Mip-mapping... Rotation makes it ugly?...

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Mip-mapping... Rotation makes it ugly?...

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Urbi et orbi...

Posted: Thu Oct 22, 2009 1:23 am

Guest

When a triangle is rotated and so it appears thinner, OpenGL renders it
with a low-level texture, although that's unnecessary and ugly... How do
you turn off this 'feature'? Smile

I want OpenGL to use the same,
high-level texture at all angles... At least when the object isn't
moving away and stays the same size...

Thanks. Smile

jbwest...

Posted: Thu Oct 22, 2009 4:22 am

Guest

"Urbi et orbi" <no.spam at (no spam) plea.se> wrote in message
news:hbnu3s$pmr$1 at (no spam) ss408.t-com.hr...

Quote:

When a triangle is rotated and so it appears thinner, OpenGL renders it
with a low-level texture, although that's unnecessary and ugly... How do
you turn off this 'feature'? Smile

I want OpenGL to use the same, high-level
texture at all angles... At least when the object isn't moving away and
stays the same size...

Thanks. Smile

Don't load mip maps, if that's really the issue (it's probably not).
What do you have for a minification filter ? (glTexParameter()) ?

Perhaps you really want trilinear mip-map filtering and/or
http://gregs-blog.com/2008/01/17/opengl-texture-filter-parameters-explained/
or
http://www.flipcode.com/archives/Advanced_OpenGL_Texture_Mapping.shtml

anisotropic filtering (see:)

http://developer.nvidia.com/object/Anisotropic_Filtering_OpenGL.html

If the texture is larger than the area of the (thinner) trinagle in pixels,
you unavoidably will get aliasing.
You need to choose an appropriate filtering technique to minimize artifacts.

-jbw

fungus...

Posted: Thu Oct 22, 2009 2:17 pm

Guest

On Oct 21, 11:23 pm, Urbi et orbi <no.s... at (no spam) plea.se> wrote:

Quote:

When a triangle is rotated and so it appears thinner, OpenGL renders it
with a low-level texture, although that's unnecessary and ugly... How do
you turn off this 'feature'? Smile

That's called Anisotropic Aliasing.

To fix it you don't turn anything off, you turn on
anisotropic filtering.

See this page:

http://www.opengl.org/registry/specs/EXT/texture_filter_anisotropic.txt

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