|
Like any
medium, there are limitations that an artist needs to work within
to turn their ideas into reality. Creating objects, clothing,
and environments in low poly 3D is no different. Depending on
the capabilities of the engine you are building for, you may
find yourself having to think of some very creative workarounds
to reach the final effect you are after.
|
Currently
IMVU does not support "spot lighting", this is the ability
to shine a light on an object, which highlights some areas (nearest
the light source) and allows other areas to fall back into shadow.
To achieve this effect without the light source we need to come up
with a way to "paint" these highlights and shadows on the
surface of our models.
In the world
of theater, where the light isn't, is frequently more
important than where the light is. Shadows act as
the framework around those areas the designer wishes his/her audience
to focus. Shadows also help define the surface of a material, and
can even enhance the sense of the solidity of an object. Best of
all, shadows can trick the eye into believing there is more detail
in an object or environments then there actually is. This is especially
handy when all you have to work with are a few polys and a handful
of textures.
The world of
the computer is a mathematically perfect one. A place without the
organic asymmetry that we are accustom to in the natural world.
This is why 3D environments can sometimes feel sterile and cold.
With everything at right angles, and every texture applied like
wallpaper, it can be an uphill battle to create places and objects
that feel "real" or natural.
|
Before & After
examples of Scene without, and with Vertex Paint applied
In this example,
you can see what this interior model looks like with just the
textures applied to it, but no further detail. The image on the
right is the same room with Vertex Paint applied to it. Although
there is no true light source, the shading applied to the surface
using the vertex paint suggests that light is coming through the
window, casting shadows on the far wall and illuminating the sidewalls. |
Vertex
Painting in 3D Studio Max
Many
3D software applications include some method for shading, tinting,
or painting the polygons beyond just the textures applied to
their surfaces. 3D Studio Max includes the ability to Vertex
Paint geometry, but it is a little misleading to call this "painting"
since your control of how the final painted object will appear
depends a lot on the way the 3D engine interprets the vertex
paint information applied to it. This being so, I prefer to
think of this as more "vertex tinting" since your
actual color results may vary from model to model, 3D engine
to 3D engine.
|
|
I also
consider this a "wide brush" approach, rather then
a fine precise tool, since how the tinting appears on your model
depends on how the geometry is constructed beneath it.
|
Above
is a screenshot of the Vertex Paint window within
Max. These are the tools you will be using most
while painting your models. |
|
|
When you
are painting (or tinting) the surface of your model, you are
not actually applying color to the surface of your polygons;
you are applying information to the vertex points and suggesting
how the color will project from that point onto the surrounding
polys. The effect can be very convincing if done correctly,
but if applied incorrectly, can expose the unflattering limits
of your geometry.
. |
In
the example to the left, a bright red color has been
applied to the uppermost vertex and it radiates onto
the poly surface nearest to it |
In some
cases, adding a little more geometry in strategic places
will give you a much better effect then leaving it out,
and can actually allow you to use less texture detail since
the vertex tinting will be doing a lot more of the aesthetic
work for you.
A good
rule of thumb is that a "grid" construction in
your mesh is better for vertex lighting then stretching
your polys to the extreme. The grid allows you more control
over how the vertex tinting will appear on the surface,
while the stretched polys will give you less desirable results.
|
|
<
In this example the application of the vertex paint is more effective
on the grid mesh on the left, than on the more "fractured"
mesh to the right. |
Vertex
Paint Tips & Tricks
Painting
in Shadows
If your model lacks depth, the easiest method is to just paint
them in! Create a color that is darker then your model and suggest
lighting applying it to those areas you wish to suggest are furthest
from that light source.
Example:
Shadows painted in the corners of the leather seat and under
the arm rests. >
|
|
|
Erasing
in Highlights
One of my favorite tricks is to use the Paint Bucket tool to completely
cover a model with a darker "shadow" color, then use
the Eraser tool to remove the paint from just those areas I would
like to suggest highlights. This is very effective if you wish
suggest drama and mood.
<
Example: Paintbucket used to fill entire model with dark
color, eraser then used to pull out highlights on bed cover and
on post details.
|
Blurring
to Blend Color
Because you are limited to the paint results only looking as good
as the geometry it is applied to, you are going to inevitably
have the edges of some polys appear on the surface of your model.
To minimize this you can use the Blur tool to soften the edges.
I also like to apply the Blur to the entire model, then come back
with the eraser to pull out the highlight once again before I
am finished.
Example:
My heavy handed application of vertex paint is softened by
the Blur Tool.
>
|
|
|
Painting
Generic Textures to Create Variety Inexpensively
Another handy trick is to create a base texture without color,
then paint that color in later with vertex paint. For these party
lanterns, I created a simple black and white texture then applied
it to each mesh and colored them separately within the model.
<
Example: These paper lanterns share the same white base
texture and have been colored using Vertex Paint.
|
Colored
Shadows
Many 3D computer games use vertex painting heavily to suggest mood
and age in their environments. As suggested earlier, they will choose
a shadow color and paint that lighting and aging in manually rather
then depend on their 3D renderer to do all the work. One of the
potential pitfalls comes when these game lean too heavily on gray
as their primary shadow color.
In
the real world light sources come in different colors, and any
first year art student knows that this means that the shadows
cast by that light will appear as the complimentary color of that
source. Although subtle, yellow sunlight casts a purple shadow,
orange a blue shadow, red will cast green, etc. Where this is
most noticeable is in flesh colors. Although next generation games
have stunning graphic capabilities, if the environmental ambient
colors, or vertex painted colors, applied to their characters
is gray their virtual human actors can look dead, or bruised.
Without closer attention paid to how shadow colors affect the
surface of objects you can end up with models that are dramatic,
but unrealistic.
In this
example, the two left-hand faces have been lit using an
unflattering gray ambient color, while the right-hand character
has been illuminated with a warmer color, creating more
appealing shadows. |
|
Too
Much of a Good Thing
I can fall into the trap of leaning too heavily on vertex paint
on my own creations, so be careful. Adding drama is nice but it
isn't appropriate for all situations. When in doubt, err to going
lighter with your vertex paint then heavier.
Example:
Proof that powerful tools in the wrong hands can be deadly...
yuck! >
|
|
Most importantly,
have fun and play around with what vertex paint can do for your scenes
and objects. Think of it as just another tool in your arsenal of tricks
to make your creations look great.
For more helpful
information on the use of Vertex Paint in your models, I highly recommend
the book, "Creating
the Art of the Game" by Matthew Omernick.
|