WIP: Build common interface for waypoint geometry constraints.

Fixes dcs-liberation#3085.

game/flightplan/waypointsolver.py

@@ -0,0 +1,59 @@
+from __future__ import annotations
+
+import json
+from pathlib import Path
+from typing import TYPE_CHECKING
+
+from dcs import Point
+
+if TYPE_CHECKING:
+    from .waypointstrategy import WaypointStrategy
+
+
+class WaypointSolver:
+    def __init__(self) -> None:
+        self.strategies: list[WaypointStrategy] = []
+        self.debug_output_directory: Path | None = None
+
+    def add_strategy(self, strategy: WaypointStrategy) -> None:
+        self.strategies.append(strategy)
+
+    def set_debug_output_directory(self, path: Path) -> None:
+        self.debug_output_directory = path
+
+    def dump_debug_info(self) -> None:
+        path = self.debug_output_directory
+        if path is None:
+            return
+
+        for idx, strategy in enumerate(self.strategies):
+            strategy_path = path / f"{idx}.json"
+            with strategy_path.open("w", encoding="utf-8") as strategy_debug_file:
+                json.dump(
+                    {
+                        "strategy_name": strategy.__class__.__name__,
+                        "geojson": {
+                            "type": "FeatureCollection",
+                            "features": [
+                                d.to_geojson() for d in strategy.iter_debug_info()
+                            ],
+                        },
+                    },
+                    strategy_debug_file,
+                )
+
+    def solve(self) -> Point:
+        if not self.strategies:
+            raise ValueError(
+                "WaypointSolver.solve() called before any strategies were added"
+            )
+
+        for strategy in self.strategies:
+            if (point := strategy.find()) is not None:
+                return point
+
+        self.dump_debug_info()
+        debug_details = "No debug output directory set"
+        if (debug_path := self.debug_output_directory) is not None:
+            debug_details = f"Debug details written to {debug_path}"
+        raise RuntimeError(f"No solutions found for waypoint. {debug_details}")

