Author Archives: Ignacio Castaño

scope(exit) in C++11

By Ignacio Castaño | Published: November 19, 2012

I really like the scope(exit) statements in D. They allow you to keep the cleanup code next to the initialization code making it much easier to maintain and understand. I wish we had them in C++. Turns out this can be implemented easily using some of the new C++ features. I’m not a big fan [...]

Posted in Engine Tech | 54 Comments

Seamless Cube Map Filtering

By Ignacio Castaño | Published: February 27, 2012
seamless_featured

Modern GPUs filter seamlessly across cube map faces. This feature is enabled automatically when using Direct3D 10 and 11 and in OpenGL when using the ARB_seamless_cube_map extension. However, it’s not exposed through Direct3D 9 and it’s just not available in any of the current generation consoles.

Posted in Engine Tech | 23 Comments

Irradiance Caching – Part 1

By Ignacio Castaño | Published: July 14, 2011

This is the first article I wanted to publish when I started writing about the technology behind The Witness. I had just spent a week or so implementing irradiance caching with rotation and translation gradients. Extending the equations of the gradient estimation to the hemicube sample distribution had proven to be tricky and had taken [...]

Posted in Engine Tech | 14 Comments

Hemicube Rendering and Integration

By Ignacio Castaño | Published: September 29, 2010

One of our aims with our global illumination implementation was to keep it as simple as possible, while still obtaining good performance, and we hoped to achieve that by using the GPU. While the are several approaches to compute global illumination in the GPU, the most simple one that we could come up with was [...]

Posted in Engine Tech | 15 Comments

Computing Alpha Mipmaps

By Ignacio Castaño | Published: September 9, 2010

A little problem that we had when we started to create trees and vegetation is that the standard mipmap generation algorithms produced surprisingly bad results on alpha tested textures. As the trees moved farther away from the camera, the leafs faded out becoming almost transparent. Here’s an example. The following tree looked OK close to [...]

Posted in Engine Tech | 29 Comments

Lightmap Parameterization

By Ignacio Castaño | Published: March 30, 2010

As explained by Jon in his previous post, we are using precomputed global illumination in The Witness, and one of my first tasks was to work on that system. I have developed some interesting technology to compute automatic paramaterizations, to formulate the lighting computations in a way that can be easily mapped to the GPU, [...]

Posted in Engine Tech | 9 Comments

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