stencil buffer is added, but not working for invert

src/sprite.rs

@@ -121,16 +121,97 @@ impl Drawable for Sprite {
     }
 }
 
-/*
 
-        let vertex_buffer = {
+#[derive(Debug, Clone)]
+pub struct Poly {
 
-            CpuAccessibleBuffer::from_iter(self.device.clone(), BufferUsage::all(), [
-                ColoredVertex2D { position: [ 1.0, 1.0 ], color },
-                ColoredVertex2D { position: [ 1.0, 0.5 ], color },
-                ColoredVertex2D { position: [ 0.5, 0.5 ], color },
-                ColoredVertex2D { position: [ 0.5, 1.0 ], color },
-            ].iter().cloned()).unwrap()
-        };
+    pub vertices: Vec<(f32, f32, f32)>,
+    pub ti_position: Vec<(f32, f32)>,
 
-*/
+    position: (f32, f32),
+    size: (f32, f32),
+    color: (f32, f32, f32, f32),
+
+    textured: bool,
+    texture_handle: Option<Arc<CanvasTextureHandle>>,
+
+}
+
+/// Container class which implements drawable.
+impl Poly {
+
+    pub fn new(position: (f32, f32), size: (f32, f32)) -> Poly {
+        Poly::new_with_color(position, size, 0, (0.,0.,0.,0.))
+    }
+
+    pub fn new_with_color(position: (f32, f32),
+                          size: (f32, f32),
+                          depth: u32,
+                          color: (f32, f32, f32, f32)) -> Poly {
+
+        let normalized_depth = (depth as f32 / 255.0);
+
+        Poly {
+            vertices: vec![
+                (position.0, position.1                  , normalized_depth),    // top left
+                (position.0, position.1 + size.1         , normalized_depth),    // bottom left
+                (position.0 + size.0, position.1 + size.1, normalized_depth),    // bottom right
+
+                (position.0, position.1                  , normalized_depth),    // top left
+                (position.0 + size.0, position.1 + size.1, normalized_depth),    // bottom right
+                (position.0 + size.0, position.1         , normalized_depth),    // top right
+
+                (position.0 - 0.1, position.1                  , normalized_depth),    // top left
+                (position.0 - 0.1 + size.0, position.1 + size.1, normalized_depth),    // bottom right
+                (position.0 - 0.1 + size.0, position.1         , normalized_depth),    // top right
+            ],
+
+            position: position,
+            ti_position: vec![
+                (-0.0, -0.0),          // top left
+                (-0.0,  1.0),          // bottom left
+                ( 1.0,  1.0),          // bottom right
+
+                (-0.0, -0.0),          // top left
+                ( 1.0,  1.0),          // bottom right
+                ( 1.0, -0.0),          // top right
+
+                (-0.0, -0.0),          // top left
+                ( 1.0,  1.0),          // bottom right
+                ( 1.0, -0.0),          // top right
+            ],
+            size: size,
+            color: color,
+            textured: false,
+            texture_handle: None
+        }
+    }
+}
+
+impl Drawable for Poly {
+
+    fn get_vertices(&self) -> Vec<(f32,f32,f32)> {
+        self.vertices.to_vec()
+    }
+
+    fn get_color(&self) -> (f32, f32, f32, f32) {
+        self.color.clone()
+    }
+
+    fn get_ti_coords(&self) -> Vec<(f32, f32)> {
+        self.ti_position.to_vec()
+    }
+
+    fn get_texture_handle(&self) -> Option<Arc<CanvasTextureHandle>> {
+        match self.textured {
+            true => {
+                self.texture_handle.clone()
+            },
+            false => None,
+        }
+    }
+
+    fn get_image_handle(&self) -> Option<Arc<CanvasImageHandle>> {
+        None
+    }
+}