game/flightplan/waypointstrategy.py

@@ -0,0 +1,235 @@
+from __future__ import annotations
+
+import math
+from abc import abstractmethod, ABC
+from collections.abc import Iterator
+from dataclasses import dataclass
+from typing import Any
+
+from dcs.mapping import heading_between_points
+from shapely import to_geojson
+from shapely.geometry import Point, MultiPolygon, Polygon
+from shapely.geometry.base import BaseGeometry as Geometry
+from shapely.ops import nearest_points
+
+from game.utils import Distance, nautical_miles, Heading
+
+
+def angle_between_points(a: Point, b: Point) -> float:
+    return heading_between_points(a.x, a.y, b.x, b.y)
+
+
+def point_at_heading(p: Point, heading: Heading, distance: Distance) -> Point:
+    rad_heading = heading.radians
+    return Point(
+        p.x + math.cos(rad_heading) * distance.meters,
+        p.y + math.sin(rad_heading) * distance.meters,
+    )
+
+
+class Prerequisite(ABC):
+    @abstractmethod
+    def is_satisfied(self) -> bool:
+        ...
+
+
+class DistancePrerequisite(Prerequisite):
+    def __init__(self, a: Point, b: Point, min_range: Distance) -> None:
+        self.a = a
+        self.b = b
+        self.min_range = min_range
+
+    def is_satisfied(self) -> bool:
+        return self.a.distance(self.b) >= self.min_range.meters
+
+
+class SafePrerequisite(Prerequisite):
+    def __init__(self, point: Point, threat_zones: MultiPolygon) -> None:
+        self.point = point
+        self.threat_zones = threat_zones
+
+    def is_satisfied(self) -> bool:
+        return not self.point.intersects(self.threat_zones)
+
+
+class PrerequisiteBuilder:
+    def __init__(
+        self, subject: Point, threat_zones: MultiPolygon, strategy: WaypointStrategy
+    ) -> None:
+        self.subject = subject
+        self.threat_zones = threat_zones
+        self.strategy = strategy
+
+    def safe(self) -> None:
+        self.strategy.add_prerequisite(
+            SafePrerequisite(self.subject, self.threat_zones)
+        )
+
+    def min_distance_from(self, target: Point, distance: Distance) -> None:
+        self.strategy.add_prerequisite(
+            DistancePrerequisite(self.subject, target, distance)
+        )
+
+
+@dataclass(frozen=True)
+class ThreatTolerance:
+    target: Point
+    target_buffer: Distance
+    tolerance: Distance
+
+
+class RequirementBuilder:
+    def __init__(self, threat_zones: MultiPolygon, strategy: WaypointStrategy) -> None:
+        self.threat_zones = threat_zones
+        self.strategy = strategy
+
+    def safe(self) -> None:
+        self.strategy.exclude_threat_zone()
+
+    def at_least(self, distance: Distance) -> DistanceRequirementBuilder:
+        return DistanceRequirementBuilder(self.strategy, min_distance=distance)
+
+    def at_most(self, distance: Distance) -> DistanceRequirementBuilder:
+        return DistanceRequirementBuilder(self.strategy, max_distance=distance)
+
+    def maximum_turn_to(
+        self, turn_point: Point, next_point: Point, turn_limit: Heading
+    ) -> None:
+
+        large_distance = nautical_miles(400)
+        next_heading = Heading.from_degrees(
+            angle_between_points(next_point, turn_point)
+        )
+        limit_ccw = point_at_heading(
+            turn_point, next_heading - turn_limit, large_distance
+        )
+        limit_cw = point_at_heading(
+            turn_point, next_heading + turn_limit, large_distance
+        )
+
+        allowed_wedge = Polygon([turn_point, limit_ccw, limit_cw])
+        self.strategy.exclude(
+            f"restrict turn from {turn_point} to {next_point} to {turn_limit}",
+            turn_point.buffer(large_distance.meters).difference(allowed_wedge),
+        )
+
+
+class DistanceRequirementBuilder:
+    def __init__(
+        self,
+        strategy: WaypointStrategy,
+        min_distance: Distance | None = None,
+        max_distance: Distance | None = None,
+    ) -> None:
+        if min_distance is None and max_distance is None:
+            raise ValueError
+        self.strategy = strategy
+        self.min_distance = min_distance
+        self.max_distance = max_distance
+
+    def away_from(self, target: Point) -> None:
+        if self.min_distance is not None:
+            self.strategy.exclude(
+                f"at least {self.min_distance} away from {target}",
+                target.buffer(self.min_distance.meters),
+            )
+        if self.max_distance is not None:
+            self.strategy.exclude_beyond(
+                f"at most {self.min_distance} away from {target}",
+                target.buffer(self.max_distance.meters),
+            )
+
+
+@dataclass(frozen=True)
+class WaypointDebugInfo:
+    description: str
+    geometry: Geometry
+
+    def to_geojson(self) -> dict[str, Any]:
+        return {
+            "type": "Feature",
+            "properties": {
+                "description": self.description,
+            },
+            "geometry": to_geojson(self.geometry),
+        }
+
+
+class WaypointStrategy:
+    def __init__(self, threat_zones: MultiPolygon) -> None:
+        self.threat_zones = threat_zones
+        self.prerequisites: list[Prerequisite] = []
+        self.allowed_area: Polygon = Point(0, 0).buffer(1_000_000)
+        self.debug_infos: list[WaypointDebugInfo] = []
+        self._threat_tolerance: ThreatTolerance | None = None
+        self.point_for_nearest_solution: Point | None = None
+
+    def add_prerequisite(self, prerequisite: Prerequisite) -> None:
+        self.prerequisites.append(prerequisite)
+
+    def prerequisite(self, subject: Point) -> PrerequisiteBuilder:
+        return PrerequisiteBuilder(subject, self.threat_zones, self)
+
+    def exclude(self, description: str, geometry: Geometry) -> None:
+        self.debug_infos.append(WaypointDebugInfo(description, geometry))
+        self.allowed_area = self.allowed_area.difference(geometry)
+
+    def exclude_beyond(self, description: str, geometry: Geometry) -> None:
+        self.exclude(description, self.allowed_area.difference(geometry))
+
+    def exclude_threat_zone(self) -> None:
+        if (tolerance := self._threat_tolerance) is not None:
+            description = (
+                f"safe with a {tolerance.tolerance} tolerance to a "
+                f"{tolerance.target_buffer} radius about {tolerance.target}"
+            )
+        else:
+            description = "safe"
+        self.exclude(description, self.threat_zones)
+
+    def prerequisites_are_satisfied(self) -> bool:
+        for prereq in self.prerequisites:
+            if not prereq.is_satisfied():
+                return False
+        return True
+
+    def require(self) -> RequirementBuilder:
+        return RequirementBuilder(self.threat_zones, self)
+
+    def threat_tolerance(
+        self, target: Point, target_size: Distance, wiggle: Distance
+    ) -> None:
+        if self.threat_zones.is_empty:
+            return
+
+        min_distance_from_threat_to_target_buffer = target.buffer(
+            target_size.meters
+        ).distance(self.threat_zones.boundary)
+        threat_mask = self.threat_zones.buffer(
+            -min_distance_from_threat_to_target_buffer - wiggle.meters
+        )
+        self._threat_tolerance = ThreatTolerance(target, target_size, wiggle)
+        self.threat_zones = self.threat_zones.difference(threat_mask)
+
+    def nearest(self, point: Point) -> None:
+        if self.point_for_nearest_solution is not None:
+            raise RuntimeError("WaypointStrategy.nearest() called more than once")
+        self.point_for_nearest_solution = point
+
+    def find(self) -> Point | None:
+        if self.point_for_nearest_solution is None:
+            raise RuntimeError(
+                "Must call WaypointStrategy.nearest() before WaypointStrategy.find()"
+            )
+
+        if not self.prerequisites_are_satisfied():
+            return None
+
+        try:
+            return nearest_points(self.allowed_area, self.point_for_nearest_solution)[0]
+        except ValueError:
+            # No solutions.
+            return None
+
+    def iter_debug_info(self) -> Iterator[WaypointDebugInfo]:
+        yield from self.debug_infos