Hello.
I read and nvidia paper about ARB_texture_compression and used the provided code to open a *.dds file and upload the data to OGL.
I am confused about how mipmapping works.
According to the paper all mipmap-levels are included in the dds file and I just have to feed it to OGL with help off an offset in to the data array.
My question: Is it guaranteed that the mipmaps are included?
If this is not the case, what happens?
Thanks for information!
I may not be good looking but I sure am dumb.
This is OT *because* you are talking about a file format,
but I`ll give a quick reply:
nope, not all DDS have a mipmap. You can generate the mipmaps yourself using any algortihm you want.
PS: you can turn on automatic mipmapping (GL_SGIS_mipmaping or whatever it`s called)
------------------------------
Sig: http://glhlib.sourceforge.net
an open source GLU replacement library. Much more modern than GLU.
float matrix[16], inverse_matrix[16];
glhLoadIdentityf2(matrix);
glhTranslatef2(matrix, 0.0, 0.0, 5.0);
glhRotateAboutXf2(matrix, angleInRadians);
glhScalef2(matrix, 1.0, 1.0, -1.0);
glhQuickInvertMatrixf2(matrix, inverse_matrix);
glUniformMatrix4fv(uniformLocation1, 1, FALSE, matrix);
glUniformMatrix4fv(uniformLocation2, 1, FALSE, inverse_matrix);
Hello.
This is not OT because I am talking about
ARB_texture_compression.
Are you sure that glTexParameteri(GL_TEXTURE_2D, GL_GENERATE_MIPMAP_SGIS, GL_TRUE) works here?
The paper says that all mipmaps have to be given to OGL manually in this case.
Sorry if I wasnt clear not the dds file-format as such is my problem, but how to correctly handle mipmapping when using ARB_texture_compression!
Thanks for the help.
I may not be good looking but I sure am dumb.
If you want to know if a given .dds file has mipmaps, check the dwMipMapCount part of the DDS header to see if its greater than zero.
Yes, automatic mipmap generation works fine with compressed textures.Are you sure that glTexParameteri(GL_TEXTURE_2D, GL_GENERATE_MIPMAP_SGIS, GL_TRUE) works here?
While it is true that SGIS_GEN_MIPMAP will work for compressed textures, (With the possible exception of a driver bug) it should be understood that this is unlikely to be something an app developer wants to do in a performance critical path.
Also, not to pile on here, but the way this question was asked also led me to believe it was an off-topic question about a file format. Something along the lines of, "How can I specify/generate mipmaps for a compressed texture of this format?", might be more likely to lead to a helpful answer.
-Evan
[This message has been edited by ehart (edited 08-11-2003).]
Thanks for the answers. Things seem much clearer now!
I appologize for the formulation of the question and I hope it turned out allright in the end.
I may not be good looking but I sure am dumb.
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