Initial pipeline abstraction

Source/Render/Pipeline/CompareFunction.rs

@@ -0,0 +1,40 @@
+use serde::{Deserialize, Serialize};
+
+/// Comparison function used for depth and stencil operations.
+#[repr(C)]
+#[derive(Copy, Clone, Debug, Hash, Eq, PartialEq, Serialize, Deserialize)]
+pub enum CompareFunction {
+    /// Function never passes
+    Never = 1,
+
+    /// Function passes if new value less than existing value
+    Less = 2,
+
+    /// Function passes if new value is equal to existing value
+    Equal = 3,
+
+    /// Function passes if new value is less than or equal to existing value
+    LessEqual = 4,
+
+    /// Function passes if new value is greater than existing value
+    Greater = 5,
+
+    /// Function passes if new value is not equal to existing value
+    NotEqual = 6,
+
+    /// Function passes if new value is greater than or equal to existing value
+    GreaterEqual = 7,
+
+    /// Function always passes
+    Always = 8,
+}
+
+impl CompareFunction {
+    /// Returns true if the comparison depends on the reference value.
+    pub fn NeedsReferenceValue(self) -> bool {
+        match self {
+            Self::Never | Self::Always => false,
+            _ => true,
+        }
+    }
+}