3D

3D graphics are a technique of creating/generating images with geometrically accurate shapes by simulating polygons - points in a space - and connecting them, creating a surface. 2D images mapped onto the 3D surface are textures. A 3D model showing no surfaces is a wireframe model.

The Utah Teapot is a standard reference object and injoke in 3D graphics.


GIF of panoramic view of 3D landscape, spinning, GIF of tesseract, a four-dimensional cube

Coordinate system:Cartesian, Cylindrical, Spherical

.obj model of cartoon duck .obj model of teapot


Primitive 3D

Primitive 3D, or 2.5D, is a technique in computer graphics that creates the illusion of 3D rendering (true 3D) while utilising simpler techniques which do not use all the aspects necessary for a "true" 3D render - an example are early FPS games where the "height" of objects was kind of arbitrary - players could not look up or down and rooms could not be placed above or below one another.

Sprites used in primitive 3D that always rotated to face the player/camera are billboards. There are two types: rotate around vertical axis, and free rotation (will follow camera up and down). There are also two types of rotation: projection plane aligned (rotate themselves in the same way as camera) and position facing

    projection plane aligned                           position facing

                 |                                          \
                 |                                           |
                 |                                            \

        _.'|                |                       _.'|                |
      <:_  |                |                     <:_  |                |
         '.|                |                        '.|                |
      camera                                      camera
                      |                                            /
                      |                                           |
              |       |                                     _    /
              |                                         _.-' 
              |

Animation