diff --git a/CMakeLists.txt b/CMakeLists.txt
index b3a459f..29ad228 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -290,6 +290,8 @@ set(VMIX_RSC_FILES
     ./rsc/shaders/simple.fs
     ./rsc/shaders/simple.vs
     ./rsc/shaders/image.fs
+    ./rsc/shaders/mask_elipse.fs
+    ./rsc/shaders/mask_box.fs
     ./rsc/shaders/image.vs
     ./rsc/shaders/imageprocessing.fs
     ./rsc/fonts/Hack-Regular.ttf
@@ -321,6 +323,7 @@ set(VMIX_RSC_FILES
     ./rsc/images/soft_shadow.dds
     ./rsc/mesh/disk.ply
     ./rsc/mesh/circle.ply
+    ./rsc/mesh/corner.ply
     ./rsc/mesh/shadow.ply
     ./rsc/mesh/glow.ply
     ./rsc/mesh/border_round.ply
diff --git a/ImGuiVisitor.cpp b/ImGuiVisitor.cpp
index 1b0e5c9..e36db02 100644
--- a/ImGuiVisitor.cpp
+++ b/ImGuiVisitor.cpp
@@ -161,6 +161,7 @@ void ImGuiVisitor::visit(Shader &n)
 {
     ImGui::PushID(std::to_string(n.id()).c_str());
 
+    // Base color
 //    if (ImGuiToolkit::ButtonIcon(10, 2)) {
 //        n.blending = Shader::BLEND_OPACITY;
 //        n.color = glm::vec4(1.f, 1.f, 1.f, 1.f);
@@ -201,29 +202,26 @@ void ImGuiVisitor::visit(Shader &n)
     ImGui::PopID();
 }
 
-void ImGuiVisitor::visit(ImageShader &n)
-{
-    ImGui::PushID(std::to_string(n.id()).c_str());
-
-    // get index of the mask used in this ImageShader
-    int item_current = n.mask;
-
-//    if (ImGuiToolkit::ButtonIcon(10, 3)) n.mask = 0;
-//    ImGui::SameLine(0, 10);
-    ImGui::SetNextItemWidth(IMGUI_RIGHT_ALIGN);
-    // combo list of masks
-    if ( ImGui::Combo("Mask", &item_current, ImageShader::mask_names, IM_ARRAYSIZE(ImageShader::mask_names) ) )
-    {
-        if (item_current < (int) ImageShader::mask_presets.size())
-            n.mask = item_current;
-        else {
-            // TODO ask for custom mask
-        }
-        Action::manager().store("Mask "+ std::string(ImageShader::mask_names[n.mask]), n.id());
-    }
-
-    ImGui::PopID();
-}
+//void ImGuiVisitor::visit(ImageShader &n)
+//{
+//    ImGui::PushID(std::to_string(n.id()).c_str());
+//    // get index of the mask used in this ImageShader
+//    int item_current = n.mask;
+////    if (ImGuiToolkit::ButtonIcon(10, 3)) n.mask = 0;
+////    ImGui::SameLine(0, 10);
+//    ImGui::SetNextItemWidth(IMGUI_RIGHT_ALIGN);
+//    // combo list of masks
+//    if ( ImGui::Combo("Mask", &item_current, ImageShader::mask_names, IM_ARRAYSIZE(ImageShader::mask_names) ) )
+//    {
+//        if (item_current < (int) ImageShader::mask_presets.size())
+//            n.mask = item_current;
+//        else {
+//            // TODO ask for custom mask
+//        }
+//        Action::manager().store("Mask "+ std::string(ImageShader::mask_names[n.mask]), n.id());
+//    }
+//    ImGui::PopID();
+//}
 
 void ImGuiVisitor::visit(ImageProcessingShader &n)
 {
diff --git a/ImGuiVisitor.h b/ImGuiVisitor.h
index 1508169..d1ee8ad 100644
--- a/ImGuiVisitor.h
+++ b/ImGuiVisitor.h
@@ -9,19 +9,18 @@ public:
     ImGuiVisitor();
 
     // Elements of Scene
-    void visit(Scene& n) override;
-    void visit(Node& n) override;
-    void visit(Group& n) override;
-    void visit(Switch& n) override;
-    void visit(Primitive& n) override;
-    void visit(MediaSurface& n) override;
-    void visit(FrameBufferSurface& n) override;
+    void visit (Scene& n) override;
+    void visit (Node& n) override;
+    void visit (Group& n) override;
+    void visit (Switch& n) override;
+    void visit (Primitive& n) override;
+    void visit (MediaSurface& n) override;
+    void visit (FrameBufferSurface& n) override;
 
     // Elements with attributes
-    void visit(MediaPlayer& n) override;
-    void visit(Shader& n) override;
-    void visit(ImageShader& n) override;
-    void visit(ImageProcessingShader& n) override;
+    void visit (MediaPlayer& n) override;
+    void visit (Shader& n) override;
+    void visit (ImageProcessingShader& n) override;
     void visit (Source& s) override;
     void visit (MediaSource& s) override;
     void visit (SessionSource& s) override;
diff --git a/ImageShader.cpp b/ImageShader.cpp
index 5f96b9d..dd0c5c6 100644
--- a/ImageShader.cpp
+++ b/ImageShader.cpp
@@ -4,27 +4,16 @@
 #include "Visitor.h"
 #include "ImageShader.h"
 #include "Resource.h"
+#include "rsc/fonts/IconsFontAwesome5.h"
+//#include
 
 static ShadingProgram imageShadingProgram("shaders/image.vs", "shaders/image.fs");
 
-const char* ImageShader::mask_names[11] = { "None", "Glow", "Halo", "Circle", "Round", "Vignette", "Top", "Botton", "Left", "Right", "Custom" };
-std::vector< uint > ImageShader::mask_presets;
+const char* MaskShader::mask_names[3] = { ICON_FA_EXPAND, ICON_FA_CIRCLE, ICON_FA_SQUARE };
+std::vector< ShadingProgram* > MaskShader::mask_programs;
 
-ImageShader::ImageShader(): Shader(), mask(0), custom_textureindex(0), stipple(0.0)
+ImageShader::ImageShader(): Shader(), /*mask(0), custom_textureindex(0),*/ stipple(0.0)
 {
-    // first initialization
-    if ( mask_presets.empty() ) {
-        mask_presets.push_back(Resource::getTextureWhite());
-        mask_presets.push_back(Resource::getTextureImage("images/mask_glow.png"));
-        mask_presets.push_back(Resource::getTextureImage("images/mask_halo.png"));
-        mask_presets.push_back(Resource::getTextureImage("images/mask_circle.png"));
-        mask_presets.push_back(Resource::getTextureImage("images/mask_roundcorner.png"));
-        mask_presets.push_back(Resource::getTextureImage("images/mask_vignette.png"));
-        mask_presets.push_back(Resource::getTextureImage("images/mask_linear_top.png"));
-        mask_presets.push_back(Resource::getTextureImage("images/mask_linear_bottom.png"));
-        mask_presets.push_back(Resource::getTextureImage("images/mask_linear_left.png"));
-        mask_presets.push_back(Resource::getTextureImage("images/mask_linear_right.png"));
-    }
     // static program shader
     program_ = &imageShadingProgram;
     // reset instance
@@ -38,12 +27,9 @@ void ImageShader::use()
     program_->setUniform("stipple", stipple);
 
     glActiveTexture(GL_TEXTURE1);
-    if ( mask < 10 )
-        glBindTexture(GL_TEXTURE_2D, mask_presets[mask]);
-    else
-        glBindTexture(GL_TEXTURE_2D, custom_textureindex);
     glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
     glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
+    glBindTexture(GL_TEXTURE_2D, mask_texture);
 
     glActiveTexture(GL_TEXTURE0);
 
