Learning 3D

Part 1
Part 2

Transparency & Refraction Index
Nothing to see here:D
Obviously if something is 100% transparent you can see right through it. In the real world when light enters or exits a transparent material it gets bent to a new direction (This is a gross simplification but all you need for this purpose). For a visual demonstration get a glass and half fill it with water stick in a straw or a pencil. where the straw goes behind the glass it seems to bend a little and where it enters the water it looks even more bent. At some angles it will look like the bottom of the straw is broken. this is all because of something called Refraction. You can set the Refraction Index in most 3D software. In this case I`m going to set it to 1.50 which would be a type of glass. It is now visible purely because it bends the light. This result looks good but it is not quite right. if you read The Elements of a Model you might remember that polygons have only one side- so when the light passes into the Glass ball it gets bent and as it exits the ball it is passing through the back of the polygon so it does not know it is back in the "air".
This might need a diagram
If you follow the path of the ray of light- the yellow arrow, see where it hits the surface, the dotted lines indicate the polygons normal or the direction it is facing. The light changes direction as it passes into the object, as it exits it doesn't hit any thing because all the normals are facing in the wrong direction, so the light continues in the same path as it was on (The Red Arrow). If the light "knew" that in was entering into air again it would be bent again like the blue arrow.

There is a way to do this. By copying the original object, flipping the polygons and giving it a surface called air( zero all the surface settings except transparency at 100% and Refraction Index at 1.0) then paste it back on top of the original object. This gives you a second set of polygons in the same exact position but facing in the opposite direction. Now the light will "know" it is exiting the glass and entering the air and will react more correctly.
This ran on longer and went more in depth than I intended. On to the next bit:wait:


Translucency
Allows light to shine through an object and will pass shadows through from the back of an object to the front. Very useful for thin objects such as curtains or leaves.














Bump
Very few surfaces are perfectly smooth, bump mapping creates the illusion of these surface bumps without having to build them in 3D, because they are fake, the illusion can be seen through by looking at the edges of the rendered object. Great for adding surface complexity without having to spent ages constructing geometry.








Smoothing
All the samples in my surfacing posts have had smoothing turned on, this is an example with it off. It looks at the angle between adjoining polygons and if the angle is below the Smoothing Threshold (defaults to 89.53) it smooths the surface between them.

This is a shot of the Surface Editor in Lightwave 3D 9
I am going to cover the first 3 Basic controls in this post(Colour, Luminosity & Diffuse). You can find the objects and scene file in Lightwave format attached in the zip file. If you want to follow along.
Anywhere you see this (Link) it is a place holder for a link to the relevant piece of information, which I have not written yet
LearningSurfacing.zip
Drag button. Click and drag to change the percentage in the corresponding field

Envelope Button. Click to open the graph editor(Link) Basically will allow you to change the value based on time.

Texture Button. Click to open Texture panel. Will allow the use of images, procedural textures or gradients(Link)




























Colour.
This is the basic color of your surface. It is fairly self explanatory but it will be effected in your final picture by all the other settings.













Luminosity
This is when a surface appears to give off light. used for things like the surface of a lit light bulb. It will not actually light up anything else in the scene unless you are using radiosity(Link) The second picture shows how it casts light when radiosity(Link) is enabled.


Diffuse
Diffuse is how much light is bounced back from the surface. The lower the diffuse the darker the surface will appear. It can be very useful for simulating dirt (Link) on a surface.
You can see above 3 different settings 10,50,200% in all of them the colour setting is the same but the diffuse is changed, resulting in a different amount of light being bounced to the virtual camera.