Validate Ground Zero safe spawn area

Scripts/setup_ground_zero_demo_map.py

@@ -93,6 +93,25 @@ RESOURCE_MATERIAL_BY_LABEL_PREFIX = {
     "AGR_GZ_FreshWaterSource": "fresh_water",
 }
 
+SAFE_SPAWN_CONFIG = {
+    "player_start_label": "AGR_DemoPlayerStart",
+    "safe_z_offset": 220.0,
+    "min_elevation_m": 2.0,
+    "max_slope_degrees": 8.0,
+    "slope_sample_distance_cm": 500.0,
+    "min_water_distance_cm": 10000.0,
+    "min_resource_distance_cm": 5000.0,
+    "fallback_location_xy": unreal.Vector(-22000.0, -3500.0, 0.0),
+    "candidate_locations_xy": [
+        unreal.Vector(-22000.0, -3500.0, 0.0),
+        unreal.Vector(-25000.0, -4000.0, 0.0),
+        unreal.Vector(-20500.0, -10500.0, 0.0),
+        unreal.Vector(-28000.0, -9000.0, 0.0),
+        unreal.Vector(-30000.0, -12000.0, 0.0),
+        unreal.Vector(-35000.0, 0.0, 0.0),
+    ],
+}
+
 
 DEMO_ACTORS = [
     {
@@ -597,6 +616,18 @@ def terrain_elevation_m(height_values, x_cm, y_cm):
     return terrain_z_cm(height_values, x_cm, y_cm) / 100.0
 
 
+def terrain_slope_degrees(height_values, x_cm, y_cm, sample_distance_cm):
+    dz_dx_m = (
+        terrain_elevation_m(height_values, x_cm + sample_distance_cm, y_cm)
+        - terrain_elevation_m(height_values, x_cm - sample_distance_cm, y_cm)
+    ) / ((sample_distance_cm * 2.0) / 100.0)
+    dz_dy_m = (
+        terrain_elevation_m(height_values, x_cm, y_cm + sample_distance_cm)
+        - terrain_elevation_m(height_values, x_cm, y_cm - sample_distance_cm)
+    ) / ((sample_distance_cm * 2.0) / 100.0)
+    return math.degrees(math.atan(math.sqrt((dz_dx_m * dz_dx_m) + (dz_dy_m * dz_dy_m))))
+
+
 def remove_existing_demo_actors(labels):
     for actor in unreal.EditorLevelLibrary.get_all_level_actors():
         if get_actor_label(actor) in labels:
@@ -607,6 +638,60 @@ def distance_2d(a, b):
     return math.hypot(a.x - b.x, a.y - b.y)
 
 
+def validate_safe_spawn_location(height_values, location_xy, resource_points, water_points):
+    failures = []
+    elevation_m = terrain_elevation_m(height_values, location_xy.x, location_xy.y)
+    slope_degrees = terrain_slope_degrees(
+        height_values,
+        location_xy.x,
+        location_xy.y,
+        SAFE_SPAWN_CONFIG["slope_sample_distance_cm"],
+    )
+    min_resource_distance_cm = min(distance_2d(location_xy, point) for point in resource_points)
+    min_water_distance_cm = min(distance_2d(location_xy, point) for point in water_points)
+
+    if elevation_m < SAFE_SPAWN_CONFIG["min_elevation_m"]:
+        failures.append(f"elevation {elevation_m:.2f}m below minimum")
+    if slope_degrees > SAFE_SPAWN_CONFIG["max_slope_degrees"]:
+        failures.append(f"slope {slope_degrees:.2f}deg above maximum")
+    if min_resource_distance_cm < SAFE_SPAWN_CONFIG["min_resource_distance_cm"]:
+        failures.append(f"resource distance {min_resource_distance_cm:.0f}cm below minimum")
+    if min_water_distance_cm < SAFE_SPAWN_CONFIG["min_water_distance_cm"]:
+        failures.append(f"water distance {min_water_distance_cm:.0f}cm below minimum")
+
+    return failures
+
+
+def select_safe_spawn_location(height_values):
+    resource_points = [spec["location_xy"] for spec in BIOME_RESOURCE_ACTORS]
+    resource_points.extend(
+        spec["location_xy"]
+        for spec in DEMO_ACTORS
+        if spec["label"] in {"AGR_DemoWoodResource_01", "AGR_DemoFiberResource_01"}
+    )
+    water_points = [spec["location_xy"] for spec in WATER_SOURCE_ACTORS]
+
+    candidates = list(SAFE_SPAWN_CONFIG["candidate_locations_xy"])
+    fallback = SAFE_SPAWN_CONFIG["fallback_location_xy"]
+    if all(distance_2d(fallback, candidate) > 1.0 for candidate in candidates):
+        candidates.append(fallback)
+
+    rejected = []
+    for candidate in candidates:
+        failures = validate_safe_spawn_location(height_values, candidate, resource_points, water_points)
+        if not failures:
+            unreal.log(
+                "Selected safe Ground Zero spawn at "
+                f"({candidate.x:.0f}, {candidate.y:.0f}) "
+                f"elevation {terrain_elevation_m(height_values, candidate.x, candidate.y):.2f}m "
+                f"slope {terrain_slope_degrees(height_values, candidate.x, candidate.y, SAFE_SPAWN_CONFIG['slope_sample_distance_cm']):.2f}deg"
+            )
+            return candidate
+        rejected.append(f"({candidate.x:.0f}, {candidate.y:.0f}): {', '.join(failures)}")
+
+    raise RuntimeError("No safe Ground Zero spawn candidate found. Rejected: " + "; ".join(rejected))
+
+
 def make_foliage_transform(height_values, x, y, yaw, z_offset, scale_xy, scale_z):
     return unreal.Transform(
         location=unreal.Vector(x, y, terrain_z_cm(height_values, x, y) + z_offset),
@@ -720,8 +805,11 @@ def spawn_foliage_actor(height_values, materials):
     return foliage_actor
 
 
-def spawn_demo_actor(spec, height_values, materials):
+def spawn_demo_actor(spec, height_values, materials, safe_spawn_location_xy=None):
     location_xy = spec["location_xy"]
+    if spec["label"] == SAFE_SPAWN_CONFIG["player_start_label"] and safe_spawn_location_xy is not None:
+        location_xy = safe_spawn_location_xy
+
     z = spec.get("fixed_z")
     if z is None:
         z = terrain_z_cm(height_values, location_xy.x, location_xy.y) + spec.get("z_offset", 0.0)
@@ -811,6 +899,7 @@ def main():
     materials = ensure_environment_materials()
     apply_landscape_material(materials["terrain"])
     height_values = load_heightmap()
+    safe_spawn_location_xy = select_safe_spawn_location(height_values)
     spawn_foliage_actor(height_values, materials)
     for spec in BIOME_RESOURCE_ACTORS:
         spawn_demo_actor(spec, height_values, materials)
@@ -823,7 +912,7 @@ def main():
     for spec in RUIN_PLACEHOLDER_ACTORS:
         spawn_environment_variation_actor(spec, height_values, materials)
     for spec in DEMO_ACTORS:
-        spawn_demo_actor(spec, height_values, materials)
+        spawn_demo_actor(spec, height_values, materials, safe_spawn_location_xy)
 
     unreal.EditorLevelLibrary.save_current_level()
     unreal.log("Ground Zero demo map setup complete.")