4.2 Recommendations for Trunk Generation

These recommendations will be divided into six steps, which are required to achieve a detailed trunk surface.

4.2.1 Step One: Creating a Guiding Curve

In order to understand how to create a complex trunk shape there should be some guidelines which indicate how the geometry of the tree will be generated. For this purpose a simple curve is generated for which the user defines its’ level of detail. This means the curve has to have a start and end point as well as a number pf points in between which the user defines. The points on the curve are generated in random positions in the x and y plane, while points positioned in z axis are fixed, and increase at each proceeding point.

The first point is generated on a “ground” or so called “world origin” meaning its’ position in a 3 dimensional space would be x-0, y-0, z-0. This example uses symbolic measures and does not refer to any measuring system. As shown in Figure 28 step 1 of all of the following points would be higher compared to the previous point’s location in the z coordinate system. The user would be able to define limitations of positions except for the first point in the x and y plane while exact values would be randomly generated within specified limitations. If these limitations are not defined by the user there will be default values which the trunk generator uses. If the first point of the curve is in position x-0,y-0,z-0; the second point should be relatively close to first one. The z value always increases in 10 units for each of the proceeding points in the curve. Therefore x and y values should be smaller than that, and the start point should be half of the z value. This recommendation is based upon observation of natural trees since usually a tree trunk tends to grow upwards, with only slight variations on this. Therefore the values for x and y will not change dramatically. In any case the user will be able to adjust these values based upon his or her taste and desired result. For clarification please look at Figure 28 step1.


side coment. when we talk about step 1, and the guiding curve.

In order to or apply this proposal to existing tree generators, we could get this first spline from our L-system, or whatever algorythm is used in the existing generator . the question would be only how to conect end result of generated tree surface from generator and a trunk generator. One way would be simply to conect resulting polys. ofcourse probably there would still remain a question of tree editing after its creation. or simmple soulution could be to simply generate trunk again after each editing step from existing tree generator, well still some room to think.

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dont like english? u can (try) readig it in lithuanian or anny other language here! alternative, has no lithuanian :(

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