Enable blitFramebuffer with ES2 when it is supported

Task-number: QTBUG-57573
Change-Id: Ie1be0282fbab6e4346a81f37eff7597b932da07e
Reviewed-by: Sean Harmer <sean.harmer@kdab.com>

3 files changed, 24 insertions, 22 deletions

diff --git a/src/render/graphicshelpers/graphicscontext.cpp b/src/render/graphicshelpers/graphicscontext.cpp
index aba74c8d9..cee1a568a 100644
--- a/src/render/graphicshelpers/graphicscontext.cpp
+++ b/src/render/graphicshelpers/graphicscontext.cpp
@@ -81,6 +81,14 @@
 
 QT_BEGIN_NAMESPACE
 
+#ifndef GL_READ_FRAMEBUFFER
+#define GL_READ_FRAMEBUFFER 0x8CA8
+#endif
+
+#ifndef GL_DRAW_FRAMEBUFFER
+#define GL_DRAW_FRAMEBUFFER 0x8CA9
+#endif
+
 namespace {
 
 QOpenGLShader::ShaderType shaderType(Qt3DRender::QShaderProgram::ShaderType type)
@@ -1630,10 +1638,8 @@ QImage GraphicsContext::readFramebuffer(QSize size)
     QImage::Format imageFormat;
     uint stride;
 
-#ifndef QT_OPENGL_ES_2
     /* format value should match GL internalFormat */
     GLenum internalFormat = m_renderTargetFormat;
-#endif
 
     switch (m_renderTargetFormat) {
     case QAbstractTexture::RGBAFormat:
@@ -1709,18 +1715,15 @@ QImage GraphicsContext::readFramebuffer(QSize size)
         return img;
     }
 
-#ifndef QT_OPENGL_ES_2
     GLint samples = 0;
     m_gl->functions()->glGetIntegerv(GL_SAMPLES, &samples);
     if (samples > 0 && !m_glHelper->supportsFeature(GraphicsHelperInterface::BlitFramebuffer))
         return img;
-#endif
 
     img = QImage(size.width(), size.height(), imageFormat);
 
     QScopedArrayPointer<uchar> data(new uchar [bytes]);
 
-#ifndef QT_OPENGL_ES_2
     if (samples > 0) {
         // resolve multisample-framebuffer to renderbuffer and read pixels from it
         GLuint fbo, rb;
@@ -1752,14 +1755,10 @@ QImage GraphicsContext::readFramebuffer(QSize size)
         gl->glBindFramebuffer(GL_FRAMEBUFFER, m_activeFBO);
         gl->glDeleteFramebuffers(1, &fbo);
     } else {
-#endif
         // read pixels directly from framebuffer
         m_gl->functions()->glReadPixels(0,0,size.width(), size.height(), format, type, data.data());
         copyGLFramebufferDataToImage(img, data.data(), stride, size.width(), size.height(), m_renderTargetFormat);
-
-#ifndef QT_OPENGL_ES_2
     }
-#endif
 
     return img;
 }
diff --git a/src/render/graphicshelpers/graphicshelperes2.cpp b/src/render/graphicshelpers/graphicshelperes2.cpp
index 1335b250f..b409cf5af 100644
--- a/src/render/graphicshelpers/graphicshelperes2.cpp
+++ b/src/render/graphicshelpers/graphicshelperes2.cpp
@@ -65,8 +65,9 @@ QT_BEGIN_NAMESPACE
 namespace Qt3DRender {
 namespace Render {
 
-GraphicsHelperES2::GraphicsHelperES2() :
-    m_funcs(0)
+GraphicsHelperES2::GraphicsHelperES2()
+    : m_funcs(0)
+    , m_supportFramebufferBlit(false)
 {
 }
 
@@ -80,6 +81,9 @@ void GraphicsHelperES2::initializeHelper(QOpenGLContext *context,
     Q_ASSERT(context);
     m_funcs = context->functions();
     Q_ASSERT(m_funcs);
+    m_ext.reset(new QOpenGLExtensions(context));
+    if (m_ext->hasOpenGLExtension(QOpenGLExtensions::FramebufferBlit))
+        m_supportFramebufferBlit = true;
 }
 
 void GraphicsHelperES2::drawElementsInstancedBaseVertexBaseInstance(GLenum primitiveType,
@@ -356,6 +360,8 @@ bool GraphicsHelperES2::supportsFeature(GraphicsHelperInterface::Feature feature
     switch (feature) {
     case RenderBufferDimensionRetrieval:
         return true;
+    case BlitFramebuffer:
+        return m_supportFramebufferBlit;
     default:
         return false;
     }
@@ -709,17 +715,10 @@ UniformType GraphicsHelperES2::uniformTypeFromGLType(GLenum type)
 
 void GraphicsHelperES2::blitFramebuffer(GLint srcX0, GLint srcY0, GLint srcX1, GLint srcY1, GLint dstX0, GLint dstY0, GLint dstX1, GLint dstY1, GLbitfield mask, GLenum filter)
 {
-    Q_UNUSED(srcX0);
-    Q_UNUSED(srcX1);
-    Q_UNUSED(srcY0);
-    Q_UNUSED(srcY1);
-    Q_UNUSED(dstX0);
-    Q_UNUSED(dstX1);
-    Q_UNUSED(dstY0);
-    Q_UNUSED(dstY1);
-    Q_UNUSED(mask);
-    Q_UNUSED(filter);
-    qWarning() << "Framebuffer blits are not supported by ES 2.0 (since ES 3.1)";
+    if (!m_supportFramebufferBlit)
+        qWarning() << "Framebuffer blits are not supported by ES 2.0 (since ES 3.1)";
+    else
+        m_ext->glBlitFramebuffer(srcX0, srcY0, srcX1, srcY1, dstX0, dstY0, dstX1, dstY1, mask, filter);
 }
 
 } // namespace Render
diff --git a/src/render/graphicshelpers/graphicshelperes2_p.h b/src/render/graphicshelpers/graphicshelperes2_p.h
index 17249ef23..ddcd28ca5 100644
--- a/src/render/graphicshelpers/graphicshelperes2_p.h
+++ b/src/render/graphicshelpers/graphicshelperes2_p.h
@@ -57,6 +57,8 @@
 
 QT_BEGIN_NAMESPACE
 
+class QOpenGLExtensions;
+
 namespace Qt3DRender {
 namespace Render {
 
@@ -148,6 +150,8 @@ public:
 
 protected:
     QOpenGLFunctions *m_funcs;
+    bool m_supportFramebufferBlit;
+    QScopedPointer<QOpenGLExtensions> m_ext;
 };
 
 } // namespace Render