http://opensimulator.org/index.php?action=history&feed=atom&title=Terrain_SplattingTerrain Splatting - Revision history2026-04-09T12:55:13ZRevision history for this page on the wikiMediaWiki 1.19.9http://opensimulator.org/index.php?title=Terrain_Splatting&diff=18645&oldid=prevBhardly: Terrain splatting algorithm2010-08-20T19:57:20Z<p>Terrain splatting algorithm</p>
<p><b>New page</b></p><div>To do the terrain splatting you build an array the size of the heightmap with values [0-3] that map to the four terrain textures. Floating point is used so you can blend between the textures when creating the final output. The array is a combination of the actual height (scaled down to 0-3) and some perlin noise. Heres clean room documentation of the noise generation:<br />
<br />
<pre><br />
vec = global_position * 0.20319f;<br />
low_freq = perlin_noise2(vec.X * 0.222222, vec.Y * 0.222222) * 6.5;<br />
high_freq = perlin_turbulence2(vec.X, vec.Y, 2) * 2.25;<br />
noise = (low_freq + high_freq) * 2;<br />
</pre><br />
<br />
To build the final values in the array the start height and height range need to be used by bilinearly interpolating between the four corners of each with the current x/y position in the array. It all comes together like:<br />
<br />
<pre><br />
value = (height + noise - interpolated_start_height) * 4 / interpolated_height_range;<br />
</pre><br />
<br />
That's all there is to it basically. The rest is an exercise in texture compositing and interpolation.</div>Bhardly