my question is just about choosing the right approach because i'm not sure about the solution.
i got 3d model in my project, at some point i want to show animated disassembly , the object is made of somthing like 200 pieces.
so animating with keyframe one by one is time consuming.
the animation i'm looking for is like explosion from the center of the object so the parts will just move out of its center.
example image:
what would you do?
what is the best way to manage such task?
I would code it. Maybe I am biased because I am a programmer, but animating it would be a pain.
So I would import the model into Unity3d. Then I would grab all the parts and store them in a list. Once I have the 200 parts then I can do anything I want to them.
I would then proceed to attach rigibodies and box colliders to them all -- this can be done programmatically. Then you can initiate the explosion by adding a velocity to each part. If you want to be fairly realistic and have something that is fairly random you can give each object mass and then use the equation F=ma for the explosion. That is, each part will get different acceleration depending on the mass they have.
Related
I think this requires a bit of background information:
I have been modding Minecraft for a while now, but I alway wanted to make my own game, so I started digging into the freshly released LWJGL3 to actually get things done. Yes, I know it's a bit ow level and I should use an engine and stuff...indeed, I already tried some engines and they never quite match what I want to do, so I decided I want to tackle the problem at its root.
So far, I kind of understand how to render meshes, move the "camera", etc. and I'm willing to take the learning curve.
But the thing is, at some point all the tutorials start to explain how to load models and create skeletal animations and so on...but I think I do not really want to go that way. A lot of things in working with Minecraft code was awful, but I liked how I could create models and animations from Java code. Sure, it did not look super realistic, but since I'm not great with Blender either, I doubt having "classic" models and animations would help. Anyway, in that code, I could rotate a box around to make a creature look at a player, I could use a sinus function to move legs and arms (or wings, in my case) and that was working, since Minecraft used immediate mode and Java could directly tell the graphics card where to draw each vertex.
So, actual question(s): Is there any good way to make dynamic animations in modern (3.3+) OpenGL? My models would basically be a hierarchy of shapes (boxes or whatever) and I want to be able to rotate them on the fly. But I'm not sure how to organize that. Would I store all the translation/rotation-matrices for each sub-shape? Would that put a hard limit on the amount of sub-shapes a model could have? Did anyone try something like that?
Edit: For clarification, what I did looked something like this:
Create a model: https://github.com/TheOnlySilverClaw/Birdmod/blob/master/src/main/java/silverclaw/birds/client/model/ModelOstrich.java
The model is created as a bunch of boxes in the constructor, the render and setRotationAngles methods set scale and rotations.
You should follow one opengl tutorial in order to understand the basics.
Let me suggest "Learning Modern 3D Graphics Programming", and especially this chapter, where you move one robot arm with multiple joints.
I did a port in java using jogl here, but you can easily port it over lwjgl.
What you are looking for is exactly skeletal animation, the only difference being the fact you do not want to load animations for your bones but want to compute / generate transforms on the fly.
You basically have a hierarchy of bones, and geometry attached to it. It looks like you want to manipulate this geometry "rigidly", so before sending your meshes / transforms to the GPU (the classic way), you want to start by computing the new transforms in model or world space, then send those freshly computed matrices to draw your geometries on the gpu the standard way.
As Sorin said, to compute each transform you simply have to iterate over your hierarchy and accumulate transforms given the transform of the parent bone and your local transform w.r.t the parent.
Yes and no.
You can have your hierarchy of shapes and store a relative transform for each.
For example the "player" whould have a translation to 100,100, 10 (where the player is), and then the "head" subcomponent would have an additional translation of 0,0,5 (just a bit higher on the z axis).
You can store these as matrices (they can encode translation, roation and scaling) and use glPushMatrix and glPop matrix to add and remove a matrix to a stack maintained by openGL.
The draw() function(or whatever you call it) should look something like :
glPushMatrix();
glMultMatrix(my_transform); // You can also just have glTranslate, glRotate or anything else.
// Draw my mesh
for (child : children) { child.draw(); }
glPopMatrix();
This gives you a hierarchical setup so that objects move with their parent. Alternatively you can have a stack in the main memory and do the multiplications yourself (use a library). I think the openGL stack may have a limit (implementation dependent), but if you handle it yourself the only limit is the amount of ram you can use. Once all the matrices are multiplied rendering is done in the same amount of time, that is it doesn't matter for performance how deep a mesh is in the hierarchy.
For actual animations you need to compute the intermediate transformations. For example for a crouch animation you probably want to have a few frames in between so that the camera doesn't just jump to the low position. You can do this with a time based linear interpolation between the start and end positions, but this only covers simple animations and you still have to implement it yourself.
Anything more complicated (i.e. modify the mesh based on the bone links) you would need to implement yourself.
Is there a way to make a mesh unprintable with a 3D printer, but still viewable with three.js.
Motivation is that I want to show users a preview of a mesh before he can buy it. But as the JS code is viewable he could download it without paying for it. Degrading the quality of the preview mesh would be a way, but as the quality of the mesh is a selling point I would like to avoid that.
My idea was to add some kind of triangulation defects which would prevent the printing of the mesh, but which would not prevent threejs from showing the mesh.
Tools like Netfabb or Meshlab should also not be able to automatically repair the mesh.
Is there something like a bad sector copy protection equivalent for 3d models?
Just a few ideas.
1) Augment your shaders to ignore some interval of vertices from the buffer (like every 3rd or something). In this way you can add "garbage" to the model file so it can not be lifted easily from the network.
