Initial pipeline abstraction

Source/Render/Pipeline/StencilOperation.rs

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+use serde::{Deserialize, Serialize};
+
+/// Operation to perform on the stencil value.
+#[repr(C)]
+#[derive(Copy, Clone, Debug, Hash, Eq, PartialEq, Serialize, Deserialize)]
+pub enum StencilOperation {
+    /// Keep stencil value unchanged.
+    Keep = 0,
+
+    /// Set stencil value to zero.
+    Zero = 1,
+
+    /// Replace stencil value with value provided in most recent call to [`RenderPass::set_stencil_reference`].
+    Replace = 2,
+
+    /// Bitwise inverts stencil value.
+    Invert = 3,
+
+    /// Increments stencil value by one, clamping on overflow.
+    IncrementClamp = 4,
+
+    /// Decrements stencil value by one, clamping on underflow.
+    DecrementClamp = 5,
+
+    /// Increments stencil value by one, wrapping on overflow.
+    IncrementWrap = 6,
+
+    /// Decrements stencil value by one, wrapping on underflow.
+    DecrementWrap = 7,
+}
+
+impl Default for StencilOperation {
+    fn default() -> Self {
+        Self::Keep
+    }
+}