Enable mercator-to-screen projection in GLSL

With this change, all the geo-to-screen conversion,
and the triangulation operations for geo polylines
and geo polygon are performed either at set time
or in the shader.
A separate bounding box geometry is processed
in the old way to provide a correct QtQuick Item
geometry, that can be used for nesting mouse areas,
performing translations, input event delivery, etc.

With this approach, performance are improved by more
than one order of magnitude in average, but complex
geometries will of course benefit more.

It also adds correct rendering support for polygons
with holes, previously only rendered correctly
by the MapboxGL plugin.

The polyline shader has basic miter joins. The miter is
skipped if the angle is too sharp to avoid complicating
the implementation.
This shader introduces some glitches when the polyline
is minified, for which the real fix is to
have LOD for the geometry, and render simplified
geometries at low zoom levels (added in a subsequent patch).

Note: this approach, at least in its current implementation,
does not support enabling layers on individual items, only
on the Map element.

Task-number: QTBUG-49303
Task-number: QTBUG-38459
Change-Id: I0c2dc0bf364d32f74ca7c4014f6d66e6219c8ae4
Reviewed-by: Alexandru Croitor <alexandru.croitor@qt.io>

1 files changed, 30 insertions, 90 deletions

diff --git a/src/location/declarativemaps/qdeclarativepolylinemapitem_p.h b/src/location/declarativemaps/qdeclarativepolylinemapitem_p.h
index 3aa0f96b..9cd20ea5 100644
--- a/src/location/declarativemaps/qdeclarativepolylinemapitem_p.h
+++ b/src/location/declarativemaps/qdeclarativepolylinemapitem_p.h
@@ -59,8 +59,6 @@
 
 QT_BEGIN_NAMESPACE
 
-class MapPolylineNode;
-
 class Q_LOCATION_PRIVATE_EXPORT QDeclarativeMapLineProperties : public QObject
 {
     Q_OBJECT
@@ -86,53 +84,23 @@ private:
     QColor color_;
 };
 
-class Q_LOCATION_PRIVATE_EXPORT QGeoMapPolylineGeometry : public QGeoMapItemGeometry
-{
-public:
-    QGeoMapPolylineGeometry();
-
-    void updateSourcePoints(const QGeoMap &map,
-                            const QList<QDoubleVector2D> &path,
-                            const QGeoCoordinate geoLeftBound);
-
-    void updateScreenPoints(const QGeoMap &map,
-                            qreal strokeWidth,
-                            bool adjustTranslation = true);
-
-    void clearSource();
-
-    bool contains(const QPointF &point) const override;
-
-    QList<QList<QDoubleVector2D> > clipPath(const QGeoMap &map,
-                    const QList<QDoubleVector2D> &path,
-                    QDoubleVector2D &leftBoundWrapped);
-
-    void pathToScreen(const QGeoMap &map,
-                      const QList<QList<QDoubleVector2D> > &clippedPaths,
-                      const QDoubleVector2D &leftBoundWrapped);
-
-public:
-    QVector<qreal> srcPoints_;
-    QVector<QPainterPath::ElementType> srcPointTypes_;
-
-#ifdef QT_LOCATION_DEBUG
-    QList<QDoubleVector2D> m_wrappedPath;
-    QList<QList<QDoubleVector2D>> m_clippedPaths;
-#endif
-
-    friend class QDeclarativeCircleMapItem;
-    friend class QDeclarativePolygonMapItem;
-    friend class QDeclarativeRectangleMapItem;
-};
-
+class QDeclarativePolylineMapItemPrivate;
 class Q_LOCATION_PRIVATE_EXPORT QDeclarativePolylineMapItem : public QDeclarativeGeoMapItemBase
 {
     Q_OBJECT
+    Q_ENUMS(Backend)
 
     Q_PROPERTY(QJSValue path READ path WRITE setPath NOTIFY pathChanged)
     Q_PROPERTY(QDeclarativeMapLineProperties *line READ line CONSTANT)
+    Q_PROPERTY(Backend backend READ backend WRITE setBackend NOTIFY backendChanged REVISION 15)
 
 public:
+    enum Backend {
+        Software = 0,
+        OpenGLLineStrip = 1,
+        OpenGLExtruded = 2,
+    };
+
     explicit QDeclarativePolylineMapItem(QQuickItem *parent = 0);
     ~QDeclarativePolylineMapItem();
 
@@ -159,70 +127,42 @@ public:
 
     QDeclarativeMapLineProperties *line();
 
+    Backend backend() const;
+    void setBackend(Backend b);
+
 Q_SIGNALS:
     void pathChanged();
-
-protected:
-    void geometryChanged(const QRectF &newGeometry, const QRectF &oldGeometry) override;
-    void setPathFromGeoList(const QList<QGeoCoordinate> &path);
-    void updatePolish() override;
+    void backendChanged();
 
 protected Q_SLOTS:
     void markSourceDirtyAndUpdate();
     void updateAfterLinePropertiesChanged();
     virtual void afterViewportChanged(const QGeoMapViewportChangeEvent &event) override;
 
-private:
-    void regenerateCache();
-    void updateCache();
+protected:
+    void geometryChanged(const QRectF &newGeometry, const QRectF &oldGeometry) override;
+    void setPathFromGeoList(const QList<QGeoCoordinate> &path);
+    void updatePolish() override;
+    void componentComplete() override;
+    void updateLineStyleParameter(QGeoMapParameter *p, const char *propertyName);
+    void updateLineStyleParameter(QGeoMapParameter *p, const char *propertyName, bool update);
 
 #ifdef QT_LOCATION_DEBUG
 public:
 #endif
-    QGeoPath geopath_;
-    QList<QDoubleVector2D> geopathProjected_;
-    QDeclarativeMapLineProperties line_;
-    QColor color_;
-    bool dirtyMaterial_;
-    QGeoMapPolylineGeometry geometry_;
-    bool updatingGeometry_;
-};
+    QGeoPath m_geopath;
+    QDeclarativeMapLineProperties m_line;
 
-//////////////////////////////////////////////////////////////////////
-
-class Q_LOCATION_PRIVATE_EXPORT VisibleNode
-{
-public:
-    VisibleNode();
-    virtual ~VisibleNode();
+    Backend m_backend = Software;
+    bool m_dirtyMaterial;
+    bool m_updatingGeometry;
 
-    bool subtreeBlocked() const;
-    void setSubtreeBlocked(bool blocked);
-    bool visible() const;
-    void setVisible(bool visible);
+    QScopedPointer<QDeclarativePolylineMapItemPrivate> m_d;
 
-    bool m_blocked : 1;
-    bool m_visible : 1;
-};
-
-class Q_LOCATION_PRIVATE_EXPORT MapItemGeometryNode : public QSGGeometryNode, public VisibleNode
-{
-public:
-    ~MapItemGeometryNode() override;
-    bool isSubtreeBlocked() const override;
-};
-
-class Q_LOCATION_PRIVATE_EXPORT MapPolylineNode : public MapItemGeometryNode
-{
-public:
-    MapPolylineNode();
-    ~MapPolylineNode() override;
-
-    void update(const QColor &fillColor, const QGeoMapItemGeometry *shape);
-
-private:
-    QSGFlatColorMaterial fill_material_;
-    QSGGeometry geometry_;
+    friend class QDeclarativePolylineMapItemPrivate;
+    friend class QDeclarativePolylineMapItemPrivateCPU;
+    friend class QDeclarativePolylineMapItemPrivateOpenGLLineStrip;
+    friend class QDeclarativePolylineMapItemPrivateOpenGLExtruded;
 };
 
 QT_END_NAMESPACE