well, I noticed that mapping seems to be a bit confusing to some people, so I thought I'd do a little walkthrough about it.
Mapping
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This time Im going to go over several of the basic ways of mapping a texture onto an object. Ill get more in depth and cover basic UV mapping another time.
Planar Mapping
This will be our example for this part: http://img28.photobucket.com/albums/v83/th...parky/map01.jpg (64k)
This is what I use the most. This takes your texture map and projects it straight in from the x, y, or z axis:
http://img28.photobucket.com/albums/v83/th...parky/map03.jpg (84k)
(note: Its easiest if you take a screen shot of your object from above (or whatever direction you want to map from) first, and then use that screen shot to make your map. Cut the map down so that it exactly fits your object. That way, if you scale it to fit, the map will fit perfectly without needing scaling within the program.)
The problem with this is that it maps the texture straight down the sides too, which causes unsightly stretching and thats bad.
http://img28.photobucket.com/albums/v83/th...parky/map04.jpg (80k)
So how can you fix this? One way is to alpha map it. Ill do a walkthrough on that later if people are interested.
A simple fix is to just make the edges all one color preferably a color that wont be easily distinguishable from the rest of the texture. This single color part only needs to come in from the edge by a couple pixels, because if the drop is straight down it will only stretch the edge pixels.
Heres an extreme example of how that works:
http://img28.photobucket.com/albums/v83/th...parky/map05.jpg (80k)
Spherical and Cylindrical Mapping
These should only be used for spheres and cylinders. With anything else youll get nasty and obvious stretching.
Heres why you shouldnt just use planar mapping for a sphere:
http://img28.photobucket.com/albums/v83/th...parky/map08.jpg (76k)
http://img28.photobucket.com/albums/v83/th...parky/map09.jpg (80k)
That same stretching problem is back, only its all over the sphere. Luckily, you can map spherically. This is like taking your map and actually wrapping it around the object.
http://img28.photobucket.com/albums/v83/th...parky/map10.jpg (80k)
Youll have to be careful when you make spherical maps, however. Keep in mind that it will squeeze the ends in and the middle will bulge out, so making the middle section more squeezed in and the top and bottom of the map stretched out, it will compensate for the stretching that happens.
Spherical mapping can be done around any of the axes:
http://img28.photobucket.com/albums/v83/th...parky/map13.jpg (note: here you can see the stretch and bulge of the map quite well, this original map was a grid.)
Cylindrical mapping is similar, except, obviously, its for cylinders.
Youre taking a map and wrapping it around the cylinder, like a label:
http://img28.photobucket.com/albums/v83/th...parky/map15.jpg
Something to keep in mind is that the map will have to go all the way around, so you might want to do a little math to figure out the surface area youre going to cover, so that your map doesnt end up stretched out like this:
http://img28.photobucket.com/albums/v83/th...parky/map16.jpg
Once again, if you either alpha map or leave a few same colored pixels at the top and bottom, it wont stretch over the top, which will look bad.
Theres also cubic mapping, Im not all that into it. Its pretty simple, so Ill just show you with a picture:
http://img28.photobucket.com/albums/v83/th...parky/map17.jpg
Im going to do more complicated stuff once school is over, so stay tuned.
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This post has been edited by sparky : 02 November 2004 - 02:34 PM