About Stitching (or Z Fighting) Effect

Stitching (also referred to as "Z fighting") is a visual effect totally independent from Version 5 and combines one or more objects on a single one, thus giving a pattern looking like stitches.

How does it happen?

When two objects are displayed approximatively at the same location in 3D, they can be mixed depending on the viewpoint and the distance from the eye. This effect is due to the Z depth precision.

The two pictures below show two objects viewed from two different viewpoints:

Now, if the distance from the eye is modified, the two objects are mixed:

When two triangles (say, a red one and a blue one) are displayed at the same location in 3D, the two colors are mixed. This is what we call the "stitching effect" and it is due to the 3D OpenGL renderer.

This is illustrated by the two pictures below:

However, there is an exception in a very specific case: when the two triangles have the same vertices, only one color is displayed since the it is exactly the same triangle which is displayed twice (in blue and in red). The color of the last triangle displayed prevails over the rest.

The first example shows two superimposed surfaces (a red one and a blue one), only the red color is visible:

Now, when the red surface is put in the No Show space, the blue color can be seen: