New feature: Texture view Mask Source

Enable use of a source as mask for another source. Improved Mask mechanism in Source class, with various flags for update of source (avoid repeated mask update (GPU costly). Using SourceLink to link source to mask (improved robustness of SourceLink).

src/Source.h

@@ -136,11 +136,15 @@ public:
     // every Source has a frame buffer from the renderbuffer
     virtual FrameBuffer *frame () const;
 
-    // a Source has a shader used to render mask
-    inline MaskShader *maskShader () const { return maskshader_; }
-
     // touch to request update
-    inline void touch () { need_update_ = true; }
+    enum UpdateFlags_ {
+        SourceUpdate_None      = 0,
+        SourceUpdate_Render    = 1 << 1,
+        SourceUpdate_Mask      = 1 << 2,
+        SourceUpdate_Mask_fill = 1 << 3
+    };
+    typedef int UpdateFlags;
+    inline void touch (UpdateFlags f = SourceUpdate_Render) { need_update_ |= f; }
 
     // informs if its ready (i.e. initialized)
     inline bool ready () const  { return ready_; }
@@ -197,9 +201,14 @@ public:
     virtual void accept (Visitor& v);
 
     // operations on mask
+    // get shader used to render mask
+    inline MaskShader *maskShader () const { return maskshader_; }
+    // set/get framebuffer used for mask painting
     inline FrameBufferImage *getMask () const { return maskimage_; }
     void setMask (FrameBufferImage *img);
     void storeMask (FrameBufferImage *img = nullptr);
+    // link to source used as mask
+    inline  SourceLink *maskSource() const { return masksource_; }
 
     // get properties
     float depth () const;
@@ -300,8 +309,8 @@ protected:
     MaskShader *maskshader_;
     FrameBuffer *maskbuffer_;
     Surface *masksurface_;
-    bool mask_need_update_;
     FrameBufferImage *maskimage_;
+    SourceLink *masksource_;
 
     // surface to draw on
     Surface *texturesurface_;
@@ -321,7 +330,7 @@ protected:
     // update
     bool  active_;
     bool  locked_;
-    bool  need_update_;
+    UpdateFlags   need_update_;
     float dt_;
     Workspace  workspace_;