# Mesh Editing

(return to Modeling)

## Answers in this category:

1. How do I split objects
2. How do I join objects
3. How do i create Blender objects like meshes based on the content of 2D image like a .png file?
4. How do I recalculate the normals of a mesh
5. How can I show the normals
6. How do I convert objects to a mesh
7. How do you make edges (lines) and faces (polygons) between vertices?
8. How do you edit a mesh?
9. How do I extrude?
10. How do I subdivide a mesh?
11. How do I use the spin function
12. How do I copy a mesh but not its IPOs?
13. How does Warp work?
14. How do I weld vertices together?
15. How does vertex painting work?
16. How do I use the screw button?
17. Can Blender perform Boolean operations on objects?
18. What does the Hash button do?
19. Can Blender perform Boolean operations on objects?
20. What does the Xsort button do?
21. I`ve got holes, missing faces in my model, how to correct?
22. I`ve got holes, missing faces in my model, how to correct?
23. how can i make a square object have rounded edges ?
24. why does Blender subdivide squares that are only partially selected
25. How do I use the proportional editing tool?
26. What is mesh decimation?
27. How can I flip an edge in a face?
28. Blender says "Not a decimated mesh" when I am trying decimator.
29. Why do polygons disapear when you change angles?
30. Is it possible to hide backfacing verts/edges/faces? I really need a little more control over what I see while modeling.

### 1 - How do I split objects

Contributed by B@rt.

To split one object into two separate objects enter editmode, select the vertices to split off and press P (for seParate ;-).

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### 2 - How do I join objects

Contributed by B@rt.

First make sure that you have two or more objects of the same type (meshes/curves/...). Select them all and press CTRL+J.

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### 3 - How do i create Blender objects like meshes based on the content of 2D image like a .png file?

Contributed by B@rt.

To learn how you can turn 2D images into 3D objects, please read my 'Creating a Logo' tutorial on
http://helium.homeip.net/xoom/tutorials/logoTut/logoTut.html

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### 4 - How do I recalculate the normals of a mesh

Contributed by B@rt.

To recalculate the normals select a mesh, enter editmode and select all vertices (AKEY). Next, press CTRL+N to recalculate the normals outside or CTRL+SHIFT+N to recalculate the normals inside.

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### 5 - How can I show the normals

Contributed by B@rt.

To display the normals of faces switch to the Edit Buttons (F9) and select 'Draw Normals' on the far right. They will only be shown in editmode.
You can change the length of the normals with the NSize slider.

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### 6 - How do I convert objects to a mesh

Contributed by B@rt.

You can only convert 'one-way': for example, you can
convert a curve to a mesh, but not a mesh to a curve.
The following conversions are possible:
- text -> curve
- surface -> mesh
- curve -> mesh
To perform a conversion, select the object and press ALT+C

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### 7 - How do you make edges (lines) and faces (polygons) between vertices?

Contributed by Nathan Vegdahl.

To create an edge between two vertices, select two vertices, and press the F-KEY.
To create a face between three or four vertices, select three or four vertices, and press the F-KEY.
*HINTS:
You must make edges one-at-a-time, because if you select more than two vertices, it makes a face instead.
You can not make faces out of more than four vertices. However, you can get around that by simply making more than one face to connect all of the vertices.
Four-vertex faces are not always flat, and are not always generated in the way you want them to be (ifor example, Blender will occationally connect them in such a way as to form an hour-glass shape). If this happens, delete the hour-glass face, and simply use a couple of triangle faces instead.

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### 8 - How do you edit a mesh?

Contributed by Nathan Vegdahl.

To edit a mesh, select the mesh and press TAB. That will put you in edit mode.
You may then modify the mesh by adding/deleting vertices, moving vertices, and adding/deleting faces and edges.
Once you are finished, you can press TAB again to leave edit mode.
*HINTS:
While in edit mode, you can press the U-KEY to undo all changes you've made durring that editing session. However, when you leave edit mode, the changes are made permenant, and you can not undo them.

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### 9 - How do I extrude?

Contributed by Alf.

Select the vertices you would like to extrude and press the E Key. Blender will automatically go into Grab mode. Move the mouse to extrude using Shift or Ctrl keys to restrict movements.

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### 10 - How do I subdivide a mesh?

Contributed by B@rt.

To subdivide a mesh enter editmode (TAB), select the edges that you want to subdivide and press W. Select 'subdivide' from the popup menu.

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### 11 - How do I use the spin function

Contributed by Michael.

