digital home of MacSlow

More WebGL

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One of the latest experiments with WebGL… Click here for a full page view This WebGL-program does not do any typical lighting calculations for the surface-shading, but instead uses spherical environment-mapping. This variation of environment-mapping is often being used in 3D-applications like blender, Modo, Zbrush etc. to allow very fast shading of the edited scene/object. This technique is beneficial for investigating the surface-features and overall shape quickly, without having to trigger the lighting-simulation offered by a ray-tracer, since it fakes the specular term in a convincing way. In order to…read more

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A small test…

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… for a friend of mine. SVG does work without a hitch in WordPress, when you invest a little effort and do not give up on the first sign of resistance.

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Terrorism is a joke…

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… especially as a justification for signing off laws cutting down civil liberties. The true origin of terrorism is not some religious belief – although often the executing pawns are staffed with individuals, who fell victim to such beliefs – but government-funded violence against its own or a foreign civil population. If directed against the own population, it is meant to urge them to “beg” the government for “stronger” laws. When the violence is targeting a foreign population, the motivation is usually to overthrow the government of that country in…read more

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US elections 2016 viewed as an outsider

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As somebody living very far away from the USA – but still being exposed to its foreign policy through cold-war relics like NATO, innocently watched by NSA and threated by TTIP (Transatlantic Trade and Investment Partnership) – the current presidential primaries of the republican and democratic parties are a sight to behold and without comparison here in Germany. The efforts of independents (well with one exception) and libertarians are not worth mentioning really. Following this spectacle for about eight months now, I learned some interesting facts and feel more sorry…read more

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noise is good

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I’ve added a new example to ToyShader, which does three-dimensional perlin-noise distortions of signed distance-fields (SDF). These SDF are used to model objects when doing rendering with the ray-marching approach. Also thanks to this noise-function, applying procedural textures becomes feasible. The whole scene is just described by a single GLSL-fragment-shader. External resources are not needed. As cool as the distortion and bending of these SDF is, it tends to cause discontinuties, which in turn lead to artefacts in the shadow-calculation and the rendering around object-silhouettes. To fight this I’ve decreased…read more

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simple physics studies in blender

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Having a full-featured 3D-suite like blender available and not knowing how to make use of its myriad of capabilities, always felt like a splinter in my eye… especially if you are very keen on all things computer-graphics and 3D. Since nothing ever happens by wishful thinking alone, you have to dive into it yourself in order to get rid of that splinter. So serving myself small helpings of written and recorded tutorials every evening, I am now able to wield some of blender’s more interesting tools at a basic level….read more

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Anti-aliasing in raymarcher

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The addition of anti-aliasing to my GLSL-based raymarcher (part of ToyShader) does result in cleaner visuals as expected (see image-sequence below), but the performance-hit is considerable (especially on my laptop’s intel HD4000 GPU). Before this can be enabled by default, I need to implement over-relaxation of the raymarching-steps. This allows to traverse the view-ray for each (sub-) pixel in larger steps – compared to classic raymarching/sphere-tracing – resulting in a considerable speed-up. The paper “Enhanced Sphere Tracing ” by Keinert et al. introduces this improvement among other enhancements with regards…read more

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Zoom baby, zoom!

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Zoom baby, zoom! When doing shader-programming a “Hello, world!”-equivalent I always considered to be an implementation of a zoom into a mandelbrot-set. And so I did… and for “just because I can”-reasons, I also wrote a GLSL-environment very much like the WebGL-based ShaderToy.com, so I can also have these as local and native shader-hacks on my desktop. Getting the browser out of the equation saves about 15% of system-load. Here is the example as WebGL-version on ShaderToy and you’ll be able to get the same on your desktop as a…read more

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Time-killer WebGL

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Time-killer WebGL There are a lot of shader-playgrounds for WebGL scattered around the net. A few of the better known ones are… Shadertoy GLSLsandbox Shdr WebGLPlayground GLSLbin Some let you mess around with the fragment-shaders only, while others expose vertex- and fragment-shaders. The great advantage you get with these WebGL-environments is the fact, that they eliminate the need for setting up your OpenGL-context using the native toolkit of your OS, though this is only mildly painful these days thanks to SDL, Qt and gtk. Thus you can concentrate on the…read more

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I’m really afraid and terrified…

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… by the developments around the crisis of Crimea and what Europe is currently tumbling towards! It feels like the Cuban crisis from 1962, as far as I can tell from having read about it in history-books. Thankfully back then it didn’t end in a catastrophe. Years later I was born. That’s something I could not influence. But now that I’m here, I’d like to keep it that way for several more decades. You can be sure I’ll do what I can to influence that! Besides me there are many…read more

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