# 4. Beat-Chart to Gray-Box
Part of [[ProBuilder Gray-Boxing and Landmarks]]. Prev: [[3. Weenies Landmarks and Lighting as Wayfinding]]. Next: [[5. Worked Example Landmark Blockout]].
Level 4 of [[Level Up! (Review)]] is the paperwork: a **beat chart** whose rows are beats and whose columns are things like setting, story, new mechanics, enemies, and power-ups. Level 9 is how those rows become a space. This part stores a *small* chart as data and stamps a gray-box from it so a critique can say "beat 3 is a long walk with no reward" while looking at both the asset and the scene.
This is not a level-streaming tool. It is a disposable blockout. Re-running the builder should replace a `BeatChart_Blockout` root, not silently stack duplicates.
## 4.1 The chart asset
```csharp
using UnityEngine;
public enum BeatRoomKind
{
Approach, // shows the weenie
Arena, // combat or challenge
Puzzle, // key, gate, or safe experiment
RewardFinger, // a dead-end with a payoff
Calm, // breath
Landmark // the weenie itself
}
[System.Serializable]
public struct BeatRow
{
public string beatName;
public BeatRoomKind kind;
[Tooltip("Length of this beat along the path, in meters.")]
public float length;
[Tooltip("Width of the space, in meters.")]
public float width;
[Tooltip("Wall height. Use MovementMetrics.height plus headroom if left 0.")]
public float height;
public bool showWeenieFromHere;
[TextArea] public string notes; // story, mechanic, enemy, reward - the other columns
}
[CreateAssetMenu(menuName = "Gameplay/Beat Chart", fileName = "BeatChart")]
public sealed class BeatChart : ScriptableObject
{
public string levelName = "Plaza Approach";
public MovementMetrics metrics;
public BeatRow[] beats;
}
```
Keep `notes` as a single text field rather than inventing a full GDD schema. The book has more columns than you need in a teaching asset; write them into `notes` in the same order every time (`Setting / Story / Mechanic / Enemy / Reward`).
## 4.2 Editor builder
Put this in an `Editor` folder ([[Custom Inspectors and Editor Tooling]]). It uses only `ShapeGenerator` APIs verified in 6.1.4 plus Editor prefab / menu hooks.
```csharp
#if UNITY_EDITOR
using UnityEditor;
using UnityEditor.ProBuilder;
using UnityEngine;
using UnityEngine.ProBuilder;
public static class BeatChartBuilder
{
const string RootName = "BeatChart_Blockout";
[MenuItem("Tools/Blockout/Build Beat Chart From Selection")]
static void BuildFromSelection()
{
var chart = Selection.activeObject as BeatChart;
if (chart == null)
{
EditorUtility.DisplayDialog("Beat Chart", "Select a BeatChart asset, then run this again.", "OK");
return;
}
Build(chart);
}
public static void Build(BeatChart chart)
{
if (chart.beats == null || chart.beats.Length == 0) return;
var existing = GameObject.Find(RootName);
if (existing != null) Undo.DestroyImmediate(existing);
var root = new GameObject(RootName);
Undo.RegisterCreatedObjectUndo(root, "Build Beat Chart");
MovementMetrics m = chart.metrics;
float defaultHeight = m != null ? m.height + 1.0f : 3.0f;
float z = 0f;
for (int i = 0; i < chart.beats.Length; i++)
{
BeatRow row = chart.beats[i];
float h = row.height > 0.1f ? row.height : defaultHeight;
float w = Mathf.Max(2f, row.width);
float len = Mathf.Max(2f, row.length);
var room = new GameObject(
quot;{i:00}_{row.beatName}");
room.transform.SetParent(root.transform, false);
room.transform.position = new Vector3(0f, 0f, z + len * 0.5f);
var floor = ShapeGenerator.GenerateCube(PivotLocation.Center, new Vector3(w, 0.2f, len));
floor.name = "Floor";
