opengl – Page 3 – hikiko-blog

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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XDC2018

I am back home after my last trip for this year and a long and great week in A Coruña where I attended my first XDC, organized and sponsored by Igalia.

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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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Fosscomm 2017 [update: slides in English]

FOSSCOMM (Free and Open Source Software Communities Meeting) is a Greek conference aiming at free-software and open-source enthusiasts, developers, and communities. The event is solely organized and ran by volunteers (usually university students, communities, Linux User Groups) and is taking place in a different city every year. The attendance is free and everyone is welcome to make a presentation or a workshop related to free and open source projects.

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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.

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Debugging graphics code using replacement shaders (Linux, Mesa)

Sometimes, when working with the mesa drivers, modifying or replacing a shader might be extremely useful for debugging. Mesa allows users to replace their shaders at runtime without having to change the original code by providing these environment variables:

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Creating cube map images from HDR panoramas on GNU/Linux

As part of my work for Igalia I wanted to do some environment mapping. I was able to find plenty of high quality .hdr images online but I couldn’t find any (OSS) tool to convert them to cubemap images. Then, Nuclear (John Tsiombikas) gave me the solution: he wrote a minimal tool that does the job quickly and produces high quality cube maps.

So, here’s a short “how to” create cubemaps on Linux using his “cubemapper” program in combination with other OSS tools:

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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).