Element_To_Draw & WolfMapViewer — Drawing architecture

This tutorial explains the object hierarchy used for rendering in the WOLF GUI.

• Element_To_Draw — base class for all drawable objects

• WolfMapViewer — the main OpenGL viewer (wxPython wx.Frame)

Note — WolfMapViewer requires wxPython and an OpenGL context. This notebook focuses on the architecture and what can be done headless. For full GUI usage, see the GUI video tutorials.

Inheritance tree

All objects that can be displayed in WolfMapViewer inherit from Element_To_Draw:

Element_To_Draw
├── WolfArray / WolfArrayModel     (raster grids)
├── WolfArrayMB                    (multi-block arrays)
├── Zones                          (vector data)
│   ├── PictureCollection          (georeferenced photos)
│   └── ImagesTiles                (tiled raster images)
├── Wolfresults_2D                 (2D simulation results)
├── Triangulation                  (triangulated meshes)
├── cloud_vertices                 (point clouds)
├── SyntheticDike                  (dike geometry)
├── crosssections                  (cross-sections)
└── ... (bridges, weirs, particle systems, ...)

from wolfhece.drawing_obj import Element_To_Draw

Element_To_Draw — base interface

Every drawable object exposes these core attributes and methods:

elem = Element_To_Draw(idx='my_layer', plotted=True)

print(f"Identifier : {elem.idx}")
print(f"Plotted?   : {elem.plotted}")
print(f"Bounds     : x=[{elem.xmin}, {elem.xmax}], y=[{elem.ymin}, {elem.ymax}]")
print(f"MapViewer  : {elem.mapviewer}")

Identifier : my_layer
Plotted?   : True
Bounds     : x=[0.0, 0.0], y=[0.0, 0.0]
MapViewer  : None

# Toggle visibility
elem.check_plot()   # plotted = True
elem.uncheck_plot() # plotted = False
print(f"After uncheck: plotted={elem.plotted}")

# Attach to a viewer (normally done automatically)
# elem.set_mapviewer(viewer)

# Compute spatial extent (overridden by subclasses)
elem.find_minmax(update=True)

After uncheck: plotted=False

Key methods to override in subclasses

When creating a new drawable class:

Method	Purpose
plot(sx, sy, xmin, ymin, xmax, ymax)	Render in OpenGL context
find_minmax(update)	Compute spatial bounding box
show_properties()	Display properties dialog
check_plot() / uncheck_plot()	Visibility toggle hooks

class MyCustomLayer(Element_To_Draw):
    def __init__(self, data, **kwargs):
        super().__init__(**kwargs)
        self.data = data

    def find_minmax(self, update=False):
        self.xmin = self.data[:, 0].min()
        self.xmax = self.data[:, 0].max()
        self.ymin = self.data[:, 1].min()
        self.ymax = self.data[:, 1].max()

    def plot(self, sx=None, sy=None, **kwargs):
        if not self.plotted:
            return
        # OpenGL rendering code here...

WolfMapViewer — the GUI viewer

WolfMapViewer is a wx.Frame that manages a list of Element_To_Draw objects and renders them in an OpenGL canvas. It handles:

• Layer management: add/remove arrays, vectors, results, etc. via the tree panel

• Pan & zoom: mouse-driven navigation

• Querying: tooltip shows values under cursor

• Actions: profile extraction, zone statistics, polygon analysis

Opening the viewer from Python

import wx
from wolfhece.PyDraw import WolfMapViewer

app = wx.App()
viewer = WolfMapViewer(title='My Viewer', w=1024, h=768)

# Add a WolfArray
from wolfhece.wolf_array import WolfArray
wa = WolfArray(fname='path/to/data.bin')
viewer.add_object('dem', newobj=wa)

viewer.Show()
app.MainLoop()

Main object lists in WolfMapViewer

Attribute	Type stored
myarrays	WolfArray, WolfArrayMB
myvectors	Zones
myclouds	cloud_vertices, cloud_of_clouds
mytri	Triangulation
myres2D	Wolfresults_2D
mypicturecollections	PictureCollection
myimagestiles	ImagesTiles

Model / GUI pattern

Many wolfhece classes follow a Model/GUI split:

Model class (headless)	GUI class (wx)	Purpose
WolfArrayModel	WolfArray	Raster grids
wolfpaletteModel	wolfpalette	Color palettes
header_wolf	—	Spatial metadata

Use Model classes for scripts, tests, and notebooks; GUI classes when running inside WolfMapViewer. See the architecture tutorial.