Decide between ANGLE/NV implementation for Framebuffer::blit() on ES.

Currently both disabled until extension loader is in place.

src/Magnum/AbstractFramebuffer.cpp

@@ -132,19 +132,27 @@ FramebufferTarget AbstractFramebuffer::bindInternal() {
 void AbstractFramebuffer::blit(AbstractFramebuffer& source, AbstractFramebuffer& destination, const Range2Di& sourceRectangle, const Range2Di& destinationRectangle, FramebufferBlitMask mask, FramebufferBlitFilter filter) {
     source.bindInternal(FramebufferTarget::Read);
     destination.bindInternal(FramebufferTarget::Draw);
-    /** @todo Re-enable when extension loader is available for ES, add also ANGLE version */
     #ifndef MAGNUM_TARGET_GLES2
     glBlitFramebuffer(sourceRectangle.left(), sourceRectangle.bottom(), sourceRectangle.right(), sourceRectangle.top(), destinationRectangle.left(), destinationRectangle.bottom(), destinationRectangle.right(), destinationRectangle.top(), GLbitfield(mask), GLenum(filter));
     #else
-    static_cast<void>(sourceRectangle);
-    static_cast<void>(destinationRectangle);
-    static_cast<void>(mask);
-    static_cast<void>(filter);
-    //glBlitFramebufferNV(sourceRectangle.left(), sourceRectangle.bottom(), sourceRectangle.right(), sourceRectangle.top(), destinationRectangle.left(), destinationRectangle.bottom(), destinationRectangle.right(), destinationRectangle.top(), GLbitfield(mask), GLenum(filter));
-    CORRADE_INTERNAL_ASSERT(false);
+    Context::current()->state().framebuffer->blitImplementation(sourceRectangle, destinationRectangle, mask, filter);
     #endif
 }
 
+#ifdef MAGNUM_TARGET_GLES2
+void AbstractFramebuffer::blitImplementationANGLE(const Range2Di&, const Range2Di&, FramebufferBlitMask, FramebufferBlitFilter) {
+    /** @todo Re-enable when extension loader is available for ES */
+    CORRADE_INTERNAL_ASSERT(false);
+    //glBlitFramebufferANGLE(sourceRectangle.left(), sourceRectangle.bottom(), sourceRectangle.right(), sourceRectangle.top(), destinationRectangle.left(), destinationRectangle.bottom(), destinationRectangle.right(), destinationRectangle.top(), GLbitfield(mask), GLenum(filter));
+}
+
+void AbstractFramebuffer::blitImplementationNV(const Range2Di&, const Range2Di&, FramebufferBlitMask, FramebufferBlitFilter) {
+    /** @todo Re-enable when extension loader is available for ES */
+    CORRADE_INTERNAL_ASSERT(false);
+    //glBlitFramebufferNV(sourceRectangle.left(), sourceRectangle.bottom(), sourceRectangle.right(), sourceRectangle.top(), destinationRectangle.left(), destinationRectangle.bottom(), destinationRectangle.right(), destinationRectangle.top(), GLbitfield(mask), GLenum(filter));
+}
+#endif
+
 AbstractFramebuffer& AbstractFramebuffer::setViewport(const Range2Di& rectangle) {
     _viewport = rectangle;
 

src/Magnum/AbstractFramebuffer.h

@@ -337,6 +337,11 @@ class MAGNUM_EXPORT AbstractFramebuffer {
         Range2Di _viewport;
 
     private:
+        #ifdef MAGNUM_TARGET_GLES2
+        static void MAGNUM_LOCAL blitImplementationANGLE(const Range2Di& sourceRectangle, const Range2Di& destinationRectangle, FramebufferBlitMask mask, FramebufferBlitFilter filter);
+        static void MAGNUM_LOCAL blitImplementationNV(const Range2Di& sourceRectangle, const Range2Di& destinationRectangle, FramebufferBlitMask mask, FramebufferBlitFilter filter);
+        #endif
+
         GLenum MAGNUM_LOCAL checkStatusImplementationDefault(FramebufferTarget target);
         #ifndef MAGNUM_TARGET_GLES
         GLenum MAGNUM_LOCAL checkStatusImplementationDSA(FramebufferTarget target);

src/Magnum/Implementation/FramebufferState.cpp

@@ -166,6 +166,19 @@ FramebufferState::FramebufferState(Context& context, std::vector<std::string>& e
     invalidateImplementation = &AbstractFramebuffer::invalidateImplementationDefault;
     invalidateSubImplementation = &AbstractFramebuffer::invalidateImplementationDefault;
     #endif
+
+    /* Blit implementation on ES2 */
+    #ifdef MAGNUM_TARGET_GLES2
+    if(context.isExtensionSupported<Extensions::GL::ANGLE::framebuffer_blit>()) {
+        extensions.push_back(Extensions::GL::ANGLE::framebuffer_blit::string());
+        blitImplementation = &AbstractFramebuffer::blitImplementationANGLE;
+
+    } else if(context.isExtensionSupported<Extensions::GL::NV::framebuffer_blit>()) {
+        extensions.push_back(Extensions::GL::NV::framebuffer_blit::string());
+        blitImplementation = &AbstractFramebuffer::blitImplementationNV;
+
+    } else blitImplementation = nullptr;
+    #endif
 }
 
 void FramebufferState::reset() {

src/Magnum/Implementation/FramebufferState.h

@@ -37,6 +37,9 @@ struct FramebufferState {
 
     void reset();
 
+    #ifdef MAGNUM_TARGET_GLES2
+    void(*blitImplementation)(const Range2Di&, const Range2Di&, FramebufferBlitMask, FramebufferBlitFilter);
+    #endif
     GLenum(AbstractFramebuffer::*checkStatusImplementation)(FramebufferTarget);
     void(AbstractFramebuffer::*drawBuffersImplementation)(GLsizei, const GLenum*);
     void(AbstractFramebuffer::*drawBufferImplementation)(GLenum);