JPH04373086A - Straight line drawing system - Google Patents

Abstract

PURPOSE:To provide the straight line drawing system which can draw a straight line at high speed. CONSTITUTION:In this straight line drawing system to calculate points connecting two points respectively applied by X-Y coordinate data one by one and to write these points in a frame memory 3 as straight line drawing data, a control part 1 monitors the Y coordinate data at the point calculated by a straight line generator 2 and temporarily stores the coordinate data in a block having the same Y coordinate data in a cache memory 4 and when a Y coordinate is changed, the coordinate data temporarily stored up to the moment are totally written in a frame memory 3.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a straight line drawing method that makes it possible to draw straight lines at high speed.

0002

2. Description of the Related Art Conventionally, as a method for drawing a straight line using a CAD device or the like, for example, the Bresenham (Bresenham)
) algorithm is known.

In the straight line drawing method using Bresenham's algorithm, when a starting point and an ending point are given, a desired straight line is drawn by repeatedly calculating which coordinates intermediate points belong to and storing them in the image memory. It has gained.

0004

[Problems to be Solved by the Invention] However, in the conventional method described above, coordinate calculation and drawing are repeatedly performed for each point in the frame memory (image memory), which has a slow drawing speed. There was a problem in that it was not possible to increase the

The present invention has been made in view of the above circumstances, and its object is to provide a straight line drawing method that can perform straight line drawing at high speed.

[0006]

[Means for Solving the Problems] In order to achieve the above object, the present invention finds points connecting two points, each of which is given by X-Y coordinate data, one by one, and uses this as straight line drawing data. In the straight line drawing method of writing to the frame memory, the Y coordinate data of the obtained point is monitored, and the coordinate data of the section where the Y coordinate data is the same is temporarily stored,
The present invention is characterized in that when the Y coordinate changes, the coordinate data that has been temporarily accumulated up to that point is written all at once into the frame memory.

[0007]

[Operation] In general, an image memory (frame memory) can draw not only dots but also several dots at a time if the Y coordinates are the same (horizontal line). Therefore, in the present invention, when the Y coordinate data does not change, that is,
In sections where data is lined up in the axial direction, the data is temporarily stored in a cache memory or the like, and when the Y coordinate data changes, the data stored up to that point is written to the frame memory. As a result, the number of accesses to the frame memory can be significantly reduced, and straight line drawing can be performed at high speed.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a block diagram showing an embodiment of a linear drawing apparatus to which the method of the present invention is applied.

The device shown in the figure includes a control unit 1 that controls the entire device, a line generator 2 that calculates approximate coordinates of points forming a straight line point by point, and a line generator 2 that calculates approximate coordinates of points forming a straight line. A frame memory 3 that stores the coordinate data of as straight line drawing data is provided between the straight line generator 2 and the frame memory 3, and is arranged between the straight line generator 2 and the frame memory 3 to store the coordinate data of The cache memory 4 temporarily stores data for the section.

Next, the operation of this embodiment will be explained with reference to the flowchart of FIG.

When a straight line drawing command is input from the outside and starting point coordinate data and ending point coordinate data are supplied, the straight line generator 2 calculates approximate coordinates of the straight line (step ST1).
. This calculation is performed using the Bresenham algorithm described above. That is, in order to find a straight line connecting the starting point and the ending point, approximate coordinate data for each point from the starting point is found until the straight line is completed (step S
T2).

At this time, the control unit 1 monitors the Y coordinate data of the obtained point, and if data with the same Y coordinate data continues, the control unit 1 temporarily stores the coordinate data of that section in the cache memory 4. (Step ST3). When the drawing condition is satisfied, that is, the Y coordinate data changes or the cache memory 4 becomes full (step ST4YE).
S), and at that point, the data accumulated in the cache memory 4 up to that point is collectively written into the frame memory 3 as straight line drawing data (step ST5). The above process is executed until straight line drawing is completed (step ST2Y
ES).

As described above, according to this embodiment, the Y coordinate data of the determined point is monitored, and the coordinate data of the section where the Y coordinate data is the same is temporarily stored in the cache memory.
When the Y coordinate changes, all the temporarily stored coordinate data is written to the frame memory all at once, so the conventional method calculates each point one by one and then accesses the frame memory to write straight line drawing data. Compared to this, the number of accesses to the frame memory can be significantly reduced, and the straight line drawing speed can be increased.

The present invention is not limited to the straight line drawing method using Bresenham's algorithm, but is applicable to all conventional methods in which calculation is performed point by point and drawn in a frame memory.

[0015]

As described above, according to the present invention, the number of accesses to the frame memory can be reduced, so that straight line drawing can be performed at high speed.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram showing an embodiment to which the system of the present invention is applied.

FIG. 2 is a flowchart illustrating the operation of the embodiment shown in FIG. 1;

[Explanation of symbols]

1 Control section 2 Linear generator 3 Frame memory 4 Cache memory

Claims (1)

[Claims] 1. In a straight-line drawing method in which a point connecting two points each given by X-Y coordinate data is found one by one and written into a frame memory as straight-line drawing data, the Y of the found point is The present invention is characterized in that the coordinate data is monitored, the coordinate data of the same interval of Y coordinate data is temporarily stored, and when the Y coordinate changes, the coordinate data that has been temporarily stored up to that point is written all at once to the frame memory. A straight line drawing method.