Questions tagged [animation]

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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 ...
trichoplax is on Codidact now's user avatar
9 votes
2 answers
10k 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 ...
Ankit singh kushwah's user avatar
5 votes
3 answers
763 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 ...
Gonrah's user avatar
  • 53
5 votes
2 answers
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 ...
handle's user avatar
  • 153
5 votes
1 answer
237 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 ...
stanleyerror's user avatar
4 votes
1 answer
150 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?
Praxeolitic's user avatar
4 votes
1 answer
957 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'...
lowq's user avatar
  • 143
4 votes
1 answer
252 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 ...
Gabor's user avatar
  • 41
4 votes
2 answers
177 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, ...
Peter Taylor's user avatar
3 votes
1 answer
305 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 ...
Sosa's user avatar
  • 133
3 votes
2 answers
629 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 ...
Henry Bergin's user avatar
3 votes
1 answer
96 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 ...
stackptr's user avatar
3 votes
2 answers
531 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 ...
legends2k's user avatar
  • 131
2 votes
1 answer
150 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 ...
Makogan's user avatar
  • 1,696
2 votes
1 answer
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 ...
Vettel.Sebastian's user avatar
2 votes
1 answer
174 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 ...
Makogan's user avatar
  • 1,696
2 votes
1 answer
296 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: ...
Jojolatino's user avatar
2 votes
1 answer
67 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 ...
Ggdev's user avatar
  • 23
2 votes
1 answer
123 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, ...
Maxpm's user avatar
  • 295
2 votes
1 answer
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 ...
Ahmed Hussein's user avatar
2 votes
1 answer
767 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 ...
Greg Gunn's user avatar
2 votes
1 answer
76 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?
Lokesh's user avatar
  • 121
2 votes
1 answer
155 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 ...
Makogan's user avatar
  • 1,696
2 votes
1 answer
511 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, ...
Vun-Hugh Vaw's user avatar
2 votes
1 answer
140 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 ...
shashack's user avatar
  • 523
2 votes
0 answers
42 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, ...
Makogan's user avatar
  • 1,696
2 votes
0 answers
213 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 ...
Lenny White's user avatar
2 votes
0 answers
157 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 ...
ViolaC's user avatar
  • 21
2 votes
0 answers
141 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 ...
Drinkwater's user avatar
2 votes
0 answers
106 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 ...
Arjan Singh's user avatar
  • 2,501
2 votes
0 answers
171 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 ...
Valentin Golev's user avatar
2 votes
0 answers
383 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 ...
Vanush Vee's user avatar
2 votes
0 answers
72 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?
alessandro308's user avatar
1 vote
1 answer
170 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 ...
Makogan's user avatar
  • 1,696
1 vote
1 answer
85 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:...
Makogan's user avatar
  • 1,696
1 vote
1 answer
76 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 ...
That_one_guy's user avatar
1 vote
1 answer
74 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 ...
ebcode's user avatar
  • 11
1 vote
0 answers
53 views

Animation issue using BVH data in OpenGL

I’m currently working on a project involving animation programming using OpenGL and BVH (Biovision Hierarchy) data for animation, and I am trying to get my head around it. I’ve run into some issues ...
blov's user avatar
  • 11
1 vote
0 answers
381 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 ...
R Bowles's user avatar
1 vote
0 answers
37 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 ...
guillefix's user avatar
  • 111
1 vote
0 answers
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 ...
Drinkwater's user avatar
0 votes
1 answer
53 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 ...
user610620's user avatar
0 votes
2 answers
63 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 ...
user610620's user avatar
0 votes
1 answer
105 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 ...
Narrateur du chaos's user avatar
0 votes
1 answer
35 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 ...
Severin Double's user avatar
0 votes
1 answer
120 views

Keep constant number of visible circles in 3D animation

I have created a 3D animation with a perspective projection of white circles moving randomly in a fake 3D space projected on a 2D computer screen (GIF 1). Since I need to keep the same number of ...
Kathia's user avatar
  • 113
0 votes
1 answer
186 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 (...
Kathia's user avatar
  • 113
0 votes
1 answer
85 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 ...
Makogan's user avatar
  • 1,696
0 votes
0 answers
64 views

What is this method of interpolation / blending?

I am reverse-engineering two classes from a game. The two classes are responsible for generating sets of t values for interpolating / blending between two points through the formula: ...
AboodXD's user avatar
0 votes
0 answers
64 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 ...
Ludovico's user avatar