Using old framebuffer binding internally if new is not supported.

src/AbstractFramebuffer.cpp

@@ -16,12 +16,19 @@
 #include "AbstractFramebuffer.h"
 
 #include "BufferImage.h"
+#include "Context.h"
+#include "Extensions.h"
 #include "Image.h"
 
 namespace Magnum {
 
+#ifndef DOXYGEN_GENERATING_OUTPUT
+AbstractFramebuffer::Target AbstractFramebuffer::readTarget = AbstractFramebuffer::Target::ReadDraw;
+AbstractFramebuffer::Target AbstractFramebuffer::drawTarget = AbstractFramebuffer::Target::ReadDraw;
+#endif
+
 void AbstractFramebuffer::read(const Vector2i& offset, const Vector2i& size, AbstractImage::Format format, AbstractImage::Type type, Image2D* image) {
-    bind(Target::ReadDraw);
+    bind(readTarget);
     char* data = new char[AbstractImage::pixelSize(format, type)*size.product()];
     glReadPixels(offset.x(), offset.y(), size.x(), size.y(), static_cast<GLenum>(format), static_cast<GLenum>(type), data);
     image->setData(size, format, type, data);
@@ -29,7 +36,7 @@ void AbstractFramebuffer::read(const Vector2i& offset, const Vector2i& size, Abs
 
 #ifndef MAGNUM_TARGET_GLES2
 void AbstractFramebuffer::read(const Vector2i& offset, const Vector2i& size, AbstractImage::Format format, AbstractImage::Type type, BufferImage2D* image, Buffer::Usage usage) {
-    bind(Target::ReadDraw);
+    bind(readTarget);
     /* If the buffer doesn't have sufficient size, resize it */
     /** @todo Explicitly reset also when buffer usage changes */
     if(image->size() != size || image->format() != format || image->type() != type)
@@ -40,4 +47,17 @@ void AbstractFramebuffer::read(const Vector2i& offset, const Vector2i& size, Abs
 }
 #endif
 
+void AbstractFramebuffer::initializeContextBasedFunctionality(Context* context) {
+    #ifndef MAGNUM_TARGET_GLES
+    if(context->isExtensionSupported<Extensions::GL::EXT::framebuffer_blit>()) {
+        Debug() << "AbstractFramebuffer: using" << Extensions::GL::EXT::framebuffer_blit::string() << "features";
+
+        readTarget = Target::Read;
+        drawTarget = Target::Draw;
+    }
+    #else
+    static_cast<void>(context);
+    #endif
+}
+
 }

src/AbstractFramebuffer.h

@@ -34,6 +34,8 @@ See DefaultFramebuffer and Framebuffer for more information.
 @todo @extension{ARB,viewport_array}
 */
 class MAGNUM_EXPORT AbstractFramebuffer {
+    friend class Context;
+
     AbstractFramebuffer(const AbstractFramebuffer& other) = delete;
     AbstractFramebuffer(AbstractFramebuffer&& other) = delete;
     AbstractFramebuffer& operator=(const AbstractFramebuffer& other) = delete;
@@ -208,7 +210,7 @@ class MAGNUM_EXPORT AbstractFramebuffer {
          * @see @fn_gl{Viewport}
          */
         inline void setViewport(const Vector2i& position, const Vector2i& size) {
-            bind(Target::ReadDraw);
+            bind(drawTarget);
             glViewport(position.x(), position.y(), size.x(), size.y());
         }
 
@@ -220,7 +222,7 @@ class MAGNUM_EXPORT AbstractFramebuffer {
          *      Renderer::setClearStencil(), @fn_gl{Clear}
          */
         inline void clear(ClearMask mask) {
-            bind(Target::ReadDraw);
+            bind(drawTarget);
             glClear(static_cast<GLbitfield>(mask));
         }
 
@@ -254,8 +256,13 @@ class MAGNUM_EXPORT AbstractFramebuffer {
 
     #ifndef DOXYGEN_GENERATING_OUTPUT
     protected:
+        static Target readTarget, drawTarget;
+
         GLuint _id;
     #endif
+
+    private:
+        static void MAGNUM_LOCAL initializeContextBasedFunctionality(Context* context);
 };
 
 inline AbstractFramebuffer::~AbstractFramebuffer() {}

src/Context.cpp

@@ -20,6 +20,7 @@
 #include <Utility/Debug.h>
 #include <Utility/String.h>
 
+#include "AbstractFramebuffer.h"
 #include "AbstractShaderProgram.h"
 #include "AbstractTexture.h"
 #include "Buffer.h"
@@ -292,6 +293,7 @@ Context::Context() {
     _state = new Implementation::State;
 
     /* Initialize functionality based on current OpenGL version and extensions */
+    AbstractFramebuffer::initializeContextBasedFunctionality(this);
     AbstractShaderProgram::initializeContextBasedFunctionality(this);
     AbstractTexture::initializeContextBasedFunctionality(this);
     Buffer::initializeContextBasedFunctionality(this);

src/DefaultFramebuffer.cpp

@@ -27,7 +27,7 @@ void DefaultFramebuffer::mapForDraw(std::initializer_list<DrawAttachment> attach
     for(auto it = attachments.begin(); it != attachments.end(); ++it)
         _attachments[it-attachments.begin()] = static_cast<GLenum>(*it);
 
-    bind(Target::Draw);
+    bind(drawTarget);
     glDrawBuffers(attachments.size(), _attachments);
     delete[] _attachments;
 }

src/DefaultFramebuffer.h

@@ -186,7 +186,7 @@ class MAGNUM_EXPORT DefaultFramebuffer: public AbstractFramebuffer {
          * @requires_gles30 %Extension @es_extension2{NV,read_buffer,GL_NV_read_buffer}
          */
         inline void mapForRead(ReadAttachment attachment) {
-            bind(Target::Read);
+            bind(readTarget);
             /** @todo Get some extension wrangler instead to avoid undeclared glReadBuffer() on ES2 */
             #ifndef MAGNUM_TARGET_GLES2
             glReadBuffer(static_cast<GLenum>(attachment));