HA4- Geometric Theory Task 3

 Geometry 

Geometry
3D computer graphics shows the exact same principles that are found in 2D vector artwork but use a better axis.when creating the 2D image the computer will draw the image by plotting points on the Y and X axis. The shapes can be filled with different colours and the lines with colour.


Geometric Theory and Polygons

The basic object used in mesh modeling is a vertex, a point in three dimensional space. Two vertices connected by a straight line become an edge. Three vertices, connected to each other by three edges, define a triangle, which is the simplest polygon in Euclidean space. More complex polygons can be created out of multiple triangles, or as a single object with more than 3 vertices. Four sided polygons (generally referred to as quads) and triangles are the most common shapes used in polygonal modeling. A group of polygons, connected to each other by shared vertices, is generally referred to as an element. Each of the polygons making up an element is called a face.

In Euclidean geometry, any three non-collinear points determine a plane. For this reason, triangles always inhabit a single plane. This is not necessarily true of more complex polygons, however. The flat nature of triangles makes it simple to determine their surface normal, a three-dimensional vector perpendicular to the triangle's surface. Surface normals are useful for determining light transport in ray tracing.

A group of polygons which are connected by shared vertices is referred to as a mesh, often ferred to as a wireframe model. 

http://en.wikipedia.org/wiki/Polygonal_modeling


Primitives

In most 3D applications, pre-created objects can be used to make different types of shapes, the very basic of shapes are the Standard Primitive shapes  or the common Primitives, these shapes can vary from the from a very basic cube or a box to spheres. they are used as the foundations and then they can be edited once created.