Improve "Quickstart" section

Co-authored-by: Adam Tyson <[email protected]>

README.md

@@ -37,28 +37,48 @@ If you encounter any issues, please consult our troubleshooting guide [here](htt
 ## Quickstart
 
 ``` python
+import random
+
+import numpy as np
+
 from brainrender import Scene
-from brainrender.actors import Neuron
+from brainrender.actors import Points
+
+def get_n_random_points_in_region(region, N):
+    """
+    Gets N random points inside (or on the surface) of a mesh
+    """
+
+    region_bounds = region.mesh.bounds()
+    X = np.random.randint(region_bounds[0], region_bounds[1], size=10000)
+    Y = np.random.randint(region_bounds[2], region_bounds[3], size=10000)
+    Z = np.random.randint(region_bounds[4], region_bounds[5], size=10000)
+    pts = [[x, y, z] for x, y, z in zip(X, Y, Z)]
+
+    ipts = region.mesh.inside_points(pts).coordinates
+    return np.vstack(random.choices(ipts, k=N))
+
 
 # Display the Allen Brain mouse atlas.
-scene = Scene(atlas_name="allen_mouse_25um")
+scene = Scene(atlas_name="allen_mouse_25um", title="Cells in primary visual cortex")
 
-# Highlight the cerebral cortex.
-scene.add_brain_region("CTX", alpha=0.2, color="green")
+# Display a brain region
+primary_visual = scene.add_brain_region("VISp", alpha=0.2)
 
-# Add a neuron morphological reconstruction,
-# with coordinates pre-registered to the Allen Brain Atlas.
-neuron = Neuron("/path/to/neuron/morphology.swc")
-scene.add(neuron)
+# Get a numpy array with (fake) coordinates of some labelled cells
+coordinates = get_n_random_points_in_region(primary_visual, 2000)
 
-# Display the figure.
-scene.render()
+# Create a Points actor
+cells = Points(coordinates)
+
+# Add to scene
+scene.add(cells)
 
-# Export to PNG.
-scene.screenshot("figure.png")
+# Add label to the brain region
+scene.add_label(primary_visual, "Primary visual cortex")
 
-# Export to HTML.
-scene.screenshot("figure.html")
+# Display the figure.
+scene.render()
 
 ```