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Patterning by triangles

This phase involves of drawing triangles on the membrane, using only points on the perimeter and the geodesic lines. WinTess3 supports using any point on the mesh, but is completely inadvisable to do this, because that will possibly lead to erroneous or distorted patterns. It should take into account that these triangles, folded and placed in a plane next to each other, form the pattern.  So it is absolutely necessary the order of introduction of the nodes that form the pattern to follow very strict rules.

 

As we said in process paragraph, this task can be tedious but allows us to find good patterns even with completely irregular forms of membrane.

Using the menu Patterns | Create a new pattern, the mouse becomes selection cursor (finger) and we select the first node of the pattern that we are going to create (the top of the screen displays the Pattern number which is being created). Before touching the first node we must think about which will be the second, third, etc. There are patterns in extreme areas where the first node is not obvious at first glance. Typically, however, the first knot is one of the ends of the geodesic and the second is the end of other geodesic. But, it is important to know that it is not always so!

Patterns, once cut into the membrane, have orientation. Most of the membranes have a surface which is different than the other surface. Either because they have a protective layer (lacquered, dust, UV  filter, etc.), or it is a bicolor membrane (different color on each surface), etc. Well, starting to triangulate a pattern we need to be aware of what will be one side or the other.

A pattern has a closed perimeter consisting of a set of segments. The nodes we select on the membrane (mesh, geodesic, auxiliaries, etc. ) are the nodes that form this perimeter. If we draw a vector from the first node selected toward the second node selected, we are setting a direction of rotation along the perimeter of the pattern. If this rotation is clockwise, this is the upper face of the membrane, which is painted blue in WinTess3. If the rotation is counterclockwise it is the underside, which is painted yellow in WinTess3.

Thus, we decided which one will be the first node to select by the mouse. A red rubber band line appears that accompanies us until we mark the second node. From this moment the process continues until we have generated all the triangles. To miss in this process WinTess3 helps us with the following criterion:

Triang8Así pues decidimos cual será el primer nudo a marcar y lo señalamos con el ratón. Aparece una línea elástica roja que nos acompaña hasta que marcamos el segundo nudo. A partir de este momento el proceso continua hasta que hayamos generado todos los triángulos. To avoid mistakes in this process, WinTess3 helps us with the following criteria:

  • From the second knot, to select the next, WinTess3 drag two elastic lines from the two nodes selected previously. One line is red and the other is blue.
  • We should mark a node so that the blue line lies always on the perimeter of the pattern and the red line is a diagonal that goes from one side of the pattern to other.

If we make a mistake and mark a wrong node, or if we have already completed the triangularization of the pattern, we have to press the right button of the mouse.
Three options will be displayed as shown on the right :

  1. create-patternIf we have finished the pattern correctly, press the Yes button and the pattern will be saved.
  2. If we decide that the finished  or half finished pattern doesn’t help us, we press the No button, and the pattern will be removed.
  3. If the node we last selected is wrong, hit the Cancel button and the last selected node will be deselected and the process will go back one step. This action to Cancel can be done as many times as needed, even up to the first node, but in this case it is easier to press directly the No button and start again.

When we have finished creating a pattern properly (we have pressed the Yes button in the previous screen), WinTess3 will ask us if we want to create another pattern. If our answer is positive, it changes the pattern number at the top of the screen for the new pattern that we’re going to start. If we respond negatively, the program returns to the normal state and the creation of patterns has finished.