add spatial index building gif

Author: asinghvi17

docs/src/experiments/spatial_index_building.jl

@@ -0,0 +1,49 @@
+using CairoMakie
+import GeoInterface as GI, GeometryOps as GO
+using NaturalEarth
+
+
+using GeometryOps.SpatialTreeInterface
+import GeometryOps.SpatialTreeInterface as STI
+using SortTileRecursiveTree
+
+function build_spatial_index_gif(geom, index_constructor, filename; plot_leaves = true, title = splitext(filename)[1], axis = (;), figure = (;), record = (;))
+    fig = Figure(; figure...)
+    ax = Axis(fig[1, 1]; title = title, axis...)
+
+    # Create a spatial index
+    index = index_constructor(geom)
+    ext = STI.node_extent(index)
+    limits!(ax, ext.X[1], ext.X[2], ext.Y[1], ext.Y[2])
+
+    rects = Rect2f[Rect2f((NaN, NaN), (NaN, NaN))]
+    colors = RGBAf[to_color(:transparent)]
+    palette = Makie.wong_colors(0.7)
+
+    plt = poly!(ax, rects; color = colors)
+
+    to_rect2(extent) = Rect2f((extent.X[1], extent.Y[1]), (extent.X[2] - extent.X[1], extent.Y[2] - extent.Y[1]))
+
+    function dive_in(io, plt, node, level)
+        if STI.isleaf(node) && plot_leaves
+            push!(rects, to_rect2(STI.node_extent(node)))
+            push!(colors, palette[level])
+        else
+            for child in STI.getchild(node)
+                dive_in(io, plt, child, level + 1)
+            end
+            push!(rects, to_rect2(STI.node_extent(node)))
+            push!(colors, palette[level])
+        end
+        update!(plt, rects; color = colors)
+        recordframe!(io)
+        return
+    end
+
+    Makie.record(fig, filename; record...) do io
+        empty!(rects)
+        empty!(colors)
+        dive_in(io, plt, index, 1)
+    end
+
+end