# Questions tagged [animation]

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236 views

### How can I model distant rain?

Close up, rain can be modeled as transparent balls of water with appropriate motion blur. This seems impractical for large volumes, which would be necessary for scenes of rain in the distance. At ...
9k views

### How to achieve gimbal lock with Euler angles?

I was studying about Euler angles and I came across the problem gimbal lock which can occur by using Euler angles. In gimbal lock we lose one axis of rotation. But how? And when does it happen? On ...
695 views

### Was Evans & Sutherland CT5 really created in 1981?

A few days ago I found a video on Twitter showing the Evans & Sutherland CT5 Flight Simulator system. It was labeled as 1981 footage and looked really amazing. The first time I saw similar 3D ...
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2k views

### Pixel dispersion (dissolving) algorithms

This YouTube video of a flip-dot display (physical b/w pixels) shows the reverse of an effect that might be called dissolve or dispersion, i.e. a text emerges from noise by pixels moving in to form ...
• 153
224 views

### Questions about Preconditioning Conjugate Gradient method in Baraff & Witkin 98?

I encountered some problems when implementing the cloth simulation algorithm from Baraff & Witkin 98's Large Steps in Cloth Simulation. Baraff & Witkin 98 Consider the cloth as a particle ...
• 153
147 views

### How does a rigged model work?

What black magic is behind this? Starting from a pile of polygons, a skeleton, and an initial conformation, how is a new conformation turned into a new pile of polygons?
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846 views

### Calculating Skeleton-Deformed Mesh Normals

I'm implementing mesh skinning in a project of mine. I can calculate vertex positions based on bone transformations, but I've run into a problem with calculating their normals. From the resources I'...
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251 views

### Spine. What is the name of the process?

https://www.youtube.com/watch?v=twUz99ek5do&list=WL&index=5 There is a process from 1:51, where the guy start making polygons around the bodyparts. I think this is this part is where (with ...
• 41
175 views

### Software to compose separate models into an articulated model?

I've inherited a system which animates a humanoid avatar by loading various models and manually calculating transformations for each one. I'm in the process of porting part of this system to Three.js, ...
• 149
316 views

### Fake cubic Hermite spline interpolation with smoothstep

When scaling an image with Bicubic Interpolation, the Cubic Hermite spline interpolation is used. smoothstep is one of the four basis/blend functions of this kind ...
• 141
287 views

### What algorithm is used in this animation from Tatami Galaxy?

Is there a name for this type of effect where many area sizes are increased/decreased in relation to each other? I'm looking for some type of algorithm, formula, logic, etc. for recreating this. Here ...
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611 views

### Storing 3D animations for ray tracing

I've just finished writing a path tracer that takes OBJ files and renders it. This is convenient for still images, but my end goal was to export a sequence from a 3D application (Blender was what I ...
• 389
94 views

### Need help reasoning about video oscillation >60hz

I want to make a basic video oscillator for the web. What I want to do is basically illustrated in a tutorial for Lumen: essentially, I want to define an oscillator to turn on and off a color signal ...
• 31
145 views

### What's the simplest, open, animation format?

I have an obj parser that handles triangle meshes specifically. I want to extend it (and the rest of my system) to handle animations as well. However, I don't think I am ready to tackle the glTF ...
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1k views

### glTF animation keyframe question

I have an animated cube with 5 keyframes and when I export it to glTF with blender, in the file I can only see 3 keyframes: But when I viewed the gltf model with viewer all 5 keyframes worked well ...
57 views

### Inspecting gltf animation data

I am trying to load gltf data onto an engine I am making and I am noticing that something is wrong with the rotations. I want to be able to see the raw numeric values of the animation data in the gltf ...
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236 views

### What is the point of having integer-based draw routines in software rasterizer?

I wonder why all the well known algorithms of drawing for example circles (bresenham, mid-point, etc) all use integer arithmetics? For example, here is a simple circle drawn with bresenham algorithm: ...
• 269
66 views

### Should animations be locked to FPS or Fixed time

I have been working on a 3D engine and I am now implementing animations, but I can't find out whether or not to use the FPS of the engine or a fixed time method for the transformation's speed. Could ...
• 23
105 views

### What noises can be sliced?

A well-known property of Perlin noise (with FBM) is that if you take a slice of it, the result is still Perlin noise. So, by taking successive slices of 4D noise, you get smoothly shifting 3D noise, ...
• 275
1k views

### How can I use 3d animation to create a character that uses sign language?

I performed a quick search on programs that translate natural language to sign language (through a 3D animation character). Here are examples: IBM SISI ProDeaf (which is an android app) My question ...
633 views

### Inverse Kinematics with more than 2 segments

I'm building a 2D inverse kinematics system and can't figure out how to find all the joint positions. I have the math to make a typical IK set up with a single bend (e.g. arm, leg), but I get stuck ...
75 views

### How to design something like this? [closed]

I am very eager to know what technology might been used to implement this piece of wonder: Any idea? I think, it's ray tracing. What do you think?
• 121
139 views

### pseudoinverse Jacobian and adding more control in computer animation

I am studying inverse kinematics. But I wonder the suggested equations. (The following equations are taken from 'Computer Animation Algorithms and Techniques Third Edition Page, 181') To better ...
• 523
35 views

### Double quaternion skinning artifacts

This is technically about PGA motors, but dual quaternions are a subalgebra of PGA so for all given purposes it's the same idea. I have an animation in gltf, specified as inverse bind pose matrices, ...
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180 views

### Pitfalls of animating with quaternions

When working with animating a rig, quaternions are often used for rotations. However sometimes we need to clear rotation along given local axis of a joint. With quaternions it's not as simple as just ...
• 506
147 views

### Triangle-based and vertex-based skinning models?

I'm reading the Loper et al. 2015 paper on the Skinned Multi-Person Linear Model and I came across this: What we would like is a vertex-based model that has the expressive power of the triangle ...
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123 views

### Interpolating normals during animation

I'm doing linear tweening of a cyllinder to a cone of equal radius and height in OpenGL. I know parametric equations of both of them, so I derived vertex normals accordingly. Now, I know, that proper ...
• 153
105 views

### How are fluid simulations handled in Computer Graphics?

How are fluid simulations handled in Computer Graphics? For a novice, there are hardly any novice friendly tutorials explaining how particles or fluids can be simulated. Things like smoke, crown ...
• 2,463
157 views

### smooth zoom animation formulas (and rounding numbers)

I need to generate an easy animation video in Python (I use PIL to create every frame, then combine them using avconv). The animation is just an image being zoomed ...
361 views

### Coordinate system transformation in motion capture files

I am trying to align two motion capture files from different sources. The motion capture file consist of a skeleton specified as a hierarchy of joints. Each joint i.e. "shoulder" has three pieces of ...
• 121
68 views

### How is smooth animation accomplished? [closed]

How are objects moved smoothly from point A to point B given matrix transformations that describe next position?
1 vote
110 views

### How to apply a linear transformation to gltf data

I am trying to transform the mesh data in a gltf file and then modify the skin and animation data accordingly. Let's say we want to transform the data using a 4x4 homogeneous matrix. For ...
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1 vote
56 views

### Why are these 2 buffers joint while extracting glTF information?

I am using tinyGLTF to parse gltf files and then render them in my program. I am currently during the third example in this page. In particular I am trying to extract the 2 animation buffers: My code:...
• 1,594
1 vote
471 views

### Why do animated CG characters always feel fake?

Why do animated CG characters always feel fake? Usually if a CG character is an animal (or humanoid creature), they tend too look kinda off. Their movement tends to look oddly smooth or lightweight, ...
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1 vote
68 views

### Consistent animation speed across systems

I recently noticed that in all games, no matter what system you play on or what specs you have, your character will always move at the same speed even if there is no frame rate limit. I was wondering ...
1 vote
72 views

### Is it possible to draw the intersection of two squares of known dimension using only x,y coordinates and without an if statement?

Say I have two squares, both 10x10, with some small, unknown overlap. Is there a way to draw the intersection of these two squares using the width, height and x,y coordinates of each square, while ...
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1 vote
80 views

### Can you encode a reflection in a quaternion?

Say we have the transformation: \begin{bmatrix} 1 & 0 & 0\\ 0 & 0 & 1\\ 0 & 1 & 0\\ \end{bmatrix} i.e. the matrix that encodes swapping the z and y axes. This is equivalent to ...
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1 vote
250 views

### How to plot an ADC value from the Raspberry PI Pico using pythons matplotlib

Being new to Python and this community, I am trying to plot the pulse return from a transducer. The pulse return is 400 uSecs in duration and occurs every 100 milliseconds. So far I can plot the ...
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1 vote
33 views

### Understanding rig joint angle definitions in Blender

I am trying to transfer some mocap data from one skeleton to another one. However, the skeletons have different rest poses (one has T-pose, and the other some other one), so I am trying to convert the ...
• 111
1 vote
69 views

### General interpolation practices

Say my animation scenario contains one mesh interpolating into another (possibly approximating over other meshes), using Bezier curves. I know that for smooth surfaces, where normals can be ...
• 153
48 views

### Animated rainbow distortion wave effect

https://foundation.app/mg/20210227-3lau-makes-history-1790 The link above shows a video animation that has a rainbow wave distortion effect applied to it, that ripples across the video. how, and in ...
• 115
58 views

### What is the name of this moving color pixels effect, for animating a painting?

https://superrare.co/artwork-v2/spring-22267 The artwork in the link seems to be based on a painting of a woman, but effects have been added that assign a pixel to each block of the painting that ...
• 115
104 views

### Which techniques do I need to animate a 3D model in my homemade engine

Suppose I am making my own C++ 3D engine; I can already load a 3D model using assimp, display it with phong lighting, and I now want to animate it. I'd like features in my engine to, say, load a run ...
34 views

### compression of gif animation

I have a parchment animation at singingdays.co.uk that is a rather large file of about 80mb which obviously is taking a long time to download. I have managed to compress it down to about 60mb using ...
168 views

### Compute Speed of Spheres in 3D animation

I have created two animations: One where a "camera" moves towards the spheres creating an optic flow (1st GIF).The code can be found here. One where spheres move randomly in a 3D coordinates space (...
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84 views

### kinematics and dynamics of a sphere in a spring mass system?

I am attempting to code a simple spring mass system simulation in which a sphere pendulus hangs from a string (a spring) by the top and then another sphere (controlled by the user) can move and ...
• 1,594
54 views

### Starting from a basic glTF (such as a static sphere or plane) exported from Blender how can I add an animation manipulating its JSON?

I'm working on a glTF, precisely I'm trying to animate a "static" mesh exported from Blender directly acting on its JSON. In doing so, I'm following the logic used in this tutorial , where a ...
12 views

### Appending animations of different rigs?

I have a gltf model that is fully rigged, I have a few animation files also in gltf. Is there a way for me to retarget the animations in the animation files to the rigged model? The positions of the ...
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