GExt

Hey there. There is a preview of the GUI library based on pure OpenGL.

This is not a claim for a best implementation, but an attempt to make good tool for constructing and managing GUIs. There is high-customization modular cross-version library with fully documented API.
It have simple implementation on the wide list of Minecraft versions. Now supported: 1.7.10-1.15.2.

Key features:

• Uniform API - extracted general graphics components' methods
• Containers - you can(and should) use relative coordinates everywhere. Creating context-free code is awesome!
• Relative positioning - Alignments(like HTML alignment) and Bounds(Component Binding). More information in wiki in the bottom of the page.
• Declarative-styled GUI construction code - no boilerplate, just content
• Modular components structure. Combine pieces to build your dream!
• Component drawing isolation - broken render can't break another
• Clipping enabled by default - we use glScissor mechanism to clip drawing area and fully isolate components' rendering apart
• Universal construction - StyleMap. Can define styles and draw interface elements from it. Any size, any context
• Listeners. You can inject your own code to any graphics component. It should be called every time the target component updates his state
• Context menus. Easy interaction with graphics components

You can get started with Github Wiki

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