HA4 Task 2 - Displaying 3D Polygon Animations

API

Application program interface also referred to as API, is a set of routines, protocols, and tools for building software applications. You can tell when you have a good API because it makes it easier to develop a program by providing all the building blocks. A programmer then puts the blocks together. This makes a big job small. 

When you are operating in environments, such as Microsoft's Windows, you should provide an API so that programmers can write their own applications consistent with the operating environment. Although APIs are designed for programmers, they are ultimately good for users because they guarantee that all programs using a common API will have similar interfaces. This makes it easier for users to learn new programs. And it makes it clear for you to use at the end of the day. 

Direct 3D 

Direct 3D is an API for Displayed and Manipulating 3D Objects in other words making an object do its job. It was developed by Microsoft to ensure that, Direct 3D provides programmers with a way to develop 3-D Programs that will utilize whatever graphics acceleration device is installed on the machine. All 3-D Accelerator cards for PCs support Direct 3D.  

OpenGL

OpenGL is a 3-D graphics language it was developed by Silicon Graphics a well-known company. There are two main implementations which are Microsoft OpenGL which was developed by Microsoft and Cosmo OpenGL which was developed by Silicon Graphics. Microsoft OpenGL was built into Windows NT and is designed to improve performance on hardware that supports the OpenGL Standard. Cosmo OpenGL, on the other hand, is a software-only Implementation specifically designed for machines that do not have a graphics accelerator.

Graphic Pipeline 
In 3D Computer Graphics the meaning of Graphic pipeline or rendering pipeline is simply the mathematics used in a game it is where the image or object is imputed into a game it is the way the object will look or how it is presented to the person who is viewing the object or item. It is the three-dimensional primitive as input and results in a 2D raster image as output. OpenGL and Direct3D are two notable 3d graphic standards; both are very similar graphic pipeline.

Stage of Graphic Pipeline 

During complete 3D scene the light is defined by the location of the light sources, reflectance, and other surface properties. Older hardware implementations of the graphics pipeline compute lighting that is only at the vertices of the polygons that are being rendered. The lighting values between vertices are then interpolated during rasterization. Per-fragment or per-pixel lighting, as well as other effects, can be done on modern graphics hardware as a post-rasterization process by means of a shaded program. Modern graphics hardware also supports per-vertex shading using vertex shades.

Clipping 

Geometric primitives that now fall completely outside of the viewing frustum will not be visible and are discarded at this stage. In other words it is when you get rid of the background of an image for example a building you would get rid of what’s behind it because you wouldn’t be able to see it so it would make your job easier to render the image if there is nothing going on behind it so therefore it will overall make your job easier.

Project transformation 

If or when you are using a perspective project, you will notice that objects which are distant from the camera are made smaller. This is created by dividing the X and Y coordinates of each vertex of each primitive by its Z coordinate which represents its distance from the camera. If there is an orthographic project, objects retain their original size regardless of distance from the camera.

View Port Transformation 

Post-clip vertices are transformed once again to be in window space. To do this it is very simple: Apply a scale (Multiplying by the width of the window) and a bias (adding to the offset from the screen origin). At this point, the vertices have coordinates which directly relate to pixels in a raster.

Scan Conversion or Rasterisation

The Term Rasterisation is the process in which the 2D image space representation of the scene is converted into raster format and the correct resulting pixel values are determined the from now on, operations will be carried out on each single pixel. This stage is rather complex, involving multiple steps often referred as a group under the name of pixel pipeline. 

Texturing Fragment Shading

During this stage of the pipeline individual fragments (or pre-pixels) are assigned a color based on values interpolated from the vertices during rasterization, from a texture in memory, or from a shader program. 

Display   

This is the final colored pixels which can then be displayed on a computer monitor or other display. It is your final product of what you have made it is the overall best in which the product can be or get too.

Bibliography
http://www.ozone3d.net/public/jegx/201006/directx-logo.jpg
http://i95.photobucket.com/albums/l157/Menty17/textureandOpenGL.jpg