diff --git a/sjplayer/src/sjplayer/CircleElement.d b/sjplayer/src/sjplayer/CircleElement.d
index 783eb99..5b819ce 100644
--- a/sjplayer/src/sjplayer/CircleElement.d
+++ b/sjplayer/src/sjplayer/CircleElement.d
@@ -8,23 +8,12 @@ import gl4d;
 
 import sjplayer.ElementDrawer,
        sjplayer.ElementInterface,
+       sjplayer.ShapeElementProgram,
        sjplayer.util.linalg;
 
 ///
 class CircleElement : ElementInterface {
  public:
-  ///
-  static struct Instance {
-    ///
-    align(1) mat3 matrix = mat3.identity;
-    ///
-    align(1) float weight = 1;
-    ///
-    align(1) float smooth = 0.001;
-    ///
-    align(1) vec4 color = vec4(0, 0, 0, 0);
-  }
-
   ///
   void Initialize() {
     alive        = false;
@@ -54,7 +43,7 @@ class CircleElement : ElementInterface {
   ///
   float nearness_coe;
   ///
-  Instance instance;
+  CircleElementProgram.Instance instance;
   alias instance this;
 }
 
@@ -65,123 +54,10 @@ alias CircleElementDrawer = ElementDrawer!(
     [vec2(-1, 1), vec2(1, 1), vec2(1, -1), vec2(-1, -1)]);
 