2) Once in the buffer it can still be pulled out with a savvy user, unless you split the model up into many chunks and render out of order or only render the front half of the model making it less useful for 3D printing. One could also render in split views or using stereoscopic interlaced with a separation of zero.
3) Only render a none symmetrical half of your model with an camera control locked to that half :P
Kinda wonky, a ton of work to implement, and still someone will find a way I'm sure. But that's my two cents worth anyway, hope it helps.
I've seen some online shops preview with renders taken from each 10-30 degrees around the model. That way you only pass the resulting image, not the model.
why not show a detailed HD video of your model?
If the mesh is non-manifold it will not print.
a) Render serverside, stream results in an interactive video
b) destroy the mesh while still keeping the normals intact for shading. You can randomly flip faces, render with double sided. You can "extrude" edges to mess up topology. As long as you map the normals correctly, it will shade without any of these defects affecting it.
My question builds up on this thread: Computer Vision / Augmented Reality: how to overlay 3D objects over vision? and on its first answer. I want to build an application that projects on real time the position of a fictional 3D object into a video feed, but the first step I have to take is: How can I do this over a single image?
What I am going for at the moment is having some kind of function that given a picture, its 6D pose (position + orientation), a 3D object (on fbx, 3ds, or something easily convertable to or from others), and its own position and orientation, returns me the projection of the 3D object over the image. Once I have that, I should be able to apply it over every frame of the video feed (how will I get the 6D information of the camera is a problem I'll deal with later)
My problem is that I am unsure where to find such a function, if it even exists. It should be offered like some kind of script or API so an external program can make use of it. Where should I look? Unity? Some kind of OpenCL functionality? So far my reading has not given me any conclusive answers, and as I am a novice in the topic, I'm sure a steep learning curve is ahead and I'd rather put my efforts on the right direction. Thank you
Indeed there's an API for that.
https://developer.vuforia.com
read the GetStarted page.
On this site, there is a "Target Manager", you'll want to upload your target images. Those will allow you to display the 3D object that you want.
On the same "page" you can have several target images.
Example : One that display your 3D object when visible, one that makes it rotates when hided. etc ...
For the real time projection video part, I will make the assumption that, on Unity, you can have a movie texture running on a plane in background and sort your layers in a way that your 3D object is above.
Please update the topic whenever you find a way.
Bye
I used ReconstructMe
to scan my first half body (arm and head). The result I got is a 3d mesh. I open them in 3dsmax. What I need to do now is to add animation/motion to the 3d arm and head.
I think ReconstructMe created a mesh. Do I need to convert that mesh to a 3d object before adding animation? If so, how to do it?
Do I need to seperate the head and arm to add different animation to them? How to do it?
I am a beginner in 3ds max. I am using 3ds max 2012, student edition.
Typically you would set up bones, and link the mesh to the bones with skin or physique modifier, then animate the bones as needed.
You can have 1 mesh, or separate meshes, depends on your needs.
For setting up the rigging, it would be good to utilize a tutorial like this
http://www.digitaltutors.com/11/training.php?pid=332
I find Digital Tutors to be very concise and detailed for anybody to grasp the concepts if your patient enough. Depending on the motion you will like some parts of the bones will require FK (forward kinematics) or IK (inverse kinematics) or a mixture of both FK/IK control in areas like the elbows of the arms etc.
Certain other parts of the character would also like the ability to utilize CAT controls. Through the whole rigging process the biggest foundation or theory to maintain is hierarchy and the process of parenting the controls/linking correctly.
Also your meshes topo needs to be correct, when scanning from an outside source you will get either a. a lot of triangles or b. bad edge flow, before the rigging process make sure to take the time to get your scan's topology to the correct state it should be in.
I have a hierarchical animated model in DirectX which loads and animates based on the following DirectX sample: http://msdn.microsoft.com/en-us/library/ee418677%28VS.85%29.aspx
As good as the sample is it does not really go into some of the details of animation that I'd like. For example, if I have a mesh which has a running animation and a throwing animation as seperate animation sets how can I get the throwing animation to occur for bones above the hip and the walking animation to occur for bones underneath the hip?
Also if I wanted to for example have the person lean left or right would I simply have to find the bone for the hip and multiplay a rotation matrix by its matrix? In this case I think the matrix is m_amxBoneOffsets?
Composing multiple animations to a single one is usually the job of an animation system, something that is way out of scope of the D3D sample.
Let's look at your 2 examples:
running and throwing
Well, in this case you could apply the animation for the lower part of the body from the running animation and the animation for the upper part of the body from the throwing animation. And you'd get a very crappy result.
The how is just a matter of knowing which bones are where in the bone palette (something that depends on how they are stored, and in which order, but nothing inherently hard. The definite reference should be the documentation of the tool generating the animation data)
In practice, you're better off with a blending of the 2 animation. This is, in general, is hard, and software packages exist out there that do this for you. Gamebryo, e.g.
Or, an animation of a running guy who throws is different enough from a standing guy who throws that you might be better off having 2 animations.
Leaning
If you apply a rotation matrix to the root bone, you'll simply rotate your whole character.
Now if you rotate the next bone in the hierarchy (from the spine), you'll get all the bones that depend on it to rotate likewise. It will probably do what you want, but there's a sure way to find out. Try it!
Well the thing is the running animation SHOULD affect the throwing animation slightly. What you need to look into is animation blending.
I'm sure Valve wrote a good paper on how they implemented it in Counter-strike many years ago. Its not on the valve site though so I'm not sure where I got this memory from ...