A technical blog from Daniel Rákos (aka aqnuep)
Posts tagged GLEW
OpenGL 4.0 – Mountains demo released
Oct 11th
OpenGL 4.0 - Mountains demo
OpenGL 3.0 capable GPUs introduced a level of processing power and programming flexibility that isn’t comparable with any earlier generations. After that, OpenGL 4.0 and the hardware supporting it even further pushed the limits of what previously seemed to be impossible. Thanks to these features nowadays more and more possibilities are available for the graphics developers to implement GPU based scene management and culling algorithms. The Mountains demo showcases some of these rendering techniques that, as far as I know, were never implemented so far using OpenGL. In this article I will present the key features of the demo that will be discussed in more detail in subsequent articles. Demo binaries with full source code are also published.
Efficient Gaussian blur with linear sampling
Sep 7th
Gaussian blur
Gaussian blur is an image space effect that is used to create a softly blurred version of the original image. This image then can be used by more sophisticated algorithms to produce effects like bloom, depth-of-field, heat haze or fuzzy glass. In this article I will present how to take advantage of the various properties of the Gaussian filter to create an efficient implementation as well as a technique that can greatly improve the performance of a naive Gaussian blur filter implementation by taking advantage of bilinear texture filtering to reduce the number of necessary texture lookups. While the article focuses on the Gaussian blur filter, most of the principles presented are valid for most convolution filters used in real-time graphics.
Instance Cloud Reduction reloaded
Jun 30th
OpenGL 3.3 - Nature
A few months ago I’ve presented an object culling mechanism that I’ve named Instance Cloud Reduction (ICR) in the article Instance culling using geometry shaders. The technique targets the first generation of OpenGL 3 capable cards and takes advantage of geometry shaders’ capability to reduce the emitted geometry amount in order to get to a fully GPU accelerated algorithm that performs view frustum culling on instanced geometry without the need of OpenCL or any other GPU compute API. After the culling step the reduced set of instance data is fed to the drawing pass in the form of a texture buffers. In this article I will present an improved version of the algorithm that exploits the use of instanced arrays introduced lately in OpenGL 3.3 to further optimize it.
Sad facts about OpenGL extension libraries
Mar 31st
Everybody who used to make OpenGL applications, whether it be a simple triangle-of-death demo or a comprehensive rendering engine at some point needs to use extensions or later OpenGL versions. Usually many people start this by creating their own initializer library that loads the required entry points from the OpenGL library by hand. What is sure is that at some point everybody realizes that this process is just a waste of time and starts to look for an extension loading library out there. This is the obvious solution as it makes no sense to reinvent the wheel all the time. However, after using a particular one from the repertoire of these libraries one will face the problem that they are not that nice as they seemed before. In this article I will talk about some of these libraries and some of my thoughts about them.
Unit testing OpenGL applications
Feb 22nd
Nowadays comprehensive testing is a must for any software product. However, it isn’t such a general rule when it comes to graphics applications. Many developers face difficulties when they have to test their rendering codes. Manual tests and visual feedback is sometimes satisfactory but if one would like to have automated regression tests usual approaches seem to fail. Even if at first sight unit testing of rendering code doesn’t look really straightforward, in fact it is. OpenGL is not an exception from this rule as well. In this article I would like to briefly present a few methods how to unit test OpenGL rendering code and also present my choice and the reasons behind the decision.
Instance culling using geometry shaders
Feb 8th
OpenGL 3.2 - Nature
Since the appearance of Shader Model 4.0 people wonder how to take advantage of the newly introduced programmable pipeline stage. The most important feature enabled by geometry shaders is that one can change the amount of emitted primitives inside the pipeline. The first thing that a naive developer would try to do with it is geometry tesselation. However, the new shader performs very bad when used for tesselation in a real life scenario even though there are demos show casting this possibility. If we take a closer look at the new feature we observe that the most revolutionary in it is not that it can raise the number of emitted primitives but that it can discard them. This article would like to present a rendering technique that takes advantage of this aspect of geometry shaders to enable the GPU accelerated culling of higher order primitives.