Culling Methods

Three hundred thousand triangles pose a problem because it creates alot of work for the CPU and the graphics card. To tackle this problem programmers created culling, a process in which the engine removes all invisible and non-essential polygons.

The difference between marketing and real world polygon rates is that the marketing polygon rate is the rate that the card can theoretically reach and the real world rate is what the card can actually achieve.

The lowest rendering unit that can be achieved is a primitive, which for most hardware is a three-point polygon (triangle).

The advantages of using a higher-order surface like patches is that it can create a higher polygon rate and has been the basis of new and experimental technologies. The disadvantages of using it are that it is not standard over all graphics cards and that it is somewhat of an expensive to buy a card that does support higher-order surfaces like patches.

There are two main types of occlusion culling. The first type is called PVS (Potentially Visible Sets), this method divides the scene into regions and pre-computes the visibility of them. These visibility sets are then indexed at run-time to obtain high quality visuals sets quickly. The second type is called portal rendering. This method entails dividing the scene into cells/sectors (rooms) and portals (doors), and computes which sectors are visible by clipping them against portals.

These are the five stages of the Basic Graphic Pipeline.

Stage 1: The Game determines what objects, models, textures and animations that will be in the game world. It also determines the positioning of the camera.

Stage 2: The game passes this information to the renderer. In the case of the models, the renderer will look at the size of the model and where the camera is located, and then it will determine if it is onscreen or off.

Stage 3: Then the world visualization system determines where in the world the camera is located, and what sections polygons are visible from the camera viewpoint. This can be done in numerous ways, from a brute force method of splitting the world up into sections, to the more elegant BSP (Binary Space Partitioned) worlds.

 Stage 4: Then the renderer transforms all the polygons that pass through according to their world mathematics and it’s local mathematics, it then examines the polygone to determines if it is back-faced or not. Those that are back-faced are thrown away. Those that are not back-faced are lit.

Stage 5: The renderer then looks at what textures the polygon uses and it ensures that the graphics card/API is using that texture at it’s rendering base. At this point polygons are fed off to the rendering API and then onto the card.

Z buffering makes the rendering of textures less important but it does not make polygons that have transparency in them less important. They have to be rendered after all the non translucent polygons are done, so what’s behind them can be shown correctly in the scene.

Here are two examples of API’s. The first is DirectX for Microsoft Windows and the second is OpenGL which is a cross platform graphics API.

Hardware-accelerated transform & lighting is a program that is used to render polygons and what ever you are trying to drawat the correct angle and position in the world relative to where the camera is positioned.

The benefit of patches are that instead of listing masses of polygon positions in the gaming world, it uses a mathematical expression instead. This makes it alot easier to build and deform a mesh of polygons by changing the equation.

Retesselation is when a low polygon mesh is converted to make a higher polygon mesh. This makes the mesh alot smoother and better looking. 

Genres

Film

Horror – Intended to scare the audience.

Action – Generally involves a moral interplay between “good” and “bad” played out through violence or physical force.

Romance – Focuses on romantic love.

Comedy – Intended to make the audience laugh.

Mystery – The progression from the unknown to the known.

Adventure – Generally involves danger, risk and/or change, often with a degree of fantasy.

Drama – Focuses on character development often in situations familiar to the general audience.

Thriller – Intended to provoke excitement and sometime nervousness within the audience.

Music

Rock – A popular form of music with a prominent vocal melody which is accompanied by guitars, drums and bass.

Folk – Traditional music that has been made popular due to the way it relates to the common people.

Reggae- Jamaican music developed in the late 1960’s, made popular by the unique rhythm styling that it has.

Country – Music developed in rural areas, it is a blend of popular music and folk music.

Jazz – Music which originated around the early 20th century in African American communities.

Pop – Popular music that can belong to any number of musical styles that are accessible by the general public.

Heavy Metal – Genre of music that was developed in the late 1960’s and early 1970’s. With roots in blues and psychedelic rock.

