[solved] Image Window alpha not working as expected

[Excizted]

Hello,

I've used the approach to have a simple Window containing an Image, as described here:
viewtopic.php?f=10&t=4744&p=22359&hilit=simple+image#p22359

It works just fine, except I want to add transparency - the Image tones out, but it seems like theres actually some constant color behind the image - it doesn't reveal whats actually behind the window.

Could anyone point me in the right direction?

Thank you so much!

[agamemnus]

Just a guess, but it might be that the color you see is the actual background behind CEGUI windows.

If so, and you are using Irrlicht, read this:
viewtopic.php?f=3&t=4943

[Excizted]

Just a guess, but it might be that the color you see is the actual background behind CEGUI windows.

If so, and you are using Irrlicht, read this:
viewtopic.php?f=3&t=4943

Not using IrrLicht though.. Ogre..

[Excizted]

I've tried so much now, really can't solve it!
Is there no one out there who has had the same issue?

[agamemnus]

Check cegui/src/RendererModules/Ogre/CEGUIOgreGeometryBuffer.cpp. You can see it has both "S_alphaBlendMode" and "S_colourBlendMode".

[Excizted]

Yes, I've checked that file and seen those two, but not been able to figure out furthermore what they are used for.
They are both used in initialiseTextureStates().

[Excizted]

I've found that you don't actually see the viewport background of the renderer.
The image just doesn't alpha at all.

[Excizted]

Finally!
Issue resolved!

Added a fifth argument to the draw call:

Code: Select all

CEGUI::ColourRect(CEGUI::colour(1.f, 1.f, 1.f, this->getAlpha()))

Ending with a function like this:

Code: Select all

void ImageWindow::populateGeometryBuffer()
{
    if(d_image)
        d_image->draw(*d_geometry, CEGUI::Vector2(0, 0), d_pixelSize, 0, CEGUI::ColourRect(CEGUI::colour(1.f, 1.f, 1.f, this->getAlpha())));
}