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Mip-mapping... Rotation makes it ugly?

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Urbi et orbi

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Oct 21, 2009, 5:23:05 PM10/21/09
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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'? :) 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. :)

jbwest

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Oct 21, 2009, 8:22:25 PM10/21/09
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"Urbi et orbi" <no....@plea.se> wrote in message
news:hbnu3s$pmr$1...@ss408.t-com.hr...

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

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Oct 22, 2009, 10:17:31 AM10/22/09
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On Oct 21, 11:23 pm, Urbi et orbi <no.s...@plea.se> wrote:
> 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'? :)

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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