Initial pipeline abstraction

Source/Render/Pipeline/StencilFaceState.rs

@@ -0,0 +1,43 @@
+use super::{CompareFunction, StencilOperation};
+use serde::{Deserialize, Serialize};
+
+/// State of the stencil operation (fixed-pipeline stage).
+#[repr(C)]
+#[derive(Copy, Clone, Debug, Hash, Eq, PartialEq, Serialize, Deserialize)]
+pub struct StencilFaceState {
+    /// Comparison function that determines if the fail_op or pass_op is used on the stencil buffer.
+    pub compare: CompareFunction,
+
+    /// Operation that is preformed when stencil test fails.
+    pub fail_op: StencilOperation,
+
+    /// Operation that is performed when depth test fails but stencil test succeeds.
+    pub depth_fail_op: StencilOperation,
+
+    /// Operation that is performed when stencil test success.
+    pub pass_op: StencilOperation,
+}
+
+impl StencilFaceState {
+    /// Ignore the stencil state for the face.
+    pub const IGNORE: Self = StencilFaceState {
+        compare: CompareFunction::Always,
+        fail_op: StencilOperation::Keep,
+        depth_fail_op: StencilOperation::Keep,
+        pass_op: StencilOperation::Keep,
+    };
+
+    /// Returns true if the face state uses the reference value for testing or operation.
+    pub fn NeedsReferenceValue(&self) -> bool {
+        self.compare.NeedsReferenceValue()
+            || self.fail_op == StencilOperation::Replace
+            || self.depth_fail_op == StencilOperation::Replace
+            || self.pass_op == StencilOperation::Replace
+    }
+}
+
+impl Default for StencilFaceState {
+    fn default() -> Self {
+        Self::IGNORE
+    }
+}