An iterative Objective-C implementation of the diamond square algorithm. This technique is useful for generating tessellated 2D height maps to be used in modeling a cloudy sky, smokey air, or terrain.
Implementation details:
The diamond square algorithm requires a 2D array with square dimensions (2^n + 1) where the four corners of the array are set to some initial identical starting value. It is important that the starting value be identical for all four points to ensure the resulting array wraps correctly. The rest of the points in the array may be set to zero or some other value, but will ultimately be overwritten. The specific implementation provided here accounts for wrapping of the far edges, as pointed out in the below StackOverflow discussion. Random amounts of noise, in the range of +/- half the default (or user-provided) height, are introduced to each point. The randomness is deterministic and based on the seed value provided.
There are two different ways of generating 2D Maps using JHDiamondSquare.
The two main class methods are:
+(NSArray *)diamondSquare:(long)seed gridSize:(NSInteger)gridSize;
+(NSArray *)diamondSquare:(long)seed gridSize:(NSInteger)size initialHeight:(CGFloat)initialHeight;
Calling NSArray *heightMap = [JHDiamondSquare diamondSquare:1 gridSize:4]; where the seed (used for deterministic noise introduced to each point) is 1 and the grid dimensions are 2^4 + 1, or 17 width and 17 height. This method will use a default initialHeight of 1000.
Using NSArray *heightMap = [JHDiamondSquare diamondSquare:1 gridSize:4 initialHeight:200]; will allow the user to specify an initialHeight of 200.
A nice online visualization of the algorithm:
http://www.paulboxley.com/blog/2011/03/terrain-generation-mark-one
Inspired by and with guidance from:
https://en.wikipedia.org/wiki/Diamond-square_algorithm
http://www.gameprogrammer.com/fractal.html#diamond
http://stackoverflow.com/questions/2755750/diamond-square-algorithm
http://weeab.eu/terrain-generation-with-the-diamond-square-algorithm/
To run the example project, clone the repo, and run pod install from the Example directory first. JHViewController.m contains a simple use-case and prints out the results to the console.
None.
JHDiamondSquare is available through CocoaPods. To install it, simply add the following line to your Podfile:
pod "JHDiamondSquare"Jared Halpern
JHDiamondSquare is available under the MIT license. See the LICENSE file for more info.