@@ -54,18 +40,16 @@ void ImageShader::reset()
     Shader::reset();
 
     // default mask
-    mask = 0;
-    custom_textureindex = mask_presets[0];
+    mask_texture = Resource::getTextureWhite();
     // no stippling
     stipple = 0.f;
 }
 
-void ImageShader::operator = (const ImageShader &S )
+void ImageShader::operator = (const ImageShader &S)
 {
     Shader::operator =(S);
 
-    mask = S.mask;
-    custom_textureindex = S.custom_textureindex;
+    mask_texture = S.mask_texture;
     stipple = S.stipple;
 }
 
@@ -74,3 +58,59 @@ void ImageShader::accept(Visitor& v) {
     Shader::accept(v);
     v.visit(*this);
 }
+
+
+
+
+MaskShader::MaskShader(): Shader(), mode(0)
+{
+    // first initialization
+    if ( mask_programs.empty() ) {
+        mask_programs.push_back(new ShadingProgram("shaders/simple.vs", "shaders/simple.fs"));
+        mask_programs.push_back(new ShadingProgram("shaders/simple.vs", "shaders/mask_elipse.fs"));
+        mask_programs.push_back(new ShadingProgram("shaders/simple.vs", "shaders/mask_box.fs"));
+    }
+    // reset instance
+    reset();
+    // static program shader
+    program_ = mask_programs[0];
+}
+
+void MaskShader::use()
+{
+    // select program to use
+    mode = CLAMP(mode, 0, mask_programs.size()-1);
+    program_ = mask_programs[mode];
+
+    // actual use of shader program
+    Shader::use();
+
+    // set parameters
+    program_->setUniform("blur", blur);
+    program_->setUniform("size", size);
+}
+
+void MaskShader::reset()
+{
+    Shader::reset();
+
+    // default mask
+    mode = 0;
+    blur = 0.5f;
+    size = glm::vec2(1.f, 1.f);
+}
+
+void MaskShader::operator = (const MaskShader &S)
+{
+    Shader::operator =(S);
+
+    mode = S.mode;
+    blur = S.blur;
+    size = S.size;
+}
+
+
+void MaskShader::accept(Visitor& v) {
+    Shader::accept(v);
+    v.visit(*this);
+}
diff --git a/ImageShader.h b/ImageShader.h
index 6ad0c0b..f944a69 100644
--- a/ImageShader.h
+++ b/ImageShader.h
@@ -20,15 +20,35 @@ public:
     void use() override;
     void reset() override;
     void accept(Visitor& v) override;
-
     void operator = (const ImageShader &S);
 
-    uint mask;
-    uint custom_textureindex;
-    float stipple;
+    uint mask_texture;
 
-    static const char* mask_names[11];
-    static std::vector< uint > mask_presets;
+    // uniforms
+    float stipple;
+};
+
+
+class MaskShader : public Shader
+{
+
+public:
+
+    MaskShader();
+
+    void use() override;
+    void reset() override;
+    void accept(Visitor& v) override;
+    void operator = (const MaskShader &S);
+
+    uint mode;
+
+    // uniforms
+    float blur;
+    glm::vec2 size;
+
+    static const char* mask_names[3];
+    static std::vector< ShadingProgram* > mask_programs;
 };
 
 #endif // IMAGESHADER_H
diff --git a/Primitives.cpp b/Primitives.cpp
index abf5558..b7f7848 100644
--- a/Primitives.cpp
+++ b/Primitives.cpp
@@ -173,7 +173,6 @@ void MediaSurface::accept(Visitor& v)
 
 FrameBufferSurface::FrameBufferSurface(FrameBuffer *fb, Shader *s) : Surface(s), frame_buffer_(fb)
 {
-
 }
 
 void FrameBufferSurface::draw(glm::mat4 modelview, glm::mat4 projection)
diff --git a/SessionCreator.cpp b/SessionCreator.cpp
index 8e3d740..bf9a6a1 100644
--- a/SessionCreator.cpp
+++ b/SessionCreator.cpp
@@ -109,52 +109,6 @@ SessionLoader::SessionLoader(Session *session): Visitor(), session_(session)
 
 }
 
-//Source *SessionLoader::createSource(XMLElement *sourceNode)
-//{
-//    // source to load
-//    Source *load_source = nullptr;
-
-//    // check if a source with the given id exists in the session
-//    uint64_t id__ = 0;
-//    sourceNode->QueryUnsigned64Attribute("id", &id__);
-//    SourceList::iterator sit = session_->find(id__);
-
-//    // no source with this id exists
-//    if ( sit == session_->end() ) {
-//        // create a new source depending on type
-//        const char *pType = sourceNode->Attribute("type");
-//        if (!pType)
-//            continue;
-//        if ( std::string(pType) == "MediaSource") {
-//            load_source = new MediaSource;
-//        }
-//        else if ( std::string(pType) == "SessionSource") {
-//            load_source = new SessionSource;
-//        }
-//        else if ( std::string(pType) == "RenderSource") {
-//            load_source = new RenderSource(session_);
-//        }
-//        else if ( std::string(pType) == "PatternSource") {
-//            load_source = new PatternSource;
-//        }
-//        else if ( std::string(pType) == "DeviceSource") {
-//            load_source = new DeviceSource;
-//        }
-
-//        // skip failed (including clones)
-//        if (!load_source)
-//            continue;
-
-//        // add source to session
-//        session_->addSource(load_source);
-//    }
-//    // get reference to the existing source
-//    else
-//        load_source = *sit;
-
-//    return load_source;
-//}
-
 void SessionLoader::load(XMLElement *sessionNode)
 {
     sources_id_.clear();
@@ -431,9 +385,24 @@ void SessionLoader::visit(ImageShader &n)
     XMLElement* uniforms = xmlCurrent_->FirstChildElement("uniforms");
     if (uniforms) {
         uniforms->QueryFloatAttribute("stipple", &n.stipple);
-        uniforms->QueryUnsignedAttribute("mask", &n.mask);
     }
+}
 
