Re: [Plib-devel] Texture and blend modes

[Steve B. <sjb...@ai...>]

Sam Stickland wrote:

> How are these specified in ssg?  I'll take a wild guess that ssg
> doesn't manage texture environment modes (GL_MODULATE, GL_DECAL etc.)
> at all, and it only cares whether blending is on or off.

Well, when you add a texture into an ssgSimpleState, you can either
pass it an 'ssgTexture' or an OpenGL texture handle - or even a
filename (which will result in an ssgTexture being constructed on
your behalf).

Hence, there are really just two options - ssgTexture or do-it-yourself.

ssgTexture does indeed only specify GL_MODULATE - it's hard-wired in
the constructor function with no way to change it.
 
> So, do I set the required mode in a predraw callback function?

You have (at least) five options:

1) Derive a new class from ssgTexture (say ssgDecalTexture) that
   does GL_DECAL instead of GL_MODULATE.

2) Load the texture yourself, do the glBindTexture, set GL_DECAL
   using glTexEnvi, pass the texture handle to SSG.

3) In a pre-draw callback, set the glTexEnv to GL_DECAL.

4) Use ssgTexture to load the texture and do either a ssgSimpleState::getTextureHandle()
   or an ssgTexture::getHandle() to get the texture handle.  Then you can
   glBindTexture(handle) and change the glTexEnv setting.

5) Edit the SSG source code to add 'setEnvMode/getEnvMode' methods to ssgTexture - then
   contribute your change via CVS and earn fame, the recognition of your peers, etc, etc.
   While you are about it - add Mag/Min filter and texture wrap options.

People who know me well soon realise that I ALWAYS put my most favored option
at the end of a list of choices.  :-)

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