Computer Graphics Stack Exchange
Computer Graphics Stack Exchange

Questions tagged [animation]

55 questions
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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 distances for which the human eye cannot resolve…
trichoplax is on Codidact now
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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 what conditions? All I know about Euler angles is…
Ankit singh kushwah
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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 grahics in computer games was in the late 90s and in ealy…
Gonrah
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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 letters. Here's a short cropped clip showing just…
handle
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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 system in 3D, which consists of N particles. Equation of…
stanleyerror
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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've read, it appears that a given vertex's skinned…
lowq
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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
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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, and rather than port the manual calculations…
Peter Taylor
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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 later transformations) you can make a single draw like a 3D…
Gabor
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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 of interpolation. $$ f(x) = 3x^2 - 2x^3 $$ I've seen a trick used in quite a few…
legends2k
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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 is the effect (which I believe was created in…
Sosa
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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 at a given frequency. This is simple to do for a…
Corey
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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 had in mind), and then render an image sequence…
Henry Bergin
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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: And this is what I get with a circle drawn using…
Jojolatino
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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 clearing out one component of the quaternion.…
Lenny White
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