Blender Modifiers | Page 9

one face and four vertices, while the grid has nine f aces and sixteen vertices, hence lots of
unneeded vertices and faces. The
Decimate modifier allows you to eliminate these unneeded faces.
Decimated cylinder
We take a simple example of decimating a cylinder using the default of 32 segments. This will generate a
cylinder with 96 faces. When the
Decimate modifier is applied, the face count goes up! This is because
the modifier converts all quadrangles ( quads) into triangles ( tris) which always increases the face count.
Each quad decomposes into two triangles.

The main purpose of the Decimate modifier is to reduce mesh resources through a reduction of vertices
and faces, but at the same time maintain the original shape of the o bject.
In the following picture, the percentage dropped in each success ive image, from 100% to 5% (a ratio
of 0.05 ). Notice that the face count has gone from 128 to 88 at a ratio of 0.6 (60% ) and yet the cylinder
continues to look very much like a cylinder and we discarded 40 unneeded faces.



1.0 (100%). Faces: 128; 0.8 (80%). Faces: 102; 0.6 (60%). Faces: 88
0.2 (20%). Faces: 24; 0.1 (10%). Faces: 12; 0.05 (5%). Faces: 6
As you can see when the ratio has reached 0.1, the cylinder looks more like a cube. And when it has
reached 0.05 it doesn’t even look like a cube!
Once you have reached the face count and appearance you were look ing for you can
Apply the modifier.
If you want to convert as many of the tris back to quads to reduce mesh resources further you can switch
to
Edit mode, select all vertices (A), and hit AltJ.

EdgeSplit Modifier
Mode: Any mode
Panel: Modifiers (Editing context, F9)
Description
The
EdgeSplit modifier splits edges within a mesh. The edges to split can be determined from the edge
angle (i.e. angle between faces forming this edge), and/or edges marked a s sharp.
Splitting an edge affects vertex normal generation at that e dge, making the edge appear sharp. Hence, this
modifier can be used to achieve the same effect as the
Autosmooth button, making edges appear sharp
when their angle is above a certain threshold. It can also b e used for manual control of the smoothing
process, where the user defines which edges should appear smoot h or sharp (see
Mesh Smoothing for
other ways to do this). If desired, both modes can be active at once. The output of the
EdgeSplit modifier
is available to export scripts, making it quite useful for creators o f game content.
Options
EdgeSplit modifier.
From Edge Angle
If this button is enabled, edges will be split if their edge ang le is greater than the
Split
Angle
setting.
 The edge angle is the angle between the two faces which use that edge.
 If more than two faces use an edge, it is always split.
 If fewer than two faces use an edge, it is never split.
Split Angle
This is the angle above which edges will be split if the
From Edge Angle button is selected,
from 0° (all edges are split) to 180° (no edges are split).
From Marked As Sharp
If this button is enabled, edges will be split if they are mar ked as sharp, using the
Edge
Specials
» Mark Sharpmenu item (CtrlE, in Edit mode).

Examples

EdgeSplit modifier output with From Marked As Sharp selected.
Sample blend file

EdgeSplit modifier output