Multi-contexts with Metal backend

[noisewuwei]

OS: Mac OS
Backend:Metal
I created two NSWindow with MTKView. When my imgui window name is the same, two NSWindows can respond to mouse events on any one window at the same time. When imgui window names are different, two NSWindows cannot respond to mouse events. What caused it?

[ocornut]

Hello,
It is ambiguous whether you created multiple imgui contexts or not, or what you do you mean by "my imgui window", etc. I think you will need to provide more details in order to receive help. Please post more details and I will reopen this issue.

[noisewuwei]

Hello,
It is ambiguous whether you created multiple imgui contexts or not, or what you do you mean by "my imgui window", etc. I think you will need to provide more details in order to receive help. Please post more details and I will reopen this issue.

I have create two MTKView. And I call ImGui::CreateContext() in each MTKView.

[ocornut]

If you create multiple contexts you need to switch context with ImGui::SetCurrentContext() before accessing the IO structure.
It is unclear which platform backend you are using (you didn't fill the requested template).

[noisewuwei]

If you create multiple contexts you need to switch context with ImGui::SetCurrentContext() before accessing the IO structure.
It is unclear which platform backend you are using (you didn't fill the requested template).

MAC OS Metal.

[noisewuwei]

@interface IMGUIMetalView (){
ImGuiContext *ctx;
}

• (void)drawRect:(NSRect)dirtyRect {
  [super drawRect:dirtyRect];
  // Drawing code here.
  ctx = ImGui::CreateContext();
  ImGuiIO& io = ImGui::GetIO(); (void)io;
  }

-(void)drawInMTKView:(MTKView*)view
{
ImGui::SetCurrentContext(ctx);

ImGuiIO& io = ImGui::GetIO();
io.DisplaySize.x = view.bounds.size.width;
io.DisplaySize.y = view.bounds.size.height;

#if TARGET_OS_OSX
CGFloat framebufferScale = view.window.screen.backingScaleFactor ?: NSScreen.mainScreen.backingScaleFactor;
#else
CGFloat framebufferScale = view.window.screen.scale ?: UIScreen.mainScreen.scale;
#endif
io.DisplayFramebufferScale = ImVec2(framebufferScale, framebufferScale);

io.DeltaTime = 1 / float(view.preferredFramesPerSecond ?: 60);

}

Is that right？

[noisewuwei]

If you create multiple contexts you need to switch context with ImGui::SetCurrentContext() before accessing the IO structure.
It is unclear which platform backend you are using (you didn't fill the requested template).

https://github.com/ocornut/imgui/commit/4cec3a0467af9cd068d85363d1a7ceaddc3b68e0

I've seen this link.
Metal cannot support multi-context ？

[ocornut]

Right, neither Metal nor OSX backend have been refactored to support multiple context.

[noisewuwei]

Right, neither Metal nor OSX backend have been refactored to support multiple context.

Metal cannot support multiple-viewprots neither.Is there any way to create multiple windows when using Metal on Macos.

[ocornut]

Well we need pull requests for both.
Multi-contexts should be quite easy to support. Multi-viewport more involved.

[noisewuwei]

Well we need pull requests for both.
Multi-contexts should be quite easy to support. Multi-viewport more involved.

Yep.Multi-viewports is like magic.

[noisewuwei]

Well we need pull requests for both.
Multi-contexts should be quite easy to support. Multi-viewport more involved.

By the way, is there any plan to make metal support multi contexts in the near future.

[ocornut]

I don't work for Mac so it depends on other users.

For multi-viewport see #2778 and #4821

For multi-contexts, we need both OSX and Metal backends to the same as e.g #4141 with 70c6038 and 4cec3a0
This probably needs to be done first before the multi-viewports stuff gets merged (then #2778 and #4821 rebased over that)

[noisewuwei]

I don't work for Mac so it depends on other users.

For multi-viewport see #2778 and #4821

For multi-contexts, we need both OSX and Metal backends to the same as e.g #4141 with 70c6038 and 4cec3a0 This probably needs to be done first before the multi-viewports stuff gets merged (then #2778 and #4821 rebased over that)

OK.I will have a try.

[noisewuwei]

I don't work for Mac so it depends on other users.

For multi-viewport see #2778 and #4821

For multi-contexts, we need both OSX and Metal backends to the same as e.g #4141 with 70c6038 and 4cec3a0 This probably needs to be done first before the multi-viewports stuff gets merged (then #2778 and #4821 rebased over that)

Hello.
#5221 pull request.
Take a look.

[ocornut]

Thank you! We have now merged e54db4e which is your PR + various fixes/cleanup done by @rokups.
(Your PR accidentally reverted the two latest commit on those files)