CODEWITHSUNDEEP
opengl-es-2.0mipmaps
Simplex
Simplex

Reputation: 1733

Disable mipmapping in OpenGL ES 2.0

I would like to draw some of the same figures (with the same texture) on screen (OpenGL ES 2.0). These figures will be different in magnification and minification filters. And different states mipmapping. The issue is: if I use mipmapping in draw any figure ( if I called glGenerateMipmap() function) I can't switch off mipmapping mode. Is it possible to switch off mipmapping mode, if I call glGenerateMipmap() at least once?

Upvotes: 2

Views: 4811

Answers (1)

Christian Rau
Christian Rau

Reputation: 45948

glGenerateMipmap only generates the smaller mipmap images (based on the top-level image). But those mipmaps are not used for filtering if you don't use a proper mipmapping filter mode (through glTexParamteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_..._MIPMAP_...)). So if you don't want your texture mipmap filtered, just disable it for this particular texture by setting either GL_NEAREST or GL_LINEAR as minification filter. Likewise does not calling glGenerateMipmap not mean that there is no mipmapping going on. A possible mipmapping filter mode (which is also the default for a newly created texture) will still be used, just that the mipmap images contain rubbish (or the texture is actually incomplete, resulting in implementation-defined behaviour, but usually a black texture).

Likewise you shouldn't call glGenerateMipmap each frame before rendering. Call it once after setting the base image of the texture. Like said it generates the mipmap images, those won't go away after they've been generated. What decides if mipmapping is actually used is the texture object's filter mode.

Upvotes: 3

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