Backends: GLFW: Accept glfwGetTime() not returning a monotonically in…

…creasing value. (#6491, #6189, #6114)
ocornut · Jun 12, 2023 · 884e3fd · 884e3fd
1 parent dec082f
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diff --git a/backends/imgui_impl_glfw.cpp b/backends/imgui_impl_glfw.cpp
@@ -17,6 +17,7 @@
 
 // CHANGELOG
 // (minor and older changes stripped away, please see git history for details)
+//  2023-06-12: Accept glfwGetTime() not returning a monotonically increasing value. This seems to happens on some Windows setup when peripherals disconnect, and is likely to also happen on browser + Emscripten. (#6491)
 //  2023-04-04: Inputs: Added support for io.AddMouseSourceEvent() to discriminate ImGuiMouseSource_Mouse/ImGuiMouseSource_TouchScreen/ImGuiMouseSource_Pen on Windows ONLY, using a custom WndProc hook. (#2702)
 //  2023-03-16: Inputs: Fixed key modifiers handling on secondary viewports (docking branch). Broken on 2023/01/04. (#6248, #6034)
 //  2023-03-14: Emscripten: Avoid using glfwGetError() and glfwGetGamepadState() which are not correctly implemented in Emscripten emulation. (#6240)
@@ -780,7 +781,10 @@ void ImGui_ImplGlfw_NewFrame()
         io.DisplayFramebufferScale = ImVec2((float)display_w / (float)w, (float)display_h / (float)h);
 
     // Setup time step
+    // (Accept glfwGetTime() not returning a monotonically increasing value. Seems to happens on disconnecting peripherals and probably on VMs and Emscripten, see #6491, #6189, #6114, #3644)
     double current_time = glfwGetTime();
+    if (current_time <= bd->Time)
+        current_time = bd->Time + 0.00001f;
     io.DeltaTime = bd->Time > 0.0 ? (float)(current_time - bd->Time) : (float)(1.0f / 60.0f);
     bd->Time = current_time;
 

diff --git a/docs/CHANGELOG.txt b/docs/CHANGELOG.txt
@@ -39,6 +39,9 @@ Other changes:
 - Tables: Fixed a regression in 1.89.6 leading to the first column of tables with either
   ScrollX or ScrollY flags from being impossible to resize. (#6503)
 - Backends: OpenGL3: Fixed support for glBindSampler() backup/restore on ES3. (#6375, #6508) [@jsm174]
+- Backends: GLFW: Accept glfwGetTime() not returning a monotonically increasing value.
+  This seems to happens on some Windows setup when peripherals disconnect, and is likely
+  to also happen on browser+Emscripten. Matches similar 1.89.4 fix in SDL backend. (#6491)
 
 
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