I improved the implementation of materials and textures with Vulkan. Now every material is translated into a GLSL shader that is converted into SPIRV code with shaderc library. The shader is generated along the graphics pipeline to match the material settings. For now materials are very simple and used to draw an image texture with alpha blending or a filled color.
As you can see from the video, now the gui has normal appearence instead of rainbow rectangles of before. The next step is to support path rendering and font rendering, for drawing the text. In the future, the same materials system will be used to draw 3D content too.