Examples: OpenGL3: Saving/restoring glActiveTexture() state (#602)

examples/opengl3_example/imgui_impl_glfw_gl3.cpp

@@ -46,6 +46,7 @@ void ImGui_ImplGlfwGL3_RenderDrawLists(ImDrawData* draw_data)
     // Backup GL state
     GLint last_program; glGetIntegerv(GL_CURRENT_PROGRAM, &last_program);
     GLint last_texture; glGetIntegerv(GL_TEXTURE_BINDING_2D, &last_texture);
+    GLint last_active_texture; glGetIntegerv(GL_ACTIVE_TEXTURE, &last_active_texture);
     GLint last_array_buffer; glGetIntegerv(GL_ARRAY_BUFFER_BINDING, &last_array_buffer);
     GLint last_element_array_buffer; glGetIntegerv(GL_ELEMENT_ARRAY_BUFFER_BINDING, &last_element_array_buffer);
     GLint last_vertex_array; glGetIntegerv(GL_VERTEX_ARRAY_BINDING, &last_vertex_array);
@@ -111,6 +112,7 @@ void ImGui_ImplGlfwGL3_RenderDrawLists(ImDrawData* draw_data)
 
     // Restore modified GL state
     glUseProgram(last_program);
+    glActiveTexture(last_active_texture);
     glBindTexture(GL_TEXTURE_2D, last_texture);
     glBindVertexArray(last_vertex_array);
     glBindBuffer(GL_ARRAY_BUFFER, last_array_buffer);

examples/sdl_opengl3_example/imgui_impl_sdl_gl3.cpp

@@ -40,6 +40,7 @@ void ImGui_ImplSdlGL3_RenderDrawLists(ImDrawData* draw_data)
     // Backup GL state
     GLint last_program; glGetIntegerv(GL_CURRENT_PROGRAM, &last_program);
     GLint last_texture; glGetIntegerv(GL_TEXTURE_BINDING_2D, &last_texture);
+    GLint last_active_texture; glGetIntegerv(GL_ACTIVE_TEXTURE, &last_active_texture);
     GLint last_array_buffer; glGetIntegerv(GL_ARRAY_BUFFER_BINDING, &last_array_buffer);
     GLint last_element_array_buffer; glGetIntegerv(GL_ELEMENT_ARRAY_BUFFER_BINDING, &last_element_array_buffer);
     GLint last_vertex_array; glGetIntegerv(GL_VERTEX_ARRAY_BINDING, &last_vertex_array);
@@ -105,6 +106,7 @@ void ImGui_ImplSdlGL3_RenderDrawLists(ImDrawData* draw_data)
 
     // Restore modified GL state
     glUseProgram(last_program);
+    glActiveTexture(last_active_texture);
     glBindTexture(GL_TEXTURE_2D, last_texture);
     glBindVertexArray(last_vertex_array);
     glBindBuffer(GL_ARRAY_BUFFER, last_array_buffer);