RE: glUniform and multiple textures

On Sun, 2008-09-14 at 11:25 -0800, Malcolm Bechard wrote:
> It expects the texture unit the texture was bound to, so you were right in
> the first case.
> 
> Not sure what the issue is.

Found it thanks to your answer.

The issue turned out to be completely outside of my render loop which is
why I didn't find it.

What happened was when loading my color map texture I was accidentally
passing my texture format variable containing
GL_COMPRESSED_RGBA_S3TC_DXT1_EXT to glBindTexture instead of passing the
type variable containing GL_TEXTURE_2D.

Amazingly enough, OpenGL still created the texture, but how this managed
to get the texture units mixed up like that I have no idea.

Fixed that and things work as they are supposed to!

Thanks,

Stephan

> 
> -----Original Message-----
> Stephan Rose
> Sent: Sunday, September 14, 2008 2:45 PM
> To: Multiple recipients of list OPENGL-GAMEDEV-L
> 
> Can someone explain what precisely glUniform expects as a value when
> using it to assign textures?
> 
> I have a shader that makes use of two textures. One is a cubemap used as
> a heightmap and the other is a color map (2D Texture) to look up values
> based on the height in the cubemap.
> 
> The heightmap is in texture unit 0, the colormap is in texture unit 1.
> 
> I've spent the whole morning trying to get this to work and it just
> wouldn't which was really strange as in a previous test application I
> got it to work just fine. Just when I took all the spaghetti code and
> made a real engine out of it, things stopped working. Go figure...
> 
> Now in my old code, I had this:
> 
> glUniform1i(glGetUniformLocation(programId, "heightMap"), 0);
> glUniform1i(glGetUniformLocation(programId, "colorMap"), 1);
> 
> And I used the same in my new code and it didn't work. It worked fine in
> my old code....
> 
> So then I figure, let me look at the texture ID numbers that OpenGL is
> giving my two textures, they turn out to be 1 and 2.
> 
> So I change the code to this:
> 
> glUniform1i(glGetUniformLocation(programId, "heightMap"), 1);
> glUniform1i(glGetUniformLocation(programId, "colorMap"), 2);
> 
> It works...flawlessly.
> 
> And just for reference, in my shader the variables are defined as:
> 
> uniform samplerCube heightMap;
> uniform sampler2D colorMap;
> 
> So what does glUniform expect here? The Texture unit or the texture ID?
> 
> And if it does expect the texture ID, why did it work in my old code
> with a Texture ID of 0? And if it expects the texture unit, why is it
> working in my new code with 1 and 2 even though the textures are in 0
> and 1?
> 
> I don't like it when something works and I don't understand why it
> works. That's just begging for an invitation to come back to haunt me
> later and the OpenGL documentation for glUniform is very vague on this
> as is trying to find any information about this on Google.
> 
> If someone could clear this up for me I would really appreciate it.
> 
> Thanks,
> 
> Stephan
> 
> 
> ----- 
> FAQ and OpenGL Resources at:
>   http://www.geocities.com/SiliconValley/Hills/9956/OpenGL
> 
> -- 
> Author: Stephan Rose
>   INET: [email protected]
> 
> Fat City Hosting, San Diego, California -- http://www.fatcity.com
> ---------------------------------------------------------------------
> To REMOVE yourself from this mailing list, send an E-Mail message
> to: [email protected] (note EXACT spelling of 'ListGuru') and in
> the message BODY, include a line containing: UNSUB OPENGL-GAMEDEV-L
> (or the name of mailing list you want to be removed from).  You may
> also send the HELP command for other information (like subscribing)
> 
> ----- 
> FAQ and OpenGL Resources at:
>   http://www.geocities.com/SiliconValley/Hills/9956/OpenGL
> 

----- 
FAQ and OpenGL Resources at:
  http://www.geocities.com/SiliconValley/Hills/9956/OpenGL

-- 
Author: Stephan Rose
  INET: [email protected]

Fat City Hosting, San Diego, California -- http://www.fatcity.com
---------------------------------------------------------------------
To REMOVE yourself from this mailing list, send an E-Mail message
to: [email protected] (note EXACT spelling of 'ListGuru') and in
the message BODY, include a line containing: UNSUB OPENGL-GAMEDEV-L
(or the name of mailing list you want to be removed from).  You may
also send the HELP command for other information (like subscribing).