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Creating Terrains - Patchwork Shaders |
Page 4 of 7 |
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The Alpha Fade system uses a special set of shaders which are only visible in the
editor. These textures are colour coded and have a percentage number which indicates
the level of the alpha transparency.
The shader file supplied with the
example map
for this article has 6 standard defined
percentage values of 0,25,50,75,85 and 100. Other values are possible as the alpha
range is 0 to 100 percent. (Actual shader values are 0.0 to 1.0)
Certain alpha values work better than others, but ultimately it always depends on the
alpha channel of the texture and the DotProduct2 parameters used.
Good additional values to try are 70,80 and 90 as they produce nice fine blends ideal
for gradual slopes or borders.
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Alpha Fade Shader explained |
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textures/terrain_example/alpha_000 // Primary texture ONLY
{
q3map_alphaMod volume
q3map_alphaMod set 0
surfaceparm nodraw
surfaceparm nonsolid
surfaceparm trans
qer_trans 0.75
}
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- Line 1 : the name of the shader prefixed with an alpha_ to help with sorting
in the texture window. Remember these shaders can go anywhere you like, but for this
example I have included them in the same directory as the rest of the resources.
- Line 3 : Tells the compiler that this is a special Alpha Fade Shader. A brush
must use this shader on all sides otherwise it will not work correctly. This is a volume
function similar to water, fog etc.
All vertex points enclosed within a brush painted with this shader will have their
alpha values changed. This process can also be fine tuned by the use of func_group
entities. Meaning that the Alpha Fade function will only try and affect brushes which
are included in the same func_group and nothing else.
- Line 4 : Tells the compiler what value to set the alpha channel fade to.
This is a specific value and will discard any previous value found. The possible range of
values which can be used is 0.0 to 1.0.
- Lines 5-8 : Various shader commands to remove this shader surface from the game
and set the transparency of the shader in the editor.
Special note: All Alpha Fade brushwork can be filtered in the editor with ALT+4
(Translucent)
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The terrain shader is setup with the moss as the primary texture (alpha 0) and the
mud as secondary. (alpha 100) The Alpha fade editor brushes are clearly marked
to help see which is primary and secondary.
The first problem is that the path lacks any kind of definition, so use the Alpha
Fade brushes as poles and plot out a route. remember to use the alpha 100 shader as
its the secondary texture which is required.
Once the initial path line is in place, then check to see what the terrain looks like
in game. Always try to allow the DotProduct2 system to create the blends first and
then fine tune the terrain afterwards. Otherwise you will end up with a lot of
Alpha Fade Brushes and not much organic looking blending.
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