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Backends: OpenGL2/3: Backup and restore GL_UNPACK state in UpdateTexture() (#9473, #8802)

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This commit is contained in:
Turtle Dove
2026-07-15 07:58:39 -05:00
committed by ocornut
parent 35a7e8e864
commit e3927dc004
2 changed files with 30 additions and 1 deletions
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11
backends/imgui_impl_opengl2.cpp
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@@ -30,6 +30,7 @@
// 2026-03-12: OpenGL: Fixed invalid assert in ImGui_ImplOpenGL3_UpdateTexture() if ImTextureID_Invalid is defined to be != 0, which became the default since 2026-03-12. (#9295)
// 2025-09-18: Call platform_io.ClearRendererHandlers() on shutdown.
// 2025-07-15: OpenGL: Set GL_UNPACK_ALIGNMENT to 1 before updating textures. (#8802)
// 2026-07-15: OpenGL: Backup and restore GL_UNPACK_ROW_LENGTH and GL_UNPACK_ALIGNMENT in UpdateTexture() to avoid corrupting caller GL state. (#8802, #9473)
// 2025-06-11: OpenGL: Added support for ImGuiBackendFlags_RendererHasTextures, for dynamic font atlas. Removed ImGui_ImplOpenGL2_CreateFontsTexture() and ImGui_ImplOpenGL2_DestroyFontsTexture().
// 2024-10-07: OpenGL: Changed default texture sampler to Clamp instead of Repeat/Wrap.
// 2024-06-28: OpenGL: ImGui_ImplOpenGL2_NewFrame() recreates font texture if it has been destroyed by ImGui_ImplOpenGL2_DestroyFontsTexture(). (#7748)
@@ -262,6 +263,12 @@ void ImGui_ImplOpenGL2_RenderDrawData(ImDrawData* draw_data)
void ImGui_ImplOpenGL2_UpdateTexture(ImTextureData* tex)
{
// Backup GL_UNPACK state that we modify, restore on exit.
// This prevents corrupting the caller's pixel store state when ImGui
// creates or updates textures mid-frame. (#8802, #9473)
GLint last_unpack_row_length = 0; GL_CALL(glGetIntegerv(GL_UNPACK_ROW_LENGTH, &last_unpack_row_length));
GLint last_unpack_alignment = 0; GL_CALL(glGetIntegerv(GL_UNPACK_ALIGNMENT, &last_unpack_alignment));
if (tex->Status == ImTextureStatus_WantCreate)
{
// Create and upload new texture to graphics system
@@ -318,6 +325,10 @@ void ImGui_ImplOpenGL2_UpdateTexture(ImTextureData* tex)
tex->SetTexID(ImTextureID_Invalid);
tex->SetStatus(ImTextureStatus_Destroyed);
}
// Restore GL_UNPACK state
GL_CALL(glPixelStorei(GL_UNPACK_ROW_LENGTH, last_unpack_row_length));
GL_CALL(glPixelStorei(GL_UNPACK_ALIGNMENT, last_unpack_alignment));
}
bool ImGui_ImplOpenGL2_CreateDeviceObjects()

20
backends/imgui_impl_opengl3.cpp
View File

@@ -32,6 +32,7 @@
// 2025-09-18: Call platform_io.ClearRendererHandlers() on shutdown.
// 2025-07-22: OpenGL: Add and call embedded loader shutdown during ImGui_ImplOpenGL3_Shutdown() to facilitate multiple init/shutdown cycles in same process. (#8792)
// 2025-07-15: OpenGL: Set GL_UNPACK_ALIGNMENT to 1 before updating textures (#8802) + restore non-WebGL/ES update path that doesn't require a CPU-side copy.
// 2026-07-15: OpenGL: Backup and restore GL_UNPACK_ROW_LENGTH and GL_UNPACK_ALIGNMENT in UpdateTexture() to avoid corrupting caller GL state. (#8802, #9473)
// 2025-06-11: OpenGL: Added support for ImGuiBackendFlags_RendererHasTextures, for dynamic font atlas. Removed ImGui_ImplOpenGL3_CreateFontsTexture() and ImGui_ImplOpenGL3_DestroyFontsTexture().
// 2025-06-04: OpenGL: Made GLES 3.20 contexts not access GL_CONTEXT_PROFILE_MASK nor GL_PRIMITIVE_RESTART. (#8664)
// 2025-02-18: OpenGL: Lazily reinitialize embedded GL loader for when calling backend from e.g. other DLL boundaries. (#8406)
@@ -666,7 +667,16 @@ static void ImGui_ImplOpenGL3_DestroyTexture(ImTextureData* tex)
void ImGui_ImplOpenGL3_UpdateTexture(ImTextureData* tex)
{
// FIXME: Consider backing up and restoring
// Backup GL_UNPACK state that we modify, restore on exit.
// This prevents corrupting the caller's pixel store state when ImGui
// creates or updates textures mid-frame. (#8802, #9473)
#ifdef GL_UNPACK_ROW_LENGTH
GLint last_unpack_row_length = 0; GL_CALL(glGetIntegerv(GL_UNPACK_ROW_LENGTH, &last_unpack_row_length));
#endif
#ifdef GL_UNPACK_ALIGNMENT
GLint last_unpack_alignment = 0; GL_CALL(glGetIntegerv(GL_UNPACK_ALIGNMENT, &last_unpack_alignment));
#endif
if (tex->Status == ImTextureStatus_WantCreate || tex->Status == ImTextureStatus_WantUpdates)
{
#ifdef GL_UNPACK_ROW_LENGTH // Not on WebGL/ES
@@ -738,6 +748,14 @@ void ImGui_ImplOpenGL3_UpdateTexture(ImTextureData* tex)
}
else if (tex->Status == ImTextureStatus_WantDestroy && tex->UnusedFrames > 0)
ImGui_ImplOpenGL3_DestroyTexture(tex);
// Restore GL_UNPACK state
#ifdef GL_UNPACK_ROW_LENGTH
GL_CALL(glPixelStorei(GL_UNPACK_ROW_LENGTH, last_unpack_row_length));
#endif
#ifdef GL_UNPACK_ALIGNMENT
GL_CALL(glPixelStorei(GL_UNPACK_ALIGNMENT, last_unpack_alignment));
#endif
}
// If you get an error please report on github. You may try different GL context version or GLSL version. See GL<>GLSL version table at the top of this file.