Why do two faces appear invisible in ThreeJs? - three.js

I've an object in Blender. Because I want to do some UV-unwrapping using ThreeJS (see here) I determined that I need merge two of the sides to correctly unwrap.
So before exporting the .blend as a .obj object I selected the Tris to Quads face option to create a square face for the two sides as opposed to it being made up of two triangles. Here's what it looked like in Blender:
But when I import the .obj and .mtl file into ThreeJs I get this:
Is this a problem to do with me not updating the material being added to the new object?
The handles appearing white makes me think this is the case. If so how can I go about fixing it?

When I see something like this, the first thing I usually do is to set the material to side: THREE.DoubleSide. If that helps, the problem has to do with the normal-directions (so the face is actually there but isn't rendered because it is facing away from you).
To fix this, you should try the following:
In blender you can enable displaying of normal-directions in the right-hand menu (select "Face normals in section "Mesh Display").
You should now see if any of the normals are pointing inwards/in the wrong direction.
There is an automatic fix that works well for properly constructed meshes:
select object and switch into edit-mode (<Tab>)
select all vertices (shortcut &ltA>)
via menu "Mesh" > "Normals" > "Recalculate Outside" (shortcut <Ctrl>+<N>).

Related

How to fix image texture not transfering to Unity from Blender

I textured an object in Blender because it wouldn't texture properly in Unity, and then imported the object and texture to Unity.
I don't know how to fix this, I'll put both pictures here.
Blender Texture Before Import
Object In Unity
Okay, so based on your screenshots..
You're going to select everything then add a modifier called "Solidify", then set this to something very small like .03. (Unity doesn't like objects that are just planes).
double check all your normals are facing out. Let me know if you don't know how to do this...
Go into edit mode select all edges, then right click, select "mark as seam".
Open UV editor window (should be split screen with Edit mode on one side, UV view on the other). In the Edit side select all, then go to UV dropdown menu and click "unwrap". You should then see your object unfolded into flat planes over on the UV window side. There's different unwrap options, like smart UV unwrap, etc. I think just "unwrap" has worked for me, but play around and there may be something that shows your object shapes in a less distorted way..
At this point, since your pattern is basically repeating. If you export the OBJ file and take it into unity, and you add the image file (make sure it's dimensions are perfectly square) it should receive the image file as an Albedo texture much better than in your screenshots. You can play with the 'tiling' and "X/Y offset" till it looks right (you might face issues with rotation though.
BUT
If you want to line it up very specifically, you can export the UV layout as a png from the UV window in blender. Then use photoshop or another photo editor to change/rotate and arrange your texture so the sides line up properly. In blender in the Edit window (assuming you still have both UV + editor open) when you select a side it will highlight in the UV window the corresponding flat plane, based on this you should be able to figure out what should be rotated up/down, etc. Then when you change that 2d image and drag it into Unity, it will adjust and wrap around the object.
I'm pretty new to both, but the advice I've been given is to not do the texturing in blender, but instead to do it in Unity.
This is a 10-month-old post but incase anyone is curious or struggling the same, Blender exports models with a scale of 100 so you need to scale up the tile of the material (in material settings) to see it.
This is a bad solution however because then you are not working with objects on a scale of 1 so you actually want to check "Apply transformations" when exporting the FBX model in blender

Material not showing correctly

I'm having an issue where the material is not showing correctly. I checked the MTL file and all looks correct but for some reason, the material seems to be flipped(I can see it through some parts while it should be the screen). Initially I thought there was something wrong with the MTL or the OBJ but here comes the funny part. On 3dviewer.net the model looks completely perfect(last screenshot).
Therefore, does anybody have a clue on what's happening?
By default, Three.js only renders the front side of faces, since there's often no reason to render the inside of objects. The problem is that the asset you've exported has the face of the screen pointing inwards. There are two ways of solving this problem:
Open the asset in a 3D editor, flip the direction of the faces that are pointing inward, and re-export.
You could change the default material.side attribute of your material. My best guess is that: material.side = THREE.BackSide would solve your problem, but you could try the other values in that documentation page.

Strange lines ("seams") appearing when applying texture to threejs model

I am rendering a model imported from a .ctm file into threejs v71. I'm then adding a texture using a MeshBasicMaterial with map.
The original model was made in Agisoft Photoscan, exported as .obj, and then converted to OpenCTM format using the official OpenCTM viewer program. The .ctm model itself is here.
It looks correct, except that strange "seams" appear on the texture when I load the .ctm . The .obj loads fine in three.js with no seams. What are these, and how do I get rid of them?
Here's a screenshot:
These "seams" are not present in the texture file:
UPDATE: I noticed that the seams are also visible when viewing the .ctm in the ctm viewer, so this is probably an OpenCtm conversion problem rather than a threejs loading issue.
To my chagrin it seems this is a longstanding bug in OpenCTM.
The other answers must not be reproducing the situation described in the question.
Edit: I now fully understand this problem and have a workaround for it. The issue is that most programs (Photoscan, Blender) have "per-loop" vertices instead of actual "per-vertex" textures. This just means that when a vertex is shared by two polygons, there can be multiple UV coordinates for that vertex. CTM can only have one UV coordinate per vertex and that's what causes the problem at texture seams.
My workaround in blender is:
Seams from Islands
Select an edge on seam, select similar --> seam. Now all seams should be selected
Mesh --> Edges --> Edge Split
Export to .obj, use ctmviewer.exe to import and export to .ctm.
The seams are still visible if you look closely but no longer obvious multicolored bands.
I had the same issue with my Agisoft Photoscan model/texture, so I opened the texture in Photoshop and noticed it had transparency between all the patches of texture. I filled all the gaps using content aware fill and saved the texture out as a .tif without layers. This solved the issue for me.
Or you can just remove the alpha-channel from the texture image file (or use JPG format during export).

