http://prideout.net/blog Tips and Tricks from a Graphics Programmer Thu, 05 Apr 2012 15:19:56 +0000 en hourly 1 http://wordpress.org/?v=3.3.2 http://prideout.net/blog/?p=72 http://prideout.net/blog/?p=72#comments Tue, 02 Aug 2011 10:21:29 +0000 Philip Rideout http://prideout.net/blog/?p=72 Some fun with Python, L-Systems, and RenderMan. This is a follow-up to a post I wrote exactly one year ago, Mesh Generation with Python.]]> http://prideout.net/blog/?feed=rss2&p=72 0 http://prideout.net/blog/?p=70 http://prideout.net/blog/?p=70#comments Sun, 15 May 2011 22:07:31 +0000 Philip Rideout http://prideout.net/blog/?p=70 http://prideout.net/blog/?feed=rss2&p=70 0 http://prideout.net/blog/?p=69 http://prideout.net/blog/?p=69#comments Wed, 16 Feb 2011 14:55:56 +0000 Philip Rideout http://prideout.net/blog/?p=69 Just a quick video to show off the latest iteration of my real-time fluid simulation, which now builds a deep opacity map for shadowing.]]> http://prideout.net/blog/?feed=rss2&p=69 0 http://prideout.net/blog/?p=67 http://prideout.net/blog/?p=67#comments Sat, 29 Jan 2011 21:35:58 +0000 Philip Rideout http://prideout.net/blog/?p=67 I updated my old noise-based particle demo so that it now builds a large 3D texture to represent velocities, performing advection on the GPU instead of the CPU. This allowed me to increase my particle count by two orders of magnitude and maintain interactivity. In this post, I cover the basics of GL_TRANSFORM_FEEDBACK (known as stream-out in DirectX land), which is used to perform advection with a vertex shader.]]> http://prideout.net/blog/?feed=rss2&p=67 0 http://prideout.net/blog/?p=66 http://prideout.net/blog/?p=66#comments Sun, 23 Jan 2011 18:06:09 +0000 Philip Rideout http://prideout.net/blog/?p=66 I finally extended my OpenGL-based Eulerian fluid simulation to 3D and managed to get it to run at interactive rates on my GeForce GTS 450. As with almost all my blog entries, I've provided source code for you to play with, but only at your own risk. :)]]> http://prideout.net/blog/?feed=rss2&p=66 0 http://prideout.net/blog/?p=64 http://prideout.net/blog/?p=64#comments Sun, 16 Jan 2011 02:59:38 +0000 Philip Rideout http://prideout.net/blog/?p=64 GPU raycasting over a volume requires ray start and stop points. Commonly these intervals are computed by drawing a cube (with perspective) into two surfaces: one with front faces, the other with back faces. The final pass is the actual raycast. In this post, I show how to avoid the overhead of the offscreen surfaces by performing a simple ray-cube intersection.]]> http://prideout.net/blog/?feed=rss2&p=64 0 http://prideout.net/blog/?p=63 http://prideout.net/blog/?p=63#comments Sun, 02 Jan 2011 02:55:41 +0000 Philip Rideout http://prideout.net/blog/?p=63 Robert Bridson, that esteemed guru of fluid simulation, wrote an interesting 2007 SIGGRAPH paper about using Perlin noise to create turbulent effects in a velocity field. In this post, I play with this approach to create a simple smoke simulation with particles, and I discuss some of the rendering issues with OpenGL. For now, I'm moving the particles with the CPU rather than the GPU. ]]> http://prideout.net/blog/?feed=rss2&p=63 0 http://prideout.net/blog/?p=61 http://prideout.net/blog/?p=61#comments Fri, 31 Dec 2010 04:28:20 +0000 Philip Rideout http://prideout.net/blog/?p=61 Volumetric lines are handy for a variety of effects, including lightsabers, lightning, and particle traces. In this article, I show how a geometry shader can emit a chamfered cuboid for each line segment. The fragment shader can then perform a variety of effects within the screen-space region defined by the cuboid, including Gaussian splats and raytraced tubes.]]> http://prideout.net/blog/?feed=rss2&p=61 0 http://prideout.net/blog/?p=60 http://prideout.net/blog/?p=60#comments Sun, 28 Nov 2010 20:22:23 +0000 Philip Rideout http://prideout.net/blog/?p=60 Volumetric splatting can be implemented efficiently with instancing. In this article, I show how to use splatting to extrude a streamline into a vector field. This technique would allow an artist to design a space-filling velocity field (e.g., for a particle system), simply by specifying an animation path through space. My article also covers some basics of modern-day volume rendering on the GPU.]]> http://prideout.net/blog/?feed=rss2&p=60 0 http://prideout.net/blog/?p=58 http://prideout.net/blog/?p=58#comments Sun, 21 Nov 2010 05:12:20 +0000 Philip Rideout http://prideout.net/blog/?p=58 In this post, I discuss a simple implementation of two-dimensional smoke using GLSL fragment shaders. I provide C source that builds with Visual Studio 2010 and gcc.]]> http://prideout.net/blog/?feed=rss2&p=58 0