Coolest Error Ever?

Blitz3D Forums/Blitz3D Programming/Coolest Error Ever?

Black Hydra

(Posted 2005) [#1]

Well I perhaps got the most bizarre and questionably *coolest* error I've ever seen. Definitely unwanted, and almost as confusing as it is interesting.

What happens is that when I switched to using skybox code for my backdrop (the exact same code from Mark's castle demo in the Blitz3D demo program) there is this occasional error that happens.

What happens is that every single polygon in the game goes awry. It looks like all of the polygons are trying to connect to each other, totally screwing up everything.

e.g. it appears as if one of the polygons from my players weapons is connecting with the polygon of an asteroid. Sometimes the enemies remain perfectly unaltered, other times they too try to connect with each other...

My HUD (3d using quads) also flickers in and out as if every surface on it is also being suddenly switched

e.g. the hud image I have for health becomes the image I have for radar, and they all flicker in and out and constantly change.

Seeing as the error only occurs with this skybox code, perhaps someone could tell me if there are any known errors or complications that would cause this. Also, perhaps somebody knows what is occuring based on the effects I described? I'm still not sure exactly WHAT is happening, so how can I possible debug it...

Here is the skybox code

Function LoadSkyBox.SkyBox( file$ )
    ;---------------------------
    ;Code provided by Mark Silby
    ;---------------------------
	m=CreateMesh(User\EnvironHandle)
	;front face
	b=LoadBrush( file$+"_FR.jpg",1 )
	s=CreateSurface( m,b )
	AddVertex s,-1,+1,-1,0,0:AddVertex s,+1,+1,-1,1,0
	AddVertex s,+1,-1,-1,1,1:AddVertex s,-1,-1,-1,0,1
	AddTriangle s,0,1,2:AddTriangle s,0,2,3:
	FreeBrush b
	;right face
	b=LoadBrush( file$+"_LF.jpg",1 )
	s=CreateSurface( m,b )
	AddVertex s,+1,+1,-1,0,0:AddVertex s,+1,+1,+1,1,0
	AddVertex s,+1,-1,+1,1,1:AddVertex s,+1,-1,-1,0,1
	AddTriangle s,0,1,2:AddTriangle s,0,2,3
	FreeBrush b
	;back face
	b=LoadBrush( file$+"_BK.jpg",1 )
	s=CreateSurface( m,b )
	AddVertex s,+1,+1,+1,0,0:AddVertex s,-1,+1,+1,1,0
	AddVertex s,-1,-1,+1,1,1:AddVertex s,+1,-1,+1,0,1
	AddTriangle s,0,1,2:AddTriangle s,0,2,3
	FreeBrush b
	;left face
	b=LoadBrush( file$+"_RT.jpg",1 )
	s=CreateSurface( m,b )
	AddVertex s,-1,+1,+1,0,0:AddVertex s,-1,+1,-1,1,0
	AddVertex s,-1,-1,-1,1,1:AddVertex s,-1,-1,+1,0,1
	AddTriangle s,0,1,2:AddTriangle s,0,2,3
	FreeBrush b
	;top face
	b=LoadBrush( file$+"_UP.jpg",1 )
	s=CreateSurface( m,b )
	AddVertex s,-1,+1,+1,0,1:AddVertex s,+1,+1,+1,0,0
	AddVertex s,+1,+1,-1,1,0:AddVertex s,-1,+1,-1,1,1
	AddTriangle s,0,1,2:AddTriangle s,0,2,3
	FreeBrush b
	;bottom face	
	b=LoadBrush( file$+"_DN.jpg",1 )
	s=CreateSurface( m,b )
	AddVertex s,-1,-1,-1,1,0:AddVertex s,+1,-1,-1,1,1
	AddVertex s,+1,-1,+1,0,1:AddVertex s,-1,-1,+1,0,0
	AddTriangle s,0,1,2:AddTriangle s,0,2,3
	FreeBrush b
	ScaleMesh m,400,400,400  
	FlipMesh m
	EntityFX m,1
	EntityOrder m, 2 ;Draw before everthing so that environs aren't obscured by this
	Sky.Skybox = New Skybox
	Sky\mesh = m
	Sky\File$ = File$
	Return Sky
End Function

So now I'm stuck. I've tried checking if it was a framerate issue, because it appears that WHATEVER is causing this is also killing the framerate down to around 3Hz. However, I managed to get the older version, using a skysphere for the backdrop, to get the game down to 2Hz and the error does not occur.

Is there anything that COULD cause an error like this? I'm in a desperate search for leads right now because I have 11000 lines of code and I'd rather not do a full code review if I don't have to.

Andy	(Posted 2005) [#2]

It's been discused before, in connection with Radeon drivers I believe.

What's your setup?

Andy

Black Hydra

(Posted 2005) [#3]

Could you give me some links to the topics about this?

My graphics card is a TNT Model 2. I sincerely doubt this is a graphics issue as the problem ONLY occurs when the skybox is inacted.

I've tried turning off the EntityOrder bit. I've tried removing the part where I parent it to the EnvironHandle. It still causes the same glitch.

Andy, if you have any links in the forums where this TYPE of problem was mentioned it would really help me in figuring out why this one is occuring for ME.

-Thanks

WolRon

(Posted 2005) [#4]

Sounds like a card/driver issue.

Black Hydra

(Posted 2005) [#5]

Okay. I think I found the source of the problem.

I think perhaps my mesh was using too high resolution images for the background. Each image was 1024x1024, apparently this might be too much for my graphics card to handle. I'm going to try it on 512x512 and again with 256 if it still looks like its doing this.

I suppose I'll have to overlay the more detailed images over-top the lower resolution backdrop...

Matty

(Posted 2005) [#6]

@Black Hydra - just looking at the code you've posted - what value does "User\Environhandle" have in the first couple of lines?

Also - this sounds a little like the old Copyentity bug where vertices/polygons flicker and stretch all over the place. Which version of Blitz are you using - if it is the copyentity bug then it should have been fixed in either 1.89 or 1.90?

Picklesworth

(Posted 2005) [#7]

It's not a bug. It's a feature!
The beginnings of metaballs.

Yep, it's a driver issue, because NVidia is evil.

Rook Zimbabwe

(Posted 2005) [#8]

down with geForce... Luke use geForce... you can't geForce me to do that!!!

Nvidia has cut some lines somewhere in trying to "accellerate" their cards... it is showing IMHO

D4NM4N

(Posted 2005) [#9]

lol dunno, but in my vocab an error like this isnt cool it sucks :P