Skybox Issues

Feb 5, 2010 at 2:28 AM
Edited Feb 5, 2010 at 2:31 AM

http://img10.imageshack.us/img10/4599/skyboxshadowfov.gif

I'm not sure if this is the fog cutting out suddenly because it may only be drawn relative to the camera's Z and Y-axis or if it's the shadow of the upper Skybox polygon or something else entirely. This happens when the camera is above a certain height.


http://img197.imageshack.us/img197/3256/skyboxshadowortho.gif

An orthographic camera view of the same phenomenon. You can also see the reflection of one (I think it's the top because of the cloud texture) of the Skybox polygons in the water.

 

http://img694.imageshack.us/img694/5120/skyboxreflectionandbads.gif

Another Skybox polygons being reflected in orthographic view as well as an unscaled Skybox polygon visible beyond the terrain.

 

Coordinator
Feb 5, 2010 at 2:38 AM

Well, I'll be honest. I can't test Ox any more since my video card died. All I can do currently is run in reference mode, meaning I can only see one or two frames.

I can tell the issues just keep getting worse and there's nothing I can really do until I can find some money to get new hardware which I don't know when it will be.

 

Coordinator
Feb 5, 2010 at 3:39 AM

Alright, I've fixed a couple of issues. I find I can run at a few frames per second by resizing my app to 50x50 pixels, so that's something.

I've 'recalled' release 67 due to these issues. I'm going to try to put up another release in a couple of hours.

Sorry for the troubles you've encountered so far. I assure you that I am far more distraught about this stuff than I've made any users.

Feb 5, 2010 at 3:47 AM

That's unfortunate about the video card. Can you still run stuff on your 360?

You should consider putting up a donation link. You're offering a pretty decent engine with a very permissive license for free so I doubt anyone could fault you for offering them the option to contribute financially in exchange for your time and expertise.

Coordinator
Feb 5, 2010 at 3:54 AM

Okay, the first and second are was a shader bug that I've fixed.

But, I will have to take a few more minutes to figure out how to make the sky box render in orthographic mode :)

Coordinator
Feb 5, 2010 at 4:03 AM

Okay, I think I'd have to totally redo the skybox algorithm to make it work in orthographic view. This will be added to the todo list and noted as a defect. Do you need your particular game to work in orthographic view?

I can test on the xbox, but I've been having horrible network issues with it lately which makes it very hard to use.

I will try to figure out how to put up a donation link. hopefully I can raise $30 or so to get another video card :) thx for the suggestion :D

 

Feb 5, 2010 at 4:26 AM

I haven't yet decided whether or not I want to use an orthographic camera but the Skybox wouldn't be a crucial issue either way. I figured I'd point it out since it seemed unintentional and in case it was a new problem.

Good work with the shadows, you got them under control pretty quick considering your new graphics limitations.

$30 seems pretty cheap for a video card but I suppose it's a lot better than nothing as an interim solution.

 

Coordinator
Feb 5, 2010 at 4:30 AM

>> Good work with the shadows, you got them under control pretty quick considering your new graphics limitations.

Thanks! I can usually fix things without much testing, the big problem is new issues silently creeping in over time with such inadequate testing schemes.

Maybe someday someone will invent a way to unit test shader code :)

Feb 5, 2010 at 4:37 AM
Edited Feb 5, 2010 at 4:37 AM
bryanedds wrote:

>> Maybe someday someone will invent a way to unit test shader code :)

http://xen.codeplex.com/wikipage?title=about_shaders

Coordinator
Feb 5, 2010 at 5:12 AM

If you're using the canned releases, I've put out another. Please let me know of any rendering issues you have as soon as you can!

 

Feb 5, 2010 at 6:12 AM
Edited Feb 5, 2010 at 6:15 AM

I've been using the SVN releases.

You mentioned that you were having network issues with your Xbox. It might not be your hardware since I've noticed that it now takes me roughly 4 minutes to deploy the Xbox 360 GameDemo whereas it previously took less than one.

Shadows disappear once the camera reaches a certain height.

