Pass projection matrix to ScreenPaintData

With this change a new ctor overload is added to ScreenPaintData
which allows passing a projection matrix through the effects. This
allows effects to put up custom shaders with a shared projection matrix
and without having to calculate it themselves.

The projection matrix is a read-only information for the effects. There
is no way to change or overwrite it.

libkwineffects/kwineffects.cpp

@@ -418,13 +418,30 @@ WindowPaintData &WindowPaintData::operator+=(const QVector3D &translation)
     return *this;
 }
 
+class ScreenPaintData::Private
+{
+public:
+    QMatrix4x4 projectionMatrix;
+};
+
 ScreenPaintData::ScreenPaintData()
     : PaintData()
+    , d(new Private())
 {
 }
 
+ScreenPaintData::ScreenPaintData(const QMatrix4x4 &projectionMatrix)
+    : PaintData()
+    , d(new Private())
+{
+    d->projectionMatrix = projectionMatrix;
+}
+
+ScreenPaintData::~ScreenPaintData() = default;
+
 ScreenPaintData::ScreenPaintData(const ScreenPaintData &other)
     : PaintData()
+    , d(new Private())
 {
     translate(other.translation());
     setXScale(other.xScale());
@@ -433,6 +450,7 @@ ScreenPaintData::ScreenPaintData(const ScreenPaintData &other)
     setRotationOrigin(other.rotationOrigin());
     setRotationAxis(other.rotationAxis());
     setRotationAngle(other.rotationAngle());
+    d->projectionMatrix = other.d->projectionMatrix;
 }
 
 ScreenPaintData &ScreenPaintData::operator=(const ScreenPaintData &rhs)
@@ -446,6 +464,7 @@ ScreenPaintData &ScreenPaintData::operator=(const ScreenPaintData &rhs)
     setRotationOrigin(rhs.rotationOrigin());
     setRotationAxis(rhs.rotationAxis());
     setRotationAngle(rhs.rotationAngle());
+    d->projectionMatrix = rhs.d->projectionMatrix;
     return *this;
 }
 
@@ -493,6 +512,11 @@ ScreenPaintData &ScreenPaintData::operator+=(const QVector3D &translation)
     return *this;
 }
 
+QMatrix4x4 ScreenPaintData::projectionMatrix() const
+{
+    return d->projectionMatrix;
+}
+
 //****************************************
 // Effect
 //****************************************

libkwineffects/kwineffects.h

@@ -40,6 +40,7 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>.
 #include <QList>
 #include <QHash>
 #include <QStack>
+#include <QScopedPointer>
 
 #include <KPluginFactory>
 
@@ -2419,7 +2420,9 @@ class KWINEFFECTS_EXPORT ScreenPaintData : public PaintData
 {
 public:
     ScreenPaintData();
+    ScreenPaintData(const QMatrix4x4 &projectionMatrix);
     ScreenPaintData(const ScreenPaintData &other);
+    virtual ~ScreenPaintData();
     /**
      * Scales the screen by @p scale factor.
      * Multiplies all three components by the given factor.
@@ -2462,6 +2465,16 @@ public:
      **/
     ScreenPaintData& operator+=(const QVector3D &translation);
     ScreenPaintData& operator=(const ScreenPaintData &rhs);
+
+    /**
+     * The projection matrix used by the scene for the current rendering pass.
+     * On non-OpenGL compositors it's set to Identity matrix.
+     * @since 5.6
+     **/
+    QMatrix4x4 projectionMatrix() const;
+private:
+    class Private;
+    QScopedPointer<Private> d;
 };
 
 class KWINEFFECTS_EXPORT ScreenPrePaintData

scene.cpp

@@ -106,7 +106,7 @@ Scene::~Scene()
 
 // returns mask and possibly modified region
 void Scene::paintScreen(int* mask, const QRegion &damage, const QRegion &repaint,
-                        QRegion *updateRegion, QRegion *validRegion)
+                        QRegion *updateRegion, QRegion *validRegion, const QMatrix4x4 &projection)
 {
     const QSize &screenSize = screens()->size();
     const QRegion displayRegion(0, 0, screenSize.width(), screenSize.height());
@@ -146,7 +146,7 @@ void Scene::paintScreen(int* mask, const QRegion &damage, const QRegion &repaint
         paintBackground(region);
     }
 
-    ScreenPaintData data;
+    ScreenPaintData data(projection);
     effects->paintScreen(*mask, region, data);
 
     foreach (Window *w, stacking_order) {

scene.h

@@ -26,6 +26,7 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>.
 #include "kwineffects.h"
 
 #include <QElapsedTimer>
+#include <QMatrix4x4>
 
 class QOpenGLFramebufferObject;
 
@@ -158,7 +159,7 @@ protected:
     void clearStackingOrder();
     // shared implementation, starts painting the screen
     void paintScreen(int *mask, const QRegion &damage, const QRegion &repaint,
-                     QRegion *updateRegion, QRegion *validRegion);
+                     QRegion *updateRegion, QRegion *validRegion, const QMatrix4x4 &projection = QMatrix4x4());
     friend class EffectsHandlerImpl;
     // called after all effects had their paintScreen() called
     void finalPaintScreen(int mask, QRegion region, ScreenPaintData& data);

scene_opengl.cpp

@@ -728,7 +728,7 @@ qint64 SceneOpenGL::paint(QRegion damage, ToplevelList toplevels)
 
             int mask = 0;
             updateProjectionMatrix();
-            paintScreen(&mask, damage.intersected(geo), repaint, &update, &valid);   // call generic implementation
+            paintScreen(&mask, damage.intersected(geo), repaint, &update, &valid, projectionMatrix());   // call generic implementation
 
             GLVertexBuffer::streamingBuffer()->endOfFrame();
 
@@ -748,7 +748,7 @@ qint64 SceneOpenGL::paint(QRegion damage, ToplevelList toplevels)
 
         int mask = 0;
         updateProjectionMatrix();
-        paintScreen(&mask, damage, repaint, &updateRegion, &validRegion);   // call generic implementation
+        paintScreen(&mask, damage, repaint, &updateRegion, &validRegion, projectionMatrix());   // call generic implementation
 
         if (!GLPlatform::instance()->isGLES()) {
             const QSize &screenSize = screens()->size();