Hi all
Since the last quick update I've turned things around. Rather than working with full models for the mountains, I decided to take another approach.
While the mountain itself only comes after the second part of the Silent Forest, I've had to make part of it already for that part, since I want a bit of continuity in the game, and not just a 'woop, here I am!' kind of vibe. It is taking 'a lot' of my time, and patience, but at least it's not wasted work since I can easily reuse what I'm making now in the actual Mountain part.
To recap last week's update, and to give a better view of the change, here's last week's photos:
As you can see the whole thing looks a bit bland and too much of the same. I know, last week I said it looked good, but the more I stared at it while making it, the more I felt I could do better, and that brings us to the following screenshots:
What you're seeing here is just a part of the mountain, it will still become much higher.
The new result looks a lot more natural, less repetitive, and takes about as long to make as a single model does. Once I got used to the tool I built for it, it even became faster.
So, let’s talk about the tool that made this all possible.
Technobabble
If you're into the technical stuff this little chapter is for you, if not, you can skip it all to the next chapter.
The tool I'm using I've named CustomSpawnZone, and works together with two other scripts CustomSpawnZoneEditor and ConnectedDirtSpawner. Now, the spawnzone script itself is what makes the zone, the polygons, etc. The editor script makes it all work in the Unity editor, makes buttons appear that I'd need to add and remove the points, and makes my clicks register the points. The spawner script makes the actual spawns, but more on that later.
CustomSpawnZone
The whole reason why I decided to go this way, as mentioned above, is because I didn't like what the model looked like. I had to find a way to make it all more flexible, as well, since working on a hard, big, dumb model would almost require me to redo it over and over.
The CustomSpawnZone script does exactly that: it allows me to define freeform areas directly in the editor, rather than having to work around a static model. Each zone stores its polygon vertices in local space, builds a triangulated surface for height sampling, and provides both fast bounding checks and precise 3D containment tests. It even supports snapping generated points to Unity's active terrain, which makes it feel surprisingly natural when placing the points.
There are three methods that are important for this to work. These methods form the foundation of the zone logic - handling everything from triangulation to terrain snapping an containment checks.
Firstly, the TriangulatePolygon() method, which builds the triangulated surface. The method creates a list of indices for the polygon vertices, after which it applies simple ear clipping triangulation for convex polygons. Here's a look at the method:
private void TriangulatePolygon()
{
if (points.Count < 3)
return;
triangles.Clear();
var indices = Enumerable.Range(0, points.Count).ToList();
for (int i = 1; i < points.Count - 1; i++)
{
triangles.Add(0);
triangles.Add(i);
triangles.Add(i + 1);
}
}
Secondly, the IsPointInside() method does the containment tests, first by checking whether a point is inside the polygon in 2D, and then checking if the point is within the vertical bounds of the polygon surface. The method looks as follows:
public bool IsPointInside(Vector3 worldPosition)
{
Vector3 localPos = transform.InverseTransformPoint(worldPosition);
Vector2 testPoint = new Vector2(localPos.x, localPos.z);
bool inside2D = IsPointInPolygon(testPoint, points);
if (!inside2D)
return false;
float surfaceHeight = GetHeightAtLocalPosition(localPos);
bool withinHeight = Mathf.Abs(localPos.y - surfaceHeight) <= heightRange * 0.5f;
return withinHeight;
}
TryGetTerrainY() lastly snaps a point to the terrain.
On top of that, random point generation (to spawn the dirt/rocks) uses rejection sampling inside the polygon's AABB - a simple but reliable approach for most shapes. To calculate surface height at any position, the system triangles the polygon (ear clipping) and uses barycentric interpolation between vertex heights, falling back to an inverse-distance weighted height when necessary. It is a nice mix of math and practicality that keeps results smooth.
The core logic for this happens in two methods, the GetRandomPoint(), which handles random rejection sampling inside the polygon bounds, and the GetHeightAtLocalPosition() method, which determines accurate height from the triangulated data. Together they decide where objects should spawn and at what height, using either the barycentric interpolation or distance-weighted height sampling.
While there isn't really much to say about the GetRandomPoint() method - it's all about using Random.Range() etc - the GetHeightAtLocalPosition() is a bit more interesting to talk about. It first gets all the triangles from the polygon triangulation, to then find which triangle a certain point contains. It then uses the barycentric coordinates to interpolate the height of the point, with the method BarycentricHeight(), which uses 4 points. If it is unable to, it falls back to the distance-weighted average of all points with the method GetDistanceWeightedHeight().
Here's a look at the full GetHeightAtLocalPosition method:
public float GetHeightAtLocalPosition(Vector3 localPos)
{
if (points.Count < 3) return localPos.y;
Vector2 testPoint = new Vector2(localPos.x, localPos.z);
List triangles = TriangulatePolygon();
for (int i = 0; i < triangles.Count; i += 3)
{
Vector3 a = points[triangles\[i]];
Vector3 b = points[triangles\;
Vector3 c = points[triangles\;
Vector2 a2 = new Vector2(a.x, a.z);
Vector2 b2 = new Vector2(b.x, b.z);
Vector2 c2 = new Vector2(c.x, c.z);
if (IsPointInTriangle(testPoint, a2, b2, c2))
{
return BarycentricHeight(testPoint, a, b, c);
}
}
return GetDistanceWeightedHeight(localPos);
}
For editor usability, I added visual gizmos that draw the zone's edges and world bounds. Seeing the triangulated surface right inside the scene view makes fine-tuning the zone layout far more intuitive, speeding up a lot of the work.
