Backends: OpenGL2, OpenGL3: Backup and restore GL_SHADE_MODAL, GL_STENCIL_TEST, clear GL_NORMAL_ARRAY. Comments., (#3671, #3668)

backends/imgui_impl_opengl2.cpp

@@ -18,7 +18,8 @@
 
 // CHANGELOG
 // (minor and older changes stripped away, please see git history for details)
-//  2020-01-23: OpenGL: Explicitly backup, setup and restore GL_TEXTURE_ENV to increase compatibility with legacy OpenGL applications.
+//  2021-01-03: OpenGL: Backup, setup and restore GL_SHADE_MODAL state, disable GL_STENCIL_TEST and disable GL_NORMAL_ARRAY client state to increase compatibility with legacy OpenGL applications.
+//  2020-01-23: OpenGL: Backup, setup and restore GL_TEXTURE_ENV to increase compatibility with legacy OpenGL applications.
 //  2019-04-30: OpenGL: Added support for special ImDrawCallback_ResetRenderState callback to reset render state.
 //  2019-02-11: OpenGL: Projecting clipping rectangles correctly using draw_data->FramebufferScale to allow multi-viewports for retina display.
 //  2018-11-30: Misc: Setting up io.BackendRendererName so it can be displayed in the About Window.
@@ -82,23 +83,29 @@ static void ImGui_ImplOpenGL2_SetupRenderState(ImDrawData* draw_data, int fb_wid
     glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
     glDisable(GL_CULL_FACE);
     glDisable(GL_DEPTH_TEST);
+    glDisable(GL_STENCIL_TEST);
     glDisable(GL_LIGHTING);
     glDisable(GL_COLOR_MATERIAL);
     glEnable(GL_SCISSOR_TEST);
     glEnableClientState(GL_VERTEX_ARRAY);
     glEnableClientState(GL_TEXTURE_COORD_ARRAY);
     glEnableClientState(GL_COLOR_ARRAY);
+    glDisableClientState(GL_NORMAL_ARRAY);
     glEnable(GL_TEXTURE_2D);
     glPolygonMode(GL_FRONT_AND_BACK, GL_FILL);
+    glShadeModel(GL_SMOOTH);
     glTexEnvi(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_MODULATE);
 
     // If you are using this code with non-legacy OpenGL header/contexts (which you should not, prefer using imgui_impl_opengl3.cpp!!),
-    // you may need to backup/reset/restore current shader using the lines below. DO NOT MODIFY THIS FILE! Add the code in your calling function:
+    // you may need to backup/reset/restore other state, e.g. for current shader using the commented lines below.
+    // (DO NOT MODIFY THIS FILE! Add the code in your calling function)
     //   GLint last_program;
     //   glGetIntegerv(GL_CURRENT_PROGRAM, &last_program);
     //   glUseProgram(0);
     //   ImGui_ImplOpenGL2_RenderDrawData(...);
     //   glUseProgram(last_program)
+    // There are potentially many more states you could need to clear/setup that we can't access from default headers.
+    // e.g. glBindBuffer(GL_ARRAY_BUFFER, 0), glDisable(GL_TEXTURE_CUBE_MAP).
 
     // Setup viewport, orthographic projection matrix
     // Our visible imgui space lies from draw_data->DisplayPos (top left) to draw_data->DisplayPos+data_data->DisplaySize (bottom right). DisplayPos is (0,0) for single viewport apps.
@@ -128,6 +135,7 @@ void ImGui_ImplOpenGL2_RenderDrawData(ImDrawData* draw_data)
     GLint last_polygon_mode[2]; glGetIntegerv(GL_POLYGON_MODE, last_polygon_mode);
     GLint last_viewport[4]; glGetIntegerv(GL_VIEWPORT, last_viewport);
     GLint last_scissor_box[4]; glGetIntegerv(GL_SCISSOR_BOX, last_scissor_box);
+    GLint last_shade_model; glGetIntegerv(GL_SHADE_MODEL, &last_shade_model);
     GLint last_tex_env_mode; glGetTexEnviv(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, &last_tex_env_mode);
     glPushAttrib(GL_ENABLE_BIT | GL_COLOR_BUFFER_BIT | GL_TRANSFORM_BIT);
 
@@ -196,6 +204,7 @@ void ImGui_ImplOpenGL2_RenderDrawData(ImDrawData* draw_data)
     glPolygonMode(GL_FRONT, (GLenum)last_polygon_mode[0]); glPolygonMode(GL_BACK, (GLenum)last_polygon_mode[1]);
     glViewport(last_viewport[0], last_viewport[1], (GLsizei)last_viewport[2], (GLsizei)last_viewport[3]);
     glScissor(last_scissor_box[0], last_scissor_box[1], (GLsizei)last_scissor_box[2], (GLsizei)last_scissor_box[3]);
+    glShadeModel(last_shade_model);
     glTexEnvi(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, last_tex_env_mode);
 }
 

