reorganized collider code

collider/types.py

@@ -0,0 +1,104 @@
+from dataclasses import dataclass
+from typing import Generator
+from abc import ABC, abstractmethod
+
+import pygame as pg
+from transform import Transform
+
+@dataclass
+class Face:
+    begin: pg.Vector2
+    end: pg.Vector2
+
+    @property
+    def normal(self) -> pg.Vector2:
+        return (self.end-self.begin).rotate(-90).normalize()
+    
+@dataclass
+class ColliderContact:
+    __slots__ = ["points", "normal", "penetration"]
+    points: list[pg.Vector2]
+    normal: pg.Vector2
+    penetration: float
+
+@dataclass(frozen=True)
+class PolygonalHull:
+    _vertices: list[pg.Vector2]
+
+    def get_vertex_at_index(self, key: int) -> pg.Vector2:
+        return self._vertices[key]
+
+    def get_face_at_index(self, key: int) -> Face:
+        return Face(self._vertices[key], self._vertices[(key + 1) % len(self._vertices)])
+    
+    def vertices(self) -> Generator[pg.Vector2, None, None]:
+        for v in self._vertices:
+            yield v
+    
+    def faces(self) -> Generator[Face, None, None]:
+        for i in range(len(self._vertices)):
+            yield self.get_face_at_index(i)
+
+    def project(self, axis: pg.Vector2) -> tuple[float, float]:
+        projections = [v.dot(axis) for v in self._vertices]
+        return (min(projections), max(projections))
+
+
+class BaseCollider(ABC):
+
+    @abstractmethod
+    def moment_of_inertia(self, mass: float) -> float:
+        pass
+
+class ConvexCollider(BaseCollider):
+
+    @abstractmethod
+    def hull(self, transform: Transform) -> PolygonalHull:
+        pass
+    
+@dataclass
+class CircleCollider(BaseCollider):
+
+    radius: float
+
+    def moment_of_inertia(self, mass: float) -> float:
+        return 0.5 * self.radius ** 2 * mass
+
+@dataclass
+class LineCollider(ConvexCollider):
+
+    length: float
+
+    def hull(self, transform: Transform) -> PolygonalHull:
+        return PolygonalHull([
+            transform.global_position - pg.Vector2(self.length / 2.0, 0).rotate(transform.global_degrees) * transform.global_scale,
+            transform.global_position + pg.Vector2(self.length / 2.0, 0).rotate(transform.global_degrees) * transform.global_scale
+        ])
+    
+    def moment_of_inertia(self, mass):
+        return 1.0 / 12.0 * mass * self.length**2
+
+
+@dataclass
+class RectCollider(ConvexCollider):
+
+    dimensions: tuple[float, float]
+
+    @property
+    def width(self):
+        return self.dimensions[0]
+    
+    @property
+    def height(self):
+        return self.dimensions[1]
+
+    def hull(self, transform: Transform) -> PolygonalHull:
+        return PolygonalHull([
+            transform.global_position - pg.Vector2(self.width / 2.0, self.height / 2.0).rotate(transform.global_degrees) * transform.global_scale,
+            transform.global_position - pg.Vector2(-self.width / 2.0, self.height / 2.0).rotate(transform.global_degrees) * transform.global_scale,
+            transform.global_position - pg.Vector2(-self.width / 2.0, -self.height / 2.0).rotate(transform.global_degrees) * transform.global_scale,
+            transform.global_position - pg.Vector2(self.width / 2.0, -self.height / 2.0).rotate(transform.global_degrees) * transform.global_scale
+        ])
+
+    def moment_of_inertia(self, mass: float) -> float:
+        return (1.0 / 12.0) * mass * (self.width ** 2 + self.height ** 2)