igl | Add static_assert for GPU-critical struct layouts

Reviewed By: dmannemela

Differential Revision: D112581392

fbshipit-source-id: ec6dc6e434f3edd4bf0e2255428662353de659a5

Author: rudybear

src/igl/Color.h

@@ -44,4 +44,7 @@ struct Color {
     return &r;
   }
 };
+
+static_assert(sizeof(Color) == 4 * sizeof(float));
+
 } // namespace igl

src/igl/Common.h

@@ -168,6 +168,9 @@ struct ScissorRect {
   }
 };
 
+static_assert(sizeof(ScissorRect) == 4 * sizeof(uint32_t));
+static_assert(std::is_trivially_copyable_v<ScissorRect>);
+
 ///--------------------------------------
 /// MARK: - Size
 
@@ -216,6 +219,9 @@ struct Viewport {
   float maxDepth = 1.0f;
 };
 
+static_assert(sizeof(Viewport) == 6 * sizeof(float));
+static_assert(std::is_trivially_copyable_v<Viewport>);
+
 inline bool operator==(const Viewport& lhs, const Viewport& rhs) {
   return lhs.x == rhs.x && lhs.y == rhs.y && lhs.width == rhs.width && lhs.height == rhs.height &&
          lhs.minDepth == rhs.minDepth && lhs.maxDepth == rhs.maxDepth;