[core] store viewport and FBO binding

include/mbgl/gl/gl.hpp

@@ -21,6 +21,7 @@
     #elif TARGET_OS_MAC
         #include <OpenGL/OpenGL.h>
         #include <OpenGL/gl.h>
+        #include <OpenGL/glext.h>
     #else
         #error Unsupported Apple platform
     #endif

include/mbgl/gl/gl_values.hpp

@@ -271,6 +271,31 @@ struct ActiveTexture {
     }
 };
 
+struct BindFramebuffer {
+    using Type = GLint;
+    static void Set(const Type& value) {
+        MBGL_CHECK_ERROR(glBindFramebuffer(GL_FRAMEBUFFER, value));
+    }
+    static Type Get() {
+        Type activeFBO;
+        MBGL_CHECK_ERROR(glGetIntegerv(GL_FRAMEBUFFER_BINDING, &activeFBO));
+        return activeFBO;
+    }
+};
+
+struct Viewport {
+    using Type = std::array<GLint, 4>;
+    static void Set(const Type& value) {
+        MBGL_CHECK_ERROR(glViewport(value[0], value[1], value[2], value[3]));
+    }
+    static Type Get() {
+        Type pos;
+        MBGL_CHECK_ERROR(glGetIntegerv(GL_VIEWPORT, pos.data()));
+        return pos;
+    }
+};
+
+
 #ifndef GL_ES_VERSION_2_0
 
 struct PixelZoom {

src/mbgl/gl/gl_config.hpp

@@ -9,6 +9,20 @@
 namespace mbgl {
 namespace gl {
 
+
+template <typename T, typename = void>
+struct DefaultValue {
+    static typename T::Type Get() {
+        return T::Get();
+    }
+};
+template <typename T>
+struct DefaultValue<T, decltype((void)T::Default, void())> {
+    static typename T::Type Get() {
+        return T::Default;
+    }
+};
+
 template <typename T>
 class Value {
 public:
@@ -25,7 +39,7 @@ public:
     }
 
     void reset() {
-        *this = T::Default;
+        *this = defaultValue;
     }
 
     void setDirty() {
@@ -40,8 +54,13 @@ public:
         return dirty;
     }
 
+    void setDefaultValue(const typename T::Type& value) {
+        defaultValue = value;
+    }
+
 private:
-    typename T::Type current = T::Default;
+    typename T::Type defaultValue = DefaultValue<T>::Get();
+    typename T::Type current = defaultValue;
     bool dirty = false;
 };
 
@@ -66,6 +85,8 @@ public:
         program.reset();
         lineWidth.reset();
         activeTexture.reset();
+        bindFramebuffer.reset();
+        viewport.reset();
 #ifndef GL_ES_VERSION_2_0
         pixelZoom.reset();
         rasterPos.reset();
@@ -94,6 +115,8 @@ public:
         program.setDirty();
         lineWidth.setDirty();
         activeTexture.setDirty();
+        bindFramebuffer.setDirty();
+        viewport.setDirty();
 #ifndef GL_ES_VERSION_2_0
         pixelZoom.setDirty();
         rasterPos.setDirty();
@@ -121,6 +144,8 @@ public:
     Value<Program> program;
     Value<LineWidth> lineWidth;
     Value<ActiveTexture> activeTexture;
+    Value<BindFramebuffer> bindFramebuffer;
+    Value<Viewport> viewport;
 #ifndef GL_ES_VERSION_2_0
     Value<PixelZoom> pixelZoom;
     Value<RasterPos> rasterPos;

src/mbgl/gl/object_store.cpp

@@ -34,6 +34,11 @@ void VAODeleter::operator()(GLuint id) const {
     store->abandonedVAOs.push_back(id);
 }
 
+void FBODeleter::operator()(GLuint id) const {
+    assert(store);
+    store->abandonedFBOs.push_back(id);
+}
+
 ObjectStore::~ObjectStore() {
     assert(pooledTextures.empty());
     assert(abandonedPrograms.empty());
@@ -41,6 +46,7 @@ ObjectStore::~ObjectStore() {
     assert(abandonedBuffers.empty());
     assert(abandonedTextures.empty());
     assert(abandonedVAOs.empty());
+    assert(abandonedFBOs.empty());
 }
 
 void ObjectStore::reset() {
@@ -74,6 +80,11 @@ void ObjectStore::performCleanup() {
         MBGL_CHECK_ERROR(gl::DeleteVertexArrays(int(abandonedVAOs.size()), abandonedVAOs.data()));
         abandonedVAOs.clear();
     }
+
+    if (!abandonedFBOs.empty()) {
+        MBGL_CHECK_ERROR(glDeleteFramebuffers(int(abandonedFBOs.size()), abandonedFBOs.data()));
+        abandonedFBOs.clear();
+    }
 }
 