 ///
-class CircleElementProgram {
- public:
-  ///
-  enum ShaderHeader = "#version 330 core
-#extension GL_ARB_explicit_uniform_location : enable";
-
-  ///
-  enum VertexShaderSrc = ShaderHeader ~ q{
-    layout(location = 0) in vec2 vert;
-
-    layout(location = 1) in vec3 m1;
-    layout(location = 2) in vec3 m2;
-    layout(location = 3) in vec3 m3;
-    layout(location = 4) in float weight;
-    layout(location = 5) in float smoooth;  // expected wrong spell
-    layout(location = 6) in vec4  color;
-
-    out vec2  uv_;
-    out float weight_;
-    out float smooth_;
-    out vec4  color_;
-
-    void main() {
-      mat3 m   = transpose(mat3(m1, m2, m3));
-      vec2 pos = (m * vec3(vert, 1)).xy;
-
-      uv_     = vert;
-      weight_ = weight;
-      smooth_ = smoooth;
-      color_  = color;
-      gl_Position = vec4(pos, 0, 1);
-    }
-  };
-  ///
-  enum FragmentShaderSrc = ShaderHeader ~ q{
-    in vec2  uv_;
-    in float weight_;
-    in float smooth_;
-    in vec4  color_;
-
-    out vec4 pixel_;
-
-    float circle() {
-      float r = length(uv_);
-      float w = 1 - weight_;
-      return
-        smoothstep(w-smooth_, w, r) *
-        (1 - smoothstep(1-smooth_, 1, r));
-    }
-
-    void main() {
-      pixel_    = color_;
-      pixel_.a *= circle();
-    }
-  };
-
-  ///
-  this() {
-    ProgramLinker linker;
-    linker.vertex   = VertexShader.Compile(VertexShaderSrc);
-    linker.fragment = FragmentShader.Compile(FragmentShaderSrc);
-    program_ = linker.Link();
-    program_.Validate();
-  }
-
-  ///
-  void SetupVertexArray(ref VertexArrayRef vao,
-      ref ArrayBufferRef verts, ref ArrayBufferRef instances) {
-    with (VertexArrayAttacher()) {
-      // verts
-      type      = GL_FLOAT;
-      dimension = 2;
-      Attach(vao, verts);
-      ++index;
-
-      type    = GL_FLOAT;
-      divisor = 1;
-      stride  = CircleElement.Instance.sizeof;
-      offset  = 0;
-
-      // matrix
-      dimension = 3;
-      Attach(vao, instances);
-      offset += float.sizeof*3;
-      ++index;
-      Attach(vao, instances);
-      offset += float.sizeof*3;
-      ++index;
-      Attach(vao, instances);
-      offset += float.sizeof*3;
-      ++index;
-
-      // weight
-      dimension = 1;
-      Attach(vao, instances);
-      offset += float.sizeof*1;
-      ++index;
-
-      // smooth
-      dimension = 1;
-      Attach(vao, instances);
-      offset += float.sizeof*1;
-      ++index;
-
-      // color
-      dimension = 4;
-      Attach(vao, instances);
-      offset += float.sizeof*4;
-      ++index;
-    }
-  }
-
-  ///
-  void Use() {
-    program_.Use();
-  }
-
- private:
-  ProgramRef program_;
-}
+alias CircleElementProgram = ShapeElementProgram!(q{
+    float r = length(uv_);
+    float w = 1 - weight_;
+    return
+      smoothstep(w-smooth_, w, r) *
+      (1 - smoothstep(1-smooth_, 1, r));
+  });
diff --git a/sjplayer/src/sjplayer/ShapeElementProgram.d b/sjplayer/src/sjplayer/ShapeElementProgram.d
new file mode 100644
index 0000000..63b9305
--- /dev/null
+++ b/sjplayer/src/sjplayer/ShapeElementProgram.d
@@ -0,0 +1,136 @@
+/// License: MIT
+module sjplayer.ShapeElementProgram;
+
+import std.string;
+
+import gl4d;
+
+///
+class ShapeElementProgram(string ShaderSrc) {
+ public:
+  ///
+  static struct Instance {
+    ///
+    align(1) mat3 matrix = mat3.identity;
+    ///
+    align(1) float weight = 1;
+    ///
+    align(1) float smooth = 0.001;
+    ///
+    align(1) vec4 color = vec4(0, 0, 0, 0);
+  }
+
+  ///
+  enum ShaderHeader = "#version 330 core
+#extension GL_ARB_explicit_uniform_location : enable";
+
+  ///
+  enum VertexShaderSrc = ShaderHeader ~ q{
+    layout(location = 0) in vec2 vert;
+
+    layout(location = 1) in vec3 m1;
+    layout(location = 2) in vec3 m2;
+    layout(location = 3) in vec3 m3;
+    layout(location = 4) in float weight;
+    layout(location = 5) in float smoooth;  // expected wrong spell
+    layout(location = 6) in vec4  color;
+
+    out vec2  uv_;
+    out float weight_;
+    out float smooth_;
+    out vec4  color_;
+
+    void main() {
+      mat3 m   = transpose(mat3(m1, m2, m3));
+      vec2 pos = (m * vec3(vert, 1)).xy;
+
+      uv_     = vert;
+      weight_ = weight;
+      smooth_ = smoooth;
+      color_  = color;
+      gl_Position = vec4(pos, 0, 1);
+    }
+  };
+  ///
+  enum FragmentShaderSrc = ShaderHeader ~ q{
+    in vec2  uv_;
+    in float weight_;
+    in float smooth_;
+    in vec4  color_;
+
+    out vec4 pixel_;
+
+    float shape() {
+      $BODY
+    }
+
+    void main() {
+      pixel_    = color_;
+      pixel_.a *= shape();
+    }
+  }.replace("$BODY", ShaderSrc);
+
+  ///
+  this() {
+    ProgramLinker linker;
+    linker.vertex   = VertexShader.Compile(VertexShaderSrc);
+    linker.fragment = FragmentShader.Compile(FragmentShaderSrc);
+    program_ = linker.Link();
+    program_.Validate();
+  }
+
+  ///
+  void SetupVertexArray(ref VertexArrayRef vao,
+      ref ArrayBufferRef verts, ref ArrayBufferRef instances) {
+    with (VertexArrayAttacher()) {
+      // verts
+      type      = GL_FLOAT;
+      dimension = 2;
+      Attach(vao, verts);
+      ++index;
+
+      type    = GL_FLOAT;
+      divisor = 1;
+      stride  = Instance.sizeof;
+      offset  = 0;
+
+      // matrix
+      dimension = 3;
+      Attach(vao, instances);
+      offset += float.sizeof*3;
+      ++index;
+      Attach(vao, instances);
+      offset += float.sizeof*3;
+      ++index;
+      Attach(vao, instances);
+      offset += float.sizeof*3;
+      ++index;
+
+      // weight
+      dimension = 1;
+      Attach(vao, instances);
+      offset += float.sizeof*1;
+      ++index;
+
+      // smooth
+      dimension = 1;
+      Attach(vao, instances);
+      offset += float.sizeof*1;
+      ++index;
+
+      // color
+      dimension = 4;
+      Attach(vao, instances);
+      offset += float.sizeof*4;
+      ++index;
+    }
+  }
+
+  ///
+  void Use() {
+    program_.Use();
+  }
+
+ private:
+  ProgramRef program_;
+}
diff --git a/sjplayer/src/sjplayer/SquareElement.d b/sjplayer/src/sjplayer/SquareElement.d
index 0b2a517..e5ba13d 100644
--- a/sjplayer/src/sjplayer/SquareElement.d
+++ b/sjplayer/src/sjplayer/SquareElement.d
@@ -8,6 +8,7 @@ import gl4d;
 
 import sjplayer.ElementDrawer,
        sjplayer.ElementInterface,
+       sjplayer.ShapeElementProgram,
        sjplayer.util.linalg;
 
