Creases

Introduction

Creases allow you to create sharp edges for SDS surfaces.

Creases are similar to 'weights' in that they allow you to control how strongly a certain point, edge or face 'attracts' the actual surface.

The four top points have a 'semi sharp' crease value. The bottom vertices have the default 'smooth' crease value.
 

Realsoft 3D supports three crease levels: sharp, semi sharp and rounded. In addition to this, there are two kinds of creases: point creases and edge creases.

Point creases are affected whenever you use the 'Sharpness' tool in the point editing mode. If you are in edge or face editing mode, edge creases are affected. This means that the result of setting creases for all points of a face is different from setting crease values for the edges of the face.

The following tutorials demonstrate how different crease values and types affect the shape of the actual surface.
 

Point creases

You can define crease values for selected points using the 'Sharpness' SDS tool.

Sharpness tool in the control bar

1. Create a SDS Cube. By default all crease values are set to 'rounded' and the resulting surface looks like a sphere.

A SDS cube with default crease values

2. Enter the point editing mode and select all points of the SDS object. The 'Sharpness' control in the tool control bar becomes enabled.

3. Set sharpness to 'Semi Sharp'.

The SDS cube with semi sharp point creases

Note: Set OpenGL shading quality to 'Good'  (hold down the 'w' key and select near northeast compass menu), else the cube will look more like a star shaped object.

Note also: OpenGL shading can represent the true shape of a SDS surface only with a limited quality. In photo realistic rendering, creases become rendered with a proper quality.

A ray traced SDS cube with semi sharp point creases

If you set a point crease to 'sharp', you'll get a sharp peak, as shown by the following image:

Two control points having a sharp crease value
 
 

Edge creases

Edge creases are defined in edge or face editing modes. Defining a crease value for a face corresponds to defining a crease value for all edges of the face.

Let's see how edge creases differ from point creases.

1. Create a SDS cube just like in the previous example.

2. This time, enter the face mode and select the top and bottom faces.

3. Set crease to 'Sharp' using the sharpness tool.

A SDS cube with 'Sharp' top and bottom face creases

The actual surface looks like a cylinder now.
 
 

Mixing point and edge creases

Point and edge creases can be mixed.

The edge creases of the top and bottom faces are 'sharp'. All point creases are set to 'semi sharp'.

Note: if you apply tools which create new points or edges for SDS object, all inserted points will have a default 'smooth' crease value.

For example, if you subdivide and extrude the top face of the SDS object in the above image, the following object is the result:

Top face subdivided and extruded