Hip Hop – Style of popular music developed in the late 1960’s and early 1970’s, originating from Jamaica and the South Bronx, New York in the early 1970’s.

Blues – Vocal and instrumental style of music which originated in the southern United States in the late 19th century.

Electronic – Music that focuses on the use of electronic instruments. It originates from the late 19th century and the early 20th century.

TV

Children’s Television – Popular form of television which focuses on a child audience presenting shows which are made for children.

Situation Comedy – Genre which started on radio but made the transaction to television. Sitcoms focus on a group of recurring characters in a common place.

Game Shows – Genre which focuses on contestants attempting to win money or prizes through a series of games or challenges.

Reality Television - Genre of television which focuses on unscripted comedy, dramatic events which involve real life people.

Sports Television - Genre of television which focuses on sport.

Science Fiction Television -Television which focuses mainly on science fiction senarios often involving some sort of fantasy.

Video Games

Action Games -The video game equivalent to an action movie. They portray the on going battle between “good” and “evil”.

Adventure Games - Game involving danger/risk and some sort of prize at the end.

Shooter Games - Games revolving around guns and weapons. The majority of these games are either 1st or 3rd person shooters.

Role Playing Games -Game genre where you take control of a character and go on a quest through many different environments to find something.

Platform Games -Game involving a character who travels from platform to platform, many of these game are side-scrollers.

Simulation Games -The aim of this genre of game is to simulate an expirience, whether it be flying and aircraft or fighting a war.

Sport Games - Game which focuses on a sport activity whether it be playing the sport or managing a team.

Horror Games – Game genre which intends to scare the audience and make them jump.

Strategy Games – Game which requires the player to think and strategies to win.

MMO Games - Game type which is played online with many other players. This genre tends to be Role Playing Games.

Level Design

To be a successful games designer the quality that I would value most is a tremendous experience in traditional art or architecture because if it doesn’t look nice no one will want to play it.

A digital architect is a person who creates spaces and buildings in a virtual world; they are usually employed by either games companies or architectural firms. They would build levels for a game company or build 3D representations of a future building for an architectural firm.

With Moore’s Law in place the processor speed of the games engine doubles every eighteen months which means that the quality of the builds that are created will increased tremendously.

Level designers are often referred to as chefs because instead of just throwing stuff into the pot they have to judge what will work and what will not to make a successful game that is going to sell.

 Peer criticism can be a good thing because it can help a game become better. This can be done by telling a designer about areas that can be worked on and areas that can be removed if necessary, though sometimes it can be bad if it is not constructive or helpful.

To make a good level it is best to plan everything out on paper first and then use some improvisation during level design to make it a little bit better.

Frame rate is important because it will depict if a game runs smoothly. Frame rate can be sacrificed for more detailed levels. Sometimes when the games pace slows down the frame rate can be lowered to increase the detail in a particular part.

Raster Graphics

A Raster Graphic image is a group of rectangular grids called pixels which form together to make an image.

Here is an example of a Raster graphic Image.

 Raster Graphic Images are viewable via a computer monitor, paper, or other display medium. Raster images are commonly stored in image files with varying formats.

 Each pixel has an individually defined color; images in the RGB color space, for instance, often consist of colored pixels defined by three bytes — one byte each for red, green and blue. Less colorful images require less information per pixel; for example, an image with only black and white pixels requires only a single bit for each pixel. One can distinguish raster graphics from vector graphics in that vector graphics represent an image through the use of geometric objects such as curves and polygons.

The Importance of a Renderer

The CPU spends 50% of its total processing time on the renderer.

The acronym “API” stands for Application Program Interface.

 

It is more difficult to develop a renderer for a PC than for a console because the hardware for the PC can be changed and upgraded over time.  

Vertices are points in space which when you connect then you get a 3D object.

 

The renderer in a games engine can be replaced, for example if a game is being developed for a PC and a console they can swap the PC renderer for the console renderer.