Backends: SDL2,SDL3: Accept SDL_GetPerformanceCounter() not returning a monotonically increasing value. (#6189, #6114, #3644)

This commit is contained in:
Adam Kewley 2023-02-23 13:06:07 +01:00 committed by ocornut
parent e9743d85dd
commit 2496b973f9
3 changed files with 10 additions and 0 deletions

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@ -17,6 +17,7 @@
// CHANGELOG
// (minor and older changes stripped away, please see git history for details)
// 2023-02-23: Accept SDL_GetPerformanceCounter() not returning a monotonically increasing value. (#6189, #6114, #3644)
// 2023-02-07: Implement IME handler (io.SetPlatformImeDataFn will call SDL_SetTextInputRect()/SDL_StartTextInput()).
// 2023-02-07: *BREAKING CHANGE* Renamed this backend file from imgui_impl_sdl.cpp/.h to imgui_impl_sdl2.cpp/.h in prevision for the future release of SDL3.
// 2023-02-02: Avoid calling SDL_SetCursor() when cursor has not changed, as the function is surprisingly costly on Mac with latest SDL (may be fixed in next SDL version).
@ -610,8 +611,11 @@ void ImGui_ImplSDL2_NewFrame()
io.DisplayFramebufferScale = ImVec2((float)display_w / w, (float)display_h / h);
// Setup time step (we don't use SDL_GetTicks() because it is using millisecond resolution)
// (Accept SDL_GetPerformanceCounter() not returning a monotonically increasing value. Happens in VMs and Emscripten, see #6189, #6114, #3644)
static Uint64 frequency = SDL_GetPerformanceFrequency();
Uint64 current_time = SDL_GetPerformanceCounter();
if (current_time <= bd->Time)
current_time = bd->Time + 1;
io.DeltaTime = bd->Time > 0 ? (float)((double)(current_time - bd->Time) / frequency) : (float)(1.0f / 60.0f);
bd->Time = current_time;

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@ -18,6 +18,7 @@
// CHANGELOG
// (minor and older changes stripped away, please see git history for details)
// 2023-02-23: Accept SDL_GetPerformanceCounter() not returning a monotonically increasing value. (#6189, #6114, #3644)
// 2023-02-07: Forked "imgui_impl_sdl2" into "imgui_impl_sdl3". Removed version checks for old feature. Refer to imgui_impl_sdl2.cpp for older changelog.
#include "imgui.h"
@ -543,8 +544,11 @@ void ImGui_ImplSDL3_NewFrame()
io.DisplayFramebufferScale = ImVec2((float)display_w / w, (float)display_h / h);
// Setup time step (we don't use SDL_GetTicks() because it is using millisecond resolution)
// (Accept SDL_GetPerformanceCounter() not returning a monotonically increasing value. Happens in VMs and Emscripten, see #6189, #6114, #3644)
static Uint64 frequency = SDL_GetPerformanceFrequency();
Uint64 current_time = SDL_GetPerformanceCounter();
if (current_time <= bd->Time)
current_time = bd->Time + 1;
io.DeltaTime = bd->Time > 0 ? (float)((double)(current_time - bd->Time) / frequency) : (float)(1.0f / 60.0f);
bd->Time = current_time;

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@ -53,6 +53,8 @@ Other changes:
avoid inteferences. (#5817, #6183) [@DimaKoltun]
- Backends: Win32: Use WM_NCMOUSEMOVE / WM_NCMOUSELEAVE to track mouse positions over
non-client area (e.g. OS decorations) when app is not focused. (#6045, #6162)
- Backends: SDL2, SDL3: Accept SDL_GetPerformanceCounter() not returning a monotonically
increasing value. (#6189, #6114, #3644) [@adamkewley]
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