load mesh from OBJ file

.gitattributes

@@ -0,0 +1 @@
+assets/ filter=lfs diff=lfs merge=lfs -text

src/Init.hs

@@ -80,6 +80,8 @@ initVulkan window = do
   allocator <- initAllocator vulkanPhysicalDevice vulkanLogicalDevice vulkanInstance
   mesh <- uploadMesh loadMeshes allocator
 
+  maskMesh <- loadFromObj "./assets/cat_mask_scaled.obj" allocator
+
   dimensions <- liftIO $ SDL.windowInitialSize <$> SDL.getWindowConfig window
   (swapchain, surfaceFormat) <-
     createSwapchain vulkanSurface surfaceFormats dimensions vulkanLogicalDevice
@@ -147,5 +149,6 @@ initVulkan window = do
     inFlightFence
     imageAvailableSemaphore
     renderFinishedSemaphore
-    mesh
+    maskMesh
+    maskMesh
     allocator

src/Mesh.hs

@@ -71,5 +71,41 @@ uploadMesh vertices allocator = do
 loadFromObj
   :: (MonadResource m, MonadFail m)
   => FilePath
+  -> VMA.Allocator
   -> m Mesh
-loadFromObj filepath = undefined
+loadFromObj filepath vma = do
+  eitherObj <- liftIO $ fromFile filepath
+  case eitherObj of
+    Left err ->
+      error ("loadFromObj:  loading mesh data: " <> err)
+    Right obj -> do
+      let vertices = digestFaces (objFaces obj) (objLocations obj)
+      uploadMesh vertices vma
+  where
+    digestFaces :: V.Vector (Element Face) -> V.Vector Location -> V.Vector Vertex
+    digestFaces faces locations =
+      V.foldl
+        (\acc (Element _ _ _ _ (Face fa fb fc others)) ->
+          if not (null others)
+          then
+            error "loadFromObj: Non-triangular face detected"
+          else
+            let newVertices = V.map
+                  (\faceIndex ->
+                    let position = faceIndexToPosition faceIndex locations
+                        normal   = V3 0 0 0
+                        color    = V4 1 1 0 1
+                    in
+                      Vertex position normal color
+                    )
+                  (V.fromList [ fa, fb, fc ])
+            in
+              acc V.++ newVertices
+          )
+        V.empty
+        faces
+    faceIndexToPosition :: FaceIndex -> V.Vector Location -> V3 Float
+    faceIndexToPosition index locations =
+      let Location x y z _ = locations V.! (faceLocIndex index - 1)
+      in
+        V3 x y z