+void SessionLoader::visit(MaskShader &n)
+{
+    const char *pType = xmlCurrent_->Attribute("type");
+    if ( std::string(pType) != "MaskShader" )
+        return;
+
+    xmlCurrent_->QueryUnsignedAttribute("mode", &n.mode);
+
+    XMLElement* uniforms = xmlCurrent_->FirstChildElement("uniforms");
+    if (uniforms) {
+        uniforms->QueryFloatAttribute("blur", &n.blur);
+        XMLElement* size = uniforms->FirstChildElement("size");
+        if (size)
+            tinyxml2::XMLElementToGLM( size->FirstChildElement("vec2"), n.size);
+    }
 }
 
 void SessionLoader::visit(ImageProcessingShader &n)
@@ -474,24 +443,29 @@ void SessionLoader::visit (Source& s)
     s.setName(pName);
 
     xmlCurrent_ = sourceNode->FirstChildElement("Mixing");
-    s.groupNode(View::MIXING)->accept(*this);
+    if (xmlCurrent_) s.groupNode(View::MIXING)->accept(*this);
 
     xmlCurrent_ = sourceNode->FirstChildElement("Geometry");
-    s.groupNode(View::GEOMETRY)->accept(*this);
+    if (xmlCurrent_) s.groupNode(View::GEOMETRY)->accept(*this);
 
     xmlCurrent_ = sourceNode->FirstChildElement("Layer");
-    s.groupNode(View::LAYER)->accept(*this);
+    if (xmlCurrent_) s.groupNode(View::LAYER)->accept(*this);
 
     xmlCurrent_ = sourceNode->FirstChildElement("Appearance");
-    s.groupNode(View::APPEARANCE)->accept(*this);
+    if (xmlCurrent_) s.groupNode(View::APPEARANCE)->accept(*this);
 
     xmlCurrent_ = sourceNode->FirstChildElement("Blending");
-    s.blendingShader()->accept(*this);
+    if (xmlCurrent_) s.blendingShader()->accept(*this);
+
+    xmlCurrent_ = sourceNode->FirstChildElement("Mask");
+    if (xmlCurrent_) s.maskShader()->accept(*this);
 
     xmlCurrent_ = sourceNode->FirstChildElement("ImageProcessing");
-    bool on = xmlCurrent_->BoolAttribute("enabled", true);
-    s.processingShader()->accept(*this);
-    s.setImageProcessingEnabled(on);
+    if (xmlCurrent_) {
+        bool on = xmlCurrent_->BoolAttribute("enabled", true);
+        s.processingShader()->accept(*this);
+        s.setImageProcessingEnabled(on);
+    }
 
     // restore current
     xmlCurrent_ = sourceNode;
diff --git a/SessionCreator.h b/SessionCreator.h
index 32d5998..a1233fb 100644
--- a/SessionCreator.h
+++ b/SessionCreator.h
@@ -41,6 +41,7 @@ public:
     void visit (MediaPlayer& n) override;
     void visit (Shader& n) override;
     void visit (ImageShader& n) override;
+    void visit (MaskShader& n) override;
     void visit (ImageProcessingShader& n) override;
 
     // Sources
diff --git a/SessionVisitor.cpp b/SessionVisitor.cpp
index 917a29c..e83f79d 100644
--- a/SessionVisitor.cpp
+++ b/SessionVisitor.cpp
@@ -203,9 +203,23 @@ void SessionVisitor::visit(ImageShader &n)
 
     XMLElement *uniforms = xmlDoc_->NewElement("uniforms");
     uniforms->SetAttribute("stipple", n.stipple);
-    uniforms->SetAttribute("mask", n.mask);
     xmlCurrent_->InsertEndChild(uniforms);
+}
 
+void SessionVisitor::visit(MaskShader &n)
+{
+    // Shader of a textured type
+    xmlCurrent_->SetAttribute("type", "MaskShader");
+    xmlCurrent_->SetAttribute("id", n.id());
+    xmlCurrent_->SetAttribute("mode", n.mode);
+
+    XMLElement *uniforms = xmlDoc_->NewElement("uniforms");
+    uniforms->SetAttribute("blur", n.blur);
+    XMLElement *size = xmlDoc_->NewElement("size");
+    size->InsertEndChild( XMLElementFromGLM(xmlDoc_, n.size) );
+    uniforms->InsertEndChild(size);
+
+    xmlCurrent_->InsertEndChild(uniforms);
 }
 
 void SessionVisitor::visit(ImageProcessingShader &n)
@@ -351,6 +365,10 @@ void SessionVisitor::visit (Source& s)
     sourceNode->InsertEndChild(xmlCurrent_);
     s.blendingShader()->accept(*this);
 
+    xmlCurrent_ = xmlDoc_->NewElement( "Mask" );
+    sourceNode->InsertEndChild(xmlCurrent_);
+    s.maskShader()->accept(*this);
+
     xmlCurrent_ = xmlDoc_->NewElement( "ImageProcessing" );
     xmlCurrent_->SetAttribute("enabled", s.imageProcessingEnabled());
     sourceNode->InsertEndChild(xmlCurrent_);
diff --git a/SessionVisitor.h b/SessionVisitor.h
index 94b48e8..54814aa 100644
--- a/SessionVisitor.h
+++ b/SessionVisitor.h
@@ -38,6 +38,7 @@ public:
     void visit(MediaPlayer& n) override;
     void visit(Shader& n) override;
     void visit(ImageShader& n) override;
+    void visit(MaskShader& n) override;
     void visit(ImageProcessingShader& n) override;
 
     // Sources
diff --git a/Shader.cpp b/Shader.cpp
index 6cdb4d4..42a4475 100644
--- a/Shader.cpp
+++ b/Shader.cpp
@@ -1,5 +1,6 @@
 #include "Shader.h"
 #include "Resource.h"
+#include "FrameBuffer.h"
 #include "Log.h"
 #include "Visitor.h"
 #include "RenderingManager.h"
@@ -119,14 +120,20 @@ void ShadingProgram::setUniform<float>(const std::string& name, float val1, floa
 }
 
 template<>
-void ShadingProgram::setUniform<glm::vec4>(const std::string& name, glm::vec4 val) {
-    glm::vec4 v(val);
-    glUniform4fv(glGetUniformLocation(id_, name.c_str()), 1, glm::value_ptr(v));
+void ShadingProgram::setUniform<glm::vec2>(const std::string& name, glm::vec2 val) {
+    glm::vec2 v(val);
+    glUniform2fv(glGetUniformLocation(id_, name.c_str()), 1, glm::value_ptr(v));
 }
 
 template<>
 void ShadingProgram::setUniform<glm::vec3>(const std::string& name, glm::vec3 val) {
     glm::vec3 v(val);
+    glUniform3fv(glGetUniformLocation(id_, name.c_str()), 1, glm::value_ptr(v));
+}
+
+template<>
+void ShadingProgram::setUniform<glm::vec4>(const std::string& name, glm::vec4 val) {
+    glm::vec4 v(val);
     glUniform4fv(glGetUniformLocation(id_, name.c_str()), 1, glm::value_ptr(v));
 }
 
