Friday, May 23, 2008

Procedural Planet

In continuation to the Procedural Sphere entry I made a few months ago, and from inspiration by the ongoing work of Jelly Edwards I decided to look into further developing the sub-dividing cube with procedural noise in order to make a planet.

The noise algorithm used is Fractional Brownian motion (fBm) which is a form of Perlin Noise.

A good article about fBm in relation to procedural planets can be seen here. This work was carried out by Sean O'Neill who has also contributed allot to atmospheric scattering.

Very early and basic attempts at a procedural planet can be seen below. For the purpose of illustrating the deformation of the sphere I have magnified the hills and valleys on the planet, which results in what looks like an asteroid or moon.

There are some key failings with this version. It is slow to render as the vertex and index buffers and built each frame. The whole planet is the same Level of Detail (LOD). This is ok for distance viewing, however as the camera approaches the surface of the planet, rendering the entire scene at a high LOD would cripple even the most powerful of computers.

Many of the techniques learned when researching and implementing my terrain system will be used here.

  • Dividing the planet surface into patches
  • Each Patch manages their own LOD (through subdivision and creation of child patches) based on distance from the camera.
  • Each Patch maintains its own Vertex Buffer, while sharing a group of Index Buffers (to cover neighbour patches with different LOD's)

Allot of my terrain modules can be reused, with perhaps a little added functionality, so I hope that, time permitting, adding these features will not take too long.

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