Over recent years, OpenGL has tremendously evolved, and a significant change occurred in the year 2003. With its new programmable pipeline (OpenGL 2.0), it allows you to have direct access to the GPU and these programs are known as Shaders. As this previous version was using the fixed pipeline but appearance of this constitutional way changed the face of OpenGL programming which makes it far more difficult to program but gave a robust tool. This blog gives details about shaders, their types and a step-by-step example of rendering a triangle in the OpenGL window. Both legacy OpenGL and modern OpenGL code blocks are given for comparison.

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.

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.