I'm trying to use the three.js physics cloth demo to create a tablecloth but the resulting cloth is always a vertical banner. Is uses the ammo softBodyHelpers.CreatePatch function to make the softbody but I could not find doc on how this can be used. Does any one know how this can be adapted to make a table cloth ? My initial mesh looks fine as a table cloth but as soon as the first physics loop updates the mesh it moves immediately vertices into a vertical banner.
According to ammo.js github page:
ammo.js is a direct port of the Bullet physics engine to JavaScript,
using Emscripten. The source code is translated directly to
JavaScript, without human rewriting, so functionality should be
identical to the original Bullet.
Looking at the documentation for Bullet's SoftBodyHelpers, CreatePatch is indeed meant for rectangular geometry only.
Good news, though - there's a separate function called CreateEllipsoid.
Do you have any other static geometry in the scene for the cloth to collide with? Otherwise it will just be a sheet, falling through frictionless space.
Related
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 compose multiple STLs for 3D printing / milling. For that I also use CSG and need some raytracing for detecting features of the models.
My scene is pretty much static. Just have to move around the models to arrange them. For this use case I'm not really sure which approach for moving / rotating the models is right.
Currently I manipulate the BufferGeometries directly. So everything in the geometry is like in the real world. Each position, each normal. No calculation from / to local or world coordinates.
On the other hand I could do the same thing with changing the meshes, which means to change just a matrix.
For me, working with the mesh is more for animation etc. While working with the geometry to manipulate the real object, which is my intention.
I'm wondering when one would translate / rotate the geometry and when the mesh. I know that manipulating the geometry is not best for CPU, which is not a problem for my use case.
Geometry can be translated so that subsequent transformations (such as scale or rotation) originate from a more preferred vector. Meshes can share a geometry. There are unique use cases for either if you care to memorize the list. Sometimes I integrate preexisting code samples. Sometimes the decision is made for me by some aspect of the process. As for the properties which may be similar, which is more convenient? I like the pattern of modifying an Object3D dummy using those methods and then updating from its matrix. There's a whole book on normals, but I didn't write it, sadly...
Using three.js am trying to create a floor that reflects the objects that sit upon it. Preferably the floor material should reflect not like a mirror but in a more 'matte' or diffused way.
To achieve this I looked to Jaume Sanchez Elias who has made a great example using a cube camera: Look for the "smooth material" example on this page:
http://www.clicktorelease.com/blog/making-of-cruciform
Here is my attempt using the same technique. But as you see the reflections are misplaced, they do not appear underneath the mountain objects as expected.
http://dev.udart.dk/stackoverflow_reflections/
I am looking to correct this or to use any other technique that will achieve a more correct diffused reflection.
There are three.js examples using the cube camera technique but they all create mirror-like effects not a soft reflection.
Vibber. Parallax-corrected cubemaps, the technique used in cru·ci·form, only works for closed volumes, like cubes. It works really well to simulate correct reflections inside a room, but not so much for outdoors or open/large scenes. They also can't reflect anything that it's inside the cubemap, you'd have to split the volume in many sub-volumes.
I can think of a couple of solutions for what you want to achieve:
SSR: Screen-space reflections, you can find more info in many places on the internet. It's not the most trivial of effects to implement, and you might have to change the way you render your scene.
Simpler post-processing approach: since you have a flat floor, render the mountains vertically flipped on a framebuffer object, blur it, and render the regular scene on top. For extra effect, render the depth of the flipped mountains, and use that value as the blur radius, to get diffuse reflections.
As always, there's a ton of ways to achieve the (un)expected result :)
Does Three.JS have a function or capability of AI( Artificial intelligence )? Specifically let's say a FPS game. I want enemies to look for me and try to kill me, is it possible in three.js? Do they have a functionality or a system of such?
Webgl
create buffer
bind buffer
allocate data
set up state
issue draw call
run GLSL shaders
three.js
create a 3d context using WebGL
create 3 dimensional objects
create a scene graph
create primitives like spheres, cubes, toruses
move objects around, rotate them scale them
test for intersections between rays, triangles, planes, spheres, etc.
create 'materials' (rather than shaders)
javascript
write algorithms
I want enemies to look for me and try to kill me
Yes, three.js is capable of doing this, you just have to write an algorithm using three's classes. Your enemies would be 3d objects, casting rays, intersecting with other objects, etc.
You would be building a game engine, and you could use three.js as your rendering framework within that engine. Rendering is just one part of it. Think of a 2d shooter, you could make it using a 2d context, but you could also enhance it and make it 2.5d, by working with a 3d context. Everything else can stay the same.
any webgl engine that might have it ? or is it just not a webgl thing
Unity probably has everything you can possibly think of. Unity is capable of outputting WebGL, so it could be considered a 'webgl engine'.