 ///
@@ -81,123 +82,10 @@ alias SquareElementDrawer = ElementDrawer!(
     [vec2(-1, 1), vec2(1, 1), vec2(1, -1), vec2(-1, -1)]);
 
 ///
-class SquareElementProgram {
- public:
-  ///
-  enum ShaderHeader = "#version 330 core
-#extension GL_ARB_explicit_uniform_location : enable";
-
-  ///
-  enum VertexShaderSrc = ShaderHeader ~ q{
-    layout(location = 0) in vec2 vert;
-
-    layout(location = 1) in vec3 m1;
-    layout(location = 2) in vec3 m2;
-    layout(location = 3) in vec3 m3;
-    layout(location = 4) in float weight;
-    layout(location = 5) in float smoooth;  // expected wrong spell
-    layout(location = 6) in vec4  color;
-
-    out vec2  uv_;
-    out float weight_;
-    out float smooth_;
-    out vec4  color_;
-
-    void main() {
-      mat3 m   = transpose(mat3(m1, m2, m3));
-      vec2 pos = (m * vec3(vert, 1)).xy;
-
-      uv_     = vert;
-      weight_ = weight;
-      smooth_ = smoooth;
-      color_  = color;
-      gl_Position = vec4(pos, 0, 1);
-    }
-  };
-  ///
-  enum FragmentShaderSrc = ShaderHeader ~ q{
-    in vec2  uv_;
-    in float weight_;
-    in float smooth_;
-    in vec4  color_;
-
-    out vec4 pixel_;
-
-    float square() {
-      float w = 1-weight_;
-      float s = smooth_;
-      return clamp(
-          smoothstep(w-s, w, abs(uv_.x)) +
-          smoothstep(w-s, w, abs(uv_.y)), 0, 1);
-    }
-
-    void main() {
-      pixel_    = color_;
-      pixel_.a *= square();
-    }
-  };
-
-  ///
-  this() {
-    ProgramLinker linker;
-    linker.vertex   = VertexShader.Compile(VertexShaderSrc);
-    linker.fragment = FragmentShader.Compile(FragmentShaderSrc);
-    program_ = linker.Link();
-    program_.Validate();
-  }
-
-  ///
-  void SetupVertexArray(ref VertexArrayRef vao,
-      ref ArrayBufferRef verts, ref ArrayBufferRef instances) {
-    with (VertexArrayAttacher()) {
-      // verts
-      type      = GL_FLOAT;
-      dimension = 2;
-      Attach(vao, verts);
-      ++index;
-
-      type    = GL_FLOAT;
-      divisor = 1;
-      stride  = SquareElement.Instance.sizeof;
-      offset  = 0;
-
-      // matrix
-      dimension = 3;
-      Attach(vao, instances);
-      offset += float.sizeof*3;
-      ++index;
-      Attach(vao, instances);
-      offset += float.sizeof*3;
-      ++index;
-      Attach(vao, instances);
-      offset += float.sizeof*3;
-      ++index;
-
-      // weight
-      dimension = 1;
-      Attach(vao, instances);
-      offset += float.sizeof*1;
-      ++index;
-
-      // smooth
-      dimension = 1;
-      Attach(vao, instances);
-      offset += float.sizeof*1;
-      ++index;
-
-      // color
-      dimension = 4;
-      Attach(vao, instances);
-      offset += float.sizeof*4;
-      ++index;
-    }
-  }
-
-  ///
-  void Use() {
-    program_.Use();
-  }
-
- private:
-  ProgramRef program_;
-}
+alias SquareElementProgram = ShapeElementProgram!(q{
+    float w = 1-weight_;
+    float s = smooth_;
+    return clamp(
+        smoothstep(w-s, w, abs(uv_.x)) +
+        smoothstep(w-s, w, abs(uv_.y)), 0, 1);
+  });