The model for interpretation of OpenGL commands is client-server. An application (the client) issues commands, which are interpreted and processed by OpenGL (the server). In this sense, OpenGL is network-transparent. A server can maintain several GL contexts, each of which is an encapsulated GL state. A client can connect to any one of these contexts. The required network protocol can be implemented by augmenting an already existing protocol or by using an independent protocol. No OpenGL commands are provided for obtaining user input.

OpenGL computes surface shading by evaluating lighting equations at polygon vertices.

The most general form of the lighting equation uses both the vertex position and a vector that is normal to the object’s surface at that position; this is called the normal vector. Ideally, these normal vectors are captured or computed with the original model data, but in practice there are many models that do not include normal vectors.

For any CAD developer who is developing interactive CAD application one of the important topic of interest is Selection or Picking. However this topic is not discussed in detailed in most of the OpenGL resources. I hope this article helps you understand basic techniques available for selection. The geometric models use complex representations such as NURBS surfaces and geometric solids that are typically converted to simpler representations for display. 

Browse Knowledge Base

Recommended By

Get Instant Updates

Subscribe to get instant updates about CFD courses, projects, blogs, webinars, software tutorials & CFD jobs

Search Knowledge Base

By Keyword

By Author

By Tag