GL/Context: Use GL_OES_draw_elements_base_vertex if GLES3.2 is missing

src/common/gl/context.cpp

@@ -77,6 +77,14 @@ static void DisableBrokenExtensions(const char* gl_vendor, const char* gl_render
       GLAD_GL_EXT_disjoint_timer_query = 0;
     }
   }
+
+  // If we're missing GLES 3.2, but have OES_draw_elements_base_vertex, redirect the function pointers.
+  if (!glad_glDrawElementsBaseVertex && GLAD_GL_OES_draw_elements_base_vertex && !GLAD_GL_ES_VERSION_3_2)
+  {
+    glad_glDrawElementsBaseVertex = glad_glDrawElementsBaseVertexOES;
+    glad_glDrawRangeElementsBaseVertex = glad_glDrawRangeElementsBaseVertexOES;
+    glad_glDrawElementsInstancedBaseVertex = glad_glDrawElementsInstancedBaseVertexOES;
+  }
 }
 
 Context::Context(const WindowInfo& wi) : m_wi(wi) {}

src/frontend-common/imgui_impl_opengl3.cpp

@@ -106,6 +106,8 @@
 // GL includes
 #include "common/gl/loader.h"
 #include "common/gl/texture.h"
+#include "common/log.h"
+Log_SetChannel(ImGui_ImplOpenGL3);
 
 // OpenGL Data
 struct ImGui_ImplOpenGL3_Data
@@ -168,6 +170,13 @@ bool    ImGui_ImplOpenGL3_Init(const char* glsl_version)
     IM_ASSERT((int)strlen(glsl_version) + 2 < IM_ARRAYSIZE(bd->GlslVersionString));
     strcpy(bd->GlslVersionString, glsl_version);
     strcat(bd->GlslVersionString, "\n");
+
+    if (!glDrawElementsBaseVertex)
+    {
+      Log_ErrorPrintf("Missing glDrawElementsBaseVertex()");
+      return false;
+    }
+
     return ImGui_ImplOpenGL3_CreateDeviceObjects();
 }