Bablyon.js is more engine like.
Three Js is the best and most powerfull WebGL 3d engine that has no equal on the market , and its missing out on such an ability
Three.js isn't exactly a 3d engine. Wikipedia says:
Three.js is a lightweight cross-browser JavaScript library/API used to
create and display animated 3D computer graphics on a Web browser.
Three.js uses WebGL.
so if i need to just draw a car, or a spinning logo, i don't need them to come looking for me, or try to shoot me. I just need them to stay in one place, and rotate.
For a graphics demo you don't even need this - with a few draw instructions, you could render a full screen quad with a very elaborate pixel shader. Three gives you a ton of options, especially if you consider all the featured examples.
It works both ways, while you can expand three.js anyway you want, you can strip it down for just a very specific purpose.
If you need to build an app that needs to do image processing, and feature no '3d' graphics, you could still leverage webgl with three.js.
You don't need any vector, matrix, ray , geometry classes.
If you don't have vector3, you probably cant keep planeGeometry, but you would use bufferGeometry, and manually construct a plane. No transformations need to happen, so no need for matrix classes. You'd use shaders, and textures, and perhaps something like the EffectsComposer.
I’m afraid not. Three.js is just a engine for displaying 3d content.
Using it to create games only is one possibility. However few websites raise with pre-coded stuff like AI (among other things) to attract game creators, but using them is more restrictive than writing the exact code you need
Three.js itself doesn't however https://mugen87.github.io/yuka/ is a great AI engine that can work in collaboration with three to create AI.
They do a line if sight and a shooting game logic, as well as car logic which I've been playing around with recently, a React Three Fiber example here: https://codesandbox.io/s/loving-tdd-u1fs9o
I am new to unity. I have two animation in .fbx format.They can move..Now i want when both will collide with each other a sound will produce.Is there any idea how i will do this.Thanks in advance
I think you need to read about how Physics work, and then how Trigger-Events and Colission detection is handled.
Read this here, and this. The first one gives you insight on how the Unity engine works. The latter provides a video tutorial on how to do Collision Detection.
If you don't want to do that and just want the code, I found this on a quick Google:
var crashSound : AudioClip; // set this to your sound in the inspector function
OnCollisionEnter (collision : Collision) {
// next line requires an AudioSource component on this gameobject5.
audio.PlayOneShot(crashSound);
}
You can add a MeshCollider to the fbx meshes. Anyway, this is not a good idea because this will cause performance issues.
You can create an empty gameobject for each character, and add to them: the fbx animation and a simple collider (some cube, sphere, capsule, etc). Then, when you use a script for them, you attach it to the parent object and from there you handle the whole thing.
If you want that the collider moves from specific places from the animation (Like the punch movement, or a kick),then you can ask to your 3D animator/modeler to add a simple mesh on that points. For example, a sphere on one punch, which will move with the animation. Then, in Unity, you will hide the mesh of the sphere but add a mesh collider to it. :)
Hope it helps!
Most of the time, if you apply an animation to an object then you'll loose the physics reaction. Don't trust me? See here: http://www.youtube.com/watch?v=oINKQUJZc1Q
Obviously, animation are not part of Unity physics. Think about it... Unity physics decide position and rotation of objects accordingly to Newton and friends laws. How do you think these laws can accord to a keyframe arbitrary animation? They can't: hence the crazy results you get when you try.
How to solve it? Use Unity physics also for animation: learn to master rigidbody.AddForce and all the other stuff described here.
You may always want to keep the physics and the animation separated. That's how you get out of trouble.
If you really want to know: here's my personal experience on how to mediate physics with animation.
Sometimes, even binding a simple parameter to the physics and another
to an animation (or a script which mediates user input) may result in
catastrophic results. I've made a starship: rotation controller by
user mouse (by flagging "block rigidbody rotation"), direction and
speed by physics. It was inside a box collider. Imagine what happens
if a cube, orientated by a few degrees angles, meets a flat ground: it
should fall and rotate until one of the faces lays completely on the
ground. This was impossible, as I blocked any physics interaction with
the rotation of the body: as a result the box wanted to get flat on
the ground but couldn't. This tension eventually made it move forward
forever: something impossible in real world. To mediate this error,
I've made the "block rotation" parameter change dynamically according
to the user input: as the ship is moving the rotation is controlled by
the user but as soon as the user stop controlling the ship the
rotation parameter is given back to the physics engine. Another
solution would be to cast a ray down the collider, check if the ground
is near and avoid collisions if the ship is not moving (this is how
the banshee in Halo Combat Evolved is controlled, I think). When
playing videogames, always have a look at how your user input is
mediated into the physics engine: you may discover things which a
normal player normally wouldn't notice.