From the easiest way to see the development of the CAD platform, all the software is similar. We hit the keyboard into the numbers and letters, and hit the mouse to adjust the route arrow position. At the same time, the software accepts the message of the mouse and keyboard and dynamically displays the result on the screen. So your eyes can see what you are doing, your words are right, your mouse arrow is moved.
Similarly, in the design software. We issued a command, now you have to draw straight segments, the system is allowed to wait after the command, start waiting, what? . . .
Still waiting for the re-message of the mouse and keyboard, the software accepts the left mouse button, and records the number of mouse buttons. And it is judged when the mouse moves. If there is a point in the point chain, then the rubber strip is painted. why? I think I want to see it. . . :)
The mouse is left again, and hurry up and ask now to have a few points in the chain? A: Two. Oh, create a straight line! ! ! ! Of course, the straight line is created. To add to the list of drawings. At the same time, it is necessary to rebuild. Here mainly handles, such as you have a black color to the line, and the background is also black. So, then increase your eyes. . . In addition, you must rebuild the largest outer casing. That is, the largest outer frame. This is used to increase speed when displaying or capturing.
What if you want to catch? ? I have just captured the midpoint of the straight segment. And the mouse will change, change your face, prompting the user to choose the middle point in the line, and the midpoint is bright? ?
Here we have to study the captured mechanism. Some CAD software captures problems, but developers say that our capture is dynamically captured, and the mouse must move to catch. The person of this statement actually does not really understand the 来 龙 去 去.
In order to capture the things you want, you must prepare a big Dongdong. First of all, what should you clearly capture? What can I capture what? Each element should have a PICK function to determine if the current mouse point is in his own home. If at home, the position of the mouse is reported immediately. At the starting point? Still in the middle? Of course, in the starting point or in the mid point, it is called the so-called relationship. Write here today, Ming Jian will follow. . .
