JPH0285977A - Closed area paint-out display method - Google Patents

Abstract

PURPOSE:To perform the paint-out of a graphic with high efficiency by preparing a memory on which an X-coordinate setting a Y-coordinate as an address when it is the Y-coordinate out of the X-coordinate and the Y-coordinate comprising plot data and a sign bit are written, and performing the plot processing and a paint-out processing of a closed curve integrally. CONSTITUTION:The memory having only capacity corresponding to the Y- coordinate of a graphic memory is prepared, and when a graphic is plotted, a bit which calls the present plotting X-coordinate in (odd-th time of) plotting for an arbitrary Y-coordinate and the sign bit is stored with an address corresponding to the present plotting Y-coordinate in a line memory. Next, a horizontal line connecting two points based on the X-coordinate stored in the line memory at the eventh time of plotting for the arbitrary Y-coordinate and the present plotting X- and Y-coordinates is drawn while performing an arithmetic operation by the exclusive OR of the data in the graphic memory on the line and the data of paint-out is performed. In such a manner, it is possible to shorten a paint-out processing time.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is used in the fields of graphic displays, CAD (computer aided design), etc. to draw a closed curve of any desired shape on a display surface, and to draw the inside of the closed curve. There are cases where it is necessary to display a closed area by filling it in, and the present invention relates to a closed area filling display method in such a case.

[Conventional technology]

FIG. 3 is an explanatory diagram showing the process of drawing processing according to a conventional method when an arbitrary desired closed curve is drawn on the display surface and the inside thereof is filled in.

As seen in Figure 3 (a), the starting point (XO.

YO) data is given, and then a desired closed curve is drawn (
When the necessary data is sequentially given, a closed curve is first drawn according to the data, and drawing data indicating the drawn closed curve is written into a drawing memory (not shown).

After drawing the closed curve in this way, it is time to draw the third closed curve.
As seen in figure (b), the starting point (XO).

From YO), a drawing process (filling process) is performed in which dots are drawn one by one along the X-axis direction.

In the figure, starting from the starting point (XO, YO), the coordinate position (X
p, YO).

This is done one dot at a time (the limit is until the boundary of the closed curve is reached, but the boundary of the closed curve can be known by reading the drawing memory. Therefore, each time one dot is drawn, the next one is drawn. The X coordinate of the dot to be drawn is compared with the boundary obtained by reading it from the drawing memory, and the drawing is continued while confirming that the boundary is not exceeded.

After completing the filling process for the Y coordinate position of the starting point, as shown in Figure 3 (c),
The coordinate position is shifted upward or downward by one position and the filling process is performed in the same way. When there is no area to be filled in in the Y coordinate direction, the filling process is completed as shown in FIG. 3(d).

[Problem to be solved by the invention]

In the conventional method described above, two processes are required to fill in one arbitrary desired figure: the process of drawing a closed curve, and the process of filling in after the process is completed.Moreover, in the process of filling, one dot is Each time the figure is filled in, a comparison operation with the boundary of the closed curve is performed, so there is a drawback that it takes time to complete the filling of the figure.

SUMMARY OF THE INVENTION An object of the present invention is to provide a closed area filling display method that reduces the time required for such filling and enables efficient filling of figures.

[Means to solve the problem]

Therefore, in the present invention, a closed curve is drawn on the display surface according to the drawing data given by the X and Y coordinates, and
In the closed area fill display method, which displays a closed area filled with a specific color, among the X coordinates and X coordinates that make up the drawing data, if the X coordinate is the X coordinate, the X coordinate and the sign bit are written using the X coordinate as the address. A memory is prepared and this is used to perform the drawing process and the filling process of the closed curve in one body, rather than performing them separately.

[Effect]

Referring to FIG. 4, the operation principle of the present invention will be explained, as well as the operation thereof.

In FIG. 4, numeral 3 is the above-mentioned memory, which will hereinafter be referred to as a line memory. 11 is an arbitrary desired figure drawn on the display surface.

The line memory 3 is a memory having an address space in one-to-one correspondence with all possible X coordinates of a drawable area on the display surface. As can be seen from the figure, in the line memory 3, the X coordinate in the drawable area of the display surface is used as an address, and the X coordinate and sign bit (l or O) are stored in each area (column) corresponding to that address.
It is designed to store. Initially, both the column storing the X coordinate and the column storing the sign bit are cleared to zero.

It is assumed that a figure 11 is drawn in a drawable area on the display surface and its interior is filled in.

When the starting point data (XO, YO) of the figure 11 is first given, the drawing on the display surface is performed by a CPU (not shown). At the same time, the CPU refers to the address YO of the line memory 3, and When it learns that 0 is stored in the sign bit storage column, it writes 1 there and writes xO in the X coordinate column.

Similarly, when the next drawing data (Xp, Yp) is given, the drawing is performed on the display surface, and at the same time, the CPU writes the address Y of the line memory 3.
Referring to p, it learns that 0 is stored in the sign bit storage column, writes 1 there, and writes Xp in the X coordinate column.