The spin function works on the mesh object, you can start with a curve or other object then convert it to a mesh to spin.
A quick spin, in top view (num pad 7) add a mesh plane then switch to front view (num pad 1)move the curser 3 grids to the right. With all the vertices selected in edit mode set Degr: to 180, steps:to 6 and click the spin button. If you have more than one window open the mouse curser will turn into a ? move it into the window you want to perform the spin in (in this case the front view num pad 1).
You can use Spin Dup in the same way, instead of a solid object you get 6 planes rotated around the cursor.

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### 12 - How do I copy a mesh but not its IPOs?

Contributed by Deraj.

If you duplicate an object (Shift+D) you might have trouble with all the IPOs being copied with it, with the link in place, any editing on the new object's IPOs will mess up the original! =(
To fix this, after you've duplicated the object, bring up the IPO window (Shift+F6) and down at the bottom, there will be (next to the datablock name) a number (possibly 2). Click on that number and it will bring up a dialogue asking if you want to make it the single user, click "OK." Now the IPOs of the new object are no longer linked to the original and you can edit them freely! (Hitting A and then X should delete all the visible IPOs)
Please note that you have to remove the different types (object/material/world/vertex keys/sequence) of IPOs separately.

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### 13 - How does Warp work?

Contributed by Michael.

Warp is used to bend an object around the curser. Warp works with mesh, curves, nurbs and it can be applied to text but it has to be converted to a curve or mesh first. A Quick Warp: In front view create a text object 'This is a test of Warp' is ok. Leave edit mode convert it to a curve with 'alt c' key. Still in front view place the curser in the center of the text and three grids down, now zoom out. Go back into edit mode and select all the vertices on the text. Move the mouse pointer to the bottom of the 3D window(in front view)press 'shift w' key move the mouse pointer towards the top of the screen, move it up until the the the T in This and the p in Warp almost touch. You should have the text 'This is a test of Warp' in a circle around the curser.

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### 14 - How do I weld vertices together?

Contributed by B@rt.

Enter editmode and select the vertices that you want to join together. Start scaling with the S key and hold down CTRL to scale the vertices all the way down to zero (this is displayed in the bottom of your current 3D window).
Switch to the Edit Buttons Window (F9) and press 'Remove Doubles'. Voila!

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### 15 - How does vertex painting work?

Contributed by Matt Hilliard.

Vertex painting is a simple process where a colour is assigned to each vertex on a mesh face. Every triangle has 3 colours, every quadrilateral has 4. When vertex painting is disabled, every corner on every face shares the same colour.
The process of adding vertex colour is as follows:
1. Select the mesh you wish to paint.
2. Ensure the mesh you wish to paint has a material if you with to render the mesh and toggle VColPaint ON under the material buttons. NOTE: For the realtime engine and games, you can skip this step.
3. Hit the V-key to enable vertex paint mode.
3a. (OPTIONAL, reccomended) You can work face select mode in parallel to vertex select mode with the F-key. By doing this, painting is restricted to only those faces you have selected in face select mode.
4. Activate the paint buttons. Here you will see the colour you are painting, the size of the brush, and the manner the paint is applied to your mesh.
5. Move the mouse over the vertices you wish to apply the paint to, and apply the paint by holding down the Left Mouse Button and moving the mouse slightly.
That's the basics of vertex paint in blender. In step 2 you can toggle VColLight in addition to or instead of VColPaint and blender will treat the color as an incoming light source rather than the material itself. VColLight is visible without the aid of lamps and can be used in the process of creating or modifying "fake radiosity"

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### 16 - How do I use the screw button?

Contributed by Michael.

The screw function works by turning an open polygon around the curser(only in the front view, num pad '1'). A quick test of the screw function: In front view (num pad 1) add a 'mesh' 'circle' deselect all of the vertices with 'a' reselect the vertices from the grid line directly below the curser going counter clock wise to the vertex one grid above and one grid to the left of the curser delete the selected vertices. You should have a short arc starting directly below the curser going clock wise to the grid intersection 45deg up and to the left of the curser. select all the vertices of the arc 'a' key. In the edit buttons window set steps to 25 and turns to 4 click on the screw button, (if you have more than one window the mouse curser will turn to a '?', click in the front view window).

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### 17 - Can Blender perform Boolean operations on objects?

Contributed by Michael.

Yes, in Blender it's called 'intersect' but you want to have your worked saved before you use it:-). There is a tutorial at http://205.152.62.12/gruff/intersect.html that explains it's use.

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### 18 - What does the Hash button do?

Contributed by Nathan Vegdahl.

