In this lesson video, we will cover two modeling features in blender. First is the knife tool and second is the bisect tool. Again as before, because these are 3d modeling features, you need to be in the edit mode to be able to use them. I already created a UV sphere here and already in the edit mode. The knife tool is used to create three form edges that will snap to any elements we wish, it can snap to vertices existing ages at random point on any faces, or even on empty spaces. There are two ways that we can use the knife feature in blender.

First is by using the knife tool and second by using the shortcut. Personally, I prefer to use the shortcut method because it is faster and you can perform it without having to activate any tool back and forth. So let's discuss how to do this using the shortcut. First to watch The knife mode we can press key in the keyboard. Notice our mouse cursor change to a knife symbol and we have this small green square whenever we move our mouse cursor on top of a mesh, this green square indicates that Blender already finds a surface for the knife to cut two. If we hover over an age we will get this age highlighting indicates that we are snapping to that age.

If we hover over a vertex, the green square will have a red border. This indicates that the knife tool will cut precisely from or to that vertex. If we click on this age, then on this age, we can see that the knife tool will keep cutting Continuing from the previous cut location. We can cut at a vertex like this, or at faces like this. If you want to confirm the cut, you can press Enter or spacebar. But if you want to cancel, you can right click with your mouse over By pressing the Escape key.

The second method of accessing the NIH feature is by using the knife tool, which is this button here in the toolbar. When you have the knife tool active, you are not automatically in the knife operation mode, you need to click on any of the sub objects here, or you can even click on the empty areas like this to start the knife operation. Notice I can create a zigzagging cut like this by clicking on the empty areas and then continue cutting by snapping to any of the sub objects in the mesh model, which is kind of cool. Let me go back to the default select box tool. The knife operation also has the ability to snap to the center of the ages and we can create for cuts in a single process. Let's see how we can do this.

Press K and then if we want to cut at the center of this age, we can hold the Ctrl key. Notice our green square cursor will snap perfectly to the center. location of the age, click to create the cut control and click in here and in here and so on. Okay. Now sometimes we need to finish a cut until this point, what we don't want to confirm and exit the knife mode yet, we want to create another cut in this area for example, we can do that by pressing the f4 key on the keyboard. As you can see, I can start a new cut without leaving the knife mode.

You might be wondering why now how do I know about this a shortcut when in a knife cutting mode. Well, you can actually read them down here at this info bar. You can see here that he is for creating a new cut. You can also see other stuff in here related to the knife operation mode. So if you ever forget these additional shortcuts, just look at this bottom area. And this basic concept also applies to all other operations in blender.

Not just for the knife mode. Okay? Another example of a new knife technique that we can draw just by looking at the information bar is this see shortcut which will make our knife becomes constrained to vertical or horizontal or diagonal direction based on our viewing angle. So I think this is more suitable for for one side top or any other axis viewpoints and not very useful in the user perspective view mode. Also, while in the knife mode, we have this option down here. This will make the knife to cut through the surface making the hidden mesh elements at the backside get cut up also, this z option will make the knife tool works more like the bisect tool, which we are going to discuss after this.

Basically, if you use a tool in blender, just try to see the options down here. And you may end up finding cool features that you never thought possible before. Next is the bisect tool. Have you ever imagine having a lightsaber that can cut through anything that you want? Well, this is exactly what I think about the bisect feature, bisect will cut anything based on our viewing angle. And then we can decide which part of it we want to keep and which part of it we want to remove.

Unlike the knife tool, by default, bisect doesn't have any shortcut assigned to it. So to use it, you need to go to the toolbar and then press and hold on the knife tool, we can see the bisect tool here. And before you can use the bisect tool, you actually need to select the faces or at least the ages that you want to by sec. If you press up A to D select everything and try to bisect by clicking and dragging on the viewport. Render will display an error message like this selected ages or faces required. Basically, it will only cut the selected mesh elements and we'll ignore the rest But let's say we want to cut the whole object, so we need to press A to select all of them.

And then click and hold and then drag like this, then release. As we can see Blender just cut the object based on our viewing angle. After bisecting an object, we can adjust the parameters using the less operation panel down here, or by pressing f9 for the shortcut, or you can also use the bias at the small if you want to do it visually. The basic principle of bicep is that first you put the initial coordinate, which is where you first click your mouse. Then when you drag the mouse renderer creates a plane where the cut will be performed. Imagine that the plane is like a giant infinite knife.

So using this Gizmo, we can move the initial coordinate by dragging the small plane here, we can see the plane point coordinate changes as we move to the square Gizmo. Next, we can move Dini She'll coordinate forward and backward locally based on a cutting plane normal direction using this arrow here. And finally, you can use the circle Gizmo to rotate the play normal. We have talked about normal before. Essentially, the term normal is a direction perpendicular to a certain plane. So again, basically this plane Gizmo and this arrow Gizmo are used for adjusting the coordinate.

While the circle Gizmo is used to adjust the orientation of it. Next are these options down here. These three options are what make bisect different from the knife tool. If you turn on the clear outer option, the parts that are on the same side as the arrow will be removed, while the clear inner option will do the opposite. So you really don't want to have both of these options turned on at the same time, as this will remove all of the geometry. Next is the field option.

Here, this field option will create faces patching the hole produced by the bisect operation. Lastly, the axis threshold value. This value determines whether the cutting line will snap to the nearest vertices or not. If you set this all the way to one, you mostly will get quad faces or at least triangles as the result, but of course at the expense of losing the perfect straight cut line. Now there is one thing that you need to be aware of about the field option here. This option will only works if the original mesh doesn't have any hole in the area where the cup happens.

Let me give you another example. To make this more clear. Let's go to the object mode and delete this sphere. Then create a monkey head object. For a stay step two, go to the edit mode, press three to use the face mode. Activate the bicep tool.

Let's say we want to split the monkey head exactly half at the center. First, remember, you need to select all of the faces that you want to by sec, then just click direct like this. Next, we want to put the initial coordinate at the center. The easiest way to do this is by hovering the mouse on top of the coordinate values and then press backspace. This will zero out everything. Next, we need to orient the cutting plane so that it aligned with the y z plane, meaning the plane should be perpendicular to the x axis.

Basically, you need to put one in the x value here and zero on both Y and Z values. So click here, type one, press tab to go to the next input fields, type zero then tab, then type zero again, then enter. Now the bisect cutting plane is perfectly straight based on the x axis. Next, if we turn on to clear out or here, we can see half of the monkey head. If you turn on the field option here, we get something like this. Now if we drag the arrow Gizmo to the left, as soon as it touches the whole area, the field stops working, but when we press the whole area, the fill option works again as expected.

The same thing happens if we drag this all the way to the right side, we can see the feelings stop working when we are in the whole area. And lastly, if we maxed out the access threshold option here, and drag the arrow again left or right, we can see the cut area jumps around as Blender tries to snap the cutting line to the nearest existing vertices.