In this way, the lowest position (X
Suppose that you have reached the position where the value of the X coordinate (L, YL) is the minimum. At this time, in exactly the same way, in the line memory 3, 1 is placed in the sign bit column corresponding to that address YL.
is written, and only X is written in the X coordinate column.

Next, the position where the value of this X coordinate is the minimum (XL).

YL) and starts to rise, the X coordinate of the drawing data given this time becomes the same value as the X coordinate of the drawing data given once before. For example, as you can see by looking at the point (XQ, Yp) that is formed after passing the position where the X coordinate value is minimum (XL, YL) and starting to rise, this is the X coordinate of the position (Xp, Yp). The same X coordinate value is taken.

At this time, CPtJ refers to the address Yp in the line memory 3 and finds that 1 has already been written in the sign bit column there. Then the CPU determines the position (XQ
, Yp), reads out the X coordinate xp previously stored at address Yρ from the line memory 3, and reads position 1f (Xp.

Filling process between (Yp) and position (XQ, Yp) (During this time, the X coordinate is constant at yp, and only the X coordinate is Xp.
If the dots in between are all 1, then they are changed to 1).

When the filling process is completed, the next drawing data is received and the process proceeds to the next drawing data. By using the line memory 3 in this manner, any desired figure 11 is drawn, and at the time the drawing is finished, the process of filling in the closed area is also finished.

[Embodiment] FIG. 1 is a block diagram showing the configuration of a filling circuit that executes filling processing according to the present invention.

In the same figure, 1 is the X of the curve to be drawn from CPU10.
2 is a drawing X coordinate generation circuit that receives coordinate starting point data and generates a drawing X coordinate; 2 is a drawing X coordinate generating circuit that similarly receives X coordinate starting point data of a curve to be drawn from CPU10 and generates a drawing The line memory (described earlier with reference to FIG. 4), 4, sends a drawing direction control B signal to the drawing X coordinate generation circuit 1 and the drawing A line memory address data control circuit generates the coordinates of drawing data after the data, 5 is a comparator, 6 is a line memory control circuit, 7 is a sign bit control circuit, 8 is a line memory input data register, and 9 is a latch.

FIG. 2 is a flowchart showing the operation flow of the filling circuit shown in FIG. The same chart is (a) to (
It consists of the processing of n).

The operation of the filling process according to the present invention will be described below with reference to FIGS. 1, 2, and 4.

First, as shown in FIG. 2(a), the line memory control circuit 6 controls the line memory 3 in response to a command from the CPU 10.
Clear to zero. That is, the X coordinate data column and the sign bit data column provided for each address are all cleared to 0.

Next, as shown in FIG. 2(b), initial values (XO, YO) are sent from the CPU 10 to the drawing X coordinate generation circuit 1 and the drawing
The drawing X coordinate generating circuit 1 and the drawing X coordinate generating circuit 2 under the control of the line memory address data control circuit 4 based on the command of CP[Jlo, hereinafter given to the coordinate generating circuit 2,
Generates the X coordinate and X coordinate along the curve to be drawn,
Each time, the coordinates are returned to the CPU 10 as YQ for the X coordinate and XQ for the X coordinate, and the CPU 10 performs drawing processing on a display surface (not shown) as shown in FIG. 2(c).

If the starting point is (XO, YO), when the drawing of the starting point (XO, YO) is completed in process (C) in FIG. 2, the process proceeds to process (d). In process (d), the current Y coordinate data YO and the previous Y coordinate data Yp are compared, and if they are equal, it is determined that drawing is proceeding in the X coordinate direction, and process (e
) and return to process (c) to continue drawing.

In process (d), if the current Y coordinate data YO and the previous Y coordinate data Yρ are not the same, process (e
), the sign bit column of the line memory 3 is referred to using the current Y coordinate data YQ as an address.

In FIG. 1, the above comparison is performed in the comparator 5, and if the results are the same, the line memory 3 does not refer to the sign bit column, and if they are not the same, the line memory controls the line memory so that the sign bit column is referred to. It controls the circuit 6.

The sign bit column of the line memory 3 is referenced, the data therein is taken into the sign bit control circuit 7, and the second
The determination process shown in FIG. (f) is performed. As a result, if the sign bit is 0, this is notified to CPU10, and CPU
Ul0 activates the line memory control circuit 6 and stores the current X coordinate data x in the X coordinate data column of the line memory 3.
If p, open gate G and write Xp, and write 1 in the sign bit data field (process (g) in Figure 2).
h)). Then, the process returns to process (c) and proceeds to the drawing process using the next coordinate data.

If the sign bit is 1 as a result of the determination process shown in FIG. If it is the X coordinate data Xp stored in the data storage, xp is read out and latched into the line memory input data register 8. And at that time X
Since the coordinates are known as addresses, the space between the current drawing coordinates (X, YQ) and the coordinates (Xp, YQ) obtained by reading from the line memory 3 is filled in (processing (i) in Figure 2). ), (f) ).

