Ok, so here's a real quicky... you want nice thick edges around your characters?
You want soft edges? You want edges that have texture and line variation? You
want edges that have a gradient on them? Here's how you too can do this. The
limits of this technique are that if your polys aren't connected to other polys
(as around the edge of the models neck in the examples) it wont work there,
but it will work around shapes with hard edges (better than fresnel) in fact
softer edges do give it more of a hard time, so in combination with fresnel
you should get some pretty nice effects. This method will never replace a dedicated
toon render engine as there are flaws, but for the meanwhile it can get some
excellent results.
This is based on an old technique and workaround that those of you who've used
Lightwave might remember. I've also seen tutorials on doing this in Max too,
so I'm just showing all you C4D users the light.
To begin with you have to duplicate the object you wish to outline (so if your
object is ultra complex this might not be the way to go for you).
What we're going to do is use Decal Shading (which is where one side of a polygon
has a different texture to the other side. The easiest way to think of this
is like a playing card. On one side it has an image of the card value, maybe
that's the Queen of Hearts. On the other side it usually has a decorative pattern,
mostly there to make sure that you can't see the value of the card through it
if it's a cheap set. Ok, got that?). This will allow us to basically show the
backside of the texture, but not the front. What we're going to do is scale
up our object based on it's normal's, and then texture it so that you see the
larger object's back faces. Here's how:
The Basic Shader
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Make a new texture, call it outline, or edge, or whatever you feel comfortable
with. First off switch off everything apart from Transparency
and Displacement.
Go to Transparency and put in a BhodiNUT
Buffy channel. This will cause only the back faces of
the polygons to be visible.
Go to the Displacement channel and put in a BhodiNUT
Gradient, take out the middle colour tag on the gradient,
and change both colours to white (so you've just got a solid white colour).
We're using a displacement to make this model larger than the original
(this is how we create the outline). Change the Maximum Height
value to something that suits your models size (this is the width of the
outline). Then make sure the Strength is set to 100%
(this just makes sure that the outline will be set to the Maximum height
value).
Next to make the texture of the original object flat shaded (like a cartoon)
go to the Render Settings dialog box and in the Effects
section add a Cel Renderer Post Effect, then in the Cel
Renderer options make sure that Color is checked,
and then check Quantize, and bring the Steps
down to 2. Keep Edges unchecked but Outline
and Illumination checked.
Render.
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A More Advanced Shader
Click here to see quick movie
(very basic glove puppet boning i warn you):
Small and cruddy
Smoother
but larger
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This is just taking the Basic Shader
a step further, and adding our own custom cel shader to the original object
to give us a little bit more control.
Start out with the Edge shader from the last tutorial. First off we might
want the colour to change within out lines, but we don't want it to be
affected by illumination (although you can get a great embossed effect
if you use the Color channel with no shadows using a
Render/Compositing Tag). So what we do is switch off
the Color channel of the material, and switch on the
illumination channel.
In the Illumination channel we can put in whatever texture
we want to appear through the lines, because Luminance isn't affected
by lighting it will appear nice and flat (just how we want), we could
just colour it or if you wanted you could put in noise to make the line
grainy, or a fresnel gradient (although it would have to be quite small
and close to the 90 degree angle for it to be visible) to make the line
tube like. What we're going to do is simply put in a Gradient so that
the line at the bottom of the object is Black, but at the top is Red.
Now because we're taking this a stage further we're going to play around
with a tint across our object too. So to start off add a BhodiNUT
Fusion, Edit this and enable the Alpha, put
a BhodiNUT Buffy in the alpha channel,
and add a BhodiNUT Gradient to the bottom
channel (this is the back of the polys), and edit it. In the gradient
options change the settings to match the following:
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Next put in another BhodiNUT Gradient into
the top channel of the Fusion. Edit the gradient so that it's just got two black
swatches in it (this gives us a plain black colour which is all we want, the
tint will be created by changing the transparency of this black... we could
have put anything into this channel, this is the tint layer for us.
Now click OK to exit the Fusion, and from the drop down next to the text "BhodiNUT
Fusion" in the Texture block, select "Copy Channel".
Go to the Transparency channel and from the same drop down
on that page select "Paste Channel" to paste our fusion into the transparency
channel. What we will want to do here is make the transparency gradated while
keeping the solid back faces solid. So edit the BhodiNUT Fusion
and start by editing the top channels gradient. With transparency remember that
white is transparent while black is opaque. So change the gradient type to a
2D-V and change the two colours in it so that the leftmost
one is a medium to light gray, and the right most colour is white. Press OK
to go back to the Fusion and now change the bottom gradient so that it's all
black (we want the back faces solid remember, although you could again put anything
here... if you wanted the line to fade out as it left the object then a fresnel
might do the trick, or a good noise or texture might make the line look hatched,
experiment to see what you can do). The alpha should just remain a BhodiNUT
Buffy. Press OK to finish editing the Fusion.
