How is the Vulkan backend intended to be used?

[tompsweeney]

I'm using Vulkan for 3D rendering in my game. I've just started integrating RmlUi into the game, but I'm having some issues. Here are the details:

I've created a separate static library as part of my CMake build that includes:
- RmlUi_Platform_SDL.cpp
- RmlUi_Renderer_VK.cpp
- RmlUi_Backend_SDL_VK.cpp

Here's the relevant section of my top level CMakeLists.txt file:

#RmlUi
set(RMLUI_SOURCE_DIR ${PROJECT_SOURCE_DIR}/third_party/RmlUi)
set(RMLUI_BACKEND_PATH ${RMLUI_SOURCE_DIR}/Backends)
add_library(rmlui_backend_SDL_VK INTERFACE)
target_sources(rmlui_backend_SDL_VK INTERFACE
	${RMLUI_BACKEND_PATH}/RmlUi_Platform_SDL.cpp
    ${RMLUI_BACKEND_PATH}/RmlUi_Renderer_VK.cpp
    ${RMLUI_BACKEND_PATH}/RmlUi_Backend_SDL_VK.cpp
)
target_include_directories(rmlui_backend_SDL_VK INTERFACE ${RMLUI_BACKEND_PATH})
target_compile_definitions(rmlui_backend_SDL_VK INTERFACE
    RMLUI_SDL_VERSION_MAJOR=2
)

When I attempt to link this static library into my game, I'm getting LNK2005 (already defined) errors for all of the Vulkan Memory Allocator functions. I'm using the official Vulkan Memory Allocator library and would like to keep doing so, but I don't see how I can use the RmlUi vulkan renderer backend since it includes its own version of the main vulkan header as well as Vulkan Memory Allocator.

How is the vulkan rendering backend supposed to integrate with a project that's already using Vulkan?

[mikke89]

Hello! Sorry for the late response here.

I think the easiest approach here is simply to delete the included Vulkan Memory Allocator and modify the RmlUi_Include_Vulkan.h file to include your own version of that library. Maybe we should have some macros to override that, but right now modifying the header would be the way to go.