Texture Painting - Blender Master Class: A Hands-on Guide to Modeling, Sculpting, Materials, and Rendering - page 159

Switching to GIMP

With my basic colors laid out, I needed more
advanced painting tools to start blending colors and
adding details. Thus, it was time to move to GIMP.
I saved my texture in Blender as a .tga image (press
F3 in the UV Image editor to save the active image).
I then loaded the saved image in GIMP and began
cleaning up and smoothing out the colors I had
painted in Blender, fixing artifacts and filling in
awkward areas. This process is best done with the
Paintbrush tool, using a relatively large, soft-edged
brush to simply color pick (use ctrl -click to do this
without switching away from the Paintbrush tool)
from existing colors and blend areas together (see
Figure 11-9). (Another way to blend colors is to use
the Smudge tool and a grungy-looking brush, like the
one we created earlier in this chapter, to blend back
and forth between two areas, mixing their colors.)
To add detail to my texture, I incorporated the
ambient occlusion map I baked in Chapter 10. Using
File 4 Open as Layers, I opened my baked ambient
occlusion map as a new layer on top of my painted
texture.
I cleaned up this layer a bit, as I had done for the
rough diffuse color. For cleaning purposes, I used
GIMP's brushes and color picking, blending areas
that didn't look right with the Paint tool or using the
Clone tool to fill in areas while preserving texture.

Figure 11-8: Adding simple lighting and materials to make tex-
ture painting in GLSL mode easier. Here, I've added a couple
Hemi lamps and turned on GLSL shading.

* If you find painting in Blender becoming unrespon-

sive, create a lower-res mesh to paint on by duplicating
the sculpted mesh and applying the Multires modifier
at a lower level. Because this lower-res mesh shares the
same UV coordinates, you can paint on it and apply
the textures to the higher-resolution model later.

Layer Modes and Opacity
Initially, our ambient occlusion map is imported
as a normal layer on top of the texture, completely
replacing it. To rectify this, we can use GIMP's layer-
blending modes to find a more appropriate way to
blend the two.
GIMP's Layers dialog shows each layer in your
image (see Figure 11-10, with the Ambient Occlusion
layer selected and its blend mode set to Multiply).
At the top of the dialog, a drop-down menu lets you
choose the Selected Layers blending mode. Different
blending modes have different effects: Normal lays
one over the other, Multiply multiplies the values of
each pixel in the two layers together, and Add adds
them together. The Overlay mode causes the layer
to brighten or darken the layers below it, depend-
ing on its value—dark values make areas darker,
light values make them lighter, and mid-gray has
no effect. Experiment with a variety of layer modes
when combining images to find the one that works
best. To combine the ambient occlusion map with
my painted colors, I set the mode to Multiply.

Laying Out Basic Textures in Blender

I could now start laying out some basic textures on
my model. Using the Standard brush in Texture
Paint mode, I sampled from my palette of colors in
the UV Image editor and then painted on my model
in the 3D Viewport.
I began by using anatomical features as a guide
for colors, making bony areas lighter and yellower;
recessed areas, like the eyes, dark and purple; and
the back darker. I made areas with a lot of blood
flow or thin skin, like the wings and ears, redder
and slightly highlighted some of the muscles on
the torso and legs with lighter colors. I worked with
Occlude turned on in Project Paint, but Normal and
Cull turned off, as these settings allow you to paint
smoothly on the mesh even at side-on angles. At this
stage, the aim is only to establish a rough idea of the
colors you want.