@@ -208,7 +215,7 @@ void Shader::use()
     program_->setUniform("iTransform", iTransform);
     program_->setUniform("color", color);
 
-    iResolution = glm::vec3( Rendering::manager().currentAttrib().viewport, 0.f);
+    glm::vec3 iResolution = glm::vec3( Rendering::manager().currentAttrib().viewport, 0.f);
     program_->setUniform("iResolution", iResolution);
 
     // Blending Function
@@ -238,7 +245,6 @@ void Shader::reset()
     projection = glm::identity<glm::mat4>();
     modelview  = glm::identity<glm::mat4>();
     iTransform = glm::identity<glm::mat4>();
-    iResolution = glm::vec3(1280.f, 720.f, 0.f);
     color = glm::vec4(1.f, 1.f, 1.f, 1.f);
 }
 
diff --git a/Shader.h b/Shader.h
index 1458abb..0043548 100644
--- a/Shader.h
+++ b/Shader.h
@@ -7,6 +7,7 @@
 
 // Forward declare classes referenced
 class Visitor;
+class FrameBuffer;
 
 class ShadingProgram
 {
@@ -22,13 +23,13 @@ public:
 	static void enduse();
 
 private:
-	void checkCompileErr();
-	void checkLinkingErr();
-	void compile();
-	void link();
-	unsigned int vertex_id_, fragment_id_, id_;
-	std::string vertex_code_;
-	std::string fragment_code_;
+    void checkCompileErr();
+    void checkLinkingErr();
+    void compile();
+    void link();
+    unsigned int vertex_id_, fragment_id_, id_;
+    std::string vertex_code_;
+    std::string fragment_code_;
     std::string vertex_file_;
     std::string fragment_file_;
 
@@ -71,7 +72,6 @@ public:
 
 protected:
     ShadingProgram *program_;
-    glm::vec3 iResolution;
 
 };
 
diff --git a/Source.cpp b/Source.cpp
index 3252b44..82de050 100644
--- a/Source.cpp
+++ b/Source.cpp
@@ -179,12 +179,18 @@ Source::Source() : initialized_(false), active_(true), need_update_(true), symbo
     // create objects
     stored_status_  = new Group;
 
-    // those will be associated to nodes later
+    // simple image shader (with texturing) for blending
     blendingshader_ = new ImageShader;
+    // mask produced by dedicated shader
+    maskshader_ = new MaskShader;
+    masksurface_ = new Surface(maskshader_);
+
+    // filtered image shader (with texturing and processing) for rendering
     processingshader_   = new ImageProcessingShader;
-    // default to image processing enabled
+    // default rendering with image processing enabled
     renderingshader_ = (Shader *) processingshader_;
 
+    // for drawing in mixing view
     mixingshader_ = new ImageShader;
     mixingshader_->stipple = 1.0;
 
@@ -198,6 +204,7 @@ Source::Source() : initialized_(false), active_(true), need_update_(true), symbo
     renderbuffer_   = nullptr;
     rendersurface_  = nullptr;
     mixingsurface_  = nullptr;
+    maskbuffer_     = nullptr;
 
 }
 
@@ -213,6 +220,8 @@ Source::~Source()
     delete stored_status_;
     if (renderbuffer_)
         delete renderbuffer_;
+    if (maskbuffer_)
+        delete maskbuffer_;
 
     // all groups and their children are deleted in the scene
     // this includes rendersurface_, overlays, blendingshader_ and rendershader_
@@ -368,6 +377,11 @@ void Source::attach(FrameBuffer *renderbuffer)
         }
     }
 
+    // (re) create the masking buffer
+    if (maskbuffer_)
+        delete maskbuffer_;
+    maskbuffer_ = new FrameBuffer( renderbuffer->resolution() );
+
     // make the source visible
     if ( mode_ == UNINITIALIZED )
         setMode(VISIBLE);
@@ -410,7 +424,7 @@ void Source::update(float dt)
     dt_ = dt;
 
     // update nodes if needed
-    if (renderbuffer_ && mixingsurface_ && need_update_)
+    if (renderbuffer_ && mixingsurface_ && maskbuffer_ && need_update_)
     {
 //        Log::Info("UPDATE %s %f", initials_, dt);
 
@@ -472,9 +486,17 @@ void Source::update(float dt)
         // 7. switch back to UV coordinate system
         texturesurface_->shader()->iTransform = glm::inverse(UVtoScene) * glm::inverse(Sca) * glm::inverse(Ar) * Rot * Tra * Ar * UVtoScene;
 
+        // draw nask in mask frame buffer
+        maskbuffer_->begin();
+        masksurface_->draw(glm::identity<glm::mat4>(), maskbuffer_->projection());
+        maskbuffer_->end();
+        // set the rendered mask as mask for blending
+        blendingshader_->mask_texture = maskbuffer_->texture();
+
         // do not update next frame
         need_update_ = false;
     }
+
 }
 
 FrameBuffer *Source::frame() const
diff --git a/Source.h b/Source.h
index d2394ca..d182f58 100644
--- a/Source.h
+++ b/Source.h
@@ -11,6 +11,7 @@
 #define DEFAULT_MIXING_TRANSLATION -1.f, 1.f
 
 class ImageShader;
+class MaskShader;
 class ImageProcessingShader;
 class FrameBuffer;
 class FrameBufferSurface;
@@ -77,6 +78,9 @@ public:
     // a Source has a shader to control mixing effects
     inline ImageShader *blendingShader () const { return blendingshader_; }
 
+    // a Source has a shader used to render mask
+    inline MaskShader *maskShader () const { return maskshader_; }
+
     // a Source has a shader used to render in fbo
     inline Shader *renderingShader () const { return renderingshader_; }
 
@@ -171,6 +175,11 @@ protected:
     ImageShader *blendingshader_;
     ImageShader *mixingshader_;
 
+    // shader and buffer to draw mask
+    MaskShader *maskshader_;
+    FrameBuffer *maskbuffer_;
+    Surface *masksurface_;
+
     // surface to draw on
     Surface *texturesurface_;
 
