threeD_window.c

Description

threeD_window.c is a source code file from the bpdemo application. It is not a standalone command-line tool. This file is responsible for creating and configuring the window intended for 3D visualization.

A key feature of this file is its support for two different rendering backends, controlled by a global GL_flag:

  1. A standard Motif DrawingArea for 2D graphics.
  2. An OpenGL widget (GLwDrawingArea) for hardware-accelerated 3D graphics.

The presence of extensive OpenGL setup code and debug statements suggests that this was a feature under development.

Functionality

void create_ThreeDShell(Widget parent)

This is the main function in the file. It is called during application startup to create the 3D window and its associated widgets.

  • OpenGL Initialization: If the GL_flag is set, it attempts to find an appropriate X11 visual that supports OpenGL and create a GLX rendering context. This is a prerequisite for any OpenGL drawing.
  • Window Creation: It creates a DialogShell titled “3D OpenGL demos” and a Form widget to manage the layout.
  • Drawing Widget: It creates the main drawing area widget (DA3D.widget). The type of widget created depends on GL_flag.
  • Callback Registration: It attaches the necessary callbacks and event handlers:
    • draw_threeD is set as the exposeCallback to handle window redraws.
    • resize_threeD is set as the resizeCallback (for the OpenGL widget only) to adjust the glViewport.
    • threeD_events is registered as the event handler for mouse and keyboard input.
  • Popup Menu: It creates a context menu (threeD_popup) with three placeholder options for the 3D window.
  • Final OpenGL Setup: If using OpenGL, it makes the rendering context current and sets up a default projection matrix and other initial GL state variables.

void resize_threeD(Widget w, ...)

This is a callback function used only when the application is running in OpenGL mode. It is automatically called when the 3D window is resized. Its sole purpose is to call glViewport to inform OpenGL of the new dimensions of the drawing area, ensuring that the rendered scene is not distorted.

This file provides the necessary framework for a 3D view but relies on draw_threeD.c for the actual rendering, which appears to be incomplete.