[core] allow disabling the use of extensions via GLContextModeupstream/glcontextmode

3 files changed, 44 insertions, 9 deletions

diff --git a/include/mbgl/renderer/mode.hpp b/include/mbgl/renderer/mode.hpp
index 6ff42d8058..c5883b8b82 100644
--- a/include/mbgl/renderer/mode.hpp
+++ b/include/mbgl/renderer/mode.hpp
@@ -1,18 +1,51 @@
 #pragma once
 
-#include <cstdint>
+#include <mbgl/util/util.hpp>
+#include <mbgl/util/traits.hpp>
 
 namespace mbgl {
 
 using EnumType = uint32_t;
 
-// We can avoid redundant GL calls when it is known that the GL context is not
-// being shared. In a shared GL context case, we need to make sure that the
-// correct GL configurations are in use - they might have changed between render
-// calls.
 enum class GLContextMode : EnumType {
-    Unique,
-    Shared,
+    Automatic = 0,
+
+    // We can avoid redundant GL calls when it is known that the GL context is not being shared. In
+    // a shared GL context case, we need to make sure that the correct GL configurations are in use 
+    // - they might have changed between render calls. If you're issuing other OpenGL calls in the
+    // same context (excluding uses of custom layers), then initialize the context with this flag set.
+    SharedState                     = 0b00000001,
+
+    // Vertex Array Objects bundle buffer state for faster binding and is available on most modern
+    // platforms. However, some older GPUs have bugs with this, and some devices don't support it
+    // altogether. Setting this flag allows testing without Vertex Array Objects.
+    DisableVAOExtension             = 0b00000010,
+
+    // Some platforms support exporting compiled shader programs as binaries. This allows us to
+    // store them and reload the precompiled binary on subsequent loads, which typically speeds
+    // up initialization. However, some GPUs have trouble reloading binaries due driver bugs.
+    // You can explicitly disable program binaries by setting this flag.
+    DisableProgramBinariesExtension = 000000100,
 };
 
+MBGL_CONSTEXPR GLContextMode operator|(GLContextMode lhs, GLContextMode rhs) {
+    return GLContextMode(mbgl::underlying_type(lhs) | mbgl::underlying_type(rhs));
+}
+
+MBGL_CONSTEXPR GLContextMode& operator|=(GLContextMode& lhs, GLContextMode rhs) {
+    return (lhs = GLContextMode(mbgl::underlying_type(lhs) | mbgl::underlying_type(rhs)));
+}
+
+MBGL_CONSTEXPR bool operator&(GLContextMode lhs, GLContextMode rhs) {
+    return mbgl::underlying_type(lhs) & mbgl::underlying_type(rhs);
+}
+
+MBGL_CONSTEXPR GLContextMode& operator&=(GLContextMode& lhs, GLContextMode rhs) {
+    return (lhs = GLContextMode(mbgl::underlying_type(lhs) & mbgl::underlying_type(rhs)));
+}
+
+MBGL_CONSTEXPR GLContextMode operator~(GLContextMode value) {
+    return GLContextMode(~mbgl::underlying_type(value));
+}
+
 } // namespace mbgl
diff --git a/include/mbgl/renderer/renderer.hpp b/include/mbgl/renderer/renderer.hpp
index db28ee92fc..ab7f70bace 100644
--- a/include/mbgl/renderer/renderer.hpp
+++ b/include/mbgl/renderer/renderer.hpp
@@ -24,7 +24,7 @@ class UpdateParameters;
 class Renderer {
 public:
     Renderer(RendererBackend&, float pixelRatio_, FileSource&, Scheduler&,
-             GLContextMode = GLContextMode::Unique,
+             GLContextMode = GLContextMode::Automatic,
              const optional<std::string> programCacheDir = {},
              const optional<std::string> localFontFamily = {});
     ~Renderer();
diff --git a/include/mbgl/renderer/renderer_backend.hpp b/include/mbgl/renderer/renderer_backend.hpp
index b83c128169..4a4c41298a 100644
--- a/include/mbgl/renderer/renderer_backend.hpp
+++ b/include/mbgl/renderer/renderer_backend.hpp
@@ -1,6 +1,7 @@
 #pragma once
 
 #include <mbgl/renderer/backend_scope.hpp>
+#include <mbgl/renderer/mode.hpp>
 #include <mbgl/util/image.hpp>
 #include <mbgl/util/size.hpp>
 #include <mbgl/util/util.hpp>
@@ -20,7 +21,7 @@ using FramebufferID = uint32_t;
 // the actual rendering.
 class RendererBackend {
 public:
-    RendererBackend();
+    RendererBackend(GLContextMode);
     virtual ~RendererBackend();
 
     // Returns the backend's context which manages OpenGL state.
@@ -81,6 +82,7 @@ protected:
 
 private:
     std::once_flag initialized;
+    const GLContextMode mode;
 
     friend class BackendScope;
 };