# Modeling with polygons deel2

## Contents

### Creating objects using faces

#### Create polygon tool

With the Create Polygon Tool it's possible to create faces in any shape by clicking the corners of the desired face. You can find this tool in the polygons menuset under Mesh > Create Polygon Tool:

Your pointer will turn into a cross and you can now start clicking the corners of the desired face. When not using snap options the points will be placed flat in the view port you're working in. If you're working in the perspective view the points will be placed flat in the y-direction. If the face is finished you press [enter] on your keyboard to close it.

If the face has the wanted shape don't click on the starting point again like when drawing with lines, this will create a double vertex there, which can cause problems later on!

If you want to create a hole in the face, you finish the shape, and before closing it with enter press control on your keyboard while clicking the first point of the shape of the hole. After that you can proceed to click the next points of the hole (without pressing control). You can start another hole by pressing control again while clicking the first point of the new hole. When your shape is finished (with or without holes) press enter to close it.

If you press backspace on your keyboard (before you've closed the face with enter) you can go back a point. You can do this as many steps back as you'd like.
If you're drawing a face it's convenient to draw counter-clockwise, in that way the normals of the face will be facing upwards, which is easier if you want to extrude the face later. See the section in this chapter about normals for more information on normals.

After you have closed the face you can adjust it in component mode like all other polygon geometry.

For a more elaborate explanation of the create polygon tool we refer to the Modeling an orthogonal pavilion tutorial.

#### Normals

In Maya each surface has a front and a back side. This has consequences for how the face responds to certain commands. Which side is the front and back can be shown by the normals. You can display the normals of a face by selecting the face, then going to Display > Polygons > Face Normals:

On one side you'll see a line perpendicular to the face. This side is the front. If you would extrude this face the arrow will point in that direction too. If you want to change front and back, select the face and go to Mesh Display > Reverse:

The faces of a volume also have normals. The normals of primitives automatically are turned outwards.

If you have created a volume out of a face and have trouble with an operation like Booleans, check if the normals of both objects are turned outwards. If not, select the object(s) with the normals in the wrong direction and reverse them.

To hide the normals, select the object and go to Display > Polygons > Face Normals again.

#### Extrude

If you have a face and want to make it into a volume you can use the extrude command. First select the face you want to extrude and then go to Edit Mesh > Extrude:

Then the Manipulator Tool appears on the face. You can now pull the arrow of the direction you want to extrude the face in to make the face into a volume. You can also numerically put in the value of the extrude in the channelbox

Always extrude the face in the direction of the arrow, otherwise you will turn the volume inside out. If the arrow doesn't point in the direction you want it to it's better to either undo the extrude command en reversing the normals of the face first or to pull it in the direction of the arrow and moving the volume afterward.
Check that point snap is not enabled, or you may experience difficulties performing an extrude (it may keep snapping to the base of the extrude)
When you have extruded a face Maya automatically jumps to component mode. Click it back to object mode to be able to select objects again.
You may want to check that keep faces together is checked in the top of the Edit Mesh menu. You can also turn on keep faces together in the inputs of the extrude through the channelbox of the object (click the polyExtrudeFace node, scroll down to keep faces together and set it to '1' or 'on').

### Split polygontool

If you want to split a face into more faces you can use the split polygon tool. With this tool extra vertices and edges are added. The exact name and location of this tool depend on the Maya version:

Maya 2011 and before
Edit Mesh » Split Polygon Tool
Maya 2012-2014
Edit Mesh » Interactive Split Tool
Maya 2015-2016
Mesh tools » Multi-Cut Tool

Click on the option box next to it. This will make the settings of the Split Polygon tool appear at the spot of your channel box:

Multi-Cut Tool (Maya 2015 and later):

Make sure the Multi-Cut Tool is selected in the Mesh Editing Tools section of the Modeling Toolkit window and use the Snap Step % setting to specify at what percentage increment to snap on an edge. Use Shift to enable snap mode.

Interactive Split Tool (before Maya 2015):

The divisions shown in the settings are the number of divisions the new inserted edge will have. With the smoothing angle you can control how hard or soft the edges of your split geometry will be; use a low value (0) to let the edges appear hard. It can be really convenient to use snapping points along the edges. The number of points is the number of points per edge your mouse will snap to. These points are evenly divided along the edge. The snapping tolerance will determines how close the vertex needs to be to the snapping point before it snaps to it.

Now you can click and drag your mouse along an edge of the face you want to split:

Now you can adjust the object further by going into component mode and moving the vertices or edges.

### Merge vertices

It is possible to merge multiple vertices into one. Select the vertices you want to merge in component mode, then go to the option box next to edit mesh > merge vertices. The settings of the merge vertices command will be shown:

The threshold is the amount of units within which the selected vertices should be for Maya to merge them and is automatically set to 0,0100. If the vertices you want to merge are further apart, put in a number that is bigger than the amount of units the vertices are apart from each other, after that press merge:

The merge vertices command can also be a solution to problems with a Boolean operation. If for instance both objects disappear when using Booleans > difference, one of the possible reasons could be that one or both of the objects have 2 vertices on the same spot. To solve this, select both objects and use the merge vertices command (for this the threshold needs to be very low, for instance 0,01, because you only want to merge the vertices that are on the same place, so check this in the option box).