IO: io.MousePos needs to be set to ImVec2(-FLT_MAX,-FLT_MAX) when mouse is unavailable/missing. Previously ImVec2(-1,-1) was enough but we'll now accept negative mouse coordinates.

examples/allegro5_example/imgui_impl_a5.cpp

@@ -262,7 +262,7 @@ void ImGui_ImplA5_NewFrame()
     }
     else
     {
-        io.MousePos = ImVec2(-1, -1);
+        io.MousePos = ImVec2(-FLT_MAX, -FLT_MAX);
     }
 
     al_get_mouse_state(&mouse);

examples/opengl2_example/imgui_impl_glfw.cpp

@@ -272,7 +272,7 @@ void ImGui_ImplGlfw_NewFrame()
     }
     else
     {
-        io.MousePos = ImVec2(-1,-1);
+        io.MousePos = ImVec2(-FLT_MAX,-FLT_MAX);
     }
 
     for (int i = 0; i < 3; i++)

examples/opengl3_example/imgui_impl_glfw_gl3.cpp

@@ -383,7 +383,7 @@ void ImGui_ImplGlfwGL3_NewFrame()
     }
     else
     {
-        io.MousePos = ImVec2(-1,-1);
+        io.MousePos = ImVec2(-FLT_MAX,-FLT_MAX);
     }
 
     for (int i = 0; i < 3; i++)

examples/sdl_opengl2_example/imgui_impl_sdl.cpp

@@ -265,7 +265,7 @@ void ImGui_ImplSdl_NewFrame(SDL_Window *window)
     if (SDL_GetWindowFlags(window) & SDL_WINDOW_MOUSE_FOCUS)
         io.MousePos = ImVec2((float)mx, (float)my);   // Mouse position, in pixels (set to -1,-1 if no mouse / on another screen, etc.)
     else
-        io.MousePos = ImVec2(-1,-1);
+        io.MousePos = ImVec2(-FLT_MAX,-FLT_MAX);
 
     io.MouseDown[0] = g_MousePressed[0] || (mouseMask & SDL_BUTTON(SDL_BUTTON_LEFT)) != 0;		// If a mouse press event came, always pass it as "mouse held this frame", so we don't miss click-release events that are shorter than 1 frame.
     io.MouseDown[1] = g_MousePressed[1] || (mouseMask & SDL_BUTTON(SDL_BUTTON_RIGHT)) != 0;

examples/sdl_opengl3_example/imgui_impl_sdl_gl3.cpp

@@ -377,7 +377,7 @@ void ImGui_ImplSdlGL3_NewFrame(SDL_Window* window)
     if (SDL_GetWindowFlags(window) & SDL_WINDOW_MOUSE_FOCUS)
         io.MousePos = ImVec2((float)mx, (float)my);   // Mouse position, in pixels (set to -1,-1 if no mouse / on another screen, etc.)
     else
-        io.MousePos = ImVec2(-1, -1);
+        io.MousePos = ImVec2(-FLT_MAX, -FLT_MAX);
 
     io.MouseDown[0] = g_MousePressed[0] || (mouseMask & SDL_BUTTON(SDL_BUTTON_LEFT)) != 0;		// If a mouse press event came, always pass it as "mouse held this frame", so we don't miss click-release events that are shorter than 1 frame.
     io.MouseDown[1] = g_MousePressed[1] || (mouseMask & SDL_BUTTON(SDL_BUTTON_RIGHT)) != 0;

examples/vulkan_example/imgui_impl_glfw_vulkan.cpp

@@ -815,7 +815,7 @@ void ImGui_ImplGlfwVulkan_NewFrame()
     }
     else
     {
-        io.MousePos = ImVec2(-1,-1);
+        io.MousePos = ImVec2(-FLT_MAX,-FLT_MAX);
     }
 
     for (int i = 0; i < 3; i++)

imgui.cpp

@@ -204,6 +204,7 @@
  Here is a change-log of API breaking changes, if you are using one of the functions listed, expect to have to fix some code.
  Also read releases logs https://github.com/ocornut/imgui/releases for more details.
 
