4 ms·

I've read and re-implemented a lot of stuff by Inigo Quilez. Much of it is ingenious but eventually straightforward once you get the hang of it. I still find th

I've read and re-implemented a lot of stuff by Inigo Quilez. Much of it is ingenious but eventually straightforward once you get the hang of it. I still find this particular snippet magical: https://www.shadertoy.com/view/MdB3Dw https://www.shadertoy.com/view/MdB3Dw Well, the code itself is simple GLSL. The math is (and I have not verified this) not that complex either, as I believe it's all about integrating the raytracing equation for a moving sphere over the time variable. I guess what I find most impressive is just the fact that it works and that someone even thought of doing that. I also think this is currently the only example of this method being used anywhere, and it might mostly stay that way because the method might not be super generalisable.

paulgb 4y ago
His “Painting a Character with Maths” video is also incredibly mind-blowing. https://www.youtube.com/watch?v=8--5LwHRhjk https://www.youtube.com/watch?v=8--5LwHRhjk
CyborgCabbage 4y ago
He has a YouTube channel as well: https://youtu.be/8--5LwHRhjk https://youtu.be/8--5LwHRhjk Also you may like Marble Marcher made by Code Parade, it's a game that uses a similar approach to rendering: https://youtu.be/9U0XVdvQwAI https://youtu.be/9U0XVdvQwAI
bob1029 4y ago
> I believe it's all about integrating the raytracing equation for a moving sphere over the time variable In all of the samples there is some iteration constant you can adjust. Take this below a certain threshold and things get really interesting. You can almost reason about how it's all working mathematically by plugging in different iteration counts.
djmips 4y ago
It sounds similar to a technique we used in video games to solve collisions so you didn't miss the interval - using quadratics to solve the swept sphere. In fact so much of what is on shadertoy looks very familiar to video game 'game physics' programmers because a lot of it is related to collision detection. See the Orange book on real-time collision detection (Christer Ericson) for a lot of good code.
- pierrec 4y ago
  Thanks, your description of the technique is simpler and probably more accurate than what I guessed - no integration required. The author gives a similar hint in the comments.
mjfl 4y ago
He's amazing.

paulgb 4y ago

His “Painting a Character with Maths” video is also incredibly mind-blowing. https://www.youtube.com/watch?v=8--5LwHRhjk https://www.youtube.com/watch?v=8--5LwHRhjk

CyborgCabbage 4y ago

He has a YouTube channel as well: https://youtu.be/8--5LwHRhjk https://youtu.be/8--5LwHRhjk Also you may like Marble Marcher made by Code Parade, it's a game that uses a similar approach to rendering: https://youtu.be/9U0XVdvQwAI https://youtu.be/9U0XVdvQwAI

bob1029 4y ago

> I believe it's all about integrating the raytracing equation for a moving sphere over the time variable In all of the samples there is some iteration constant you can adjust. Take this below a certain threshold and things get really interesting. You can almost reason about how it's all working mathematically by plugging in different iteration counts.

djmips 4y ago

It sounds similar to a technique we used in video games to solve collisions so you didn't miss the interval - using quadratics to solve the swept sphere. In fact so much of what is on shadertoy looks very familiar to video game 'game physics' programmers because a lot of it is related to collision detection. See the Orange book on real-time collision detection (Christer Ericson) for a lot of good code.

pierrec 4y ago
Thanks, your description of the technique is simpler and probably more accurate than what I guessed - no integration required. The author gives a similar hint in the comments.

mjfl 4y ago

He's amazing.