http://bundysoft.com/docs/ 2026-05-13T15:44:40+00:00 http://bundysoft.com/docs/ http://bundysoft.com/docs/lib/images/favicon.ico text/html 2017-08-31T06:53:15+00:00 http://bundysoft.com/docs/doku.php?id=l3dt:algorithms:hf:design_inflate&rev=1504162395&do=diff Introduction The design/inflate algorithm begins with a low-resolution design map in which the basic shape of the final heightfield is laid out, including land altitudes, the position of volcanos, etcetera. This map is called a design map because it allows the user to design the heightfield prior to calculation (, below). text/html 2017-08-31T04:29:06+00:00 http://bundysoft.com/docs/doku.php?id=l3dt:algorithms:hf:erosion&rev=1504153746&do=diff Erosion, in its many guises, is perhaps the major shaping force of terrain in the real-world (refer to Exhibit A, below). Unfortunately, erosion processes are highly iterative and therefore computationally slow. Approximations are required! Exhibit A: Normals map of Baia Mare, Romania (from 8.5m DEM). text/html 2017-08-31T06:17:31+00:00 http://bundysoft.com/docs/doku.php?id=l3dt:algorithms:hf:fileoverlay&rev=1504160251&do=diff A 'file overlay' is a special terrain type that places on the terrain a pre-made feature from a file. Example and usage Please consult the 'using file overlays' tutorial. Overlay settings The settings for each overlay, which you can edit using the 'edit' button in the overlay manager utility, include: text/html 2017-08-31T06:52:20+00:00 http://bundysoft.com/docs/doku.php?id=l3dt:algorithms:hf:fractal&rev=1504162340&do=diff L3DT uses the 'diamond-square' fractal algorithm to generate terrain. For a basic outline of how the DS algorithm works, please refer to the very useful GameProgrammer tutorial by Paul Martz. There are a lot of post-processing algorithms for making fractal maps look more like real terrain. L3DT includes none of them. I have spent much more time/thought developing the design/inflate heightfield routine. text/html 2017-08-31T06:26:56+00:00 http://bundysoft.com/docs/doku.php?id=l3dt:algorithms:hf:inflate&rev=1504160816&do=diff L3DT uses a diamond-square subdivision fractal algorithm to 'inflate' the heightfield during the design/inflate algorithm. This algorithm up-sizes the map by a power of two, and fills in the missing values by linear (or was it cubic?) interpolation, with a fractal perturbation to introduce some noise. The fractal 'persistence' (ie. roughness) of this noise is controlled locally by the interpolated value of the 'Frac' parameter in the design map. text/html 2017-08-31T05:28:44+00:00 http://bundysoft.com/docs/doku.php?id=l3dt:algorithms:hf:mountain&rev=1504157324&do=diff The mountain peak overlay is made from a reasonably rough 128×128 or 256×256 fractal (depending on desired size). This fractal is made by a modified diamond-square algorithm in which the edges smooth to zero such that no seams are visible when it is overlaid on the heightfield. text/html 2017-08-31T04:24:52+00:00 http://bundysoft.com/docs/doku.php?id=l3dt:algorithms:hf:peakrough&rev=1504153492&do=diff One method of making heightfields is to 'deposit' onto a flat heightfield a large number of geometric shapes like cones, pyramids or hemispheres. Prime examples of terrain made by this technique are shown on www.robot-frog.com (Bob Nystrom), using hemispheric peaks, and www.lighthouse3d.com (António Ramires Fernandes), using sinusoidal peaks. text/html 2017-08-31T05:01:48+00:00 http://bundysoft.com/docs/doku.php?id=l3dt:algorithms:hf:perlin&rev=1504155708&do=diff How does perlin work? If you want to learn how perlin synthesis works, please have a look at: * Wikipedia, or; * Paul Bourke's perlin tutorial (with Perlin's original source-code), or; * Hugo Elias' longer perlin tutorial, which also includes example source code. text/html 2017-08-31T05:50:50+00:00 http://bundysoft.com/docs/doku.php?id=l3dt:algorithms:hf:plateau&rev=1504158650&do=diff The concept of the plateau overlays used in the design/inflate algorithm is based on the method in Joerg Schrammel's Genesis Toolkit, although the implementation in L3DT is quite different. The first step in making a plateau overlay is to make a fractal heightfield about 256×256 in size, where the roughness and amplitude of the fractal falls off to zero with increasing distance from the centre (as with the mountain overlay). The resultant peak in the centre of the overlay is made into a pla… text/html 2017-08-31T05:04:37+00:00 http://bundysoft.com/docs/doku.php?id=l3dt:algorithms:hf:terrace&rev=1504155877&do=diff The terracing routine 'smooshes' (for lack of a better term) terrain up or down depending on its place within a certain altitude band. How far a height value is moved up or down is a function of a fractal line profile. The effect strength decays with radius from the centre of the terrace/cliff to keep things nice and smooth. Terraces and cliffs require fairly high detail to 'look right', so this routine is called after all inflation is done, when the heightfield has reached full resolution. Than… text/html 2017-08-31T05:14:19+00:00 http://bundysoft.com/docs/doku.php?id=l3dt:algorithms:hf:volcano&rev=1504156459&do=diff The volcano overlay used in the design/inflate algorithm is made by adding cones of specific radii and heights such that their sum approximates the shape of a volcano: Profile of component peaks of a volcano and the resultant summation.(note vertical and horizontal scaling are arbitrary)