+ - 2017/08/25 (1.52) - io.MousePos needs to be set to ImVec2(-FLT_MAX,-FLT_MAX) when mouse is unavailable/missing. Previously ImVec2(-1,-1) was enough but we now accept negative mouse coordinates. In your binding if you need to support unavailable mouse, make sure to replace "io.MousePos = ImVec2(-1,-1)" with "io.MousePos = ImVec2(-FLT_MAX,-FLT_MAX)".
  - 2017/08/22 (1.51) - renamed IsItemHoveredRect() to IsItemRectHovered(). Kept inline redirection function (will obsolete).
                      - renamed IsMouseHoveringAnyWindow() to IsAnyWindowHovered() for consistency. Kept inline redirection function (will obsolete).
                      - renamed IsMouseHoveringWindow() to IsWindowRectHovered() for consistency. Kept inline redirection function (will obsolete).
@@ -754,8 +755,8 @@ ImGuiIO::ImGuiIO()
     FontGlobalScale = 1.0f;
     FontDefault = NULL;
     DisplayFramebufferScale = ImVec2(1.0f, 1.0f);
-    MousePos = ImVec2(-1,-1);
+    MousePos = ImVec2(-FLT_MAX, -FLT_MAX);
-    MousePosPrev = ImVec2(-1,-1);
+    MousePosPrev = ImVec2(-FLT_MAX, -FLT_MAX);
     MouseDoubleClickTime = 0.30f;
     MouseDoubleClickMaxDist = 6.0f;
     MouseDragThreshold = 6.0f;
@@ -2151,9 +2152,9 @@ void ImGui::NewFrame()
     g.RenderDrawData.CmdListsCount = g.RenderDrawData.TotalVtxCount = g.RenderDrawData.TotalIdxCount = 0;
 
     // Update mouse input state
-    if (g.IO.MousePos.x < 0 && g.IO.MousePos.y < 0)
+    // 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
-        g.IO.MousePos = ImVec2(-9999.0f, -9999.0f);
+    const float MOUSE_INVALID = -256000.0f;
-    if ((g.IO.MousePos.x < 0 && g.IO.MousePos.y < 0) || (g.IO.MousePosPrev.x < 0 && g.IO.MousePosPrev.y < 0))   // if mouse just appeared or disappeared (negative coordinate) we cancel out movement in MouseDelta
+    if ((g.IO.MousePos.x < MOUSE_INVALID && g.IO.MousePos.y < MOUSE_INVALID) || (g.IO.MousePosPrev.x < MOUSE_INVALID && g.IO.MousePosPrev.y < MOUSE_INVALID))
         g.IO.MouseDelta = ImVec2(0.0f, 0.0f);
     else
         g.IO.MouseDelta = g.IO.MousePos - g.IO.MousePosPrev;

imgui.h

@@ -828,7 +828,7 @@ struct ImGuiIO
     // Input - Fill before calling NewFrame()
     //------------------------------------------------------------------
 
-    ImVec2      MousePos;                   // Mouse position, in pixels (set to -1,-1 if no mouse / on another screen, etc.)
+    ImVec2      MousePos;                   // Mouse position, in pixels. Set to ImVec2(-FLT_MAX,-FLT_MAX) if mouse is unavailable (on another screen, etc.)
     bool        MouseDown[5];               // Mouse buttons: left, right, middle + extras. ImGui itself mostly only uses left button (BeginPopupContext** are using right button). Others buttons allows us to track if the mouse is being used by your application + available to user as a convenience via IsMouse** API.
     float       MouseWheel;                 // Mouse wheel: 1 unit scrolls about 5 lines text.
     bool        MouseDrawCursor;            // Request ImGui to draw a mouse cursor for you (if you are on a platform without a mouse cursor).