Start implementing a span allocator

game/container/spanpool/doc.odin

@@ -0,0 +1,81 @@
+package spanpool
+
+import "core:slice"
+
+Element :: struct($E: typeid) {
+	value: $T,
+	gen:   i32,
+}
+
+Span :: struct {
+	first, len: i32,
+}
+
+Span_Pool :: struct($E: typeid) {
+	elems: [dynamic]Element(E),
+	free_spans: [dynamic]Span,
+}
+
+Handle :: struct {
+	first: i32,
+	len:   i32,
+	gen:   i32,
+}
+
+allocate :: proc(s: ^$T/Span_Pool($E), elems: []T) -> (handle: Handle) {
+	handle = _allocate(s, len(elems))
+
+	for i in 0..<handle.len {
+		s.elems[i + handle.first].value = elems[i]
+	}
+}
+
+_allocate :: proc(s: ^$T/Span_Pool($E), count: i32) -> (handle: Handle) {
+	handle.len = count
+
+	maybe_existing_span: Maybe(i32)
+	for span, i in s.free_spans {
+		if span.len >= count {
+			maybe_existing_span = i
+			break
+		}
+	}
+
+	existing_span, ok := maybe_existing_span.?
+	if ok {
+		span := s.free_spans[existing_span]
+		handle.first = span.first
+		new_len := span.len - count
+
+		if new_len == 0 {
+			ordered_remove(&s.free_spans, existing_span)
+		} else {
+			s.free_spans[existing_span].first += count
+			s.free_spans[existing_span].len = new_len
+		}
+	} else {
+		handle.first = len(s.elems)
+		resize(&s.elems, len(s.elems) + count)
+	}
+
+	// Now figure out the generation index
+	max_gen := 0
+	for i in handle.first..<handle.first + handle.len {
+		gen = max(s.elems[i].gen)
+	}
+
+	handle.gen = max_gen + 1
+	for i in handle.first..<handle.first + handle.len {
+		s.elems[i].gen = handle.gen
+	}
+
+	return
+}
+
+free :: proc(s: ^$T/Span_Pool($E), handle: Handle) {
+	append(&s.free_spans, Span{first = handle.first, len = handle.len})
+}
+
+reconcile :: proc(s: ^$T/Span_Pool($E)) {
+	
+}

game/container/spanpool/spanpool.odin

@@ -0,0 +1 @@
+package spanpool

game/game.odin

@@ -581,7 +581,7 @@ draw :: proc() {
 				mesh := car_model.meshes[hit_mesh_idx]
 				vertices := (cast([^]rl.Vector3)mesh.vertices)[:mesh.vertexCount]
 				indices := mesh.indices[:mesh.triangleCount * 3]
-				car_halfedge := halfedge.mesh_from_vertex_index_list(vertices, indices, context.temp_allocator)
+				car_halfedge := halfedge.mesh_from_vertex_index_list(vertices, indices, 3, context.temp_allocator)
 
 				face_idx := halfedge.Face_Index(mesh_col.prim)
 				face := car_halfedge.faces[face_idx]

game/halfedge/halfedge.odin

@@ -32,11 +32,13 @@ Half_Edge_Mesh :: struct {
 mesh_from_vertex_index_list :: proc(
 	vertices: []Vec3,
 	indices: []u16,
+	vertices_per_face: int = 3,
 	allocator := context.allocator,
 ) -> Half_Edge_Mesh {
+	num_faces := len(indices) / vertices_per_face
 	mesh: Half_Edge_Mesh
 	verts := make([]Vertex, len(vertices), allocator)
-	faces := make([]Face, len(indices) / 3, allocator)
+	faces := make([]Face, num_faces, allocator)
 	edges := make([]Half_Edge, len(indices), allocator)
 
 	mesh.vertices = verts
@@ -50,49 +52,35 @@ mesh_from_vertex_index_list :: proc(
 
 	temp_edges: map[[2]u16]Edge_Index = make_map(map[[2]u16]Edge_Index, context.temp_allocator)
 
-	triangle_num := len(indices) / 3
+	for f in 0 ..< num_faces {
-	for i in 0 ..< triangle_num {
+		for i in 0..<vertices_per_face {
-		i1, i2, i3 := indices[i * 3 + 0], indices[i * 3 + 1], indices[i * 3 + 2]
+			e := f * vertices_per_face + i
-		// v1, v2, v3 := vertices[i1], vertices[i2], vertices[i3]
+			index := indices[e]
-		e1, e2, e3 := i * 3 + 0, i * 3 + 1, i * 3 + 2
 
-		faces[i].edge = Edge_Index(e1)
+			if i == 0 {
-		edges[e1] = {
+				faces[f].edge = Edge_Index(e)
-			origin = Vertex_Index(i1),
+			}
-			twin   = -1,
-			face   = Face_Index(i),
-			next   = Edge_Index(e2),
-			prev   = Edge_Index(e3),
-		}
-		edges[e2] = {
-			origin = Vertex_Index(i2),
-			twin   = -1,
-			face   = Face_Index(i),
-			next   = Edge_Index(e3),
-			prev   = Edge_Index(e1),
-		}
-		edges[e3] = {
-			origin = Vertex_Index(i3),
-			twin   = -1,
-			face   = Face_Index(i),
-			next   = Edge_Index(e1),
-			prev   = Edge_Index(e2),
-		}
 
-		edge_stable_indices := [][2]u16 {
+			next_edge := f * vertices_per_face + ((i + 1) % vertices_per_face)
-			{min(i1, i2), max(i1, i2)},
+			prev_edge := f * vertices_per_face + ((i - 1) % vertices_per_face)
-			{min(i2, i3), max(i2, i3)},
-			{min(i3, i1), max(i3, i1)},
-		}
 
-		for stable_idx, j in edge_stable_indices {
+			edges[e] = {
+				origin = Vertex_Index(index),
+				twin = -1,
+				face = Face_Index(f),
+				next = Edge_Index(next_edge),
+				prev = Edge_Index(prev_edge),
+			}
+
+			next_index := indices[next_edge]
+			stable_idx := [2]u16{min(index, next_index), max(index, next_index)}
 			twin, ok := temp_edges[stable_idx]
-			ei := i * 3 + j
+
 			if ok {
-				edges[ei].twin = twin
+				edges[e].twin = twin
-				edges[twin].twin = Edge_Index(ei)
+				edges[twin].twin = Edge_Index(e)
 			} else {
-				temp_edges[stable_idx] = Edge_Index(ei)
+				temp_edges[stable_idx] = Edge_Index(e)
 			}
 		}
 	}