diff --git a/UserInterfaceManager.cpp b/UserInterfaceManager.cpp
index ded5400..aec2e75 100644
--- a/UserInterfaceManager.cpp
+++ b/UserInterfaceManager.cpp
@@ -1976,7 +1976,7 @@ void Navigator::Render()
         }
         if (ImGui::IsItemHovered())
             about = "Layers [F3]";
-        if (ImGui::Selectable( ICON_FA_SIGN, &selected_view[4], 0, iconsize))
+        if (ImGui::Selectable( ICON_FA_VECTOR_SQUARE, &selected_view[4], 0, iconsize))
         {
             Mixer::manager().setView(View::APPEARANCE);
             view_pannel_visible = previous_view == Settings::application.current_view;
diff --git a/View.cpp b/View.cpp
index 38abf44..0e7bcc6 100644
--- a/View.cpp
+++ b/View.cpp
@@ -823,14 +823,11 @@ void showContextMenu(View::Mode m, const char* label)
     if (ImGui::BeginPopup(label)) {
         Source *s = Mixer::manager().currentSource();
         if (s != nullptr) {
-            if (ImGui::Selectable( ICON_FA_CROSSHAIRS "  Center" )){
-                s->group(m)->translation_ = glm::vec3(0.f);
-                s->touch();
-            }
-            else if (ImGui::Selectable( ICON_FA_VECTOR_SQUARE "  Reset" )){
+            if (ImGui::Selectable( ICON_FA_VECTOR_SQUARE "  Reset" )){
                 s->group(m)->scale_ = glm::vec3(1.f);
                 s->group(m)->rotation_.z = 0;
                 s->group(m)->crop_ = glm::vec3(1.f);
+                s->group(m)->translation_ = glm::vec3(0.f);
                 s->touch();
             }
             else if (ImGui::Selectable( ICON_FA_EXPAND "  Fit" )){
@@ -848,6 +845,10 @@ void showContextMenu(View::Mode m, const char* label)
                 s->group(m)->translation_ = glm::vec3(0.f);
                 s->touch();
             }
+            else  if (ImGui::Selectable( ICON_FA_CROSSHAIRS "  Center" )){
+                s->group(m)->translation_ = glm::vec3(0.f);
+                s->touch();
+            }
             else if (ImGui::Selectable( ICON_FA_PERCENTAGE "   Original aspect ratio" )){ //ICON_FA_ARROWS_ALT_H
                 s->group(m)->scale_.x = s->group(m)->scale_.y;
                 s->group(m)->scale_ *= s->group(m)->crop_;
@@ -1853,6 +1854,7 @@ AppearanceView::AppearanceView() : View(APPEARANCE), edit_source_(nullptr), need
     else
         restoreSettings();
 
+    //
     // Scene background
     //
     // global dark
@@ -1860,62 +1862,108 @@ AppearanceView::AppearanceView() : View(APPEARANCE), edit_source_(nullptr), need
     tmp->scale_ = glm::vec3(20.f, 20.f, 1.f);
     tmp->shader()->color = glm::vec4( 0.1f, 0.1f, 0.1f, 0.6f );
     scene.bg()->attach(tmp);
-    // frame showing the source original shape
-    backgroundchecker_ = new ImageSurface("images/checker.dds");
+    // frame showing the source original shape    
+    background_surface_= new Surface( new Shader);
+    background_surface_->scale_ = glm::vec3(20.f, 20.f, 1.f);
+    background_surface_->shader()->color = glm::vec4( COLOR_BGROUND, 1.0f );
+    scene.bg()->attach(background_surface_);
+    background_frame_ = new Frame(Frame::SHARP, Frame::THIN, Frame::NONE);
+    background_frame_->color = glm::vec4( COLOR_HIGHLIGHT_SOURCE, 0.6f );
+    scene.bg()->attach(background_frame_);
+    // frame with checkerboard background to show cropped preview
+    preview_checker_ = new ImageSurface("images/checker.dds");
     static glm::mat4 Tra = glm::scale(glm::translate(glm::identity<glm::mat4>(), glm::vec3( -32.f, -32.f, 0.f)), glm::vec3( 64.f, 64.f, 1.f));
-    backgroundchecker_->shader()->iTransform = Tra;
-    scene.bg()->attach(backgroundchecker_);
-    backgroundframe_ = new Frame(Frame::SHARP, Frame::THIN, Frame::GLOW);
-    backgroundframe_->color = glm::vec4( COLOR_HIGHLIGHT_SOURCE, 1.f );
-    scene.bg()->attach(backgroundframe_);
-    // Horizontal axis
-    horizontal_line_ = new Mesh("mesh/h_line.ply");
-    horizontal_line_->shader()->color = glm::vec4( COLOR_TRANSITION_LINES, 0.9f );
-    horizontal_line_->translation_ = glm::vec3(0.f, 1.12f, 0.0f);
-    horizontal_line_->scale_.x = 1.0f;
-    horizontal_line_->scale_.y = 3.0f;
-    scene.bg()->attach(horizontal_line_);
-    show_horizontal_scale_ = false;
-    horizontal_mark_ = new Mesh("mesh/h_mark.ply");
-    horizontal_mark_->translation_ = glm::vec3(0.f, 1.12f, 0.0f);
-    horizontal_mark_->scale_ = glm::vec3(2.5f, -2.5f, 0.0f);
-    horizontal_mark_->shader()->color = glm::vec4( COLOR_TRANSITION_LINES, 0.9f );
-    scene.bg()->attach(horizontal_mark_);
-    // vertical axis
-    vertical_line_ = new Group;
-    Mesh *line  = new Mesh("mesh/h_line.ply");
-    line->shader()->color = glm::vec4( COLOR_TRANSITION_LINES, 0.9f );
-    line->translation_ = glm::vec3(-0.12f, 0.0f, 0.0f);
-    line->scale_.x = 1.0f;
-    line->scale_.y = 3.0f;
-    line->rotation_.z = M_PI_2;
-    vertical_line_->attach(line);
-    vertical_mark_  = new Mesh("mesh/h_mark.ply");
-    vertical_mark_->translation_ = glm::vec3(-0.12f, 0.0f, 0.0f);
-    vertical_mark_->scale_ = glm::vec3(2.5f, -2.5f, 0.0f);
-    vertical_mark_->rotation_.z = M_PI_2;
-    vertical_mark_->shader()->color = glm::vec4( COLOR_TRANSITION_LINES, 0.9f );
-    vertical_line_->attach(vertical_mark_);
-    scene.bg()->attach(vertical_line_);
+    preview_checker_->shader()->iTransform = Tra;
+    scene.bg()->attach(preview_checker_);
+    preview_frame_ = new Frame(Frame::SHARP, Frame::THIN, Frame::GLOW);
+    preview_frame_->color = glm::vec4( COLOR_HIGHLIGHT_SOURCE, 1.f );
+    scene.bg()->attach(preview_frame_);
 
