I will give you a detailed analysis of the Illustrator software and share with you the tutorial on creating complex and smooth curves.
Tutorial sharing:
Like other flat vector software, Adobe Illustrator uses the besell curve and cubic curve. It uses four control points to describe and control the curve, in Illustrator, the control part is set to the anchor and the handle. Therefore, the starting and ending positions of the lines are controlled by the first and last two anchor points.
When using the pen tool to draw A curve, click a and drag it to A, and then click B to drag it to c, that is, to confirm that B forms the AB curve, then, in general, using A pen to draw a curve is achieved by dragging, unlike some of the 3D software's curve drawing tools by placing A a B B, the advantage of this method of plotting in Illustrator is that it is easier to control (it is determined by two points). The most obvious disadvantage is c. That is to say, when you want to draw B, c has been determined. That is to say, if this curve is to be continued, c has been determined in advance. If you have no idea about the next curve when drawing B points, c is placed only to meet the requirements of B, and the next section is not realized, it will bring more follow-up work to the drawing work, by adjusting the control point of the handle.
In some tutorials on curve drawing, we can see a 1/3 rule, that is, the distance from the anchor point to the control point of the handle is about 1/3 curve length, which is of course a common experience, it is not strictly observed. It depends on the shape of the curve.
1/3 the rule is designed to avoid situations similar to those on the right. In fact, this specification is easy to understand. The simpler the curve we are pursuing in terms of mathematical description, the better. The simpler it is, the shorter it is, even means that the weights of each control point are even, and the weights of each control point are not necessarily the same. However, if the curves between the left and right points are symmetric, the weights of the control points must be the same, it includes not only the curve stretching weight, but also the curve direction weight. Simply put, we can't stretch and relax too much, but keep it tight in a simple way.
A curve, that is, the curve formed by the two handles of the two anchor points, is easy to draw and control. You only need to adjust it with patience, because any change can be within the controllable range. However, a complex curve is not a curve formed by two anchor points. It must be at least three anchor points.
If we plot a curve, it would be best to use two anchor points to form it. If we put another anchor point in the middle of the curve at this time, it would be a hassle, and the complexity of general control would suddenly double, but because of the shape requirement, more anchor points must be placed, and a simple curve can express a limited shape.
There is one more anchor to fit a curve. The so-called fitting is like hand-drawn shape first, then scanning the image into the software, and then sketching the contour. Sometimes we do not have this step, for example, you can draw a line directly by hand, with a head, or even a feeling. In this case, you may draw a curve that looks similar to the shape. There are many ways to draw it, you can put the anchor here, or you can put it there, but you can drag the handle a little longer, so how do you choose.
Experience, because it is a craft. However, it is important to remember the word "uniform" and pursue "simplest ".
Once you increase the number of anchor points to four, it will become very complicated. Even experienced people still need to make continuous adjustments to achieve satisfactory results.
The goal of drawing a curve is to determine, rather than simply looking at it, that is, to include in a "simple", each point can be determined, just like a circle, its control points are OK. The determination of the curve we draw is certainly not 100%, and it is also a sense of precision. If we have rich experience, we can know where the next control point is.
However, if a curve is symmetric, we have another certainty. When creating the anchor, we can make the left point as high as the right, and so on, we can find a lot of certainty, or fit such determination, such as the proportion, this section is half of that section, and so on. Instead, it uses the help of the grid to plot, or it can be regarded as looking for confirmation.
Even if we use a grid, it takes a lot of work to determine the length and direction of the four anches and the stretch of the handle. In reality, the method we use depends on the eyes, after the general requirements are met, the dimension is adjusted again, and the "OK" value is anchored, which is constantly adjusted during the normalization process.
However, this method is inefficient, especially when the number of anches reaches and exceeds four complex curves.
It is similar to the shape of the phone icon on iOS 7, and the symmetry between the left and right is obvious, but it is difficult to use three anchor points to determine this shape, especially the requirement for "uniform ", there is no excessive stretching or a high degree of shape fitting.
When using Illustrator to draw a curve, it is very rare to draw it directly, because the curve we mentioned above is not deterministic, unlike the combination of the quadrilateral and the circle and these basic shapes, the confirmation is in advance. Therefore, no matter whether we input hand-drawn data for fitting, it is always in a fitting state during the painting process.
In this proposal, we will introduce more certainty in the process of drawing these complex smooth curves. Just as we realize that images are symmetric, we need to find some internal logic, controls the combination of lines in a controllable manner.
This strategy is the curve Dismantling. The most basic unit of curve drawing in the complex and smooth curve disassembling is the curve of two handles of the two anchor points, and then the curve is connected after the dismantling, make some minor adjustments.
The curves of the two anchor points are controllable, that is, there is a high degree of certainty, and the handle length is independently controlled, it is not as influential as it is in normal plotting (as we mentioned at the beginning, we Plot c to get B, the handle direction is easily controlled in the process of drawing and subsequent connection and adjustment.
Then the curve drawing technique is transformed into the curve dismantling technique, and the dismantling technique is still "uniform" and "simple" for the purpose, that is to say, if there is symmetric and similar symmetry, that is the easiest part to disassemble. If it is difficult to disassemble, we will analyze the curvature changes of the curve, and combine our awareness of the shape of the basic curves of the two anches, find but start with the goal of "simple.
This dismantling strategy is also common in three dimensions, but the operation methods are different. Here, we rely on the operation means to be the basic control unit of the curve at the beginning.
Note: The image is just an example. This type of splitting is not unique, and I fit the 120*120 px icon of Apple in my own way. The error must be very large. This method is found between three dimensions and two dimensions. For example, you can import a high-order smooth curve into a cubic besell curve environment to see how the software automatically places the anchor.
All right, the above information is the detailed design, complex and smooth curve drawing tutorial for the users of this software of Illustrator, users have seen this, and I believe that you are also very clear about the method of drawing, so next we will go to follow the tutorial to draw a complex smooth curve to try the effect.
