2 files changed, 92 insertions, 0 deletions
diff --git a/murl/world/__init__.py b/murl/world/__init__.py
new file mode 100644
index 0000000..254a0f6
--- /dev/null
+++ b/murl/world/__init__.py
@@ -0,0 +1,15 @@
+from abc import ABC, abstractmethod
+
+class World(ABC):
+    ROBOT_RADIUS = 0.105 / 2.
+    @abstractmethod
+    def is_valid(self, pose):
+        raise NotImplementedError
+
+    @abstractmethod
+    def get_dist(self, sources, angles):
+        raise NotImplementedError
+
+    @abstractmethod
+    def sample(self, particles):
+        raise NotImplementedError
diff --git a/murl/world/simple.py b/murl/world/simple.py
new file mode 100644
index 0000000..195c4db
--- /dev/null
+++ b/murl/world/simple.py
@@ -0,0 +1,77 @@
+import numpy as np
+
+from murl.world import World
+
+WALL_OFFSET = 2.
+CYLINDER_POSITION = np.array([.3, .2], dtype=np.float32)
+CYLINDER_OFFSET = .3
+
+SEGMENTS = list(map(lambda ps: (np.array(ps[0]), np.array(ps[1]), ps[2]),
+                    [[[-WALL_OFFSET, -WALL_OFFSET], [0, 1], 2*WALL_OFFSET],
+                     [[-WALL_OFFSET, WALL_OFFSET], [1, 0], 2*WALL_OFFSET],
+                     [[WALL_OFFSET, WALL_OFFSET], [0, -1], 2*WALL_OFFSET],
+                     [[WALL_OFFSET, -WALL_OFFSET], [-1, 0], 2*WALL_OFFSET]]))
+
+class SimpleWorld(World):
+    WALL_RADIUS = WALL_OFFSET - World.ROBOT_RADIUS
+    CYLINDER_RADIUS = CYLINDER_OFFSET + World.ROBOT_RADIUS
+
+    def __init__(self, rng):
+        self._rng = rng
+
+    def is_valid(self, poses):
+        return ((-self.WALL_RADIUS < poses[...,0])
+              & (poses[...,0] < self.WALL_RADIUS)
+              & (-self.WALL_RADIUS < poses[...,1])
+              & (poses[...,1] < self.WALL_RADIUS)
+              & (np.sum((poses[...,:2] - CYLINDER_POSITION) ** 2, axis=-1) > self.CYLINDER_RADIUS ** 2))
+
+    def get_dist(self, sources, angles):
+        def dot(x, y):
+            return x[...,0] * y[...,0] + x[...,1] * y[...,1]
+        def cross(x, y):
+            return x[...,0] * y[...,1] - x[...,1] * y[...,0]
+
+        def intersect_segment(sources, angle, start, direction, length):
+            Y = start - sources[:,:2]
+            r = np.stack((np.cos(angle + sources[:,2]),
+                          np.sin(angle + sources[:,2]))).T
+            t = cross(Y, direction) / cross(r, direction)
+            t1 = cross(Y, r) / cross(r, direction)
+
+            return np.where((t >= 0) & (t1 >= 0) & (t1 <= length), t, float('inf'))
+
+        def intersect_cylinder(sources, angle, center, radius):
+            Y = center - sources[:,:2]
+            d = np.stack((np.cos(angle + sources[:,2]),
+                          np.sin(angle + sources[:,2]))).T
+            b = dot(d, Y)
+            c = dot(Y, Y) - radius**2
+            disc = b**2 - dot(Y, Y) + radius**2
+
+            mask = (disc > 0) & (b > 0) & (b ** 2 > disc)
+
+            b[~mask] = float('inf')
+            b[mask] -= np.sqrt(disc[mask])
+
+            return b
+
+        intersections = np.stack([np.stack(
+                (intersect_segment(sources, angle, *SEGMENTS[0]),
+                 intersect_segment(sources, angle, *SEGMENTS[1]),
+                 intersect_segment(sources, angle, *SEGMENTS[2]),
+                 intersect_segment(sources, angle, *SEGMENTS[3]),
+                 intersect_cylinder(sources, angle, CYLINDER_POSITION, CYLINDER_OFFSET))
+            ) for angle in angles])
+
+        return np.amin(intersections, axis=(0,1))
+
+    def sample(self, particles):
+        particles[:,2] = self._rng.uniform(-np.pi, np.pi, size=len(particles))
+
+        invalid = np.ones(shape=len(particles), dtype=np.bool)
+        while np.any(invalid):
+            count = np.ma.array(particles[:,0], mask=~invalid).count()
+            particles[invalid,0] = self._rng.uniform(-self.WALL_RADIUS, self.WALL_RADIUS, size=count)
+            particles[invalid,1] = self._rng.uniform(-self.WALL_RADIUS, self.WALL_RADIUS, size=count)
+            invalid = ~self.is_valid(particles)