simulating the sun

The suns surface wouldn't really be visible when looking at it with the bare eye due to all the bright light (which can be modelled using HDR and a bloom filter). But you're looking for something like this?

You could maybe try a plasma fractal to generate the texture. With the right functions, colours, and some added glow effects this could look pretty good I imagine. Possibly if you used several layers of fractal brownian noise which you move over each other at different rates and blend together to get the colour look up value you could even get it to animate.

[Edited by - Motorherp on September 13, 2006 5:22:29 AM]

Quote:

Original post by e-u-l-o-g-y The suns surface wouldn't really be visible when looking at it with the bare eye due to all the bright light (which can be modelled using HDR and a bloom filter). But you're looking for something like this?

Yes I am, I need something to simulate the dynamic nature of the surface when you are close enough to view it.

I've been thinking of doing the same.

For the surface I plan to modify a wood procedural texture to create the cell like structures on the surface.

For the coronal ejection i.e. the sheets of glowing plasma, I plan to use a sheet with a vertex shader to curve and stretch the sheet out in the normal direction to look like the magnetic loops. I will also change the alpha component to make it look more tenuous as it moves away from the sun.

To the human eye (with enough shielding to not go blind), the surface of the sun would appear just about pure white gradually becoming yellowish toward the edge of the disk. Sunspots would be dark reddish black with orange-yellow fringes. The corona is sort of a blue-white color and very faint in comparison to the disk.

Pictures like that link are done using some specific wavelength of light that may or may not be in the visible range, and don't represent what you'd really see (in particular when it comes to sunspots). But there are some visible-light textures on the sun as well. Closeups show an overall "cellular" texture, with streaky stuff near the spots.

Sun image on a regular film ... A bit yellower than I'd expect (probably because it's taken through Earth's atmosphere) but it is the real thing.

Sunspot close up
Another

If you can afford a ridged 4D perlin noise function that'd be a good way to do the cells (The "ridges" being the dark lines between the cells). 4D so you can animate it by slowly moving through the 4th dimension over time. The sunspots could be on a separate texture overlaid on top, with "multiply" blending.