2010 September 25 / j|d|a|v|i|s|@|c|a|r|l|e|t|o|n|.|e|d|u

Introduction

Bopagopa is a basic 2D/3D graphics library for Python. The user creates 2D objects such as rectangles and text and 3D objects such as spheres and boxes. Bopagopa handles the drawing and redrawing of the objects using OpenGL and GLUT. It also provides hooks for user interaction via keyboard and mouse. The 2D objects are drawn in an "overlay" layer above the 3D objects. Most Bopagopa programs fall into one of two categories: 2D applications, and 3D applications with a 2D user interface superimposed.

Bopagopa comes in two versions: Bopagopa and Bopagopa Jr. New users are recommended to start with Bopagopa Jr.; the tutorials and demos deal only with it. The relationship between the two versions is this:

• Bopagopa is more flexible than Bopagopa Jr., and more difficult to use. It implements a high-level interface, with a lighting model similar to classic OpenGL's, but using shader programs for high performance and great generality. Graphical objects are constructed by connecting data sources (e.g. meshes, textures) to various geometric and material properties (e.g. vertices, material color, material shininess). The user is allowed — in fact, required — to write small chunks of OpenGL Shader Language (GLSL) code to specify how the data sources connect to the geometric/material properties.
• Bopagopa Jr. is less flexible than Bopagopa but less difficult to use. The user is not required — but is also not allowed — to customize Bopagopa's behavior with GLSL code. Essentially, Bopagopa Jr. is Bopagopa with the following choices locked in. 2D objects have a single uniform color and a single texture, and the uniform color modulates (tints) the texture color. 3D objects have a single uniform color and a single texture, and the uniform color modulates the texture color; the resulting color is used in diffuse and ambient light reflections; there is no emissive light or specular light reflection.

Bopagopa includes utility functions for creating common geometric shapes such as rounded rectangles, annuli, surfaces of revolution, boxes, tc. Arbitrary triangular meshes are fully supported, but they are not easy to construct currently, because there is no mesh editor and there are no importers for common 3D file formats.

Bopagopa is loosely integrated with the Open Dynamics Engine (ODE). Each Bopagopa window possesses an ODE World; each 3D object possesses an ODE Body. With these, the user can perform arbitrary rigid-body dynamics and collision detection.

There is currently no friendly user manual for Bopagopa. On the other hand, there are 16 tutorials and two demos that demonstrate how to use Bopagopa Jr. Also, all classes, methods, and functions have docstrings; the user-facing ones are listed in this HTML reference.