Sculpt Textures in Paint Programs

For a better understanding of the processes described in this article, you may want to read Sculpted Prim Explanation.

While paint programs like Photoshop or Paint Shop Pro or The GIMP are no substitute for a good 3d modeling program, when it comes to sculpt textures, there are some pretty cool things you can do with those tools. The processes themselves are not terribly difficult but an understanding of how sculpt textures work can help quite a bit.

Manipulating Existing Sculpt Textures

Credit goes to Deanna Trollop for these tricks.

• "To scale along a given axis, keeping the positive/negative end of that axis fixed:
  • Using Levels, increase shadow/decrease hilight value of the desired channel (red for x, green for y, blue for z), respectively.
• To shift the entire model along a given axis:
  • Increase or decrease brightness of the desired channel. (Note, values that get "clipped" to pure black or pure white will cause the associated verts to "squish" against the side of the bounding box.)
• To mirror-flip the model on a given axis:
  • Invert the desired channel (transposing the verts on the + side to the - side, and vice versa) AND mirror-flip the image horizontally or vertically. (Skipping the second step would end up with a model mirrored and turned inside-out, because the vertex order of the polys would be reversed, similar to a 180 twist on a prim sphere)"

Vinnie Baxter adds the following to the above instructions to make symmetrical objects:

• Think of a symmetrical axis in the texture around which it should be symmetrical
• manipulate the different RGB channels:
  • for two channels just the good half should be copied, flipped and put at the opposite side
  • for one channel the good half should be copied, flipped, inverted and put at the opposite side - failing to do so gives a half/hollow object.. which could also be useful in some cases..

The only difficult part is to figure out which rules apply to which channel. Reasoning along these lines of thought it's easy to flip orientation by interchanging the R/G/B channels.

Argent Stonecutter suggests this methood of creating "bumpmaps" on a sculpted object like a sphere.

"The following scheme came to mind, as a way to create a bump on a sphere in any direction. I don't think it would work exactly as I've laid it out, but soem such scheme where you use the math-like operations in adjustment layers on maps should be useful... any thoughts?

• Create a layer containing the "unit sphere" map.
• Duplicate it
• Create a mask containing a fairly blurred greyscale blob.
• Create a multiply adjustment layer using this mask.
• Apply the multiply layer to the duplicate sphere layer.
• Add the layers."

Painting "Heightmaps" using RGB Channels

Pamagester Darracq figured out how to do this using Paint Shop Pro, but the same process should apply to any similar program.

• First you have to create a plane.
  • Go to the Channels pallate and select just the Red channel. Select white as a foreground color and black as the background color and create a horizontaly mirrored gradient, like so.
  • Now select the Blue channel and create a linear gradient like this.
• Now the pattern.
  • Select the green channel and the paintbrush tool, load the brush with a shade of grey and paint the pattern...the darker the color, the higher the bump.
  • "This might get tricky, the left half of the green channel is the front (top) section, the right side is the back (underside) section, so (to get them to line up if you create a low contrast image of what you want and paste it on both sides of the channel". Like so. Remember that sculpted prims can't be one-sided.
• When you're satisfied with your work, merge/select all your channels, save, upload and savor your results: the resulting sculpt texture and the rendered prim.

Converting Images to Models within the GIMP

Converting an image to a mesh is a simple process from within the GIMP. This script can be plugged into the GIMP to allow any RGB image to be exported as a Wavefront OBJ, which can be uploaded to a 3D modelling tool to preview what it will look like in Second Life.

Feed free to add more tricks to these pages!