Flat2D Shader - Alpha (transparency) Support?

[miguelmartin75]

Is the Flat2D shader supposed to have transparency support? It seems that it doesn't on my machine, and I'm not sure if it's supposed to or not. Either way it would be lovely to have alpha support without having to create another shader.

Evidence of no alpha support:

Running Mac OS X 10.9.

Compiler:

Apple LLVM version 5.0 (clang-500.2.79) (based on LLVM 3.3svn)
Target: x86_64-apple-darwin13.0.0
Thread model: posix

OpenGL context information:

Vender: Intel Inc.
Renderer: Intel HD Graphics 3000 OpenGL Engine
Version: 3.3 INTEL-8.18.27

[miguelmartin75]

This issue had nothing to do with the flat shader, and instead, me not enabling blending, with the following code:

Magnum::Renderer::setFeature(Magnum::Renderer::Feature::Blending, true);
Magnum::Renderer::setBlendFunction(Magnum::Renderer::BlendFunction::SourceAlpha, Magnum::Renderer::BlendFunction::OneMinusSourceAlpha);
Magnum::Renderer::setBlendEquation(Magnum::Renderer::BlendEquation::Add, Magnum::Renderer::BlendEquation::Add);

LibRocket Integration is complete! Now I just have to get it working completely with SDL 2. :)

The cropped image in the background of the libRocket window is just a triangle with the texture of libRocket's GUI. I forgot to remove the code to render that triangle.

[miguelmartin75]

If you would like to see the code used to integrate Magnum with libRocket, you can look at my recently added repository on github. Here: https://github.com/miguelishawt/Magnum-libRocket.

[Jmgr]

Great, this will save me a lot of time. Thank you!

[mosra]

Awesome :-) Is there anything that can be done on Magnum side to simplify the integration (i.e. conversion between libRocket and Magnum vector types)? Or the integration class is all you need on the C++ side and everything else is done in HTML?

[miguelmartin75]

Is there anything that can be done on Magnum side to simplify the integration (i.e. conversion between libRocket and Magnum vector types)?

The only thing that I can think of is that libRocket supplies vertices that contain a colour component within them. And Flat2D does not support colour per vertex. But it seems that it does not affect the resulting images rendered.

The conversion between magnum and libRocket's vector types are not required, but it may be if sizeof(Magnum::Vector2) != sizeof(Rocket::Core::Vector2f). This may be the case if you are using a vector with double's in the implementation within magnum (that is a Magnum::Vector2<double> within the Flat2D shader's implementation for the attributes).

Or the integration class is all you need on the C++ side and everything else is done in HTML?

On magnum's side yes, but you do require a system interface, which basically handles the input for libRocket. I have implemented a SystemInterface with SDL 2, which is located here on GitHub: https://github.com/miguelishawt/SDL2-libRocket-SystemInterface.