cairosvg code

topologytool.py

@@ -147,7 +147,55 @@ class Topology:
         else:
             print("Elevation file does not exist, fetching")
             self.create_elevation_file()
+        # get png data to cols x rows grid
+        values = self.convert_png_to_data()
 
+        # now make a line drawing of it
+        surface = cairo.SVGSurface(self.target_region_name+".svg",
+                                   self.linemap_size[0],
+                                   self.linemap_size[1])
+        cr = cairo.Context(surface)
+
+        # Background
+        cr.set_source_rgb(1, 1, 1)
+        cr.paint()
+
+        # Simple Orthographic Projection Matrix (pseudo-3D)
+        # Projects (x,y,z) -> (x+z/2, y+z/2)
+        def project(x, y, z, xscale=20, yscale=10, offset=(0, 0)):
+            shelf = 0 if z == 0 else z + 2
+            shelf = z
+            return (offset[0] + x * xscale, offset[1] + y * yscale + shelf)
+            # return (offset[0] + x * scale + z * 2, offset[1] + y * scale + z * 2)
+
+        rows, cols = values.shape
+        max_val = values.max()
+
+        # Normalize data for visualization height (0-100)
+        norm_data = (values / max_val) * 100
+
+        # Draw Lines along rows
+        cr.set_source_rgb(0, 0, 0)  # Black lines
+        cr.set_line_width(1.0)
+        x = 0
+        y = 0
+        for r in range(rows):
+            for c in range(cols):
+                z = norm_data[r, c]
+                x, y = project(c, r, -z, xscale=800 / cols, yscale=800 / rows)  # -z to make higher values go "up" in 2D
+                if c == 0:
+                    cr.move_to(x, y + 50)
+                    cr.line_to(x, y)
+                else:
+                    cr.line_to(x, y)
+            cr.line_to(x, y + 50)
+            cr.close_path()
+            cr.set_source_rgb(1, 1, 1)
+            cr.fill_preserve()
+            cr.set_source_rgb(0, 0, 0)
+            cr.set_line_width(1.0)
+            cr.stroke()
+    surface.finish()
 
 def main():
     topology = Topology(country="Switzerland",