The hash button scrambles the order of the vertices in a mesh. But that is a very simplistic explination. To truely understand what it does, you must first know how vertices are stored.
All of the vertices of a mesh in Blender are stored in a list: vertex1, vertex2, vertex3, etc. It really doesn't matter what order the vertices are in, since the actual data (i.e. their XYZ positions) isn't changed.
But there is one case where it does matter: when you use a mesh to emit particles. The reason for that is that the particle emitter emits the particles IN ORDER. (i.e. it emits the first particle from the first vertex in the list, the second particle from the second vertex in the list, etc.)
So, when you hash a mesh, it scrambles the order of the vertices, causing particles to be emited in a more random order.
To see the effect that this has, create a UV sphere, and use it as a particle emitter. When you animate it (ALT-A), you will notice that the particles are emitted in a very obvious, ordered pattern. That pattern happens to be the order that Blender generated the vertices.
Then go into edit mode, select all of the vertices (by pressing the A-KEY), and then click on the Hash button. Leave edit mode and animate it again, you will see that the particles are now emitted in a scrambled order. This feature is very useful for creating particle generaters for things such as smoke or fire, where you don't want the particles to be emited in an obvious order.
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*HINTS:
The _xsort_ button organizes the list of vertices, incase you want particles to be emitted in a more ordered pattern. It is used in the same way as the hash button.

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### 19 - Can Blender perform Boolean operations on objects?

Contributed by Richard Kennedy.

Blender boolean operations are done using the "Intersect" button.
1) Position two or more objects so that they overlap or intersect in space.
2) Select those objects with "shift+right mouse click" and (CTRL-J) join them.
3) In editmode (TAB), select all (A) then hit the "Intersect" button.
This will perform a boolean operation that creates all standard forms of booleans at one time. You must then select which parts you want to keep. This is done in editmode. You simply put your mouse over the area you want to select and press the "L" key on your keyboard. This will select all of the connected points on an object. You can then move, rearrange or delete any portion of the new objects created by the boolean intersect.
As far as I know they will remain as joined meshes so that they can only be manipulated independently in editmode with the "L" key. Use "P" seperate the selected verticies.

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### 20 - What does the Xsort button do?

Contributed by Nathan Vegdahl.

The xsort button organizes the order of the vertices in a mesh. But that is a very simplistic explination. To truely understand what it does, you must first know how vertices are stored.
All of the vertices of a mesh in Blender are stored in a list: vertex1, vertex2, vertex3, etc. It really doesn't matter what order the vertices are in, since the actual data (i.e. their XYZ positions) isn't changed.
But there is one case where it does matter: when you use a mesh to emit particles. The reason for that is that the particle emitter emits the particles IN ORDER. (i.e. it emits the first particle from the first vertex in the list, the second particle from the second vertex in the list, etc.)
This is where the xsort button comes in. It will sort the list of vertices based on their position. If I remember correctly, it will sort them from left to right, top to bottom, and front to back.
To see the effect of xsort at work, start Blender, and create a mesh-cube. Make certain that you are in edit mode. Press the A-KEY to select all of the vertices, and then subdivide it several times (perhaps 2 or 3 times).
Now exit edit mode and set up the cube as a particle emitter. Play the animation (ALT-A), and notice the order in which the vertices are emitted.
Go back into edit mode and select all of the vertices again (A-KEY). Click on the xsort button. Exit edit mode, refresh the particle calculations, and play it again (ALT-A). You will notice that the particles are now being emmited in a much more ordered pattern.
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*HINTS:
The hash button randomises the order of the vertex list, incase you want the particles to be emitted in a more random order. The hash button is used in the same way as the xsort button.

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### 21 - I`ve got holes, missing faces in my model, how to correct?

Contributed by TankCommander.

Select the verticies that make up the hole and press shift+F. Shift+F only works for vertices in one plane (i.e. flat objects).
To fill non-flat holes, select one face at a time by selecting the three or four vertices that define it and press F and then press shift+F.

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### 22 - I`ve got holes, missing faces in my model, how to correct?

Contributed by Lyndsy Simon.

First, enter editmode. Next, select the vertices outlining the "hole" in your model. To make this more clear, you may want to turn "Draw Faces" in the edit buttons on, so you can tell where faces need to be added. After selecting the vertices, simply press FKey. This will form a face between them. Please note you can only select 3 or 4 vertices at a time - if you try to do more, you will receive an error. I recommend trying to always use 4 vertices if possible, as quads make better smoothing than triangles.

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### 23 - how can i make a square object have rounded edges ?

Contributed by Randall.

