[cyhawk]

I am just getting to know ArcLib and wanted to try the lighttest example. It compiles and runs fine, but there are no shadows (or no light depending on how you look at it).

A screenshot:
[img]http://s3.amazonaws.com/scrnshots.com/screenshots/119974/lighttestpng[/img]
http://www.scrnshots.com/users/cyhawk/screenshots/119974

I have made the image files accessible and arc.log says:

[clayasaurus]

Hello,

This is good for me to know, actually. What operating system are you running on?

My advice would be to wait until I get the problem figured out, unfortunately. The lighting code does work fine on Windows, however it may have problems on linux, which is weird because the code uses OpenGL and was originally developed on linux.

~ Clay

[SirAlaran]

[clayasaurus]

Wait, OK, you are on Windows. It should be working.

Let's try a little bit of trouble shooting here then.

Do you have this folder

http://svn.dsource.org/projects/arclib/downloads/testbin/

in the same directory as your exe file?

~ Clay

[cyhawk]

Yes, I have copied testbin with the images to the folder. I will try to follow what goes on in OpenGL and try to find out where things disappear. Thanks for any tips in the meanwhile.

[clayasaurus]

Tips... let's see...

1) http://www.incasoftware.de/~kamm/projects/index.php/2007/09/08/soft-shadows-2d/#more-4

2) http://www.gamedev.net/reference/articles/article2032.asp

3) The lighting code uses some fairly basic OGL features and doesn't use any extensions, which is why I'm having trouble thinking of what is going wrong. However, I'd recommend concentrating on the lighttest.d file and tweaking OpenGL parameters there to see if you get any interesting results.

[cyhawk]

Thanks, I've read those articles! I really like this method for 2D shadows!

It turns out that my OpenGL context has no destination alpha channel and so when the lights are about to be drawn with "GL_ONE_MINUS_DST_ALPHA" they do not get drawn at all (the alpha defaults to 1).

I see that setupPixelFormat sets up the bit depths of the SDL window in arc/arc/window.d. Is there a hook for modifying the window setup procedure?

[clayasaurus]

No there isn't a hook for modifying it. Would you be able to test out different alpha settings and see if you can find one that works for you, then tell me which one you used?

[cyhawk]

I have now created a copy of window.d to compile with lighttest.d and changed setupPixelFormat to

[clayasaurus]

I put the fix in. Thanks for finding it!
~ Clay

[cyhawk]

I have played with this example a bit more and modified a few things:

http://home.sch.bme.hu/~cyhawk/lighttest2.zip

One is important: set filtering to linear for the penumbrae (filtering defaults to nearest_mipmap_nearest which I think is a bit unexpected).

The others are not that important. I replaced light.png with a physically correct attenuation (1/(1 + d^2)). Of course now the lights have infinite range which may be a bit of a problem but looks alright. I also replaced penumbra.png with a physically more correct version. Instead of a linear gradient it is based on how much of a circle would be visible, so it is an approximation of spherical lights while the linear gradient (at least I think it was linear) was an approximation of cylindrical lights.

I like how it looks now and feel inspired to create a game that uses it heavily .

[clayasaurus]

Alright, I applied your new changes + lightmaps into the ArcLib trunk.
I also added the py files to the trunk so others can generate their own light maps.

Do you want your name as cyhawk in the 'AUTHORS' file? Are you fine with your codes being zlib/png licensed?

[cyhawk]

My name is Daniel Darabos, and I am fine with the licensing. My changes are miniscule, but thanks for the attribution!

[clayasaurus]

I appreciate all the help I can get Especially if lighting will now work on more gfx cards.

[cyhawk]

I have merged the "dominos" blaze demo with the lighttest! There are some artifacts (the rectangles in the demo are quite thin), but the dynamic interplay of shadows and physics is very nice.

http://www.scrnshots.com/users/cyhawk/screenshots/123706