test: geometry and slope collision coverage

tests/test_slopes.py

@@ -0,0 +1,58 @@
+import pytest
+
+from game.sim import physics
+from game.sim.entity import Actor
+
+
+class FakeSlopeTerrain:
+    def __init__(self, slopes):
+        self.slopes = slopes
+
+    def slopeAt(self, col, row):
+        return self.slopes.get((col, row))
+
+
+def test_slopeSurfaceAscendRight():
+    assert physics.slopeSurfaceY(0, 0, 0, "ascendRight") == pytest.approx(16.0)
+    assert physics.slopeSurfaceY(0, 0, 16, "ascendRight") == pytest.approx(0.0)
+    assert physics.slopeSurfaceY(0, 0, 8, "ascendRight") == pytest.approx(8.0)
+
+
+def test_slopeSurfaceAscendLeft():
+    assert physics.slopeSurfaceY(0, 0, 0, "ascendLeft") == pytest.approx(0.0)
+    assert physics.slopeSurfaceY(0, 0, 16, "ascendLeft") == pytest.approx(16.0)
+
+
+def test_resolveSlopeSnapsPenetratingActor():
+    terrain = FakeSlopeTerrain({(0, 0): "ascendRight"})
+    actor = Actor(2, -6, 12, 16)
+    actor.vy = 1.0
+    snapped = physics.resolveSlope(actor, terrain, wasOnGround=False)
+    assert snapped
+    assert actor.onGround
+    assert actor.bottom == pytest.approx(physics.slopeSurfaceY(0, 0, actor.centerX, "ascendRight"))
+    assert actor.vy == 0.0
+
+
+def test_walkingUpSlopeGainsHeight():
+    terrain = FakeSlopeTerrain({(0, 0): "ascendRight"})
+    actor = Actor(0, 0, 12, 16)
+    actor.vy = 1.0
+    physics.resolveSlope(actor, terrain, wasOnGround=False)
+    lowBottom = actor.bottom
+    actor.x = 6
+    actor.vy = 1.0
+    physics.resolveSlope(actor, terrain, wasOnGround=True)
+    assert actor.bottom < lowBottom
+
+
+def test_resolveSlopeClingsWhenDescending():
+    terrain = FakeSlopeTerrain({(0, 0): "ascendLeft"})
+    actor = Actor(2, 0, 12, 16)
+    surface = physics.slopeSurfaceY(0, 0, actor.centerX, "ascendLeft")
+    actor.y = surface - actor.h - 3.0
+    actor.vy = 0.5
+    snapped = physics.resolveSlope(actor, terrain, wasOnGround=True)
+    assert snapped
+    assert actor.onGround
+    assert actor.bottom == pytest.approx(surface)