refactor(draw): use macro for buffer attribute descriptions

1 files changed, 101 insertions, 0 deletions

diff --git a/stockton-render/src/draw/macros.rs b/stockton-render/src/draw/macros.rs
new file mode 100644
index 0000000..d191d5b
--- /dev/null
+++ b/stockton-render/src/draw/macros.rs
@@ -0,0 +1,101 @@
+// Copyright (C) Oscar Shrimpton 2019
+
+// This program is free software: you can redistribute it and/or modify it
+// under the terms of the GNU General Public License as published by the Free
+// Software Foundation, either version 3 of the License, or (at your option)
+// any later version.
+
+// This program is distributed in the hope that it will be useful, but WITHOUT
+// ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+// FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+// more details.
+
+// You should have received a copy of the GNU General Public License along
+// with this program.  If not, see <http://www.gnu.org/licenses/>.
+//! Helper macros, mostly for the graphics pipeline definitions
+
+/// Macro for easily defining buffer attribute descriptions
+/// Usage:
+/// ```
+/// // 0 is the binding value
+/// let attributes: Vec<AttributeDesc> = pipeline_vb_attributes!(0,
+///		size_of::<f32>() * 3; Rgb32Sfloat
+///		size_of::<f32>() * 2; Rg32Sfloat,
+///		size_of::<u32>(); R32Sint
+///	);
+/// ```
+/// See the hal::pso::Format enum for possible types
+macro_rules! pipeline_vb_attributes {
+	// Start of recursion
+	( $binding:expr,
+		$firstSize:expr; $firstType:ident,
+		$( $size:expr; $type:ident ),*
+	) => ({
+		use hal::pso::{AttributeDesc, Element};
+
+		let mut vec = Vec::new();
+
+		vec.push(AttributeDesc {
+			location: 0,
+			binding: $binding,
+			element: Element {
+				format: Format::$firstType,
+				offset: 0
+			}
+		});
+
+		pipeline_vb_attributes!(
+			vec; $binding; 1; $firstSize,
+			$($size; $type),*
+		);
+
+		vec
+	});
+
+	// Special case for single item
+	( $binding:expr; $firstSize:expr; $firstType:ident ) => ({
+		vec![
+			AttributeDesc {
+				location: 0,
+				binding: $binding,
+				element: Element {
+					format: Format::$firstType,
+					offset: $firstSize as u32
+				}
+			}
+		]
+	});
+
+	// Middle of recursion
+	( $vec:ident; $binding:expr; $location:expr; $prevSize:expr,
+		$firstSize:expr; $firstType:ident,
+		$($size:expr; $type:ident),* ) => ({
+
+		$vec.push(AttributeDesc {
+			location: $location,
+			binding: $binding,
+			element: Element {
+				format: Format::$firstType,
+				offset: $prevSize as u32
+			}
+		});
+
+		pipeline_vb_attributes!(
+			$vec; $binding; ($location + 1); ($prevSize + $firstSize),
+			$($size; $type),*
+		);
+	});
+
+	// End of recursion
+	( $vec:ident; $binding:expr; $location:expr; $prevSize:expr,
+		$firstSize:expr; $firstType:ident ) => ({
+			$vec.push(AttributeDesc {
+				location: $location,
+				binding: $binding,
+				element: Element {
+					format: Format::$firstType,
+					offset: $prevSize as u32
+				}
+			});
+		});
+}
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