OnDrawGizmos() renders both polygon edges and its triangulated surface for a visual on where the spawn logic would succeed or fail. Failing usually results in 2 planes, of a sort, to show up. Rather than one smooth plane as it should be. Here's the OnDrawGizmos() method:
private void OnDrawGizmos()
{
Gizmos.color = Color.magenta;
for (int i = 0; i < points.Count; i++)
{
Vector3 current = transform.TransformPoint(new Vector3(points[i].x, points[i].y, points[i].z));
Vector3 next = transform.TransformPoint(new Vector3(points[(i + 1) % points.Count].x, points[(i + 1) % points.Count].y, points[(i + 1) % points.Count].z));
Gizmos.DrawLine(current, next);
}
Bounds b = GetBounds();
Gizmos.color = new Color(1, 1, 0, 0.1f);
Gizmos.matrix = transform.localToWorldMatrix;
Gizmos.DrawWireCube(b.center, b.size);
DrawTriangulatedSurfaceGizmo();
}
All of this, and more, make it so that, in the editor, it looks like this:
As you can see, even from this side view it’s perfectly manageable — and more importantly, flexible.
This setup means I can shape and rework the environment freely without touching a single model again. Every small improvement to the logic makes the mountain come alive a bit more — one spawn zone at a time.
CustomSpawnZoneEditor
Of course, just having the zone logic wasn't enough. I needed a way to actually work with it comfortably inside the Unity editor. So, I wrote a custom editor script (one of over a dozen already....) to make that possible. It handles point placement, snapping, live distance display, and visual feedback right in the scene view, letting me draw and shape spawn zones directly on terrain with ease.
The script adds a gid system, real-time distance measurements from the last point placed, and even smaller helper visuals to make sure I'm following my roadmap correctly when transferring the layouts into Unity. Toggling Add Mode lets me click directly in the scene to define new vertices, while grid snapping ensures everything stays consistent and evenly spaced. It's a big help for building large, natural-looking areas quickly.
Under the hood it's just using Handles, Undo recording, and a bit of math for snapping - nothing fancy - but it makes the entire workflow feel ten times smoother. What used to take several back-and-forth tweaks between Blender and Unity now happens in a single scene view, interactively.
I could go into a lot more detail with this, but since it's more on the developer side than the player side, I’ll keep it short and just show a few screenshots. It’s one of those tools that quietly makes things possible behind the scenes.
If you’re curious about how it actually works or want me to go deeper into it in a future devlog, let me know in the comments!
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ConnectedDirtSpawner
Last but certainly not least - this is the thing that actually makes thing visual, after all - the ConnectedDirtSpawner script. It is the last piece of the system and probably one of the easiest to explain. While the CustomSpawnZone defines where things can spawn, the ConnectedDirtSpawner decides what actually goes where.
The script loops through each part of the zone, figures out where the dirt pieces (or rocks, or anything, really) could fit, checks if the point is inside the polygon, and then spawns one of the assigned prefabs at that position. It adds a bit of randomness to the placement and rotation to avoid patterns, and even applies a slight color variation using a MaterialPropertyBlock, so no two dirts look exactly the same.
Each spawned object is also scaled up a little, and optionally snapped to the terrain if the zone supports it. That keeps the visuals consistent across slopes or uneven terrain. And, since we're talking about a mountain, there's going to be lots of that...
The placement logic itself is pretty straightforward:
It takes the prefab size to determine spacing.
Iterates over the zone's bounding box.
Randomly offsets each position slightly.
Uses the IsPointInside() check to make sure the point lies within the polygon.
Uses GetPointOnPolygonSurface() to find the correct Y height.
Spawns the object with random rotation and color tint.
Here's a look at the helper method that calculates the surface height, making sure each piece aligns perfectly with the zone surface:
private Vector3 GetPointOnPolygonSurface(CustomSpawnZoneDirt zone, Vector3 localPosition)
{
float height = zone.GetHeightAtLocalPosition(localPosition);
Vector3 worldPos = zone.transform.TransformPoint(new Vector3(localPosition.x, height, localPosition.z));
return worldPos;
}
The script also includes an editor-only context menu that lets me preview the whole spawn setup right inside Unity.
That’s been incredibly useful — I can clear and respawn the dirt layer instantly without entering play mode.
Lastly, for debugging and visualization, there’s an OnDrawGizmosSelected() method that outlines each zone and shows where the spawn points might appear as little green spheres. It’s an easy way to see how dense the spawn grid is and where the logic succeeds or fails.
Forests, Mountains... and beyond
Now that I've got everything in place to make the mountains - something that was kind of a bigger hurdle than you might imagine - I'm starting to think beyond it again, what the rest of the game will look like, not just in terms of levels, but how players experience the world as a whole.
I've already mentioned I prefer continuity in the game, being able to move from place to place seamlessly (not talking about the loading screen, but the journey of Boll itself). So... What really is next?
The original way I saw it was that Boll ends up on a glider or a small plane of some kind, at the top of the mountain, and then glides off to the next part of the journey. The issue I have with that, however, is where does that glider come from? Isn't it all too convenient for there to be a glider? But then I'm also thinking: anything I'd do would end up being too convenient.
What's new between the original plan and how things have turned out so far, is the whole dimension thing. And I think that's exactly what I'm going to be using. Maybe I'll skip whole parts of the original plan altogether.... Who wants to see more Forests, anyways? Or head back into suburbs? Or walk along a river?
Maybe I better start focusing on heading into a city, an industrial area, or an airport, rather than more of the same. There's still time to think about it, I still need to get up the mountain, after all. One thing's for sure, however: What goes up, must come down. The question is just: how?
Future-me will likely have all the answers. For now, I'll just focus on the present.
Happy playing!