Ceci est une ancienne révision du document !
After a month off, we are back together to explore modifiers. One of my favorites is subdivision surface!
Tip: Modifiers are automatic operations that work with how an object looks and renders but without changing the actual geometry of your object.
Subdivision Surface (Subsurf in short) is a method of subdividing the faces of a mesh to give a smooth appearance, to enable modeling of complex smooth surfaces with simple, low-vertex meshes (source: wiki.blender.org).
Open a new project in blender and select (if not already) the cube.
Now, let’s look to the modifiers tab (shown below) under the properties window.
Notice a little wrench. This is the symbol of modifiers in blender. Press with your left mouse button the wrench icon and then press the “Add modifier” button.
A large window appears with all the available modifiers in blender. For now we will stick with the Subdivision Surface (Subsurf from now on). Locate it (highlighted in the image above) and select it to add this modifier to your cube.
Your cube changes to a 24-faces shape! But if you render your image, you will get a 96-faces object… Weird! Let see why this is happening.
When you add the Subsurf modifier to your cube by default the modifier subdivides the cube faces (6 faces) by 4, giving you a new shape with 24 faces. You can control how many times to subdivide your object’s faces under Subdivisions section as shown in the image below. The “View:1” indicates that you subdivide your object one time.
There is another control button under Subdivisions section to change the subdivisions when you render your image (Render:2). That’s why in the 3D view window you have a 24-faces shape (subdivided one time), but, when you rendered it, you had a 6x4x4=96-faces shape (subdivided two times). Press the right arrow to increase the View subdivisions to 2. Now what you see is what you render.
Increase the View and the Render subdivisions by one. Now, under Subdivisions you should have 3 subdivisions for View and for Render: On the left of your 3D view window, under object tools (shortcut T for show/hide), smooth your cube’s shading
Your “cube” now has to look something like this:
The secret of the power that Subsurf has is revealed when you press the TAB key to enter the edit mode You can see the sphere that we created with the Subsurf, and your original shape, the cube. You cannot edit the sphere (remember that your actual object is the cube) but you can edit the cube.
Select the top face of your cube and press E key to extrude and Enter key to confirm the extrusion. Scale it down to 50% by pressing the S key and 0.5.
Move the extruded face down by 2 units (Press G key, then Z key to lock the movement to the Z-axis and then press -2 to move it down).
You created a highly detailed pot! By editing the cube, dynamically you edit the sphere in an organic way. Without the Subsurf you’d need a lot of time and effort to create this pot.
Another critical tool to use with Subsurf is the loop cut.
Tip: Loop Cut or Loop Subdivide (shortcut Ctrl-R) splits a loop of faces by inserting a new edge loop intersecting the chosen edge (source: wiki.blender.org)
Deselect all by pressing the A key, and then press Ctrl-R. Hover your mouse over the cube faces and you will notice a purple line “cutting” the edges as shown to the image below: Press 2 or scroll your mouse wheel to add 2 loop cuts. Press enter to confirm.
After that, you have 2 yellow edge loops selected and by moving your mouse you can slide them freely. Press the right mouse button to place them to the center of your edge (default position). Press A key to deselect everything.
Now, to select one of the two edge loop cuts that we just created, we have to use the shortcut Shift-Alt-Right Mouse Button
Tip: The actual shortcut for Loop Cut Select is Alt-RMB but under linux it conflicts with the functions that are assigned by the system to the alt key.
With the leftmost edge loop selected, press Ctrl-E to open the edge special menu, and select edge slide as shown in the image on the next page.
You can slide the edge loop by moving your mouse or by entering directly the value of the movement (for example -0.8). Deselect all by pressing the A key, and select the other edge loop. Slide it by 0.8 units.
Create another two edge loop cuts to the other side of your cube (check image above right)
Select and deselect anything you like. Grab a simple vertex and move it around to see what is happening to your shape. Select two vertices and scale them up or down. While in the edit mode, add a new shape, for example a plane, and see what is going on.
Next month we will continue our journey with Subsurf, and we will try to create something. Please send me your suggestions or questions at blender5d@gmail.com