textures not looking good

[JanHH]

Hello,

the textures in my program look rather ugly, you can see where abruplty changes from one mipmap level to another. I know this effect from games like Unreal (1), but there, when you turn on trilinear filtering, it gets filtered smooth and looks fine. But my linux opengl app won't behave this way, even with

glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR_MIPMAP_LINEAR);

which according to the red book are the best quality settings, it looks like sh*t. Does anybody know how this is going to work? with aniso filtering and antiaaliasing textures look great but as we know, on a gf4 ti this really costs performance.

Regards
Jan

[dorbie]

Some graphics drivers limit the filtering in order to run faster. There are also hardware limits to these.

You are making the correct OpenGL call to improve quality, but there is obviously a driver setting you need to adjust (perhaps an environment variable) that will tell the graphics card to honour your request for trilinear filtering. In windows this is all done through the display->settings->advanced dialog.

On linux you might want to use a friendly tool like this:
http://yanc.sourceforge.net/index-en.html

[This message has been edited by dorbie (edited 05-08-2003).]

[JanHH]

thanks for the link.. looks like a convenient tool to enable/disable antialiasing and anisotropic filterung. But there is nothing about trilinear filtering http://www.opengl.org/discussion_boards/ubb/wink.gif. Anyway, there definitely IS trilinear filterung in my 3d scene, the problem rather seems to be that the lower mipmap level texture, which gets magnified, is not filtered at all but you can really see each texel, like a "brick" or something, really looks like software rendering, pre-opengl quake and stuff like that. maybe GL_LINEAR for texture magnification is not the best?

Jan

[JanHH]

what i found most interesting about yanc is that is is a kylix program.. the first i have ever seen http://www.opengl.org/discussion_boards/ubb/smile.gif. Is there OpenGL support for kylix?

[JanHH]

I found out that when I use GL_NEAREST and GL_NEAREST_MIPMAP_NEAREST as texParameter, it still looks the same.. is it possible that these commands do not have any effect at all, and the driver/graphics chip simply does "what is wants"? Am I missing something that is not part of OpenGL 1.1 (which is my version of the red book)? Am I just too stupid?

Jan

[JanHH]

I got it, I was too stupid.. the glTexParameteri(..) have to be between glBindTexture and gluBuild2DMimpams.. I thought that they were global settings for all textures.

Thanks,
Jan