floor.transform.SetParent(room.transform, false);
floor.transform.position = room.transform.position + Vector3.up * 0.1f;
TintAndCommit(floor, ColorFor(row.kind));
var wallL = ShapeGenerator.GenerateCube(PivotLocation.Center, new Vector3(0.3f, h, len));
wallL.name = "Wall_L";
wallL.transform.SetParent(room.transform, false);
wallL.transform.position = room.transform.position + new Vector3(-w * 0.5f, h * 0.5f, 0f);
TintAndCommit(wallL, new Color(0.2f, 0.2f, 0.2f));
var wallR = ShapeGenerator.GenerateCube(PivotLocation.Center, new Vector3(0.3f, h, len));
wallR.name = "Wall_R";
wallR.transform.SetParent(room.transform, false);
wallR.transform.position = room.transform.position + new Vector3(w * 0.5f, h * 0.5f, 0f);
TintAndCommit(wallR, new Color(0.2f, 0.2f, 0.2f));
if (row.kind == BeatRoomKind.Landmark)
{
float weenieHeight = Mathf.Max(8f, h * 3f);
var weenie = ShapeGenerator.GenerateCone(PivotLocation.Center, 1.2f, weenieHeight, 12);
weenie.name = "Weenie";
weenie.transform.SetParent(room.transform, false);
weenie.transform.position = room.transform.position + Vector3.up * (weenieHeight * 0.5f);
TintAndCommit(weenie, new Color(1f, 0.85f, 0.2f));
}
z += len;
}
Selection.activeGameObject = root;
}
static Color ColorFor(BeatRoomKind kind) => kind switch
{
BeatRoomKind.Approach => new Color(0.55f, 0.55f, 0.55f),
BeatRoomKind.Arena => new Color(0.45f, 0.45f, 0.5f),
BeatRoomKind.Puzzle => new Color(0.35f, 0.55f, 0.65f),
BeatRoomKind.RewardFinger => new Color(0.35f, 0.6f, 0.35f),
BeatRoomKind.Calm => new Color(0.5f, 0.6f, 0.5f),
BeatRoomKind.Landmark => new Color(0.55f, 0.5f, 0.35f),
_ => Color.gray
};
static void TintAndCommit(ProBuilderMesh pb, Color color)
{
// Official 6.1.4 API: colors (IList<Color>, length must match positions) and vertexCount.
if (pb.colors == null || pb.colors.Count != pb.vertexCount)
{
var colors = new Color[pb.vertexCount];
for (int i = 0; i < colors.Length; i++) colors[i] = color;
pb.colors = colors;
}
else
{
var colors = pb.colors;
for (int i = 0; i < colors.Count; i++) colors[i] = color;
pb.colors = colors;
}
pb.ToMesh();
pb.Refresh();
EditorMeshUtility.Optimize(pb, true);
}
}
#endif
```
`ProBuilderMesh.colors` and `vertexCount` are official 6.1.4 APIs (`colors` is an `IList<Color>` whose length must match the positions array). After assigning colors, `ToMesh()` + `Refresh()` applies them; the URP sample shaders must be imported or the tint may not show. `GetColors()` also exists (returns white if the mesh has no colors). You can instead paint with the Vertex Color tool after a build.
`Undo.DestroyImmediate` on the previous root is an Editor-only rebuild. It is not a runtime API. Never hook this builder to Play Mode.
`GameObject.Find` is acceptable in a one-off Editor menu; do not copy it into gameplay.
## 4.3 After the stamp
The generated spine is a *starting* corridor: two walls and a floor per beat, plus a cone on Landmark rows. You then:
- Cut doorways between beats (or leave gaps).
- Pull a RewardFinger off to the side and put a green prop at the end.
- Place a `LandmarkSightline` at beat 0 if `showWeenieFromHere` is set.
- Add a spotlight on the cone (part 3).
- Play it. If beat 3 "feels long," it *is* long - shorten `length` and rebuild, or put a reward mid-span.
## 4.4 Exercise
Write a five-row chart: Approach (weenie visible), Calm, Arena, RewardFinger, Landmark. Build it, play it, and change one length because it bored you. That is the whole loop.
## Sources
- `ShapeGenerator` (6.1.4): https://docs.unity3d.com/Packages/