I am using blender 2.77. I wanna ask why is the upper part of my cloth is flying upwards instead of dropping down when animated? And it is also slightly deform as well when animated. But the bottom part of it is work just fine...I had tried different setting, like adjusting the gravity, self collision distance, material mass, steps, cloth collision setting and it still do not solve the problem...Anyone can give me a solution regarding this problem? thank you :)
here is the link of the image: http://i.stack.imgur.com/NHIFT.jpg 1
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I'm trying to create a fluid simulation on blender 2.92 but after the bake of the fluid, this one is not laying on the floor. It's floating at around 10cm above and also, it stays at 10cm from the walls.
Space between fluid and floor
Space between fluid and walls
Low res render
Does anybody know what I'm setting wrong ? The obstacle is inside a cube which has a solidify modifier applied and set up as Effector / Collision.
Any help will be appreciated
Did
Without having much to look at other than what you had provided, it's the resolution of your domain. When you look at your domain box, there should be a small "cube" in the corner. If you move the cube down under your floor to where the top of the cube is touching the floor, this will fix the gap between the floor and water. Just keep in mind, when you increase that resolution, that cube will get smaller. Meaning, you will need to adjust the position of it yet again. For the walls, you will need to widen your domain until the side of the cube is on the outside of the wall.
Think of the cube as a "safety boundary/perimeter" or something like that. Hopefully that all makes sense?
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.
When using DeviceOrientationControls, I need to allow the user to reset their view to an arbitrary direction. Basically if I'm sitting in a chair with limited range of head motion, I want to allow the camera to switch to a different direction (how I trigger that change is not important).
alphaOffsetAngle works great for resetting the view to look left, right, or behind, but not for looking up or down (or left/right, but rotated).
I tried adding offset angles for Beta and Gamma, but that isn't as straightforward as I hoped. I also tried adding the camera to an Object3D and rotating the parent. That sortof worked, but the controls got all wonky when the camera's parent was rotated.
lookAt() is pretty much what I want, but the DeviceOrientationControls update() seems to blow that away.
Does anyone have a working example of this arbitrary camera direction with the deviceorientationcontrols?
This question is similar these, but I have not found a workable solution:
Add offset to DeviceOrientationControls in three.js
and:
DeviceOrientationControls.js - Calibration to ideal starting center
A quick introduction:
We're developing a positioning system that works the following way. Our camera is situated on a robot and is pointed upwards (looking at the ceiling). On the ceiling we have something like landmarks, thanks to whom we can compute the position of the robot. It looks like this:
Our problem:
The camera is tilted a bit (0-4 degrees I think), because the surface of the robot is not perfectly even. That means, when the robot turns around but stays at the same coordinates, the camera looks at a different position on the ceiling and therefore our positioning program yields a different position of the robot, even though it only turned around and wasn't moved a bit.
Our current (hardcoded) solution:
We've taken some test photos from the camera, turning it around the lens axis. From the pictures we've deduced that it's tilted ca. 4 degrees in the "up direction" of the picture. Using some simple geometrical transformations we've managed to reduce the tilt effect and find the real camera position. On the following pictures the grey dot marks the center of the picture, the black dot is the real place on the ceiling under which the camera is situated. The black dot was transformed from the grey dot (its position was computed correcting the grey dot position). As you can easily notice, the grey dots form a circle on the ceiling and the black dot is the center of this circle.
The problem with our solution:
Our approach is completely unportable. If we moved the camera to a new robot, the angle and direction of tilt would have to be completely recalibrated. Therefore we wanted to leave the calibration phase to the user, that would demand takings some pictures, assessing the tilt parameters by him and then setting them in the program. My question to you is: can you think of any better (more automatic) solution to computing the tilt parameters or correcting the tilt on the pictures?
Nice work. To have an automatic calibration is a nice challenge.
An idea would be to use the parallel lines from the roof tiles:
If the camera is perfectly level, then all lines will be parallel in the picture too.
If the camera is tilted, then all lines will be secant (they intersect in the vanishing point).
