Databases
StackOverflow2013
Postsdbo
PO
 

Note that there are some explanatory texts on larger screens.

plurals
  1. PO
    primarykey
    data
    text
    <p>(1) it seems unlikely; I'd expect it just to use a box filter, which is average four points in effect. Possibly it's just switching from one texture to a higher resolution one at a different moment — e.g. it "Chooses the mipmap that most closely matches the size of the pixel being textured", so a 256x256 map will be used to texture a 383x383 area, whereas the manual system it replaces may always have scaled down from 512x512 until the target size was 256x256 or less.</p> <p>(2) not that I'm aware of in base GL, but if you were to switch to GLSL and the programmable pipeline then you could use the 'bias' parameter to texture2D if the problem is that the lower resolution map is being used when you don't want it to be. Similarly, the <a href="http://www.opengl.org/registry/specs/EXT/texture_lod_bias.txt" rel="noreferrer">GL_EXT_texture_lod_bias</a> extension can do the same in the fixed pipeline. It's an NVidia extension from a decade ago and is something all programmable cards could do, so it's reasonably likely you'll have it.</p> <p>(EDIT: reading the extension more thoroughly, texture bias migrated into the core spec of OpenGL in version 1.4; clearly my man pages are very out of date. Checking the <a href="http://www.opengl.org/documentation/specs/version1.4/glspec14.pdf" rel="noreferrer">1.4 spec</a>, page 279, you can supply a GL_TEXTURE_LOD_BIAS)</p> <p>(3) yes — if you disable GL_GENERATE_MIPMAP then you can use glTexImage2D to supply whatever image you like for every level of scale, that being what the 'level' parameter dictates. So you can supply completely unrelated mip maps if you want.</p>
    singulars
    1. This table or related slice is empty.
    1. POhow to make opengl mipmaps sharper?
      singulars
      1. PTQuestion
    1. PTAnswer
    1. USTommy
    1. USTommy
    plurals
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. POhow to make opengl mipmaps sharper?
      singulars
      1. PTQuestion
    1. This table or related slice is empty.
    1. VO
      singulars
      1. PO
      1. This table or related slice is empty.
      1. VTUpMod
    2. VO
      singulars
      1. PO
      1. This table or related slice is empty.
      1. VTAcceptedByOriginator
    3. VO
      singulars
      1. PO
      1. This table or related slice is empty.
      1. VTUpMod
    1. COThanks for the quick reply. Aha! The "level" parameter is the key, so now I understand you can use glTexImage2D to provide your own mipmaps. I will try it and report back if it increases the sharpness. As a follow-up question, is the way it works that if you provide a mipmap for a certain level opengl uses it, and if you don't provide it, it generates one for you (up to the max mipmaps specified)? And does it generate those mipmaps up front, or only as they are actually needed?
      singulars
      1. PO
      1. USM Katz
    2. COAlthough if what you say for question (1) is true, it seems like I'm doomed. Although if what you say for question (2) is true, I'm not necessarily doomed, but potentially in for a lot or work... Or actually, perhaps in (3) by providing mipmaps one size too large for the given level I can achieve the same effect???
      singulars
      1. PO
      1. USM Katz
    3. CO@M Katz: OpenGL didn't generate mip maps in early versions, hence the glu method that automatically scales and uploads a texture at every level. So I think the default is for GL to do nothing. GL_GENERATE_MIPMAP generates new mip maps when level 0 is uploaded, its replacement in 3.0 is glGenerateMipmap which generates mip maps only upon command. So either way, you've got to give GL a push to get mip maps generated. Supposing my guess for (1) is correct, you should be able to fix the problem using GL_TEXTURE_LOD_BIAS as per my edit.
      singulars
      1. PO
      1. USTommy
 

Querying!

 
Guidance
A row detail

Detail views are divided into sections. All the information in the data section comes from columns in the selected row. The other sections display data from other, related rows.

Related data can be related in a to-one or a to-many fashion. Captions of data related in a to-many fashion link to a list view showing a filtered view of the table.

Try moving around until you find a non-empty to-many entry and click on the label to get to one. You can move back to the root by clicking on the database name in the header.

SQuiL has stopped working due to an internal error.

If you are curious you may find further information in the browser console, which is accessible through the devtools (F12).

Reload