Celestia Forums

I don't know if this is outdated but, is the cloud shadows render really doesn't work with vt cloud texture? I've reinstalled my celestia and try only a vt cloud texture, and the render doesn't show.

processor: intel core 2 duo
vga card: Nvidia geforce 9600gt, 1gb vram
RAM: 4gb vgen
OS: windows vista ultimate service pack 2 (with latest open gl and directX)

Verz Veraldi a question
is your nvidia driver FROM the nvidia web site or from "windows update"

auto updates will reinstalled there gl disabled driver ( and it WILL ) on top of the driver from nvidia's web site

you might want to check

You also have to
1. use Render path: OpenGL 2.0 (type Ctrl-V several times if necessary)
2. enable CloudShadows in the Render/View Options menu
3. look very closely. They're easier top see if you increase CloudHeight substantially.

although so high a cloud height does reveal a defect in Celestia!

To be specific, clouds beyond the rim of the planet are drawn on the night side where they should be in the planet's shadow-cone. Maybe that'll be fixed with the new shadow code which Chris has not yet finished.

Well, i believe it's not from my celestia itself because i've tried selden'd suggestion from the start (i turn on and off and on and off the render and see if there any difference), nothing work... just for info, i've installed many games in my computer that uses directX 9 or 10, and i DO update my directX from the nvidia web, not from the windows update.... maybe that's the problem?

--- edit ---

i've check with opengl extension viewer, it says i've got opengl 3.3.... and about the directX, it's long ago so i forgot.. sorry

I've verified that VT clouds do not cast shadows on my system, too.
I'm using Harald Smith's VT cloud texture downloaded from the MotherLode
http://celestiamotherlode.net/catalog/earthcloud.php

When I combined the two level0 dds images into a single dds, that does cast shadows.

System:
8GB, 1.6GHz, Core i7-Q720; Win7 Pro x64
512MB Nvidia NVS-3100M; ForceWare v258.96; OpenGL v3.3.0
Celestia r5053 & Celestia v1.6.0

p.s. The image below reveals that Celestia is not projecting the shadows accurately.
Apparently they're being drawn on the surface directly beneath the clouds instead
of being projected from the direction of the Sun. I have a vague recollection of Chris
mentioning that he'd changed to using this method because the algorithm he'd been
using to cast them "correctly" was using too many shaders, causing OpenGL errors.

Note that the shadows of clouds in the northern hemisphere are cast to their south,
while shadows of clouds in the southern hemisphere are cast to their north.
The viewpoint is Celestia's initial default, with the sun directly behind the viewpoint.
No shadows should be visible because they should be obscured by the clouds above them
But VTs don't cast any shadows no matter what viewpoint is used.

I think that clouds doesn't cast shadows because the alpha level isn't a true alpha level but it seem to be. With the rubber tool of a paint program, do try to erase the alpha parts; they will be erased too. The fainty remnants of the cloud's color, prevent the shadows because is as it were a global tint.

EDIT LATER:
It should be the loss dds compression that "moves" the colors on the alpha part, whether the original were good png's.

The alpha channels in the DDS images are fine. Otherwise the clouds wouldn't be transparent.

selden wrote:The alpha channels in the DDS images are fine. Otherwise the clouds wouldn't be transparent.

I do not understood. From your images seem that you have the same my cloud map, I reckon it from the sharp profile bordering the South America. But mine is a 2k PNG no longer available on ML now. If I'd wish to see the shadows, I'd wish to pass again the rubber tool on the alpha parts. And when I passed on the rubber, I'd saw the faintest white color, that superficially seemed the alpha part, erased during the tool's movement.

I'm not sure what you mean by "rubber tool" -- "eraser" maybe?

Most of Celestia's cloud textures are entirely solid white in the color channels. The shapes of the clouds are only in the Alpha channel, not in the color channels. (This makes them easier to compress, since all of the pixels are exactly the same color.) When you erase using a paint program, it will change both the color channels and the Alpha channel. Maybe you're seeing the change that's happening in the color channels.

selden wrote:I'm not sure what you mean by "rubber tool" -- "eraser" maybe?

Most of Celestia's cloud textures are entirely solid white in the color channels. The shapes of the clouds are only in the Alpha channel, not in the color channels. (This makes them easier to compress, since all of the pixels are exactly the same color.) When you erase using a paint program, it will change both the color channels and the Alpha channel. Maybe you're seeing the change that's happening in the color channels.

Yes, I mean the "eraser"; sometime is named "rubber" For the second question, there is one fault in my way of expression, indeed. I know what you mean with "alpha channel", you mean the correct, original, "way of style". Unfortunately, I call "alpha" also the simple transparent canvas, on which is painted on. Thus, I consider the parts of an image which are "transparents" the "alpha channel" of the image. My fault.

see that? the second image of selden's post still cast shadows... i've tried setting the height to 200.. nothing work... but, when i tried removing the vt cloud addon, the default cloud still cast shadows.... so, i bet it's a bug. i hope it's fixed in the next version..

Verz,

Yes, it is a bug (or missing feature).