Lighting

API (Application Programming Interface):

An API is an interface that uses source code that a computer application will use to help with requests for services given by a computer program. Its basically a gateway between two programs that will use code to do different functions on one of the programs.

Examples of an API:

• Google search API
• Java API
• GoogleMaps API
• WebMail API

Lighting Offered By OpenGL:

There are three different lighting used in OpenGL, these are Vertex lighting, Polygon lighting and pixel lighting.

Advantages And Disadvantages Of Using Vertex Lighting:

The advantage of using vertex lighting is that the hardware can normally help speed up the process using hardware transform and lighting  (T & L)

The disadvantage of using vertex lighting is that it does not support shadowing, e.g. when a actor has lighting on his body in areas where you normally get shadow, you dont.

Transform and Lighting:

Transform is the process when abit of world space is transformed into a 2d screen view.

Lighting is added after the transform has happened and is added to all the objects in view.

 Shaders:

Shaders are the algorthm that shows how lighting is used and how lighting responds to lighting on an object.

Light Maps:

A light map is premade static light used in games/programs.Light maps are still used today in games because they are a very cheap way to show some lighting.

Tron 2.0

Rendering – Fogging

Why Is Fogging ‘Handy’?

Fogging is handy because it fades the world in the distance so you dont see models and landscape popping up as they come in view.

What Is A Clipping Plane?

The clipping plane is the area where models and landscape come into view to the player.

Is Volumetric Fog Considered To Be An Object Or A Result Of Distance From The Camera?

Volumetric fog is considred to be an actual phusical object rather than a result of distance from the camera.

What Is Volumetric Fogging Like?

Volumetric fogging  is like walking through a big cloud.

What Is A Read – Modify – Write Operation ?

This is when a pixel may have to be changed or combined with another pixel, so the pixel is taken out and edited/combined with another pixel and then put back in the same place.

Name And Describe Two Blend Modes.

The first blend mode is straight Alpha blending , this just simply adds a percentage of background pixel to an inverse percentage of the new pixel.

The second is additive blending, this is when it takes a percentage of the old pixel and then just adds a specific amount of new pixel (rather than a percentage).

Rendering – Anti-Aliasing

What Does Anti-Aliasing Actually Do To Pixels?

When rendering a polygon the graphics card will look at what has already been rendered and then blur  the edges so you dont get jagged pixel edges that would normally be visable.

How Many Ways Are There For A 3D Card To Generate Anti-Aliased Images?

There are two ways for a 3d card to generate anti-aliased images, the first is an approach at the individual polygon level.This requires for you to render polygons back to front of the view, so each polygon can blend with what is behind it.

The second is that you render the whole frame at a much larger resolution that you intend to desplay it, and then when you scale the image down you sharp jagged edges tend to blended with the scaling.

Pro’s And Con’s

When using the first approach if you render out of order you can end up with all sorts of strange effects.

As for the second approach you can get nice results but requires a large amount of memory bandwidth because the card has to render more pixels than are in the resulting frame.