Blender exports a three.js animation - bones rotate strangely

I'm currently trying to export an animated blender model to three.js using the exporter of three.js (github.com/mrdoob/three.js/tree/dev/utils/exporters/blender/2.66/scripts/addons).
I've created a model including bones and weights and a tiny animation.
The problem I have: The model gets broken. Somehow the bones don't rotate around their origin but around the origin of the root bone. Moving the bones manually does not make a difference.
I followed these tutorials:
devmatrix.wordpress.com/2013/02/27/creating-skeletal-animation-in-blender-and-exporting-it-to-three-js/
dev.mothteeth.com/2012/10/threejs-blender-exporting-skeletal-animations/
I have:
Deleted the Armature
Checked the Vertex Groups
Keyed all bones in the first and last frame.
I've been to pretty much every thread I could find on github and stack overflow. These seem to be the main issues for these errors. But I guess I still miss any point. :(
I have uploaded all files including the blender files and exported animation.
http://www.file-upload.net/download-8068001/forum-files.rar.html
Any suggestions?
Thanks a lot in advance.
The problem was that the location/rotation/scale were not reset before exporting the model.
Before You export Your model, select the mesh and press CTRL+A and select location. Repeat for rotation and scale, then select the armature and do the same. Now it works.
I've downloaded both the tutorial package and your code. The code aspect looks fine. So looking over the model I see that your vertex groups are not well defined. When I select the Left_collarbone bone, left_upperarm, left_lowerarm I seem to be getting vertices from parts of the torso, head, etc... in the mix. I suspect that what your seeing with your funky shoulder stretch animation is that the collarbone is part of some other groupings and when exported the "weights" of the mesh are confused causing the bone to pull badly on the mesh. Try cleaning up the vertex groups and see if that helps. #lukasz1985 has the right idea, nice one! +1
P.S. Thanks for the link to the cool animation tutorials for Three.js :)
I had an issue where calling THREE.GeometryUtils.center(geometryWithBones) on a the newly imported geometry would make all the skinning look very strange. Getting rid of that fixed things.
Also make absolutely sure, that the three.js blender exporter is not set to to align your model in any way. (I had it set to "center" and it took me 4 hours to figure out why my bones rotate around some spot that was NOT the spot they rotate around in blender.)

Three.js shadow map stripes in each light (now simplified, and with jsfiddle!)

I'm trying to create, modify and update (directional only for now) lights and shadowmaps dynamically. The light, shadow and shadow camera helper gets updated correctly as I move the light around or change shadow properties, except from the light's point of view, everything behind the origin (0,0,0) is shadowed for no apparent reason.
Screenshots:
http://i.imgur.com/n4AHvle.png
http://i.imgur.com/l0uaZHD.jpg
http://i.imgur.com/brKwCof.jpg
http://i.imgur.com/a6dqMGo.jpg (new, with spotlight)
You can see a scene with car and a piece of ground, they belong to a geometry imported with ColladaLoader. The problem is with shadowmapping, the car throws shadow correctly, but there are stripy shadows on the ground even though there is nothing else than the car obscuring light.
If I add more similar lights, they also have the same 4 stripes. They also appear with spotlight. If I change shadow map resolution, the stripes' size changes relative to each other, but there seems to be always four of them, spaced from center to both directions.
EDIT: JSFiddle here: http://jsfiddle.net/cL3hX/1/ There shouldn't be any shadows in the scene, unless some new geometry is introduced inside the shadow camera frustum.
Couple of notes on the fiddle:
I have r55, but the demo is r54 because jsfiddle apparently does not yet have r55.
I could only reproduce this with a Collada file. So it probably has something to do with the model. I created a simple cube in Sketchup 8, and tried to export it with various collada options.
In the JSFiddle I could only reproduce the bug with a file exported with "doublesided faces" -setting enabled. In my own application code, I do have the same bug on models created with or without that setting enabled, but in the fiddle, the bug seems to be triggered only when "doublesided faces" are exported. Anyway I do need to somehow show backsides of faces, because the tool I'm developing must work with Sketchup exports, and it's very hard to make models in Sketchup without having a mess of frontsides/backsides visible.
The very simple Collada file is included in the JSFiddle as javascript variable. Here's a download link for the same file: https://dl.dropbox.com/u/14489569/shadowmapdemo.dae
The problem is your Collada model.
Your "plane" is actually multiple coplanar faces back-to-back in a single geometry.
It's no wonder there are artifacts.
Replace it with a THREE.CubeGeometry.

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