set([])
for g in grid:
print('####')
print(g)
matrix = np.eye(4)
matrix[:3, 3] = np.array(g)
debug_box = box.copy()
debug_box.apply_transform(matrix)
debug_box.visual.material = debug_material
hit, hit_list, l = cm.in_collision_single(box, transform=matrix, return_names=True, return_data=True)
if hit:
for item in hit_list:
if item is not 'selection':
mesh_name = scene.graph.get(item)[1]
if item not in was_hit:
was_hit.add(mesh_name)
scene.add_geometry(debug_box)
scene.export(file_obj=open('/tmp/debug.glb', 'wb'), file_type='glb')
print('Total hit %s' % len(was_hit))
print('Total geo %s' % len(scene.geometry))
And here is the sample GLB I'm using
Only 10 mesh are hit, but there are 16 in the scene. Initially, I thought it was missing objects that were fully enclosed by the box collider, but, but I'm finding to two large objects that should intersect multiple times also do not register.
My gut tells me that my "debug" object is not accurately representing the CollissionManager transform, but I can't figure out what I'm doing wrong.
how can we add a mesh to another mesh ?
mesh1 = mesh1 + mesh2
gauss = np.array([discrete_gaussian_curvature_measure(mesh, mesh.vertices, r)/sphere_ball_intersection(1, r) for r in radii])
why is the division of sphere_ball_intersection ?
hey all, I am running into an issue with ray.intersects_location returning much larger distances than expected between two meshes. I first use
closest_point to find points on the lower surface of interest and the indexes for the normals. then use ray.intersects_location with those lower surface points using the closes face normals to those points from the index returned by closest_point. I can tell something is off because if I explicitly set the normals to be [0,0,1], ray.intersects_location return points with different x and y coordinates then the ray origins (the rays should be orthogonal to the xy axis plane). am I missing something?
Hey at all,
i do have a question but i don't know if this is the right place.
I tried the voxel package and voxeled a lot of stuff. But now i wan't to digg deeper but i'm stuck now.
I want to extract the vertex information of every voxel, bacause i need them to manipulate the geometry. So i'm looking for something like: for voxel in allvoxels: give me voxel with his eight vertices. Is this possible?
i do have a question but i don't know if this is the right place.
I tried the voxel package and voxeled a lot of stuff. But now i wan't to digg deeper but i'm stuck now.
I want to extract the vertex information of every voxel, bacause i need them to manipulate the geometry. So i'm looking for something like: for voxel in allvoxels: give me voxel with his eight vertices. Is this possible?
Hi, so I am just getting started with trimesh, is there some documentation I am missing or is it a matter of going through the code?
I am trying the basic example but with a 3mf file and I get "'Scene' object has no attribute 'is_watertight'", how do I import a 3mf as a mesh or how do I split/convert a Scene to a mesh? Thanks
I am trying the basic example but with a 3mf file and I get "'Scene' object has no attribute 'is_watertight'", how do I import a 3mf as a mesh or how do I split/convert a Scene to a mesh? Thanks
@ChrisCarragher If your question is still open, I would export an mesh in STL format from your 3mf file, and then load this STL with Trimesh.
@science-code were you using
scene.save_image?
$ pip show pillow
Version: 7.0.0
Required-by: scikit-image, imageio
Version: 7.0.0
Required-by: scikit-image, imageio
Name: scikit-image
Version: 0.15.0
Version: 0.15.0
Name: imageio
Version: 2.8.0
Version: 2.8.0
they released recently
data = scene.save_image(resolution=[480,480], visible=True) #False)
It works with "visible=True", but does not work with "visible=False".
Moreover, even with "visible=True", the first mesh image is completely black.
Moreover, even with "visible=True", the first mesh image is completely black.
Alternative code for generating a mesh-image
from trimesh import viewer as trimesh_viewer
...
data = trimesh_viewer.render_scene(mesh.scene(), resolution=[480,480], visible=True)
I suppose it also slows down image generation, due to "visible=True".
@wwwslinger another alternative would be to simplify the mesh while enforcing constraints on its surface. You can use the "Decimate" function of MeshLabServer for this.
@mikedh It used to work with visible=False, but stopped since I installed some python packages. The platform is the same as before, so this isn't the issue. I've tried to identify which python package broke the mesh-image generation, but in vain.
@science-code I can seem to find Decimate in there, just ParaDecimate -- is that the same? Do you have link to an example perhaps?
You need to install meshlab for that work.
To change the number of triangles in the final mesh, edit the value on line 21:
<Param type="RichInt" value="2000" name="TargetFaceNum"/>