Hair simulation with a mass-spring system (punk’s not dead!)

Hair rendering and simulation can be challenging, especially in real-time. There are many sophisticated algorithms for it (based on particle systems, hair mesh simulation, mass-spring systems and more) that can give very good results. But in this post, I will try to explain a simple and somehow hacky approach I followed in my first attempt to simulate hair (the mohawk hair of the video below) using a mass-spring system.


 

The code can be found here: https://github.com/hikiko/mohawk

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A short OpenGL / SPIRV example.

It’s been a while since Igalia is working on bringing SPIR-V to mesa OpenGL. Alejandro Piñeiro has already given a talk on the status of the ARB_gl_spirv extension development that was very well received at FOSDEM 2018 . Anyone interested in technical information can watch the video recording here: https://youtu.be/wXr8-C51qeU.

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A terrain rendering approach (part 1)

There are several methods to create and display a terrain, in real-time. In this post, I will explain the approach I followed on the demo I’m writing for my work at Igalia. Some work is still in progress.

The terrain had to meet the following requirements:

  • its size should be arbitrary
  • parts outside the viewer’s field of view should be culled

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Morphing test

So far, I hadn’t try to morph 3D objects to other 3D objects and I thought it’s something tricky to do. Today, I realized how simple and easy it is when I wrote this small test:

If you carefully choose the 3D models to have the same number of polygons, and to meet a few topological requirements, then you only need to interpolate the values of the meshes’ vectors, normals (and materials, textures, whatever you need) and draw the intermediate mesh every time. As interpolation parameter you can choose the values of a positive function that varies from 0 to 1 and backwards (I used (sin(msecs/factor) + 1)/2) to have that continuously changing effect. And that’s all!

The test is here: https://bitbucket.org/eleni-hikiko/morphing and it includes an obj with a scene with 3 meshes that meet the morphing requirements  (I only used the first two meshes here).

How to create a gbm buffer under X.

To create a GBM buffer you first need to create a drm device and then use its device descriptor to create a gbm device. To do this under X you need a way to tell xserver which device you use to avoid permission issues. Here’s an example where I create a gbm buffer under X and then authenticate to the X server:

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Winnie: a framebuffer window system

A few weeks ago, I started a minimal window system, which performs software rendering on the linux /dev/fb0. My aim was to learn some systems programming and familiarize myself with concepts like event and device handling, memory management, window management, drawing on the framebuffer, IPC mechanisms etc (and certainly not to create a full linux window system! :)p) I call the program winnie and the code is available on github here: https://github.com/hikiko/winnie/tree/winnie.clients-as-plugins, https://github.com/hikiko/winnie and lp.

The program is not finished yet and I don’t know if I ever finish it, since I came up with new project ideas again.. Nevertheless, you can see some videos of the development stages below if you are interested (most recent first):

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