Backends: OpenGL3: Backup/restore GL_PRIMITIVE_RESTART state (#3544)

backends/imgui_impl_opengl3.cpp

@@ -13,6 +13,7 @@
 
 // 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.
 //  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.
@@ -134,6 +135,11 @@ using namespace gl;
 #define IMGUI_IMPL_OPENGL_MAY_HAVE_BIND_SAMPLER
 #endif
 
+// Desktop GL 3.1+ has GL_PRIMITIVE_RESTART state
+#if !defined(IMGUI_IMPL_OPENGL_ES2) && !defined(IMGUI_IMPL_OPENGL_ES3) && defined(GL_VERSION_3_1)
+#define IMGUI_IMPL_OPENGL_MAY_HAVE_PRIMITIVE_RESTART
+#endif
+
 // OpenGL Data
 static GLuint       g_GlVersion = 0;                // Extracted at runtime using GL_MAJOR_VERSION, GL_MINOR_VERSION queries (e.g. 320 for GL 3.2)
 static char         g_GlslVersionString[32] = "";   // Specified by user or detected based on compile time GL settings.
@@ -244,6 +250,10 @@ static void ImGui_ImplOpenGL3_SetupRenderState(ImDrawData* draw_data, int fb_wid
     glDisable(GL_CULL_FACE);
     glDisable(GL_DEPTH_TEST);
     glEnable(GL_SCISSOR_TEST);
+#ifdef IMGUI_IMPL_OPENGL_MAY_HAVE_PRIMITIVE_RESTART
+    if (g_GlVersion >= 310)
+        glDisable(GL_PRIMITIVE_RESTART);
+#endif
 #ifdef GL_POLYGON_MODE
     glPolygonMode(GL_FRONT_AND_BACK, GL_FILL);
 #endif
@@ -334,6 +344,9 @@ void    ImGui_ImplOpenGL3_RenderDrawData(ImDrawData* draw_data)
     GLboolean last_enable_cull_face = glIsEnabled(GL_CULL_FACE);
     GLboolean last_enable_depth_test = glIsEnabled(GL_DEPTH_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;
+#endif
 
     // Setup desired GL state
     // Recreate the VAO every time (this is to easily allow multiple GL contexts to be rendered to. VAO are not shared among GL contexts)
@@ -419,6 +432,11 @@ void    ImGui_ImplOpenGL3_RenderDrawData(ImDrawData* draw_data)
     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_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);
+#endif
+
 #ifdef GL_POLYGON_MODE
     glPolygonMode(GL_FRONT_AND_BACK, (GLenum)last_polygon_mode[0]);
 #endif

docs/CHANGELOG.txt

@@ -59,8 +59,9 @@ Other Changes:
 - Tab Bar: Do not display a tooltip if the name already fits over a given tab. (#3521)
 - Drag and Drop: Fix drag and drop to tie same-size drop targets by choosen the later one. Fixes dragging
   into a full-window-sized dockspace inside a zero-padded window. (#3519, #2717) [@Black-Cat]
-- Backends: OpenGL: use glGetString(GL_VERSION) query instead of glGetIntegerv(GL_MAJOR_VERSION, ...) 
+- 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: OpenGL3: Backup and restore GL_PRIMITIVE_RESTART state. (#3544) [@Xipiryon]
 - Docs: Split examples/README.txt into docs/BACKENDS.md and docs/EXAMPLES.md improved them.
 - Docs: Consistently renamed all occurences of "binding" and "back-end" to "backend" in comments and docs.