Short Detail Brushes Guide

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Jay
RF Dev Team
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Joined: Fri Jul 08, 2005 1:56 pm
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Short Detail Brushes Guide

Post by Jay » Thu Jan 14, 2010 3:47 pm

This little guide is for everyone who does not know how detail brushes work, or who has problems determining which brushes should be flagged as 'Detail'.

First, to understand Detail Brushes: In the BSP rendering algorithm, the computer first determines which faces are visible and which are not before rendering. Those which are completely occluded by other faces will not be rendered. A Detail-Brush now is a brush which faces cannot occlude other faces (but still can be occluded).

Because of this, big brushes - which can occlude other faces completely, like the walls of a house for example, should NOT be flagged as detail, so the thinghs outside the house can be cut away (in best case) Instead, flag your chairs, tables, basically everything that has detail, as 'Detail'.

When you have a terrain, you must think: Which brushes can occlude other brushes? If you have caves in your hills, it might be good to NOT flag those hills as Detail. If nothing is beneath, mark as Detail again.

Not marking anything as Detail might be a good idea at first glance, but firstly your compile times will be ridicously high (And don't even start with a full vis, it might never finish), and secondly the BSP tree becomes more complex (->slower).

Therefore it is a speed GAIN to flag the small brushes as 'Detail'. While marking all brushes as Detail can also devestate the rendering speed because then everything will be rendered all the time.

I hope that helped understanding Detail Brushes a bit better.
Everyone can see the difficult, but only the wise can see the simple.
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