+    //
     // surface to show the texture of the source
-    surfacepreview = new Surface; // to attach source preview
-    surfacepreview->translation_.z = 0.002f;
-    scene.bg()->attach(surfacepreview);
+    //
+    preview_shader_ = new ImageShader;
+    preview_surface_ = new Surface(preview_shader_); // to attach source preview
+    preview_surface_->translation_.z = 0.002f;
+    scene.bg()->attach(preview_surface_);
+
+
+//    // Horizontal axis
+//    horizontal_line_ = new Mesh("mesh/h_line.ply");
+//    horizontal_line_->shader()->color = glm::vec4( COLOR_TRANSITION_LINES, 0.9f );
+//    horizontal_line_->translation_ = glm::vec3(0.f, 1.12f, 0.0f);
+//    horizontal_line_->scale_.x = 1.0f;
+//    horizontal_line_->scale_.y = 3.0f;
+////    scene.bg()->attach(horizontal_line_);
+//    show_horizontal_scale_ = false;
+//    horizontal_mark_ = new Mesh("mesh/h_mark.ply");
+//    horizontal_mark_->translation_ = glm::vec3(0.f, 1.12f, 0.0f);
+//    horizontal_mark_->scale_ = glm::vec3(2.5f, -2.5f, 0.0f);
+//    horizontal_mark_->shader()->color = glm::vec4( COLOR_TRANSITION_LINES, 0.9f );
+////    scene.bg()->attach(horizontal_mark_);
+//    // vertical axis
+//    vertical_line_ = new Group;
+//    Mesh *line  = new Mesh("mesh/h_line.ply");
+//    line->shader()->color = glm::vec4( COLOR_TRANSITION_LINES, 0.9f );
+//    line->translation_ = glm::vec3(-0.12f, 0.0f, 0.0f);
+//    line->scale_.x = 1.0f;
+//    line->scale_.y = 3.0f;
+//    line->rotation_.z = M_PI_2;
+////    vertical_line_->attach(line);
+//    vertical_mark_  = new Mesh("mesh/h_mark.ply");
+//    vertical_mark_->translation_ = glm::vec3(-0.12f, 0.0f, 0.0f);
+//    vertical_mark_->scale_ = glm::vec3(2.5f, -2.5f, 0.0f);
+//    vertical_mark_->rotation_.z = M_PI_2;
+//    vertical_mark_->shader()->color = glm::vec4( COLOR_TRANSITION_LINES, 0.9f );
+//    vertical_line_->attach(vertical_mark_);
+////    scene.bg()->attach(vertical_line_);
+
+/// Tests
+//    test_buffer = new FrameBuffer(800, 450);
+//    Log::Info("test_buffer %s", test_buffer->info().c_str());
+//    test_shader = new MaskShader;
+//    test_shader->type = 0;
+//    test_shader->blur = 0.0;
+//    test_surface = new Surface(test_shader);
+//    preview_mask_ = new FrameBufferSurface(test_buffer); // to attach source preview
+//    preview_mask_->translation_.z = 0.002f;
+////    scene.bg()->attach(preview_mask_);
 
     // Scene foreground
     //
-    // crop icons
-    crop_horizontal_ = new Symbol(Symbol::ARROWS);
-    crop_horizontal_->translation_ = glm::vec3(1.0f, 1.12f, 0.f);
-    scene.fg()->attach(crop_horizontal_);
-    crop_vertical_ = new Symbol(Symbol::ARROWS);
-    crop_vertical_->rotation_.z = M_PI_2;
-    crop_vertical_->translation_ = glm::vec3(-1.12f, -1.0f, 0.f);
-    scene.fg()->attach(crop_vertical_);
+//    // crop icons
+//    crop_horizontal_ = new Symbol(Symbol::ARROWS);
+//    crop_horizontal_->translation_ = glm::vec3(1.0f, 1.12f, 0.f);
+////    scene.fg()->attach(crop_horizontal_);
+//    crop_vertical_ = new Symbol(Symbol::ARROWS);
+//    crop_vertical_->rotation_.z = M_PI_2;
+//    crop_vertical_->translation_ = glm::vec3(-1.12f, -1.0f, 0.f);
+////    scene.fg()->attach(crop_vertical_);
 
+    //
     // User interface foreground
     //
+
+    // Mask manipulation
+    mask_node_ = new Group;
+    mask_square_ = new Frame(Frame::SHARP, Frame::LARGE, Frame::NONE);
+    mask_square_->color = glm::vec4( 0.2f, 1.f, 1.f, 1.0f );  //BLUE
+    mask_node_->attach(mask_square_);
+    mask_handle_ = new Handles(Handles::CROP);
+    mask_handle_->color = glm::vec4( 0.2f, 1.f, 1.f, 1.0f );  //BLUE
+    mask_node_->attach(mask_handle_);
+    mask_circle_ = new Mesh("mesh/circle.ply");
+    mask_circle_->shader()->color = glm::vec4( 0.2f, 1.f, 1.f, 1.0f );
+    mask_node_->attach(mask_circle_);
+    mask_corner_  = new Mesh("mesh/corner.ply");
+    mask_corner_->shader()->color = glm::vec4( 0.2f, 1.f, 1.f, 0.9f );
+    mask_corner_->translation_ = glm::vec3(-1.f, -1.0f, 0.0f);
+    mask_node_->attach(mask_corner_);
+
+    scene.fg()->attach(mask_node_);
+
+    // Source manipulation (texture coordinates)
+    //
     // point to show POSITION
     overlay_position_ = new Symbol(Symbol::SQUARE_POINT);
     overlay_position_->color = glm::vec4( COLOR_APPEARANCE_SOURCE, 1.f );
@@ -2081,7 +2129,11 @@ std::pair<Node *, glm::vec2> AppearanceView::pick(glm::vec2 P)
                     pick = *itp;
                     break;
                 }
-                else if ( (*itp).first == crop_horizontal_ || (*itp).first == crop_vertical_ ) {
+                //                else if ( (*itp).first == crop_horizontal_ || (*itp).first == crop_vertical_ ) {
+                //                    pick = *itp;
+                //                    break;
+                //                }
+                else if ( (*itp).first == mask_handle_ ) {
                     pick = *itp;
                     break;
                 }
@@ -2110,36 +2162,63 @@ std::pair<Node *, glm::vec2> AppearanceView::pick(glm::vec2 P)
 void AppearanceView::adjustBackground()
 {
     // by default consider edit source is null
+    mask_node_->visible_ = false;
     float image_original_width = 1.f;
-//    glm::vec2 image_crop_area = glm::vec2(1.f, 1.f);
-    surfacepreview->setTextureIndex( Resource::getTextureTransparent() );
+    glm::vec3 scale = glm::vec3(1.f);
+    preview_surface_->setTextureIndex( Resource::getTextureTransparent() );
 
     // if its a valid index
     if (edit_source_ != nullptr) {
         // update rendering frame to match edit source AR
         image_original_width = edit_source_->frame()->aspectRatio();
-        surfacepreview->setTextureIndex( edit_source_->frame()->texture() );
-        surfacepreview->scale_ = edit_source_->mixingsurface_->scale_;
+        scale = edit_source_->mixingsurface_->scale_;
+
+        preview_surface_->setTextureIndex( edit_source_->frame()->texture() );
+        preview_shader_->mask_texture = edit_source_->blendingShader()->mask_texture;
+        preview_surface_->scale_ = scale;
+
+        mask_node_->visible_ = edit_source_->maskShader()->mode > 0;
+        mask_circle_->visible_ = edit_source_->maskShader()->mode == 1;
+        mask_square_->visible_ = edit_source_->maskShader()->mode == 2;
+        mask_node_->scale_ = scale * glm::vec3(edit_source_->maskShader()->size, 1.f);
+        mask_corner_->scale_.y = mask_node_->scale_.x / mask_node_->scale_.y;
+
+//        crop_horizontal_->translation_.x = image_original_width * edit_source_->maskShader()->size.x;
+//        crop_vertical_->translation_.y = -edit_source_->maskShader()->size.y;
+//        crop_vertical_->translation_.x = -image_original_width - 0.12f;
+
+
+///// Tests
+//        preview_mask_->scale_ = edit_source_->mixingsurface_->scale_;
 
