Ring's shadows

ElPelado · Post #1by **ElPelado** » 05.06.2003, 23:20

Is it possible to see in saturn(for example) the shadow produced by his rings??(not saturn's shadow on the rings, the opossite)

Post #2by **chris** » 05.06.2003, 23:21

Yes, but this is only supported on certain graphics cards . . . It should work on a GeForce3, GeForce4 Ti, GeForce FX, or Radeon 9500+.

--Chris

jrobert · Post #3by **jrobert** » 05.06.2003, 23:33

What is it that allows a Geforce3 or 4 to render the rings shadow upon the planet that a Geforce2 or earlier card can't handle?

I guess what I'm saying is it seems like it'd be possible to do with an earlier card. Even if it's accomplished with imposters which can mimic shadow behavior.

ElPelado · Post #4by **ElPelado** » 06.06.2003, 11:07

so, with a GeFroce 2 i cant??
can someone put a picture of the rings' shadow in saturn??

Post #5by **selden** » 06.06.2003, 12:51

shadows by the rings on the planet, like bumpmaps, use "vertex shaders". You need a card that has vertex shader support in its drivers in order to see the shadows.

The surface of Saturn is just a jpeg image. You can use your favorite paint program to draw the shadows onto it, if you want.

marc · Post #6by **marc** » 06.06.2003, 13:30

The surface of Saturn is just a jpeg image. You can use your favorite paint program to draw the shadows onto it, if you want.

Only problem is that the shadows wont move as Saturn orbits the sun.

I have a GF2 as well, my flatmate recently bought a dual G4 Apple, I convinced him to try Celestia on it and I was surprised to see the second ring shadows. They look fantastic.

jrobert · Post #7by **jrobert** » 06.06.2003, 15:06

Well how are moon shadows projected onto planet surfaces? I was figuring that when I brought this issue up before v1.2.5 was released, that the ring shadows were going to be rendered the same way as moon shadows upon planets. What is it about the rings that makes it have to be rendered with vertex shaders?

Post #8by **chris** » 06.06.2003, 16:16

selden wrote:shadows by the rings on the planet, like bumpmaps, use "vertex shaders". You need a card that has vertex shader support in its drivers in order to see the shadows.

Vertex shaders can be emulated reasonably well in software, so that's not the problem . . . The missing feature on a GeForce2 is clamp to texture border color. Without this extension, I'd have to ensure that the edge texels on every ring texture were completely transparent. For ring textures, mipmapping would also have to be turned off. Not that big of a deal really, but I don't want to introduce annoying restrictions for add-on creators just to support older hardware. If you want ring shadows, upgrade!

The surface of Saturn is just a jpeg image. You can use your favorite paint program to draw the shadows onto it, if you want.

They wouldn't be dynamic . . . and you'd have to make the surface texture of Saturn very high-resolution to get shadows with a clean edge (up close anyhow.)

--Chris

ElPelado · Post #9by **ElPelado** » 06.06.2003, 19:08

can someone pos ta picture of the shadows??

Post #10by **selden** » 06.06.2003, 20:41

Note the shadows on the upper part of Saturn.

ElPelado · Post #11by **ElPelado** » 06.06.2003, 22:45

thanks selden. its very beautiful, and its a shame that i cant see it on my celestia.

when i bought my computer(a year ago) i thought that my GeForce 2 was one of the bests video cards, now i know that is not such a thing, or at least not in celestia. :cry:

jrobert · Post #12by **jrobert** » 07.06.2003, 01:24

ElPelado,

That's the problem with todays technology -- it's advancing just way too fast. I also bought my system about a year ago. Here's the basic rundown of my system:

Basically, Top-of-the-line when I got it.