What is OpenGL® selection?
OpenGL® collection in computer programming is the process of determining the object within the three -dimensional (3D) scene is located at the point on the screen as soon as the scene is depicted. It can also refer to the location of multiple objects at a point or inside the box. Most often, OpenGL® collection is used to determine what 3D object on the screen is trying to select using the mouse cursor. Although this operation may seem simple, there are several fineness in how OpenGL® portrays a scene that can be quite complex. In addition, there are internal defects in certain graphics cards and controls that can cause OpenGL® selection function and return false results.
When a user looks at the 3D scene on the computer monitor, the resulting picture is known as the scene rendering. The scene is actually stored in memory as a collection of primitive shapes or polygons, which in itself is only collections of 3D points in the space. The computer uses world coordinates that are sometimes called AbsolutCoordinates, to perform most of the basic functions that manipulate objects in the scene. In most applications, the user is able to maneuver the view of the scene at different angles, so objects can be seen in different perspectives. The user's virtual location in the scene is called the camera angle or the camera position.
The complexity of OpenGL® selection comes from determining the location of the mouse on a two -dimensional (2D) screen from perhaps any position and angle inside the scene, the camera position. In addition, because plotting from the perspective of a human viewer is really 2D, there is no way to provide a user depth of the mouse click inside the scene. The OpenGL® selection function solves this complex problem in two ways.
The first is that instead of pervying a series of separate translation calculations, where the viewer is abstractly, and then finds an object in the plot window, the function actually portrays the scene as in normal operation, except that rendering afterUsed for selection is not only displayed to calculate the correct positions of objects. The difference is that instead of rendering the whole area that would be visible to users, only the area where the mouse is placed. This means that any rendered objects are technically at the point where the mouse indicator is located.
The second problem, and that it has no way to mark the depth of the selected area is solved by returning all objects that are under the coordinates of the mouse in the scene. OpenGL® selects all objects in the field along with how far they are from the location of the viewer. This allows the program to quickly find the nearest object if necessary.
One way of visualization of PENGL® SECONDS is to imagine a line, sometimes referred to as a beam in 3D programming, move from the location of the mouse pointer into the scene and far from the viewer's position. Every object that touches this beam is added to a number of objects, along with how far it is from the viewer. This is a very simple explanation of how one foOpenGL® RMA works.
Another method of selecting objects in OpenGL® includes finding an object by color and can be significantly faster. This method draws the scene, but instead of using lighting and texture on objects, they are instead rendered by a single simple color. Each object or group of objects has its own clear color. The scene is portrayed only in memory and is not displayed, so it does not affect what the user sees. Instead of searching for 3D collisions between objects, the color in the mouse cursor will return instead and this color will correlate with a particular object.