backends/imgui_impl_opengl3.cpp

@@ -13,7 +13,8 @@
 
 // CHANGELOG
 // (minor and older changes stripped away, please see git history for details)
-//  2020-10-23: OpenGL: Save and restore current GL_PRIMITIVE_RESTART state.
+//  2021-01-03: OpenGL: Backup, setup and restore GL_STENCIL_TEST state.
+//  2020-10-23: OpenGL: Backup, setup and restore GL_PRIMITIVE_RESTART state.
 //  2020-10-15: OpenGL: Use glGetString(GL_VERSION) instead of glGetIntegerv(GL_MAJOR_VERSION, ...) when the later returns zero (e.g. Desktop GL 2.x)
 //  2020-09-17: OpenGL: Fix to avoid compiling/calling glBindSampler() on ES or pre 3.3 context which have the defines set by a loader.
 //  2020-07-10: OpenGL: Added support for glad2 OpenGL loader.
@@ -249,6 +250,7 @@ static void ImGui_ImplOpenGL3_SetupRenderState(ImDrawData* draw_data, int fb_wid
     glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
     glDisable(GL_CULL_FACE);
     glDisable(GL_DEPTH_TEST);
+    glDisable(GL_STENCIL_TEST);
     glEnable(GL_SCISSOR_TEST);
 #ifdef IMGUI_IMPL_OPENGL_MAY_HAVE_PRIMITIVE_RESTART
     if (g_GlVersion >= 310)
@@ -343,6 +345,7 @@ void    ImGui_ImplOpenGL3_RenderDrawData(ImDrawData* draw_data)
     GLboolean last_enable_blend = glIsEnabled(GL_BLEND);
     GLboolean last_enable_cull_face = glIsEnabled(GL_CULL_FACE);
     GLboolean last_enable_depth_test = glIsEnabled(GL_DEPTH_TEST);
+    GLboolean last_enable_stencil_test = glIsEnabled(GL_STENCIL_TEST);
     GLboolean last_enable_scissor_test = glIsEnabled(GL_SCISSOR_TEST);
 #ifdef IMGUI_IMPL_OPENGL_MAY_HAVE_PRIMITIVE_RESTART
     GLboolean last_enable_primitive_restart = (g_GlVersion >= 310) ? glIsEnabled(GL_PRIMITIVE_RESTART) : GL_FALSE;
@@ -431,6 +434,7 @@ void    ImGui_ImplOpenGL3_RenderDrawData(ImDrawData* draw_data)
     if (last_enable_blend) glEnable(GL_BLEND); else glDisable(GL_BLEND);
     if (last_enable_cull_face) glEnable(GL_CULL_FACE); else glDisable(GL_CULL_FACE);
     if (last_enable_depth_test) glEnable(GL_DEPTH_TEST); else glDisable(GL_DEPTH_TEST);
+    if (last_enable_stencil_test) glEnable(GL_STENCIL_TEST); else glDisable(GL_STENCIL_TEST);
     if (last_enable_scissor_test) glEnable(GL_SCISSOR_TEST); else glDisable(GL_SCISSOR_TEST);
 #ifdef IMGUI_IMPL_OPENGL_MAY_HAVE_PRIMITIVE_RESTART
     if (g_GlVersion >= 310) { if (last_enable_primitive_restart) glEnable(GL_PRIMITIVE_RESTART); else glDisable(GL_PRIMITIVE_RESTART); }

docs/CHANGELOG.txt

@@ -117,7 +117,10 @@ Other Changes:
 - Demo: Clarify usage of right-aligned items in Demo>Layout>Widgets Width.
 - Backends: OpenGL3: Use glGetString(GL_VERSION) query instead of glGetIntegerv(GL_MAJOR_VERSION, ...)
   when the later returns zero (e.g. Desktop GL 2.x). (#3530) [@xndcn]
+- Backends: OpenGL2: Backup and restore GL_SHADE_MODAL and disable GL_NORMAL_ARRAY state to increase compatibility
+  with legacy code. (#3671)
 - Backends: OpenGL3: Backup and restore GL_PRIMITIVE_RESTART state. (#3544) [@Xipiryon]
+- Backends: OpenGL2, OpenGL3: Backup and restore GL_STENCIL_TEST enable state. (#3668)
 - Backends: Vulkan: Added support for specifying which subpass to reference during VkPipeline creation. (@3579) [@bdero]
 - Backends: Win32: Fix setting of io.DisplaySize to invalid/uninitialized data after hwnd has been closed.
 - Backends: OSX: Fix keypad-enter key not working on MacOS. (#3554) [@rokups, @lfnoise]

examples/example_glfw_opengl2/main.cpp

@@ -136,7 +136,7 @@ int main(int, char**)
         glClear(GL_COLOR_BUFFER_BIT);
 
         // If you are using this code with non-legacy OpenGL header/contexts (which you should not, prefer using imgui_impl_opengl3.cpp!!),
-        // you may need to backup/reset/restore current shader using the commented lines below.
+        // you may need to backup/reset/restore other state, e.g. for current shader using the commented lines below.
         //GLint last_program;
         //glGetIntegerv(GL_CURRENT_PROGRAM, &last_program);
         //glUseProgram(0);