Ceci est une ancienne révision du document !
As I promised for this month, we will introduce Bezier Curves.
Bezier curves (named by the French engineer Pierre Bezier) are used in computer graphics to set the coordinates for a smooth curve really easily.
Lets see what we are talking about. Start a new project in Blender and get rid of the cube (select the cube, press X to delete and confirm).
Now, press Ctrl-A to add a Curve–>Bezier Press R for rotation, X for the X-axis, and 90 for the degrees of the rotation. Then, press Numpad-1 for Front view and Numpad-5 for orthographic view.
You should have something like the image below
Lets press the Tab key to enter the edit mode. You can see a strange looking shape of something like a fish skeleton or pointing arrows – whatever you prefer to call it …
The interesting stuff is the two pink lines representing the edges of the shape (this “shape” is the actual segment of the curve). Let’s focus on the right pink line. Press the A-key to deselect everything. Select the middle vertex (called control point) as shown below:
Notice that the other 2 vertices (called handles) are selected as well. Press the G-key to move the control point. Your curve's right edge moves. Press the RMB (right mouse button) to cancel or the LMB (left mouse button) to confirm the movement. Now, select the right-most vertex (handle for now on). Move it as we did earlier with the control point.
The control point stays in place but the handles are moving. Also, the curvature of the curve is changing! Moving the other handler also changes the curve. Moving the handler towards the control point changes the curvature of the curve respectively.
With the right control point selected, press Ctrl+LMB. You create another control point and actually extrude your curve. The newly created control point is the last now, the last one represents where your curve is finished. If you want to extend your curve from the starting edge, select the starting edge and press Ctrl+LMB to add a new control point as the starting edge. If you want to close the curve, select the two edges and press the F-key to add a closing segment. This is all we need in order to create our logo with Bezier curves.
For more details about Bezier Curves go to http://wiki.blender.org/index.php/Doc:2.6/Manual/Modeling/Curves
Our goal is to create a three-dimensional logo from a two-dimensional logo, and we will start from an easy one. My favorite Greek team is Panathinaikos, so let’s google to find the team's logo.
I came across this jpg that is just fine for the work.
I don't really care about the text so if I want to I can crop it using Gimp. It's fine for my purposes, so I'll leave it the way it is. The good thing is that we have to model just a clover. An easy task for bezier curves.
So start a new project, remove the cube, and have a Front Orthographic view on your 3d view window.
One powerful tool is the ability blender gives us to have as a blueprint an image at the background, for easy modeling.
Press N-key to toggle hide/unhide the right side panel (properties panel) at the 3d view window. Leave it unhide, scroll it down, and “tick” the Background Images
Press the Open button and navigate to the location that you downloaded the image. Select and open that image.
The image appears at the background. You can alter some of its properties (the transparency or the position, for example) from the panel that appeared just below the open button that we pressed earlier.
Tip: The background images are visible only at orthographic view and only at precise angle (front, left, top etc). At a later stage, I can show you techniques to handle images as 3d objects viewable from any angle and any view.
Now, add a Curve–>Bezier. Press Tab-key to go to edit mode and using the Ctrl+LMB to add the necessary control points, create an outline of the clover as shown at the image below. Use the handles in order to create the curves that you need:
After that, we don't need the background image. Untick it at the properties panel or press the X icon just below and to the right of the Add Image button.
Up to now, we have a two-dimensional shape, and we have a little more work to do for the third dimension.
To be continued…