Modeling the wheelsIt's about time to give our Lamborghini some wheels. So let's model one, which of course you can duplicate three times :-) We start with a reference image and will map that reference image on a rectangle. Create a rectangle (can be Analytical) and parallel map the reference image on it. To create a perfect square rectangle, just press and hold the Shift key, while creating the rectangle. Scale the rectangle to the proper dimensions, so it covers the wheel in the blueprint.
First create a new level called 'Wheel'. Then start with the profile (as seen from the front of the car) of the metal part of the wheel. Because your reference image is only 2 dimensional, you have to use your imagination a little to get this done. We use the NURBS curve tool to create the profile curve in front view. Remember that you need to click two or three times in the same place to create sharp corners! More clicks means sharper corners, but more then three points at the same place is useless ;-) When done, rename the curve to 'Profile'.
Take a front view and create a new horizontal two points NURBS curve, which will be used as a rotation axis for the profile curve. To create a perfectly straight curve, start the NURBS curve tool, click to enter your first point, press and hold the Shift key, move the mouse horizontally and click again. Move the rotation axis to the centre of the wheel. When done, rename this curve to 'Axis'.
Now we will rotate the Profile curve around the Axis. First make sure the profile curve is perfectly positioned at the top of the wheel, or else the wheel gets distorted. To do this, first select the Axis (in the Select Window), press and hold the Shift key and then select the Profile. Next, apply the Rotate tool from the NURBS tool bar. Before accepting the Rotate tool, set the Resolution to 12:
Accepting the tool creates the basic outer shape of the wheel. In the Select Window a new level is created, called 'mesh..'. Inside that level you will find both the profile curve and the axis curve. The good part is that you can now edit the shape of the profile curve and the mesh will immediately adjust to show you the new shape. So you can tweak the shape until you are satisfied with it.
Next, create a 12 point NURBS circle, which has the same radius as the inner side of the wheel.
In the Select Window, duplicate the red NURBS curve, and size the duplicate curve down. Use the Size tool and also check the 'About Pivot' option.
Make it just big enough to contain the inner wheel screws. See next image. Remember that the order in which you created the curves here is important. So a new curve should always be at the bottom of the hierarchy. The importance of this will be shown later.
Select both these curves in the same order you created them and apply the XSect tool from the NURBS toolbar. Use default tool settings. The result is that the space between the selected curves is closed. A new level, called 'Mesh' is added to the hierarchy in the Select Window. Rename this mesh to 'Wheel plate'. Change the view and check if the wheel plate mesh is correctly positioned and move it into position when necessary.
Now select the inner NURBS circle inside the Wheel plate mesh, duplicate it and make it just a little smaller (see next image). Then take the inner circle, duplicate and resize that, so it has just enough space for the centre axis of the wheel. Move the small circle just a little inwards (when seen from the side). Because these NURBS circles are also in the Wheel plate level, the shape of the mesh remains closed and a small cone is created at the centre of the wheel.
Make all the current wheel parts wireframe invisible (WF Inv), so we get a clear
view window and have room to model the other details on the wheel. As we can
clearly see on the reference image, the wheel plate contains five larger 'air
holes'. In the Wheel level, create a new NURBS circle (12 points will do)
that has the size of one of these large air holes in the wheel. Make sure
your circle does not touch the outer rim of the wheel (see next image).
To cut a hole in the wheel plate mesh, we use the Trim tool. The Trim tool icon is located at the far right of the NURBS toolbar. You may need to drag the NURBS toolbar a bit to the left to see the icon.
Using the Trim tool is easy. Select the 'large hole' circle, press and hold the Shift key and then select the Wheel plate level. Click the Trim icon and accept the tool. The NURBS circle is cut out of the Wheel plate mesh, leaving a nice hole. Also, after applying the Trim tool, a new object is added to the hierarchy. This is a so called 'trimcurve'. This curve defines where the wheel plate mesh is cut. Deleting the trimcurve from the hierarchy immediately restores the wheel plate mesh to its original state.
