I've been fighting with a three.js issue for a few 12 hour days trying to determine why some outward pointed object faces are missing. It only seems to happen if I've modified the mesh model, extruded a plane, or knife projected a hole into a mesh.
I've found a few solutions online that don't seem to be working for me: I've added in the double-sided hack for all materials and this does allow me to see into objects with holes so it is partially working. I've fiddled with different importers (JSONLoader, OBJLoader) which all seem to have the same issues as listed above, so it leads me to believe it is indeed the model itself.
The research I've seen online says that modifying a mesh can leave the normals screwed up so any faces I CAN'T see on my model viewer I just flip and do the UV Map again, but this doesn't fix it.
I'm hoping someone who knows Blender and three.js will know what the problem is. I know it's simple and I'm just missing a step because I'm new.
Here's a link to the demo site and code: http://guitar.dodgestat.com/objloader/
It seems that OBJMTLLoader can handle only triangles and quadrangles, but obj files can describe faces with any number of vertices, but the faces should be convex.
If you check your model with http://3dviewer.net, you can see that every face exists, but there are some issues with non-convex faces.
So I recommend you to triangulate your model before export.
Related
I have been trying to instance some tree meshes in react-three-fiber and threejs,
this is what i have got so far: https://codesandbox.io/s/silly-sunset-74wmt?file=/src/App.js
The trees from one angle look see through, I am able to see the barks of ALL trees.
but the behavior is normal from the opposite angle.
To me it seems to be some issue with render order or meshes or the shader, not able to wrap my head around it.
I need the see-through thing to not happen and the set should look like how it looks like in the second picture from all angles
As suggested in the comments byDon McCurdy. I needed to use AlphaClip property on blender while exporting my mesh.
Found an answer here which was quite helpful in understanding the problems with threejs transparency at play
Updated with the solution: https://codesandbox.io/s/silly-sunset-74wmt?file=/src/App.js
I am displaying a number of different models simultaneously in three.
Some models have the same texture, and it can make it hard to tell where one starts and another ends.
As an example, first image is from my three viewer, second image is from Blender:
It is not obvious in three where the two objects intersect.
I've so far attempted to alter lighting and material settings but have been without success on that front.
I also tried an outline post processing effect but due to what I think is a disorderly output from Sketchup (where the models were made) the outline effect is chaotic:
I am trying to find a good way to clearly delineate between models.
Raycaster from mouse position. De-emphasize the other models' opacity or something. Or if you're serious, you could try the clipping stencil. There's some really good examples for mesh BVH that demonstrates this. https://gkjohnson.github.io/three-mesh-bvh/example/bundle/clippedEdges.html
I created a model in Blender of a block with a hole in it:
I export it as an .obj file, and import it in ThreeJS with the OBJLoader add-on.
When I use it in my app, it appears to draw a face over the sides of the hole:
Is there a setting I need to use in ThreeJS to avoid having it close over gaps like this? Or is the problem in how I'm creating the model? I'm totally lost here, any guidance appreciated.
EDIT: I discovered through trial-and-error that the problem is having irregularly-shaped faces, like the ones adjacent to the hole. I "solved" my problem by triangulating the model; while this changes its shape slightly, it ensures that every vertex in the hole is part of a triangle face, which seems to be the magic answer.
I'm still very curious about why this is, especially since the triangulation has made the corners of the box a bit weird.
EDIT 2: Sorry for the delay. Here's the blender file: https://gofile.io/?c=EoxH1r
The problem you are having is because of ngons (polygons with more than 4 sides).
Modelling for three.js is just like modelling for games, so it is best to avoid polygons with more than 4 sides because when the renderer (or video card, I dunno) tries to render the model, it has to apply triangulation and may do it in an unexpected way.
As you said, applying triangulation to the model fixed the issue, but automatically applying triangulation in your modelling app may also yield unexpected results. So your best bet is to alter the model so you get the results you expect.
Here is a youtube video I found that seems to explain a lot about ngons.
https://www.youtube.com/watch?v=BjnCV2PIkKA
(though I only watched the first minute or so)
Here is an example of how I would do it, red lines representing added edges. Remember to do it all the way around on both sides and apply your smoothing groups before exporting.
I've got a question regarding the exporting of Blender scenes to be loaded into Three.js, with the focus on lighting.
We're using Blender to create our 3D environments, interiors in this case. In Blender the scenes look like they should. Here's an example I've put together with a single point light with Energy: 50 and Distance: 30. I've made these values so high so the problem is visible clearly inside Three.js. Here is a screen from blender:
Now, when exported using the Three.js exporter for Blender and imported using the SceneLoader, the result in Three.js is:
Don't might the ugly brightness, the problem is the fact that it lights only parts of the scene. It looks like Three.js incorrectly lights different triangles of an object. Our 3D artist makes the objects in Blender using quads.
To make sure the problem lies not within the exporting and importing process, I've created a PointLight within Three with the same position, distance and brightness. This gives the exact same result as above.
I've tried using different lights as well. So far only the Sun light (Directional in Three) seems to give the correct result. The other lights don't work at all when exported from blender, but that is a problem outside of the scope of this post.
My question is: Is it in fact the triangles Three.js creates that cause the problem? Would making the triangles in Blender to begin with fix this problem, or is there a different approach that might fix the problem?
EDIT: Using Phong mats fixed it, but lighting seems incorrectly divided over objects individually:
For a while now I've been having difficulty correctly applying textures to three.js custom objects. Specifically extruded elliptical objects. I have looked around and from what I can see I need to generate the objects UV mapping by using it's bounding box. However, I am unsure exactly how to do this and I can't seem to find any detailed explanation on how this works. Can anyone help explain this process to me in detail?
Thanks,
zaidi92