The line is still very even so now lets change that to make a more organic
line. Go to the Displacement channel in the material and add
a BhodiNUT Noise to it. Edit the BhodiNUT
Noise and change the settings to make the noise nice and large,
to give a good uneven line shape across the surface (without being too frenetic,
or causing sharp edges to appear where there shouldn't be), you can even animate
the noise if you want that hand-drawn line flickering, changing shape effect.
Now the Edge Shader is complete, time to move on and start editing the original
objects shader to make a nice basic cel shader.
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Create a new Material for the original objects surface.
in this material we only want the Luminance channel switched on (although
it will still be convincing if you use Bump, Displacement, and Alpha, I'd
suggest leaving it at that if at all possible). |
| Now the simplest way possible to make a cel shader
using Smells Like Almonds is colorize a BhodiNUT
Lumas shader (which gives you the luminance of the surface)
and change the gradients interpolation in the BhodiNUT
Colorizer to "None", that way the colours of
the gradient will be nice and stepped, and will give you the cel shades
that you want. However I want to give my cell shader more of a graffiti
spray paint style, so I'll guide you through how to do this. |
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Start by adding a BhodiNUT Fusion
to the Luminance channel. Edit it, and in the top channel
put in another BhodiNUT Fusion, this we will use to get
our spray can texture using overlay, in the bottom channel put in a BhodiNUT
Colorizer, this is going to give a gentle cel shade and colour
to the surface. |
| Edit the BhodiNUT Colorizer and add
a BhodiNUT Lumas channel to it. Change the ramp to give
you three clearly demarcated ramps, going left to right, dark to light.
These would normally be our cell colours, but I want a slight softness to
their edges. |
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| Next edit the BhodiNUT Lumas channel,
and switch off all the specular layers, then go to the Diffuse
layer of the Lumas, and change Illumination to 100% and
the Color to white. Click OK and then copy the BhodiNUT
Lumas channel (as we're going to use this elsewhere). Then click
OK to get out of the BhodiNUT Colorizer and go back to
the Fusion. |
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Edit the BhodiNUT Fusion in the top channel and paste
the BhodiNUT Lumas that we copied into the top channel
of the fusion. |
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In the bottom channel make a new BhodiNUT 3D Noise
channel, edit it, and change the scale of the noise right down so that it's
pretty small. |
| Click OK to get back to the second BhodiNUT
Fusion channel, and change the Mode (blending
mode) to "Levr". What this does is it takes the top channels luminance
and depending on the luminance of the bottom channel outputs either white
or black, so it's like using a hard light blend and then upping the contrast
al the way, although it does work in reverse! |
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This means that as far as we're concerned
the dots of the noise will get larger as the Lumas channel gets
darker, until they merge together. You can create some wonderful
line art style work by using a good texture in the bottom layer,
or even a tiles layer with a really wide grout (to make the tiles
soft edged) and this fusion on it's own in the Luminance
channel would make another great line art cel effect, or even a
nice random sketchy effect in photoshop, blurred and brought in
to the bottom channel would give a great sketched look.
On top of this you can use a BhodiNUT Colorizer
to change the colour of this, so it needn't be just black and white,
or even only a single colour (if you lower the opacity of a Levr
you lower the contrast at the edge, and Colorizer works on the luminance
of an image) |
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Some samples of different tiles patterns
and noise patterns using this technique |
Take down the Opacity slider a little bit to around 85%,
as we don't want completely harsh edges and click Invert Output. as Levr on
it's own works in reverse! Click OK to go back to the original Fusion channel,
and change the Mode to "Overlay", if you want you
can lower the Opacity a bit to get more of your Colorizer cell
shading showing through. Click OK again to go back to the Luminance
channel of the material. Make the Mix "Multiply"
and change the colour of the channel to match your objects colour,
Now change the Cel Renderer settings in the Render Settings dialog box, so
that Quantize is switched off and you're ready to render.
To carry on...
Further experiments with this can give nice planetary atmospheric halos, and
other effects. You can also blend in a BhodiNUT Fresnel in the luminance channel
of your cel shader and ramp it up with a black edge to help with the edge shading.
Another thing you can do to give you real time feedback of the edge shading
is to either use a Smooth shift operator on your object to scale it up as much
as you want (for the edge) or to use DiTools to give you real time feedback
for the displacement map in the Edge Shader (remember to turn off the actual
edge shader's displacement otherwise it will be twice as large). Then rather
than using Buffy, you can make a front face shader (usually totally transparent)
and a back face shader (whatever colour you want your lines to be) and just
apply these directly to your object, and in the settings for how the materials
are applied make sure that they're set to "Front" and "Back"
Side respectively. That way you should get real time toon shading
directly in C4D's view ports!
Files
The More Advanced Texture Files (ZIP) |
