Blue Marble part 2

Guy Allard — 2008-06-03T12:58:39+00:00

After my last blog post, I received plenty of emails asking to see the planet shaders I was working on in action. So, here's a demo you can download which gives you a fly-by of the earth in TGEA1.7.

Download the demo here, extract the zip somewhere and run it.

There's a readme in the zip that gives some brief background information, and I've also commented the shaders (a little) so you should be able to figure out how they work if you want to use it for your own purposes. The main planet shader should work out of the box. The atmosphere shader requires a small modification to the engine if you want to use it in your own project, I'll post the necessary changes in the private forums.

The shaders do not have any fallbacks, so if your graphics card can't handle them, then either the demo won't run, or you'll be missing some visuals.

Enjoy.

Blue Marble - (warning - pictures)

Guy Allard — 2008-05-17T09:05:44+00:00

Having recently purchased TGEA, I thought I'd try and get to grips with shaders and materials. I stumbled across the blue planet demo during a random google search, and thought I'd have a go at producing something similar.

The result:

To model the earth, I used three spheres, one for the earths surface, a second sphere scaled up slightly for the cloud layer, and a third sphere scaled up again for the atmosphere.

The Surface of the earth is rendered by a custom shader using three textures
- a diffuse map with a specular map in the alpha channel, which limits the specular reflection to the oceans.
- a normal map that gives height to the mountains and valleys
- an emission map which illuminates the cities at night time.
The shader that renders the planet restricts the emission map to the dark side of the planet, so cities only glow at night time.

The cloud layer is a standard material which is rendered translucent, and is also bump mapped so that the clouds have depth.

For the atmosphere, I managed to port the shader from the the blue planet demo. The color of the atmosphere can be specified in the material definition.

The sun is a simple fxSunlight, and the moon is a single textured and bump-mapped sphere.
I'm pretty pleased with the outcome. As always, there's still plenty of tweaking to be done.

Anyway, I'll leave you with a few more gratuitous screenshots.

Earthrise

Europe at night

Sunset of West Coast USA

Blog for Guy Allard at GarageGames.com

Blue Marble part 2

Blue Marble - (warning - pictures)