Wednesday, 21 May 2014

Cartesian Co-ordinates

Cartesian Co-ordinates
An example of 3 point axis (X,Y,Z)
Cartesian is a co-ordinate system which shows points on a graph. On a graph there is two points which were made up, X and Y. The X value represents where the point is horizontally (left and right) so the Y value would represent the vertical value (up and down). This theory was invented by Rene Descartes. The proper explanation for his invention  was "allowing reference to a point in space as a set of numbers, and allowing algebraic equations to be expressed as geometric shapes in a two-dimensional coordinate system". The co-ordinate system has been around since the 17th Century and has been adapted from then to now. This is important today because this co-ordinate system is used today for nearly all 3d modelling software. A key thing added to the system was the value for depth or 3d space. It was thought the 3 point axis was needed as there was no way to display a number in 3d space so the Z axis was invented. The Z axis represents horizontal but a different direction to X (forward and back). The axis are all at a 90 degree angle and are simple for people to use.

Axis picture with the origin point 
Origin
The origin point is the most central point in a co-ordinate system. In a 2 point axis is it point (0X,0Y). In a 3 point axis it the same but with the Z co-ordinate so (0X,0Y,0Z). It is known as the area where the axis is the system intersect.

Monday, 4 February 2013

Comparing 3d Software Appications

3ds max
I have used 3 different 3d application software which all have different pro's and cons. I'am going to compare these from my experience. The first software is called 3DS Max by Autodesk. It is a software where you create models for a game for example. Its good for making characters and objects but very complicated to use. Since the UI is so complicated its hard for people to make what they want. This is good for rendering out still images and animations of your models.

Secondly is Sculptris which is a modelling software which follows the same physics of clay. It is made by Pixologic. This software is good for making characters using precise shapes.In this you can make very detailed models where you can mould the character yourself using very easy tools. The good thing about Sculptris that 3DS Max doesn't have is a easy to use interface. This is very important as Sculptris makes it very easy to make a basic model and you don't have to research into it loads so make a starter model.

Sketchup
Thirdly is SketchUp which is made by SketchUp . This is good for making environments and buildings. This is because it uses simple shapes which work well in making buildings. The main use of SketchUp is for architects to make buildings and see how they will plan out size-wise. Since its used for buildings, all its tools make it easier for you to make shapes and manipulate them to look how you want. The disadvantage is that you cant make models of a weapon for example but then you just use another software. When you have made your environment you can then export it into 3ds max and edit it or texture it since 3ds max has a more in depth features.

Autodesk Maya is a mix between Sculptris and 3ds max. The program mixes 3d modelling with animation mainly revolving around characters and people. There are alot of other programs out there which are similar to this. The two main programs that I have tried myself are Blender and 3D Canvas. Obviously Maya is the better choice because all around they're more features, less limits and a lot more professional. The main trade off is the price since Blender and 3d Canvas are free whereas Maya varies but can go up to 7000$.








Thursday, 17 January 2013

Graphics Pipeline and Shaders

The graphics pipeline is the process the GPU goes through to display 3d graphics in a game for example. There are various steps in this process which you don't see since it needs to complete them multiple times a second.

The first process is Vertex Processing also known as Pre-vertex lighting and shading. This is the process where is plots out all the vertices of the shapes in camera view. This is needed for a later stage because it needs to know where each model is to then display them in view.

3D Projection










The second process is clipping. This determines what can be "seen" and what can't. This varies when the game is being played as it changes once a second, maybe even more. To do this the GPU works out the co-ordinates of each of the vertex's and the distance between that and the camera. By doing this it can work out what is behind the other. Since it can't be seen at that precise moment it can hide it and not display it, saving processing power while doing this making the game run smoother overall.

Thirdly is projection transformation. This is a set of complicated calculations to again work out distance from camera. Basically this is achieved by dividing the X and Y co-eds by each of their Z co-ord. The end product of this is that no matter where the camera is, the object will keep its original size which is important for the proportion of them in the game.

Next is a process called rasterization. This is when it converts the image to a raster format. Raster images makes it so it works out each single pixel and doesn't resize it in real time. This makes it so it doesn't lag out the game and cause problems. This starts a whole other process called pixel pipeline.

Next is texturing and fragment shading. This is basically just texturing all the visible objects with the correct texture. This is done so you can tell what each item is and to make the game look better. Lighting is also done in this stage. The type of lighting changes depending how advanced the game is. The types are flat shading , gouraud shading and phong shading.

Finally the last process is display. This displays the view onto the screen for the player to see.It colours the final pixels so it can be displayed on a monitor.

Tuesday, 27 November 2012

Constraints Of 3D

Why do poly counts matter
All type of polygons have constraints. If there is too many polygons it can effect the game in many ways such as lower frame rates , slow scrolling , slow zooming , game freezes , system freezes , graphic related errors  and graphic anomalies.

Personal Computer
The polygon constraints on a pc varies massively because developers make games with different benchmarks to run on a vary of pc's. It mainly depends on the game and what software is out at the time. For example Half Life 2 in 2004 - Alyx Vance had 8323 polygons which was a main character. A more common character where a couple would be on screen at once had around 4682. A more recent high demanding game such as Crysis in 2007 for the main character uses round 60k - 80k whereas a teammate uses round 22k - 24k and an enemy korean solder round 12k - 16k. This shows the constraints of a game can change rapidly. The thing about polygons on pc is that it can handle a lot higher than consoles if you have a high spec pc.
Polygons in head

Home Console
The current generation of consoles have increased the amount of polygons it can handle. The max a large model can have on the ps3 is probably 150k polygons since Lair had that amount on the dragon and that game had quite a lot of fps lag.On a smaller model than a such as a car in gran turismo 5 a car had 200k polygons.On the Xbox 360 a launch game such as gears of war for the main character had 15k polygons because it was badly optimised. A game like lost planet had loads of polygons used. A main character would have round 17k polygons but the background had an estimate of 500k polygons. The cap on consoles is a lot lower than pc's but is still quite high. The advantage of making of making a a game for a console is you have a set limit of how much polygons and quality of textures you can use.

http://gamrconnect.vgchartz.com/thread.php?id=126802

Polygons of car in xbox game
Mobile Devices
Mobile devices have a much lower polygon count that consoles and pc since it has greater limitations since it has smaller processors. They would only have a max of round 50k for the iPhone 3gs

Example of a game on the iphone