- Gimp [You are not allowed to view external links. Register or Login to see them]
- Normal map plugin for Gimp [You are not allowed to view external links. Register or Login to see them]
- Generating the normal map
Just open or import the color map on Gimp. Go to Filters -> Map -> Normal Map
You'll see a window that shows options for the normal map it's gonna generate. Click 3D Preview to see how it'll affect the texture in game. Change the shape to sphere on options. You can move the lights too.
You may need to change the filter to adjust the sharpness and invert X and/or Y axises. When you're satisfied with the looks of the 3d preview, press OK and export the generated normal map as a TGA image.
- Generating the cosine power map
If the texture has too many areas that shouldn't reflect ligts, it's best to use the normal map to generate the cosine power maps. You can also use the colour map to generate the cosine power map. To do that you'll just need to do what's written in the parentheses on the second step.
Import the normal map into gimp. Go to Colors -> Colorify, select white and press OK. (you can also do this by converting the image to grayscale, but there's a chance of fucking it up when grayscale is used.)
Go to Colors -> Invert (you may probably not need to invert the colours if you're using the colour map to generate the cosine power map)
Go to Colors -> Brightness & Contrast
You'll need to adjust the brightness and the contrast to make the image darker or lighter depending on how you want the cosine power map to look.
Since what the cosine power maps basically do is to show the engine which parts of the texture will shine, the image below will do a decent job for the texture i'm using.
Note: I know some of you might think it's stupid to use the normal , but based on my experience, generating the cosine power maps using the normal sometimes gives you better results on some textures. For example, if you generate the cosine power map by converting the color map to grayscale and darkening it, it'll make the cracks shiny too; but if you generate them with the normal map, the ares that shouldn't shine like cracks will stay dark.
- Generating the specular map
What specular maps basically do is adjust the intensity of the reflection on a surface. So you'll just need to adjust the brightness and contrast depending on how you want it to shine. The image below is how i made the specular map for the texture I'm using.
After generating each image, you can convert the material using the images you generated. You can see how my example looks in game in the video below.
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You can also see how it affects the weapon models below.
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