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| "Procedural Modelling to fake a double sweep surface modelling method" and "Chrome" |
| Author: Martin Poirier (Aka theeth) |
| Topics: Modelling Techniques and Textures |
| Difficulty: Medium large all dressed wihout onions |
| Introduction | |||
| Hi, welcome to my tutorial. In this tutorial, two subject which I'm sure you will appreciate. First, I'll explain a procedural modelling technique that can be used to fake a tool found in other program (like Amapi) called double sweep surface modelling. ShOOOla gave me the idea to do a tutorial on that after explaining it to some people on the Blender Chat forum. Second subject will be a description of Rixtr66 (aka the chrome guy) chrome method. Thanks to him for giving me the ok to tell his little secret (Personnaly I would have waited AFTER the F1 challenge is finish, but that's his business  ). To all you people, a good reading and a good day! 
Oh yeah, I almost forgot: In the .blend file, the objects before applying Dupliframes are on layer 2 and the results are on layer 3 (with the Chrome material). Other stuff (like lighting) is on layer 1. |
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| DOUBLE SWEEP?? Will I need a broom to do that? | |||
| The Double Sweep modelling tool works like this: you
supply the program with any number of 3D curves that will control the
outline of a shape. Blender has no such tool as is, but you can easily do
it with procedural modelling. Now, what exactly is procedural modelling? In short, procedural modelling is any technique that let you modelling an object without having to manually edit the state of the object. It can be as simple as Duplivert, or as complicate as using a Python script that will do it giving some user setting. No no, don't panic, I'm not going to ask you to code something, this is a very simple yet powerful method. That method used NURBS Surface and Dupliframe to create smooth curved objects. Basicly what it does is this: Dupliframe makes a virtual copy of the object's data at each given frame in an interval. These copies will take into accound posotion, size and rotation variations. I.E. you can animate the Dupliframed object with IPO, Path curves, but NOT vertex keys (unfortunatly), because of the way it works (it makes virtual linked copy, so if the base object changes, all the other copies change). The Dupliframe button (and the button linked to it) are located in the Animation Buttons window ("F7"). How it works: Pressing the Dupliframe buttons turns it on and off The DupSta and DupEnd buttons control when the duplication starts and ends The DupOff button sets an offset value that will determines how much frame does Blender need to skip between each copies. The technique I'm going to describe (it's not MY technique, as other people have though about it before) also takes advantage of a NURBS feature called Skinning. Basicly, you take any number of NURBS Surface curve and that method will strech a surface between the CVs (Control Vertice) while keeping the order of the CVs in each curve. That is, the 2nd CV in the curve will link to another 2nd CV. WARNING:Skinning in Blender only works if the surface curves have the exact same number of CVs. How it works: Select any number of surface curves (they must be joined before) and press the SHIFT+"F" keys. As simple as that!  |
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| ON WITH THE SHOW! | |||
| Now, here's the full Step By Step way to do it, for those
of you that needs it. -> Create a curve path (Add - Curve - Path) -> Create a surface circle (Add - Surface - Circle). I've include a screenshot of the toolbox menu for that step since, by personnal experience, that's the place where people makes a major mistake and choose (Add - curve - circle) instead. -> Parent the surface circle to the curve path CTRL+"P" You may have to clear the origin of the surface circle with ALT+"O" to have it sit on the curve path -> Keyframe the surface circle along the path (ARROW UP ARROW DOWN ARROW LEFT ARROW RIGHT and "I") You should only keyframe Size and Rot, since Loc will be defined by the curve path -> Go to the Animation Buttons window ("F7") and press the Dupliframe button You might want to set the DupOff walue to something greater than 0, to have less copies while maintaining a sufficient smoothness -> Press Make Dupli Real hotkeys CTRL+SHIFT+"A" DO NOT UNSELECT ANYTHING when you make the copies real, Blender will automaticly select them The original object is still the active object, so: -> Go to the Edit Buttons window ("F9") next to the name of the surface data (in blue) at the right of the header, there will be a number indicating the number of time that data is used. That's right, you guessed it, making the duplication real only create linked copies of the curve. -> Press the number button next to the surface name. Click on the pop up to confirm We've just isolated the data of the curve, so that any change to the copies will not reflect on the original object. Just in case you need to redo it. -> Move all the surface curves to another layer ("M") -> Select the original surface curve and move it back to where it was before whistling... "trying to find a passage back to the place I was before..." sorry, I got carried away! -> Now, select all the copies with box selection bode "B" Box selection doesn't change change the active object though. -> Select any of the surface curve with RIGHT MOUSE CLICK -> Join them in a single object (CTRL+"J") -> Enter Edit Mode "TAB" -> Select all the surface curves "A" -> Skin them SHIFT+"F" Now, the result can be a little messed up, so play with the Cyclic option [icon#c] and the settings in the Edit Buttons window "F9": Uniform(U, V) , EndPoint(U, V). That's it for this part! |
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| CHROME: MY PRECIOUSSSSSS | ||
| Ok, here's the deal: the material file is in the example
blend file that comes with that collumn, so I won't describe all the aspects of the technique, but only the most important ones High Spec value (around 1.5) Low Hard value (around 35) Basic material color: Black Maxed out Ref value: 1.0 A little Ambient value (around 0.2) A fake black and white environement map. It can be just about anything as long as there's some gradient changes in it. The one in the file is particularly good at it. That texture is mapped with Refl to the Col, Mir and Ref channel A real envmap mapped the same way to the same channel, but with a lower Col value. The view point of that envmap (the "Ob:" field in the Texture Buttons window) must be in the middle of the object, but must NOT render it (use the Don't Render Layer buttons). Another envmap' mapped the same way to the same channel as the previous two, but this one must render the object the chrome will be mapped to. It has an even lower Col value than the other, and a SizeX and SizeY value different than 1.0. All these settings must be tweaked a bit, so it can fit your scene perfectly, but it's a really good start. Thanks Rixtr66 for sharing that with us! |
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| THAT'S ALL THERE IS TO
WRITE ABOUT THIS
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| That's the end! If you like it, come back next CJ for
more! In the mean time, if you have any suggestion or comments, BIM (For
the newbies out there, that means "Blender Instant Messager") me if I'm
online or drop me a mail at theeth@yahoo.com. I hope you've learned something, if not, you may be too good for me (or you might be [insert your favorite Blenderhead's nickname here] )! Martin |
Files: Procedural.blend |