Now, this is probably very hard to implement. With the camera you're using, distortion needs to be corrected first so that lines are indeed straight.
Your practical approach is probably simpler and more robust. As you describe it, it seems it can be automated to become user friendly. Make the robot turn on itself and identify pragmatically which point remains at the same place in the picture.
I'm having an issue with back faces (to the light) and shadow mapping that I can't seem to get past. I'm still at the relatively early stages of optimizing my engine, however I can't seem to get there as even with everything hand-tuned for this one piece of geometry it still looks like garbage.
What it is is a skinny wall that is "curved" via about 5 different chunks of wall. When I create my depth map I'm culling front faces (to the light). This definitely helps, but the front faces on the other side of the wall are what seem to be causing the z-fighting/projective shadowing.
Some notes on the screenshot:
Front faces are culled when the depth texture (from the light) is being drawn
I have the near and far planes tuned just for this chunk of geometry (set at 20 and 25 respectively)
One directional light source, coming down on a slight angle toward the right side of the scene, enough to indicate that wall should be shadowed, but mostly straight down
Using a ludicrously large 4096x4096 shadow map texture
All lighting is disabled, but know that I am doing soft lighting (and hence vertex normals for the vertices) even on this wall
As mentioned here it concludes you should not shadow polygons that are back faced from the light. I'm struggling with this particular issue because I don't want to pass the face normals all the way through to the fragment shader to rule out the true back faces to the light there - however if anyone feels this is the best/only solution for this geometry thats what I'll have to do. Considering how the pipeline doesn't make it easy/obvious to pass the face normals through it makes me feel like this isn't the path of least resistance. And note that the normals I am passing are the vertex normals, to allow for softer lighting effects around the edges (will likely include both non-shadowed and shadowed surfaces).
Note that I am having some nasty Perspective Aliasing, but I'm hoping my next steps are to work on cascaded shadow maps, but without fixing this I feel like I'm just delaying the inevitable as I've hand-tightened the view as best I can (or so I think).
Anyways I feel like I'm missing something, so if you have any thoughts or help at all would be most appreciated!
EDIT
To be clear, the wall technically should NOT be in shadow, based on where the light is coming from.
Below is an image with shadowing turned off. This is just using the vertex normals to calculate diffuse lighting - its not pretty (too much geometry is visible) but it does show that some of the edges are somewhat visible.
So yes, the wall SHOULD be in shadow, but I'm hoping I can get the smoothing working better so the edges can have some diffuse lighting. If I need to have it completely in shadow, then if its the shadow map that puts it in shadow, or my code specifically putting it in shadow because the face normal is away, I'm fine with that - but passing the face normal through to my vertex/fragment shader does not seem like the path of least resistance.
Perhaps these will help illustrate my problem better, or perhaps bring to light some fundamental understanding I am missing.
EDIT #2
I've included the depth texture below. You can see the wall in question in the bottom left, and from the screenshot you can see how i've trimmed the depth values to ~0.4->1. This means the depth values of that wall start in the 0.4 range. So its not PERFECTLY clipped for it, but its close. Does that seem reasonable? I'm pretty sure its a full 24 or 32 bit depth buffer, a la DEPTH_COMPONENT extension on iOS. For #starmole, does this help to determine if its a scaling error in my projection? Do you think the size/area covered of my map is too large, hence if it focuses closer it might help?
The problem seems to be that you are
Culling the front faces
Looking at the back face
Not removing the light from the back face because it's actually not lit by the normal - or there is some inaccuracy in the computation
Probably not adding some epsilon
(1) and (2) mean that there will be Z-fighting between the shadow map and the back faces.
Also, the shadow map resolution is not going to help you - just look at the wall in the shadow map, it's one pixel thick.
Recommendations:
Epsilons. Make sure that Z > lightZ + epsilon
Epsilons. Make sure that the wall is facing the light (dot of normal > epsilon) to make sure the wall is shadowed if it's very nearly orthogonal