18-06-2013, 02:53 PM
Clipping Model in Open GL
Clipping Model.doc (Size: 526 KB / Downloads: 16)
Abstract
Main aim of this is to illustrate the concepts and usage of clipping model in open GL. We have used input devices like mouse and key board to interact with program. We have used four sphere one among the other to explain usage of clipping planes. When we clip the sphere we can see all other spheres clipped also. We have also used wireframe draw mode with which we can understand concept of clipping very well. To differentiate between spheres we have used different colors for different spheres. We have added menu which makes the program more interactive. This project illustrates the usage of the clipping planes in open GL.
ABOUT GRAPHICS
What is a Graphics API?
A set of tools that allow a programmer to work in an application area. Thus a graphics API is a set of tools that allow a programmer to write applications that use computer graphics. These materials are intended to introduce you to the OpenGL graphics API and to give you a number of examples that will help you understand the capabilities that OpenGL provides and will allow you to learn how to integrate graphics programming into your other work.
Computer graphics, emphasizing 3D graphics and interactive graphical techniques, and show how OpenGL provides the graphics programming tools that implement these principles. We do not spend dine describing in depth the way the techniques are implemented or the algorithms behind the techniques; these will be provided by the lectures if the instructor believes it necessary. Instead, we focus on giving some concepts behind the graphics and on using a graphics API (application programming interface) to carry out graphics operations and create images.
What is Computer Graphics?
We view computer graphics as the art and science of creating synthetic images by programming the geometry and appearance of the contents of the images, and by displaying the results of that programming on appropriate display devices that support graphical output. The programming may be done (and in these notes, is assumed to be done) with the support of a graphics API that doesmost of the detailed work of rendering the scene that the programming defines. The work of the programmer is to develop representations for the geometric entities that are to make U the images, to assemble these entities into an appropriate geometric space where they can have the proper relationships with each other as needed for the image, to define and present the look of each of the entities as part of that scene, to specify how the scene is to be viewed, and to specify how the scene as viewed is to he displayed on the graphic device. These processes are supported by the 3D graphics pipeline, as described below, which will be one of our primary tools in understanding how graphics processes work.
OpenGL Fundamentals
This section explains some of the concepts inherent in OpenGL.
Primitives and Commands
OpenGL draws primitives—points, line segments, or polygons—subject to several selectable modes.
You can control modes independently of each other; that is, setting one mode doesn't affect whether other modes are set .Primitives are specified, modes are set, and other OpenGL operations are described by issuing commands in the form of function calls.
Primitives are defined by a group of one or more vertices. A vertex defines a point, an endpoint of a line, or a corner of a polygon where two edges meet. Data is associated with a vertex, and each vertex and its associated data are processed independently, in order, and in the same way. The type of clipping depends on which primitive the group of vertices represents.
Commands are always processed in the order in which they are received, although there may be an indeterminate delay before a command takes effect. This means that each primitive is drawn completely before any subsequent command takes effect. It also means that state-querying commands return data that's consistent with complete execution of all previously issued OpenGL commands.
Conclusions
The project “CLIPPING MODEL” is based on clipping in three dimensions.
This program illustrate usage of clipping planes in openGL using various functions. This also shows the different stages of clipping. This program illustrates the three dimensional clipping.
Finally we conclude that this program clearly illustrate the clipping process in three dimension and has been completed successfully and is ready to be demonstrated.