 } // namespace gl

src/mbgl/gl/object_store.hpp

@@ -41,11 +41,17 @@ struct VAODeleter {
     void operator()(GLuint) const;
 };
 
+struct FBODeleter {
+    ObjectStore* store;
+    void operator()(GLuint) const;
+};
+
 using UniqueProgram = std_experimental::unique_resource<GLuint, ProgramDeleter>;
 using UniqueShader = std_experimental::unique_resource<GLuint, ShaderDeleter>;
 using UniqueBuffer = std_experimental::unique_resource<GLuint, BufferDeleter>;
 using UniqueTexture = std_experimental::unique_resource<GLuint, TextureDeleter>;
 using UniqueVAO = std_experimental::unique_resource<GLuint, VAODeleter>;
+using UniqueFBO = std_experimental::unique_resource<GLuint, FBODeleter>;
 
 class ObjectStore : private util::noncopyable {
 public:
@@ -82,6 +88,12 @@ public:
         return UniqueVAO { std::move(id), { this } };
     }
 
+    UniqueFBO createFBO() {
+        GLuint id = 0;
+        MBGL_CHECK_ERROR(glGenFramebuffers(1, &id));
+        return UniqueFBO { std::move(id), { this } };
+    }
+
     // Actually remove the objects we marked as abandoned with the above methods.
     // Only call this while the OpenGL context is exclusive to this thread.
     void performCleanup();
@@ -96,7 +108,8 @@ public:
             && abandonedShaders.empty()
             && abandonedBuffers.empty()
             && abandonedTextures.empty()
-            && abandonedVAOs.empty();
+            && abandonedVAOs.empty()
+            && abandonedFBOs.empty();
     }
 
 private:
@@ -105,6 +118,7 @@ private:
     friend BufferDeleter;
     friend TextureDeleter;
     friend VAODeleter;
+    friend FBODeleter;
 
     std::vector<GLuint> pooledTextures;
 
@@ -113,6 +127,7 @@ private:
     std::vector<GLuint> abandonedBuffers;
     std::vector<GLuint> abandonedTextures;
     std::vector<GLuint> abandonedVAOs;
+    std::vector<GLuint> abandonedFBOs;
 };
 
 } // namespace gl

src/mbgl/renderer/painter.cpp

@@ -65,6 +65,10 @@ void Painter::setClipping(const ClipID& clip) {
 }
 
 void Painter::render(const Style& style, const FrameData& frame_, SpriteAtlas& annotationSpriteAtlas) {
+    if (frame.framebufferSize != frame_.framebufferSize) {
+        config.viewport.setDefaultValue(
+            { { 0, 0, frame_.framebufferSize[0], frame_.framebufferSize[1] } });
+    }
     frame = frame_;
 
     PaintParameters parameters {
@@ -121,6 +125,8 @@ void Painter::render(const Style& style, const FrameData& frame_, SpriteAtlas& a
     // tiles whatsoever.
     {
         MBGL_DEBUG_GROUP("clear");
+        config.bindFramebuffer.reset();
+        config.viewport.reset();
         config.stencilFunc.reset();
         config.stencilTest = GL_TRUE;
         config.stencilMask = 0xFF;
@@ -271,6 +277,8 @@ void Painter::renderPass(PaintParameters& parameters,
             setDepthSublayer(0);
             layer.as<CustomLayer>()->impl->render(state);
             config.setDirty();
+            config.bindFramebuffer.reset();
+            config.viewport.reset();
         } else {
             MBGL_DEBUG_GROUP(layer.baseImpl->id + " - " + util::toString(item.tile->id));
             if (item.bucket->needsClipping()) {

src/mbgl/renderer/painter.hpp

@@ -63,7 +63,7 @@ class BackgroundLayer;
 } // namespace style
 
 struct FrameData {
-    std::array<uint16_t, 2> framebufferSize;
+    std::array<uint16_t, 2> framebufferSize = {{ 0, 0 }};
     TimePoint timePoint;
     float pixelRatio;
     MapMode mapMode;