104 lines
4.6 KiB
Python
104 lines
4.6 KiB
Python
import pygame as pg
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from collider.types import *
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from transform import Transform
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def _interval_overlap(a: tuple[float, float], b: tuple[float, float]) -> float | None:
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if a[0] <= b[1] and b[0] <= a[1]:
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return min(a[1], b[1]) - max(a[0], b[0])
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return None
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def _collide_circle_circle(a: CircleCollider, b: CircleCollider, a_transform: Transform, b_transform: Transform) -> ColliderContact | None:
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delta = a_transform.global_position - b_transform.global_position
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dist = delta.length()
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radii = b.radius + b.radius
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if dist >= radii or dist == 0:
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return None
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normal = delta.normalize()
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return ColliderContact(
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point=a_transform.global_position + normal * b.radius,
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normal=normal,
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penetration=radii - dist,
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)
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def _collide_convex_circle(a: ConvexCollider, b: CircleCollider, a_transform: Transform, b_transform: Transform) -> ColliderContact | None:
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hull = a.hull(a_transform)
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normals = [face.normal for face in hull.faces()]
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circle_normal = min([(b_transform.global_position - v) for v in hull.vertices()], key=lambda v: v.length()).normalize()
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normals.append(circle_normal)
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collision_normal: pg.Vector2 | None = None
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lowest_pen = float('inf')
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for normal in normals:
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center_proj = normal.dot(b_transform.global_position)
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circle_interval = (center_proj - b.radius, center_proj + b.radius)
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convex_interval = hull.project(normal)
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penetration = _interval_overlap(circle_interval, convex_interval)
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if penetration is None:
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return None
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if penetration < lowest_pen:
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lowest_pen = penetration
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collision_normal = normal
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return ColliderContact(
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points=[b_transform.global_position - b.radius*normal],
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normal=collision_normal,
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penetration=lowest_pen
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)
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def _collide_convex_convex(a: ConvexCollider, b: ConvexCollider, a_transform: Transform, b_transform: Transform) -> ColliderContact | None:
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#SAT
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hull_a = a.hull(a_transform)
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hull_b = b.hull(b_transform)
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normals = [*[face.normal for face in hull_a.faces()],*[face.normal for face in hull_b.faces()]]
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collision_normal: pg.Vector2 | None = None
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lowest_pen = float('inf')
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for normal in normals:
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a_interval = hull_a.project(normal)
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b_interval = hull_b.project(normal)
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penetration = _interval_overlap(a_interval, b_interval)
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if penetration is None:
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return None
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if penetration < lowest_pen and (a_transform.position - b_transform.position).dot(normal) > 0:
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lowest_pen = penetration
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collision_normal = normal
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#sutherland hodgman clipping
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ref_face = max(hull_b.faces(), key=lambda f: f.normal.dot(collision_normal))
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incident_face = min(hull_a.faces(), key=lambda f: f.normal.dot(collision_normal))
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left_normal = (ref_face.begin - ref_face.end).normalize()
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right_normal = (ref_face.end - ref_face.begin).normalize()
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contact_manifold = [incident_face.begin, incident_face.end]
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def clip(normal: pg.Vector2, ref_point: pg.Vector2) -> None:
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d1 = (contact_manifold[0] - ref_point).dot(normal)
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d2 = (contact_manifold[1] - ref_point).dot(normal)
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if d1 > 0 and d2 > 0:
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raise Exception("CLIPPING ERROR")
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if d1 > 0:
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contact_manifold[0] = contact_manifold[0] + (d1 / (d1 - d2)) * (contact_manifold[1] - contact_manifold[0])
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if d2 > 0:
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contact_manifold[1] = contact_manifold[1] + (d2 / (d2 - d1)) * (contact_manifold[0] - contact_manifold[1])
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clip(right_normal, ref_face.end)
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clip(left_normal, ref_face.begin)
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clip(ref_face.normal, ref_face.begin)
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return ColliderContact(
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points=contact_manifold,
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normal=collision_normal,
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penetration=lowest_pen
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)
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def intersect(a: BaseCollider, b: BaseCollider, a_transform: Transform, b_transform: Transform) -> ColliderContact | None:
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if isinstance(a, ConvexCollider) and isinstance(b, ConvexCollider):
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return _collide_convex_convex(a,b,a_transform,b_transform)
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if isinstance(a, ConvexCollider) and isinstance(b, CircleCollider):
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return _collide_convex_circle(a, b, a_transform, b_transform)
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if isinstance(a, CircleCollider) and isinstance(b, ConvexCollider):
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collision = _collide_convex_circle(b,a,b_transform,a_transform)
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if collision: collision.normal *= -1
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return collision
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if isinstance(a, CircleCollider) and isinstance(b, CircleCollider):
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return _collide_circle_circle(a,b,a_transform,b_transform)
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raise NotImplementedError(f"No collision defined between collider types {type(a)} and {type(b)}") |