obs, moving: Fix setting source index.

internal/ctl/moving.go

@@ -324,11 +324,20 @@ func (m *MovingWall) layoutGroup(group cfg.Group, startZ int, instances []int) {
 func (m *MovingWall) layoutObs() {
 	m.obs.BatchAsync(obs.SerialFrame, func(b *obs.Batch) {
 		visible := make([]bool, len(m.instances))
+		var minIndex int = 1e2
+		for i := len(m.hitboxes) - 1; i >= 0; i -= 1 {
+			h := m.hitboxes[i]
+			name := fmt.Sprintf("Wall MC %d", h.id+1)
+			idx := b.GetSceneItemIndex("Wall", name)
+			if minIndex > idx {
+				minIndex = idx
+			}
+		}
 		for i := len(m.hitboxes) - 1; i >= 0; i -= 1 {
 			h := m.hitboxes[i]
 			visible[h.id] = true
 			name := fmt.Sprintf("Wall MC %d", h.id+1)
-			b.SetItemIndex("Wall", name, 0)
+			b.SetItemIndex("Wall", name, minIndex)
 			b.SetItemBounds(
 				"Wall",
 				name,

internal/obs/batch.go

@@ -49,6 +49,14 @@ func (b *Batch) SetItemIndex(scene, name string, index int) {
 	b.requests = append(b.requests, req)
 }
 
+func (b *Batch) GetSceneItemIndex(scene, name string) int {
+	idx, err := b.client.GetSceneItemIndex(scene, name)
+	if err != nil {
+		panic(batchError{err})
+	}
+	return idx
+}
+
 func (b *Batch) SetItemVisibility(scene, name string, visible bool) {
 	id, err := b.client.getSceneItemId(scene, name)
 	if err != nil {