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Amiga Plus Extra 1996 #6
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AmigaPlus-eXtra-6-96.iso.7z
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AmigaPlus-eXtra-6-96.iso
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programme
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a-render
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glossary.doc
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Glossary of Terms:
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3-D :
3-D stands for Three-Dimension. First, imagine a piece of paper. On a
piece of paper, you can draw in 2 dimensions, up-down and left-right.
These two dimensions can be called height and width. Now, 3-D is just
like 2-D, with the added dimension of depth. So, in 3-D, everything has
height, width, and depth. Example: A painting is generally 2-D (flat),
while a sculpture is generally in 3-D. (a sculpture has width, height,
and depth).
Coefficient:
Another word for MULTIPLIER, usually in the range of 0 to 1, including
anything in between. The diffuse and specular values for a surface are
set by coefficients. If you want a surface to reflect all the diffuse
light that hits it, use a value of 1. A value of 0 will reflect no
diffuse light. Fine tuning the diffuse and specular coefficients will
make the surface look shiny or dull.
Edworld :
An A-Render support program.
See A-RENDER.DOC for more information on using the Edworld program.
Define :
One of the core A-Render programs.
See DEFINE.DOC, and MORE_DEFINE.DOC for more information.
Diffuse Lighting :
See LIGHT.DOC.
Digitizer / Extruder :
A core program of A-Render, it helps us build objects for display.
For the best description of this, see DIGI.DOC.
Entity :
An entity is the attributes associated with an object. An object is
simply a geometric description, it has no location in our 3-D world,
it has no rotation, no color, and no lighting parameters. An entity
refers to one (and only one) 'parent' object for its shape, and
contains the parameters just listed.
So, to put an item in your scene, you must first build an object.
Then you make an entity that places that object in space, and specifies
the entity parameters as desired. Many entities can refer to one parent
object for their shape description. Each entity can have it's own
location, rotation, scale (size), color, and lighting parameters.
Global Lighting :
See LIGHT.DOC.
HAM :
HAM is the Hold-and-Modify mode of the Amiga, giving the capability to
display more than 32 colors at a time.
Image :
Generally, just another name for a picture.
Lathe :
A core program of A-Render. See LATHE.DOC for my best description.
Object :
An object in A-Render is the description of an item you want to put in
a scene. The object data consists of the X, Y, and Z points for all the
corners (verticies) of an object. Object data also includes a vertice
list for each polygon. This list is simply an ordered list of the points
required to describe each polygon.
An object is not a complete description of an item in a scene. See the
glossary entry 'entity' for more information on those.
Sometimes, in the early sections of this manual I used the word object
where it really meant entity, to try and limit confusion during your
introduction to A-Render.
Ray :
A ray is another name for a line with a specific direction. A ray is
specified by direction, in X, Y, & Z. A ray can also have a start or
end point.
Ray-tracing :
For my best description of ray-tracing, see RAY_TRACING.DOC .
Render :
The core A-Render program is called render. Also the process of
calculating an image can be called 'rendering'.
Scene :
The complete environment we have described to the computer. (aka world).
Specular Lighting :
See LIGHT.DOC.
Pixel :
A pixel is normally considered to be one dot on the screen. In A-Render,
to speed up the image, we may calculate less rays and blow up the size
of the displayed dot to occupy many screen pixels. This creates a
picture with a 'blocky' look. These calculated blocks, although they may
consist of many screen pixels, can also be called pixels.
View Pyramid :
The view pyramid is the description of the view parameters. Some of
the most important view parameters are the position and direction.
This is like placing a camera in a scene, and then aiming it.
Another parameter is the view plane, (your monitor screen). The size of
the view plane can be specified, along with it's distance from your eye.
This is like changing the lens on the camera for a different field of
view, or zooming in or out on a subject. When a scene is rendered,
render will generate the image as seen from the current view position.
(The current view is the one listed in the .world file for the current
frame.)
The name view PYRAMID comes from the imaginary pyramid drawn with 4
lines from the eye through the four corners of the view plane. Define
will display the view as a pyramid.
World :
The complete environment we have described to the computer.