How Can Gradient Circles and a Modified Diamond-Square Algorithm Generate More Natural-Looking Random Islands?

Gradient Circles for Map Generation

In this discussion, we delve into an alternative approach for generating random islands in map generators that utilizes gradient circles. This technique aims to overcome the unnatural circular edges commonly encountered in other methods.

Diamond and Square Algorithm with Modifications

Instead of using Perlin Noise, we employ a modified version of the Diamond and Square algorithm. Key distinctions from traditional implementations include:

• Initial Conditions: Terrain height map is initialized with minimum elevation at corners and a random value for the midpoint.
• Island Modification: The first diamond step is omitted, and the midpoint is initialized with a random elevation value.
• Border Adjustment: Border points are adjusted to the minimum elevation (underwater or a random value close to it).
• Elevation Normalization: The generated terrain heights are rescaled to a specified elevation range.

Surface Type and Features

Once the terrain height map is created, surface features are added based on elevation ranges: water, sand, vegetation, rocks, and snow. Elevation-based slope parameters influence feature placement, and additional features like rivers and waterfalls can be incorporated using additional rules.

Diamond and Square Algorithm in C

The provided C code demonstrates the modified Diamond and Square algorithm:

• Configuration Parameters: Minimum and maximum elevation, sea level, elevation ranges for various surface types, and slope parameters.
• Terrain Height Map: A two-dimensional array (ter[][]) stores the terrain elevation values.
• Surface Type Map: A second two-dimensional array (typ[][]) represents surface types.
• Random Elevation: Diamond and square steps use random elevations within specified ranges.
• Border Adjustment: Border points are set to the minimum elevation or random values near it.

Advantages and Considerations

This approach offers benefits over Perlin Noise-based methods:

• Facilitated configuration with well-defined parameters.
• Good elevation distribution with island-like characteristics.
• Incorporation of diverse surface features and additional elements like rivers.

Notes

• The algorithm tends to produce a single large hill on islands. Multiple terrain maps can be layered to address this.
• Adjustments can be made to the randomization process to introduce more central hills.
• Lighting techniques can enhance the visual appearance of the terrain.

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