IO: Added ImGuiConfigFlags_NoMouse to force clear/disable mouse inputs in NewFrame().

CHANGELOG.txt

@@ -91,7 +91,13 @@ Other Changes:
 - Context: Removed allocator parameters from CreateContext(), they are now setup with SetAllocatorFunctions() and shared by all contexts. (#1565, #586, #992, #1007, #1558)
 - Context: You may pass a ImFontAtlas to CreateContext() to specify a font atlas to share. Shared font atlas are not owned by the context and not destroyed along with it.
 - Context: Added IMGUI_DISABLE_DEFAULT_ALLOCATORS to disable linking with malloc/free. (#1565, #586, #992, #1007, #1558)
-- IO: Added io.ConfigFlags for user application to store settings for imgui and for the back-end (currently: _NavEnableKeyboard, _NavEnableGamepad, _NavEnableSetMousePos, _NoMouseCursorChange).
+- IO: Added io.ConfigFlags for user application to store settings for imgui and for the back-end:
+    - ImGuiConfigFlags_NavEnableKeyboard: Enable keyboard navigation.
+    - ImGuiConfigFlags_NavEnableGamepad: Enable gamepad navigation (provided ImGuiBackendFlags_HasGamepad is also set by back-end).
+    - ImGuiConfigFlags_NavEnableSetMousePos: Instruct navigation to move the mouse cursor. May be useful on TV/console systems where moving a virtual mouse is awkward.
+    - ImGuiConfigFlags_NoMouseCursorChange: Instruct back-end to not alter mouse cursor shape and visibility (by default the example back-end use mouse cursor API of the platform when available)
+    - ImGuiConfigFlags_NoMouse: Instruct imgui to clear mouse position/buttons in NewFrame(). This allows ignoring the mouse information passed by the back-end.
+    - ImGuiConfigFlags_IsSRGB, ImGuiConfigFlags_IsTouchScreen: Flags for general application use.
 - IO: Added io.BackendFlags for back-end to store its capabilities (currently: _HasGamepad, _HasMouseCursors, _HasSetMousePos). This will be used more in the next version.
 - IO: Added ImGuiKey_Insert, ImGuiKey_Space keys. Setup in all example bindings. (#1541)
 - IO: Added Horizontal Mouse Wheel support for horizontal scrolling. (#1463) [@tseeker]

imgui.cpp

@@ -3373,6 +3373,11 @@ void ImGui::NewFrame()
 
     // Update mouse input state
     // If mouse just appeared or disappeared (usually denoted by -FLT_MAX component, but in reality we test for -256000.0f) we cancel out movement in MouseDelta
+    if (g.IO.ConfigFlags & ImGuiConfigFlags_NoMouse)
+    {
+        g.IO.MousePos = ImVec2(-FLT_MAX, -FLT_MAX);
+        memset(g.IO.MouseDown, 0, sizeof(g.IO.MouseDown));
+    }
     if (IsMousePosValid(&g.IO.MousePos) && IsMousePosValid(&g.IO.MousePosPrev))
         g.IO.MouseDelta = g.IO.MousePos - g.IO.MousePosPrev;
     else

imgui.h

@@ -779,7 +779,8 @@ enum ImGuiConfigFlags_
     ImGuiConfigFlags_NavEnableGamepad       = 1 << 1,   // Master gamepad navigation enable flag. This is mostly to instruct your imgui back-end to fill io.NavInputs[]. Back-end also needs to set ImGuiBackendFlags_HasGamepad.
     ImGuiConfigFlags_NavEnableSetMousePos   = 1 << 2,   // Instruct navigation to move the mouse cursor. May be useful on TV/console systems where moving a virtual mouse is awkward. Will update io.MousePos and set io.WantSetMousePos=true. If enabled you MUST honor io.WantSetMousePos requests in your binding, otherwise ImGui will react as if the mouse is jumping around back and forth.
     ImGuiConfigFlags_NavNoCaptureKeyboard   = 1 << 3,   // Instruct navigation to not set the io.WantCaptureKeyboard flag with io.NavActive is set. 
-    ImGuiConfigFlags_NoMouseCursorChange    = 1 << 4,   // Instruct back-end to not alter mouse cursor shape and visibility.
+    ImGuiConfigFlags_NoMouse                = 1 << 4,   // Instruct imgui to clear mouse position/buttons in NewFrame(). This allows ignoring the mouse information back-end
+    ImGuiConfigFlags_NoMouseCursorChange    = 1 << 5,   // Instruct back-end to not alter mouse cursor shape and visibility.
 
     // User storage (to allow your back-end/engine to communicate to code that may be shared between multiple projects. Those flags are not used by core ImGui)
     ImGuiConfigFlags_IsSRGB                 = 1 << 20,  // Application is SRGB-aware.