This is fairly easy to do, and there are a few ways you can go, depending on the results desired.
First, create a cube. Go to edit mode (Tab key) and select all vertices by hitting the A key. Subdivide by using W_1. Or you can go to the edit buttons (F9) and click the subdivide button. If your cube is scaled to a larger size, you'll need to subdivide more. For starters, just leave the cube at it's default size, and subdivide 5 to 6 times.
Leaving all vertices selected, click the Smooth button in the Edit buttons (F9) menu a few times. You'll notice the edges start to smooth out. Then if you want, you can click the Set Smooth button to further smooth when rendering.
You can also play around with the S-mesh button to get good results, as well as the Auto Smooth button.
There are many other ways I'm sure, but this is a good starting point to practice and play with, and to learn other things from.

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### 24 - why does Blender subdivide squares that are only partially selected

Contributed by frank.

Why does Blender subdivide squares that are only partially selected. And why does Blender subdivide these squares into triangles ?
Subdividing the adjacent squares as well prevents 'cracking'.
If one of the sides of a square has an edge that goes from x-coordinate 0.0 to 1.0 and you subdivide that edge, you'll get two new edges: one from 0.0 to 0.5 and one from 0.5 to 1.0.
99.99% of the time these two edges will align perfectly with the original edge. But computers are digital and there will be viewing angles and rotations where the 3D calculations will result in very small differences between the original edge and the two new edges.
So if we subdivide only one of two squares that share an edge there is a very small chance (and we all know Murphys law) that you will see some stray background pixels peeping through where the two squares meet.
To prevent that, the adjacent square has to be subdivided as well. But if we would subdivide it in squares the edge on the other side of the square would be subdivided. So then we would have to subdive the square sharing that edge as well...

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### 25 - How do I use the proportional editing tool?

Contributed by B@rt.

You can use the proportional editing tool (or 'magnet tool') on any kind of object as long as you are in edit mode. To activate it, enter edit mode and press O (not zero!). Grab a vertex and move it - a dotted sphere will appear. This indicated the range of influence of the magnet. To change the range, press numpad + or -.
You can toggle between smooth and sharp falloff with SHIFT+O.
Of course you can also access these functions with the icons in the header of the 3D window: the buttons will appear once you enter editmode. They are drawn to the right of the Face Select button.

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### 26 - What is mesh decimation?

Contributed by B@rt.

Mesh Decimation is the new polygon reduction tool that is available since 2.14. To use it, select a mesh and switch to the Edit Buttons Window (F9). The purple 'Decimator' slider button in the middle displays the current number of faces in your object. Drag the slider to the left to reduce the number of faces. Release the mousebutton to see the effect on your object. Once you're happy with the result, click 'Apply'. Otherwise, click 'Cancel'.
Note: This tool is not 100% stable in 2.14 yet - especially coplanar faces can cause problems. Better save your work before using it!

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### 27 - How can I flip an edge in a face?

Contributed by Johnny Matthews.

In version 2.20 select two adjacent triangles and press CTRL-F.

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### 28 - Blender says "Not a decimated mesh" when I am trying decimator.

Contributed by B@rt.

It gives the message when you press "Apply" without having decimated, or
with an Object active that has not been decimated.
To decimate a mesh, drag the polygon count slider until you're happy with the count and look of your object and press "Apply".

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### 29 - Why do polygons disapear when you change angles?

Contributed by asdf_46.

In the 3D world faces really have only one side. They have a normal that stick out a right angle to the face showing what side the face is visibal on. Blender shows both side when you are in normal flat shading mode. When you go into shaded Blender dosen't render these polygons.
The simplest way to fix this is to go into edit mode and select all of the verticies. The push Ctrl-N to recalculate the normals outside. If this dosen't work or fix them all you can push F to go into face mode, click on faces you can not see (It's tricky) then go into edit with out leaving face mode and hit "flip normals" in the edit buttons. You may have to go in and out of edit mode a several times, but don't recalc the Normals or you will undo what you have done.
asdf_46

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### 30 - Is it possible to hide backfacing verts/edges/faces? I really need a little more control over what I see while modeling.

Contributed by Peter Taylor.

It is not possible to automatically hide back facing verts or polys.
Instead, in edit mode, you may manually select (usually with the b key) any verts that you want to hide. To hide the verts, you need to press the h key. This will hide all vertexes until you leave edit mode. At this point the vertexes are made visible again.
Other options:
SHIFT+H : hide unselected vertices
ALT+H: unhide all vertices

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This Blender FAQ was generated on September 24, 2001, 8:40 am. For the most recent version and for searching the tutorial database, please visit the on-line version at http://helium.homeip.net/support