Because the Trim tool created the trimcurve inside the mesh level, we can now move our original NURBS circle to a new position and repeat the process. The Trim tool will add a new trimcurve to the hierarchy every time. This allows us to create the other four holes easily.
Working with trimcurves can cause an unexpected problem, which leads to terribly deformed meshes. The trimcurve has to lie within the UV space of the mesh (as mentioned in the RS user manual). See next image: It is not allowed to put circle B across the line between the starting points of the circles that define the cross section mesh. The starting point looks like a small triangle on both the outer and inner rings of the mesh (see arrow in next screenshot pointing at the starting point of the outer ring). If you break this rule, your mesh gets deformed! If this occurs, select the trimcurve in the hierarchy that causes the problem and open it's properties at the Spec tab. At the bottom of the Property Window, check both the Wrap U and Wrap V options and the deformation problem should be gone!
Later on we will add some more smaller holes to the mesh for the wheel screws. For that we will also use trimcurves and we know there is a good chance you will get into troubles at that point. The troubles again will be caused by the starting point of the mesh. Only this time the Wrap U and Wrap V options are not going to be much help, because later on we will use these smaller trimcurves in combination with the Weld tool. When the Wrap options are checked, the Weld tool does not work properly. So, we need to plan ahead in this case. As you may know, you can also change the starting point of either the mesh or the curves afterwards. The disadvantage of that solution is that it also affects on the holes you already made: they will change shape and position. Not what you want ;-) Have a look at the next image, that shows how the starting line only crosses the large hole, but not the smaller one. This is what we are aiming for eventually:
To give the 'air holes' the proper shape (also see reference image at the beginning of this chapter), we need to build 3D cylinder shaped objects from the curves. The process is simple: duplicate NURBS circle, scale, move a few times and finally apply XSect to create a cylinder shape. Each cylinder will consist of four circles. Then we will use instances to create 4 more cylinders. Here we go: Go to wireframe display. Select the 'large hole' circle in the hierarchy, press and hold the Ctrl key and drag the red transformation handle a little forward to duplicate the circle. Select the duplicate circle (called 'copy of large hole'), duplicate that again (use the Ctrl + d keys) and resize this copy: make it just a little bigger. Select the second duplicate curve (now called 'copy1 of large hole'), press and hold the Ctrl key and use the red transformation handle to move that a little backwards again. This again creates a new circle, called 'copy2 of large hole'. Now we have 4 curves. Multi select these in the order they were created, select the XSect tool again, set the Closed option and accept the tool. A cylinder shape is created. Also a new mesh level containing all 4 curves is added to the hierarchy. Rename the mesh level to 'cylinder'.
Now move the cylinder to the hole which we previously cut out from the Wheel plate mesh. To prevent render errors, we need to scale the cylinder down just a tiny bit, so that the trimcurve is between the inner and outer cylinder walls. See next image: the red arrow points at the trimcurve (dark red color).
With the cylinder created, it is easy to create the other ones using instances. An instance is created as follows: select an object, press and hold the Alt key and drag one of the objects transformation handles. Now you have an instance, which basically is a very memory efficient copy of an object. We created all the instances from the original cylinder object. To create the holes for the wheel screws, we perform the same procedure as for creating the air holes. Create a NURBS circle, rename it to 'wheelscrewhole' and use the Trim tool to cut holes in the 'Wheel plate' object. Note that you do not need to create cylinders, only holes. When done, you may want to save your work now!
The holes for the screws are shaped like cylinders pointing inwards. So we use the same procedure like we did for the air hole cylinders to add the cylinder shapes. Here we go. You may want to set the outer mesh, the cylinders for the air holes and the instances to WF Inv to clear the view. Select the NURBS circle, used to cut out the first wheel screw hole (we called it ' wheelscrewhole '). Make sure it is positioned a little behind the first screw hole you created in the Wheel plate (so, it's at the rear side of the wheel). Duplicate that NURBS circle and move it a bit backwards. Multi select both circles and apply the XSect tool. This creates a hollow cylinder and adds a new mesh to the hierarchy (see next image).