-//        surfacepreview->scale_.x = image_original_width;
-//        image_crop_area.x *= image_original_width;
     }
 
-    // update objects in the scene to represent the image and crop area
+
+
+//    /// Tests
+//    // update mask
+//    test_buffer->begin();
+//    test_surface->draw(glm::identity<glm::mat4>(), test_buffer->projection());
+//    test_buffer->end();
+
 
     // background scene
-    horizontal_line_->scale_.x = image_original_width;
-    vertical_line_->translation_.x = -image_original_width;
-    backgroundframe_->scale_.x = image_original_width;
-    backgroundchecker_->scale_.x = image_original_width;
-    glm::mat4 Ar  = glm::scale(glm::identity<glm::mat4>(), glm::vec3(image_original_width, 1.f, 1.f) );
-    static glm::mat4 Tra = glm::scale(glm::translate(glm::identity<glm::mat4>(), glm::vec3( -32.f, -32.f, 0.f)), glm::vec3( 64.f, 64.f, 1.f));
-    backgroundchecker_->shader()->iTransform = Ar * Tra;
+//    horizontal_line_->scale_.x = image_original_width;
+//    vertical_line_->translation_.x = -image_original_width;
 
-    // foreground
-//    crop_horizontal_->translation_.x = image_crop_area.x;
-//    crop_vertical_->translation_.y = -image_crop_area.y;
-//    crop_vertical_->translation_.x = -image_original_width - 0.12f;
+    background_surface_->scale_.x = image_original_width;
+    background_surface_->scale_.y = 1.f;
+    background_frame_->scale_.x = image_original_width;
+    preview_frame_->scale_ = scale;
+    preview_checker_->scale_ = scale;
+    glm::mat4 Ar  = glm::scale(glm::identity<glm::mat4>(), scale );
+    static glm::mat4 Tra = glm::scale(glm::translate(glm::identity<glm::mat4>(), glm::vec3( -32.f, -32.f, 0.f)), glm::vec3( 64.f, 64.f, 1.f));
+    preview_checker_->shader()->iTransform = Ar * Tra;
+
+//    backgroundchecker_->scale_.x = image_original_width;
+//    glm::mat4 Ar  = glm::scale(glm::identity<glm::mat4>(), glm::vec3(image_original_width, 1.f, 1.f) );
+//    static glm::mat4 Tra = glm::scale(glm::translate(glm::identity<glm::mat4>(), glm::vec3( -32.f, -32.f, 0.f)), glm::vec3( 64.f, 64.f, 1.f));
+//    backgroundchecker_->shader()->iTransform = Ar * Tra;
 
 }
 
@@ -2203,19 +2282,55 @@ void AppearanceView::draw()
 //        }
 //    }
 
+
     // draw general view
     Shader::force_blending_opacity = true;
     View::draw();
     Shader::force_blending_opacity = false;
 
-    // force to redraw the frame of the edit source (even if source is not visible)
+    // if source active
     if (edit_source_ != nullptr){
+
+        // force to redraw the frame of the edit source (even if source is not visible)
         DrawVisitor dv(edit_source_->frames_[mode_], Rendering::manager().Projection(), true);
         scene.accept(dv);
+
+        // display interface
+        glm::vec2 P = Rendering::manager().project(glm::vec3(-background_frame_->scale_.x - 0.03f, 1.2f, 0.f), scene.root()->transform_, false);
+        ImGui::SetNextWindowPos(ImVec2(P.x, P.y), ImGuiCond_Always);
+        if (ImGui::Begin("##AppearanceMaskOptions", NULL, ImGuiWindowFlags_NoMove | ImGuiWindowFlags_NoDecoration | ImGuiWindowFlags_NoBackground
+                         | ImGuiWindowFlags_AlwaysAutoResize | ImGuiWindowFlags_NoSavedSettings
+                         | ImGuiWindowFlags_NoFocusOnAppearing | ImGuiWindowFlags_NoNav))
+        {
+            ImGuiToolkit::PushFont(ImGuiToolkit::FONT_LARGE);
+
+            int type = edit_source_->maskShader()->mode;
+            ImGui::SetNextItemWidth(100.f);
+            if ( ImGui::Combo("Mask    ", &type, MaskShader::mask_names, IM_ARRAYSIZE(MaskShader::mask_names) ) ) {
+                edit_source_->maskShader()->mode = type;
+                edit_source_->touch();
+                need_edit_update_ = true;
+            }
+
+            if (edit_source_->maskShader()->mode > 0) {
+                int val = int(edit_source_->maskShader()->blur * 100.f);
+                ImGui::SameLine();
+                ImGui::SetNextItemWidth(190.f);
+                if (ImGui::DragInt("Smooth", &val, 1, 0, 100, "%d%%") ) {
+                    edit_source_->maskShader()->blur = float(val) / 100.f;
+                    edit_source_->touch();
+                    need_edit_update_ = true;
+                }
+            }
+
+            ImGui::PopFont();
+            ImGui::End();
+        }
+
     }
 
-    show_vertical_scale_ = false;
-    show_horizontal_scale_ = false;
+//    show_vertical_scale_ = false;
+//    show_horizontal_scale_ = false;
 
     // display popup menu
     if (show_context_menu_) {
@@ -2224,6 +2339,7 @@ void AppearanceView::draw()
     }
     showContextMenu(mode_,"AppearanceContextMenu");
 
+
 }
 
 View::Cursor AppearanceView::grab (Source *s, glm::vec2 from, glm::vec2 to, std::pair<Node *, glm::vec2> pick)
@@ -2241,44 +2357,70 @@ View::Cursor AppearanceView::grab (Source *s, glm::vec2 from, glm::vec2 to, std:
         // work on the edited source
         if ( edit_source_ != nullptr ) {
 