On the Xbox, using an OrthoCamera there are bands of shadows that appear around the terrain which rise and fall according to the height of the camera.

The frame rate on the 360 at 1920x1080 feels significantly lower than it did a couple weeks ago but it might be my imagination.

Editor
Feb 5, 2010 at 6:25 AM

what interface does your graphics card use bryan? sure i got one lying around here somewhere i can ship to you.

Coordinator
Feb 5, 2010 at 2:19 PM

bubzy, my interface is AGP 8x. I'd be ecstatic if you'd be willing to donate one :)

Alt,

>> You mentioned that you were having network issues with your Xbox. It might not be your hardware since I've noticed that it now takes me roughly 4 minutes to deploy the Xbox 360 GameDemo whereas it previously took less than one.

This might be because I turned on mip-map generation for most textures. Although, at most it should take only twice as long. You might try a clean deploy on the Xbox as I've known deployment time to slow over time.

>> Shadows disappear once the camera reaches a certain height.

That is actually correct behavior. The shadow map renders from above the camera and can only render with so much depth. There are some properties you can adjust on IDirectionalLight such as ShadowCameraRelativeToViewCamera and the like to change the behavior.

>> On the Xbox, using an OrthoCamera there are bands of shadows that appear around the terrain which rise and fall according to the height of the camera.

Please try adjusting DirectionalShadowDepthBias in Scene.xml upward and let me know what value if any makes the bands go away.

>> The frame rate on the 360 at 1920x1080 feels significantly lower than it did a couple weeks ago but it might be my imagination.

These perf issues may be caused by the larger depth stencil buffer and shadow map. If you lower DirectionalShadowMapSize in Scene.xml to 1, you can also lower DepthStencilBufferSize to 1, and the perf should improve a lot.

Cheers!

Editor
Feb 5, 2010 at 7:50 PM

got a radeon 9500 128mb agp card. check it out, if its good enough ill be happy to ship it to ya, just email me your address :) rich@greymatterscomic.com

 

Coordinator
Feb 5, 2010 at 7:58 PM

oh man, you are my hero ~~~ :D Should be great since radeon 9500 runs shader model 3.0 I think!

I'll e-mail you :D

Feb 10, 2010 at 12:14 AM
bryanedds wrote:

This might be because I turned on mip-map generation for most textures. Although, at most it should take only twice as long. You might try a clean deploy on the Xbox as I've known deployment time to slow over time.

Ah, that explains it. Clean deploying hasn't made any noticable difference for me besides the obvious initial deployment taking longer.

Please try adjusting DirectionalShadowDepthBias in Scene.xml upward and let me know what value if any makes the bands go away.

I've tried many different combinations of the DirectionalShadowMapSize, DirectionalShadowDepthBias, DirectionalShadowRange, and DirectionalShadowSize properties. Adjusting each of them changes the frequency of the bands and the camera/ball heights at which they appear but no combination seems to eliminate the bands entirely that does not also remove or mess up the shadows of all objects touching or very close to the ground.

These perf issues may be caused by the larger depth stencil buffer and shadow map. If you lower DirectionalShadowMapSize in Scene.xml to 1, you can also lower DepthStencilBufferSize to 1, and the perf should improve a lot.

I didn't do extensive testing but reducing them both to 1 in addition to reducing the performance of the PhysicsSystem was still not enough to kick the FPS from 30 to 60, even in Release configuration. Got any other simple optimization ideas?

Coordinator
Feb 10, 2010 at 12:39 AM

Shadows and water and etc seem to have shader bugs. I've manually checked the math over and over but have found nothing wrong. Hopefully I'll be able to solve this when my video card arrives :)

As to your perf issues, it's probably the resolution being too high. My only guess is to tone the resolution down to something more reasonable for the hardware.

Feb 10, 2010 at 5:25 AM

The shadow issues I pointed out mostly arise on the Xbox though I have seen banding on Windows with super low DirectionalShadowDepthBias values.

Also on Xbox, with an FovCamera you can see the edges of the Skybox and it just behaves like a huge textured cube.

Hopefully I'll be able to figure out some ways to bump the frame rate up a bit.