QClearBuffers: clear specific QRenderTargetOutputs

If QClearBuffers::colorBuffer is set to a non-NULL value, only
this color buffer will be affected by the Clear operation.

Right now, only clamped color values are supported by the frontend.
OpenGL also supports non-clamped float and integer values, depending
on the type of the target buffer.

Task-number: QTBUG-50116
Change-Id: I2786c0603b24b4af0d24751151d64be7504b3e92
Reviewed-by: Sean Harmer <sean.harmer@kdab.com>

1 files changed, 17 insertions, 2 deletions

diff --git a/src/render/framegraph/clearbuffers_p.h b/src/render/framegraph/clearbuffers_p.h
index 4b2f262bd..e25860b03 100644
--- a/src/render/framegraph/clearbuffers_p.h
+++ b/src/render/framegraph/clearbuffers_p.h
@@ -68,18 +68,33 @@ public:
     ClearBuffers();
 
     void sceneChangeEvent(const Qt3DCore::QSceneChangePtr &e) Q_DECL_OVERRIDE;
+
     QClearBuffers::BufferType type() const;
-    QColor clearColor() const;
     float clearDepthValue() const;
     int clearStencilValue() const;
+    Qt3DCore::QNodeId bufferId() const;
+
+    // in the backend we store this as a QVector4D, as the clearBuffer
+    // functions do support all float values (also those not clamped to [0,1])
+    // (for non-clamped float or int buffer types)
+    // we don't support this in the frontend yet, but let's keep our options for now
+    // and avoid QColor->QVector4D conversion every frame.
+    QVector4D clearColor() const;
+
+    // some clear operations only accept clamped values
+    QColor clearColorAsColor() const;
+
+    bool clearsAllColorBuffers() const;
 
 private:
     void initializeFromPeer(const Qt3DCore::QNodeCreatedChangeBasePtr &change) Q_DECL_FINAL;
 
     QClearBuffers::BufferType m_type;
-    QColor m_clearColor;
+    QVector4D m_clearColor;
+    QColor m_clearColorAsColor;
     float m_clearDepthValue;
     int m_clearStencilValue;
+    Qt3DCore::QNodeId m_colorBufferId;
 };
 
 } // namespace Render