-            // picking on the resizing handles in the corners
-            if ( pick.first == crop_horizontal_ ) {
-                float max_width =  edit_source_->frame()->aspectRatio();
-                // discretized scaling with ALT
-                float val = scene_to.x;
-                if (UserInterface::manager().altModifier()) {
-                    val = ROUND(val, 5.f);
-                    show_horizontal_scale_ = true;
-                }
-                // crop horizontally
-//                edit_source_->texturesurface_->scale_.x = CLAMP(val, 0.2f, max_width) / max_width;
-//                edit_source_->touch();
-//                // update background and frame
-//                adjustBackground();
-//                // cursor indication
-//                info << "Crop " << std::fixed << std::setprecision(3) << max_width * edit_source_->texturesurface_->scale_.x;
-//                info << " x "  << edit_source_->texturesurface_->scale_.y;
-                ret.type = Cursor_ResizeEW;
-            }
-            if ( pick.first == crop_vertical_ ) {
-                float max_width =  edit_source_->frame()->aspectRatio();
-                float val = -scene_to.y;
+            // match edit source AR
+//            float image_original_width = edit_source_->frame()->aspectRatio();
+            glm::vec3 scale = edit_source_->mixingsurface_->scale_;
+            glm::vec3 delta = glm::vec3(0.1) / glm::vec3(scene.root()->scale_.x, scene.root()->scale_.y, 1.0);
+
+            if ( pick.first == mask_handle_ ) {
+                // compute scaling of mask
+                glm::vec3 val = -scene_to + delta;
+                val /= scale;
                 // discretized scaling with ALT
                 if (UserInterface::manager().altModifier()) {
-                    val = ROUND(val, 5.f);
-                    show_vertical_scale_ = true;
+                    val.x = ROUND(val.x, 5.f);
+                    val.y = ROUND(val.y, 5.f);
                 }
-                // crop vertically
-//                edit_source_->texturesurface_->scale_.y = CLAMP(val, 0.2f, 1.0f);
-//                edit_source_->touch();
-//                // update background and frame
-//                adjustBackground();
-//                // cursor indication
-//                info << "Crop " << std::fixed << std::setprecision(3) << max_width * edit_source_->texturesurface_->scale_.x ;
-//                info << " x "  << edit_source_->texturesurface_->scale_.y;
-                ret.type = Cursor_ResizeNS;
+                // crop mask horizontally
+                edit_source_->maskShader()->size.x = CLAMP(val.x, 0.3f, 2.f);
+                edit_source_->maskShader()->size.y = CLAMP(val.y, 0.3f, 2.f);
+                edit_source_->touch();
+                // update
+                need_edit_update_ = true;
+                // cursor indication
+                info << "Mask " << std::fixed << std::setprecision(3) << edit_source_->maskShader()->size.x;
+                info << " x "  << edit_source_->maskShader()->size.y;
+                ret.type = Cursor_ResizeNESW;
             }
 
+//            // picking on the resizing handles in the corners
+//            if ( pick.first == crop_horizontal_ ) {
+//                float max_width =  edit_source_->frame()->aspectRatio();
+//                // discretized scaling with ALT
+//                float val = scene_to.x;
+//                if (UserInterface::manager().altModifier()) {
+//                    val = ROUND(val, 5.f);
+//                    show_horizontal_scale_ = true;
+//                }
+//                // crop mask horizontally
+//                edit_source_->maskShader()->size.x = CLAMP(val, 0.2f, max_width) / max_width;
+//                edit_source_->touch();
+//                // update
+//                need_edit_update_ = true;
+//                // cursor indication
+//                info << "Mask " << std::fixed << std::setprecision(3) << max_width * edit_source_->maskShader()->size.x;
+//                info << " x "  << edit_source_->maskShader()->size.y;
+//                ret.type = Cursor_ResizeEW;
+//            }
+//            if ( pick.first == crop_vertical_ ) {
+//                float max_width =  edit_source_->frame()->aspectRatio();
+//                float val = -scene_to.y;
+//                // discretized scaling with ALT
+//                if (UserInterface::manager().altModifier()) {
+//                    val = ROUND(val, 5.f);
+//                    show_vertical_scale_ = true;
+//                }
+//                // crop mask vertically
+//                edit_source_->maskShader()->size.y = CLAMP(val, 0.2f, 1.0f);
+//                edit_source_->touch();
+//                // update
+//                need_edit_update_ = true;
+//                // cursor indication
+//                info << "Mask " << std::fixed << std::setprecision(3) << max_width * edit_source_->maskShader()->size.x ;
+//                info << " x "  << edit_source_->maskShader()->size.y;
+//                ret.type = Cursor_ResizeNS;
+//            }
+
             // store action in history
             current_action_ = edit_source_->name() + ": " + info.str();
             current_id_ = edit_source_->id();
diff --git a/View.h b/View.h
index 326df13..d15b211 100644
--- a/View.h
+++ b/View.h
@@ -249,17 +249,35 @@ private:
     Source *getEditOrCurrentSource();
     void adjustBackground();
 
-    Surface *surfacepreview;    
-    Surface *backgroundchecker_;
-    Frame *backgroundframe_;
-    Mesh *horizontal_line_;
-    Mesh *horizontal_mark_;
-    bool show_horizontal_scale_;
-    Group *vertical_line_;
-    Mesh *vertical_mark_;
-    bool show_vertical_scale_;
-    Symbol *crop_horizontal_;
-    Symbol *crop_vertical_;
+
+// /// tests
+//    Surface *preview_mask_;
+//    Surface *test_surface;
+//    class MaskShader *test_shader;
+//    FrameBuffer *test_buffer;
+
+
+    Surface *preview_surface_;
+    class ImageShader *preview_shader_;
+    Surface *preview_checker_;
+    Frame *preview_frame_;
+    Surface *background_surface_;
+    Frame *background_frame_;
+//    Mesh *horizontal_line_;
+//    Mesh *horizontal_mark_;
+//    bool show_horizontal_scale_;
+//    Group *vertical_line_;
+//    Mesh *vertical_mark_;
+//    bool show_vertical_scale_;
+//    Symbol *crop_horizontal_;
+//    Symbol *crop_vertical_;
+
+    Group *mask_node_;
+    Frame *mask_square_;
+    Mesh *mask_circle_;
+    Mesh *mask_corner_;
+    class Handles *mask_handle_;
+
     Symbol *overlay_position_;
     Symbol *overlay_position_cross_;
     Symbol *overlay_scaling_;
diff --git a/Visitor.h b/Visitor.h
index 423bb42..ff2437d 100644
--- a/Visitor.h
+++ b/Visitor.h
@@ -25,6 +25,7 @@ class Stream;
 class MediaPlayer;
 class Shader;
 class ImageShader;
+class MaskShader;
 class ImageProcessingShader;
 class Source;
 class MediaSource;
@@ -64,6 +65,7 @@ public:
     virtual void visit (MediaPlayer&) {}
     virtual void visit (Shader&) {}
     virtual void visit (ImageShader&) {}
+    virtual void visit (MaskShader&) {}
     virtual void visit (ImageProcessingShader&) {}
 
     // utility
diff --git a/rsc/images/mask_circle.png b/rsc/images/mask_circle.png
index ac105c6..01555e5 100644
Binary files a/rsc/images/mask_circle.png and b/rsc/images/mask_circle.png differ
diff --git a/rsc/shaders/image.fs b/rsc/shaders/image.fs
index 750e92f..94a8699 100644
--- a/rsc/shaders/image.fs
+++ b/rsc/shaders/image.fs
@@ -7,7 +7,7 @@ in vec2 vertexUV;
 
 // from General Shader
 uniform vec3 iResolution;           // viewport image resolution (in pixels)
-uniform mat4 iTransform;            // UV image transformation
+uniform mat4 iTransform;            // image transformation
 uniform vec4 color;
 uniform vec4 uv;