Create four copies of this cylinder and move them in position behind the other wheelscrew holes. To close the gap between the wheel plate and the cylinders we will use the Weld tool. The weld tool will add a so called Weld object to the hierarchy. Make sure the cylinders are not too far away from the trimcurves. In the Select window, select the trimcurve (in our example ' trimc53' ) and then multi select the cylinder (in our example called ' mesh9' ).
Click the Weld tool and in the Weld tool control bar set both 'Size1' and 'Size2' to a value of 0,05.
When you now would accept the tool the weld would probably not look good. You see a twisted mesh added to your scene. This is easily fixed before you accept the tool!
To fix the twist you have to tell the Weld tool which parts of the meshes need to be connected. Turn the view cam so you can see the cylinder from the side and press and hold the left mouse button and draw a line as shown in the next image. Make sure you stay inside the boundaries of the cylinder. Then rotate the view, so you also can see the wheelscrew hole and draw a second line as indicated in the other image. Then accept the tool. Repeat this process for the remaining wheelscrew holes and cylinders. Then save your work!
Just one more detail to fix. If you look closely to the reference image at the beginning of this chapter, it is clear that the air holes are not complete circles. This effect is easy to do. Just slightly tilt (rotate) the cylinders and move them into the outer rim of the wheel, so the wheel covers part of the cylinder. See next images:
When done you can render an image that looks like this:
Now save all your hard work before continuing! The BrakesWhen you take a look at the reference image of the wheel (beginning of this chapter), you can clearly see the Brakes (basically a disk with many small holes in it). We are going to use analytics, instances and the Macro recorder to build one. You can build the rest of the details yourself then ;) Make sure you saved your previous work, so you can clear the view window and start fresh. Take a front view and create an Analytic Cylinder and rename it to 'Brake'. Make it not too thick. The brake is punctured with many smaller holes and all these smaller holes are made in series of five. We will create these smaller holes using one small analytic cylinder and four instances of that cylinder. Create a small cylinder at the rim of the Brake (at the 12 o'clock position) and rename that to 'small hole'. See left side image. Take a top view and extend the small hole cylinder, so it sticks out on both sides of the Brake cylinder. (see right side image for top view).
Then, just like in the reference image add four more instances (not duplicates!) of the 'small hole' and place them diagonally below the first one. When ready, drop the small hole and its instances in a level (select them and press the 'd' key)
Now for the magic... Press the F8 key to invoke the Numeric Window. Select the small hole level (the one containing the instances) and from the top menu bar select Macros -> Record (Ctrl + m). This starts the Macro recording mode. All actions taken from here are recorded and can be played back later. Select from the top menu bar Edit -> Instance. A new instance of the 'small hole' level is added to the hierarchy. Select this new instance level, click the Transformation tool tab and click the Rotate icon. Click at the center of the Brake cylinder, click again at the cylinder called 'small hole'. Now the Rotate tool is activated. Move the mouse pointer to the Angle field in the Numeric Window and enter a value of 30. This rotates the instanced level 30 degrees around the center of the Brake, counter clockwise. Select Macros -> Record (Ctrl + m) again to end the macro recording. Now, with the new instance level still selected, press Ctrl + g to execute the current macro (the one you just recorded). Another instance with five holes is added to the hierarchy. Keep on repeating this macro, until you have created a circular pattern of small holes. See next image:
Almost there! Select the small hole level and all its instances and again drop these to a level. Your hierarchy looks now like shown in the next right hand image. Then multi-select the original Brake cylinder and the small hole level (containing all the instances!) and perform a Boolean Remove. After that your hierarchy looks like shown in the center image. A test render shows the Brake cylinder after the Boolean Remove.
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