Method and device for graphic rendering

Abstract

The invention discloses a method for protracting figures and a device thereof. The method comprises the following steps of: judging the distance between a present sampling point and a last sampling point, discarding the present sampling point when the distance therebetween is undersized to avoid wobbles caused by the sampling points centralizing in a small area; modifying the position coordinates of the present sampling point when the distance therebetween is oversized to replace the position coordinates of the present sampling point and to avoid cusps on the corner caused by the oversized conversion angles of the two sampling points; and protracting a track of a painting brush via a cardinal spline curve, wherein each control point only affects the two curves in the front thereof and the at the back thereof without the influence on the curves in other area, thus obtaining the smooth painting track and avoiding wobbles and cusps.

Description

Technical field [0001] The invention relates to a method and device for drawing graphics in a computer. Background technique [0002] With the increasing popularity of computer applications, computer drawing technology is becoming more and more common, involving art, design, education, military, and conferences. Generally, the computer draws an image by identifying some points when the brush (mouse) moves. These points are connected by straight line segments according to the brush trajectory to obtain a brush fold line. When there are enough sampling points, the fold line can roughly represent the path of the brush. However, because the slope of each fold line is different, the two straight lines Sharp points will appear when they are connected, resulting in a lot of sharp points in the trace of the brush written, and the writing handwriting is not smooth. [0003] In the prior art, in order to reduce the sharp points that appear in the brush trajectory, there are the following t...

AI Technical Summary

Problems solved by technology

[0002] With the increasing popularity of computer applications, computer drawing technology is also becoming more and more common, involving fields such as art, design, education, military affairs, and conferences. Usually, the computer draws images by recognizing some points when the brush (mouse) moves, and will These points are connected according to the brush trajectory through straight line segments to obtain a brush polyline. When there are enough sampling points, the polyline can roughly represent the path of the brush. There will be sharp points when they are connected, resulting in many sharp points in the written brush trajectory, and the writing is not smooth

[0003] In the prior art, in order to reduce the cusps that brush trail occurs, following technical scheme is arranged: one is in the process that paintbrush moves, every collects 4 points, promptly uses cubic Bezier curve (Bezier curve) to these However, due to the simple end-to-end connection between each curve, the drawn curve will still have sharp points; the second is to draw the curve by using the B-spline function, but due to the B-spline curve Convex hull / local support, resulting in not only the appearance of nodes in the drawn curve, but also the appearance of concave and convex inside the curve; the third is to use the first-order splicing of Bezier curves or the second-order splicing of Bezier curves to draw, which is passed Add additional points on the extension line of the connection line connecting the first two sampling points, but based on the end-to-end connectivity of the Bezier curve, there will still be unsmoothness

[0004] In addition, in the process of drawing graphics, due to the vibration of the brush when the user writes, it is easy to cause jagged, lagging, and broken pens when writing, which affects the aesthetics and smoothness of the handwriting. In the prior art, no Solution to brush shake problem

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