Revert "Use deriving via Packed (Vertex ...) for Vertex Data"

This reverts commit 26dc573.

Actually, that didn't go so well.

Author: alt-romes

ghengin-core/ghengin-core-indep/Ghengin/Core/Mesh/Vertex.hs

@@ -101,11 +101,12 @@ instance (Block (Vertex (y:ys)), Block x) => Block (Vertex (x:y:ys)) where
     writePacked p (Diff o) (Sin a)
     writePacked p (Diff $ o + sizeOfPacked (Proxy @(Vertex '[x]))) b
 
--- NB: We use Packed for Storable Vertex
+-- NB: We use Std140 for Storable Vertex, which isn't quite right since
+-- vertices need to abide by the location/component layout, but is fine for now.
+--
 -- A good explanation is in https://developer.apple.com/library/archive/documentation/3DDrawing/Conceptual/OpenGLES_ProgrammingGuide/TechniquesforWorkingwithVertexData/TechniquesforWorkingwithVertexData.html
--- See also https://github.com/alt-romes/ghengin/pull/16#issuecomment-3563044060
-deriving via (Graphics.Gl.Block.Packed (Vertex '[x])) instance Block x => Storable (Vertex '[x])
-deriving via (Graphics.Gl.Block.Packed (Vertex (x:y:ys))) instance (Block x, Block (Vertex (y:ys))) => Storable (Vertex (x:y:ys))
+deriving via (Std140 (Vertex '[x])) instance Block x => Storable (Vertex '[x])
+deriving via (Std140 (Vertex (x:y:ys))) instance (Block x, Block (Vertex (y:ys))) => Storable (Vertex (x:y:ys))
 
 instance Show x => Show (Vertex '[x]) where
   show (Sin x) = show x

ghengin-core/ghengin-core/Ghengin/Core/Renderer/Buffer.hsig

@@ -4,7 +4,7 @@ import Data.Word (Word, Word32)
 import Data.Int (Int32)
 import qualified Data.Vector.Storable as SV
 -- TODO:Exchange Vk specific types to renderer agnostic enumerations
-import qualified Vulkan as Vk (BufferUsageFlags)
+import qualified Vulkan as Vk (DescriptorType, BufferUsageFlags)
 
 import Ghengin.Core.Mesh.Vertex
 import Ghengin.Core.Renderer.Kernel
@@ -35,7 +35,8 @@ writing into mapped buffers we know what layout to use (std140).
 
 However, for `DeviceLocalBuffer`s, at the moment, we don't know its use, so we
 delegate the decision of what standard to use to the definition site of the
-`Storable` instance which should in theory be derived via `Packed` from `gl-block`.
+`Storable` instance which should in theory be derived via `Std140` or `Std430`
+or `Packed` from `gl-block`.
 
 Furthermore, for Vertex buffers, given that (1) we use device local buffers and
 (2) when copying data from CPU to the device buffers it's useful to have

ghengin-core/ghengin-vulkan/Ghengin/Vulkan/Renderer/Buffer.hs

@@ -49,11 +49,12 @@ data VertexBuffer where
   VertexBuffer :: !DeviceLocalBuffer
                 ⊸ Word32               -- ^ N vertices
                -> VertexBuffer
+-- NB: We use Std140 throughout this module for Vertex, which isn't quite
+-- right since vertices need to abide by the location/component layout
+-- specification... but since Std140 gives some padding this should work fine
+-- if you are using Vertices with Vector attributes only.
+-- Ghengin.Core.Mesh.Vertex also defines a Storable instance for vertices based on Std140
 
--- | Create vertex buffer. Vertices are laid out in packed memory in the given vector.
---
--- If your type instances @'Block'@, you can get a correct Storable instance by
--- @deriving via Packed MyTy instance Storable MyTy@
 createVertexBuffer :: ∀ αs. Storable (Vertex αs) => SV.Vector (Vertex αs) -> Renderer VertexBuffer
 createVertexBuffer vv =
   flip VertexBuffer (fromIntegral $ SV.length vv) <$>