After that, the CPU 10 controls the line memory control circuit 6 to clear the X coordinate data column corresponding to the address in the line memory 3, and also clears the sign bit data column to 0.
(processes (j) and (k) in Figure 2).

Thereafter, the CPU 10 executes the process (mL (n)) shown in FIG. 2 to complete the drawing (filling ends when the drawing of the curve ends), or otherwise returns to the process (c).

The above embodiments can be summarized as follows.

First, prepare a memory with enough capacity to correspond to the X coordinate of the graphic memory called line memory.When drawing a figure, 2n-1(n
=1.2.3...) In the (that is, odd-numbered) drawing, the current drawing X coordinate and the bit that calls the sign bit are stored in the line memory at an address corresponding to the current drawing Y coordinate.

Next, for any Y coordinate, 2n (n-1, 2゜3...
・During the )th (that is, even-numbered) drawing (determined as the 2nth drawing when the above-mentioned sign bit is 1"), based on the X coordinate stored in the line memory and the current drawing X, Y coordinate. 2
A horizontal line connecting points is drawn while performing an exclusive OR operation between the data in the graphic memory and the fill data on the line.

Assuming that an arbitrary figure is drawn as a series of vectors, the line memory operations (storing the X coordinate and setting the sign bit to "1") at the end points of each vector are as follows. .

At the starting point of the vector, the line memory is not operated as shown in FIG. 5(a). The line memory is operated from the next point following the starting point, and at the end point of the vector, the line memory is also operated as shown in FIG. 5(b).

As long as the Y coordinate is constant, the line memory is not operated, and only after the Y coordinate changes, as shown in Figure 5 (c),
Manipulate line memory.

As a result, the following inconveniences may occur.

Bad point 1> In the case of a figure like Figure 6 (a), points A and B
, D are on the same horizontal line, points B, which should not be connected,
It connects between D. The reason is as follows.

In the above embodiment, no line memory operation is performed at point B because the Y coordinate has been constant up to that point. And here, point 0. When drawing between points A, the line memory corresponding to the Y coordinate at point A is operated and the sign bit is set, so when drawing between points C and D, when the point is reached, Between points B and D (actually point A
, D).

Bad point 2: In the case of a figure like Figure 6 (b), you connect points B and D, which should not be connected, and do not connect points C and E, which should be connected and filled in. The reason is as follows.

Between points B and D, in the line memory operation of the above embodiment, points 0. When drawing between points A, the line memory for the Y coordinate of point B is manipulated and the sign bit becomes "1", and when drawing between points C and D, point B is
, D will be connected.

Regarding points C and E, when drawing between points B and C, connect points A and C when reaching point C, and the sign bit in the line memory for this Y coordinate is cleared and becomes "0". . Therefore, when drawing between points C and F, even if the point E is reached, the points C and E are not connected (not filled).

A sign bit operation that eliminates the above disadvantage will be described below.

First, save the direction of each vector when drawing it, compare it with the direction of the vector (excluding horizontal vectors) immediately before drawing that vector, and calculate the Y coordinate of the vector as shown in Figure 7 (a). When the displacement in the direction is reversed, the sign bit of the line memory for the Y coordinate of the starting point of the vector is changed to
When it is "0", it is inverted to "1".

As a result, in FIG. 6(b), at point B, the sign bit in the line memory for that Y coordinate is inverted and cleared and becomes "'0", and conversely, at point C, the sign bit in the line memory for that Y coordinate is The place that should be “0” is reversed and set to I11, so when drawing between points C and D, points B and D will not be connected when the dot is reached, and the point In addition, when drawing between F, there is no need to connect points C and E even when the point is reached.

In addition to the above operations, the vector to be drawn is
As shown in figure (b), when Y=a (a is a constant), that is, when the Y coordinate is a constant horizontal vector, no operations are performed on the line memory, and the vector direction is not stored. do. This is why it is written as ``Horizontal vector is excluded <°'' when inverting the sign bit mentioned above.

As a result, when drawing between points B and C in FIG. 6(a), the stored vector direction is point 0. It is between A,
Compared to that, the Y coordinate direction is reversed, so point B
The sign bit in the line memory for the Y coordinate of point A is inverted and becomes "0".

Therefore, when drawing between points C and D, points B and D will not be connected when the dot is reached. However, when the sign bit is inverted, the following two new problems arise.

Problem 1> As shown in Figure 8 (a), points O1α, that is, the drawing starting point O of an arbitrary figure, are connected to point α, whose X coordinate is O and Y coordinate is the same as the drawing starting point. There are cases. The reason is as follows.

Since the judgment of whether the displacement of a vector in the Y-coordinate direction has been reversed is made by comparing it with the Y-coordinate direction of the vector drawn immediately before, when drawing the first vector of an arbitrary figure, it is necessary to Since the Y coordinate of the vector is undefined (originally, the previous vector should not exist because it is the first one, but in reality this is not the case and it becomes undefined), if by chance they are in the same direction, This problem does not occur, but if it is in the opposite direction, the sign bit in the line memory corresponding to the Y coordinate of the drawing start point will be inverted. Since the line memory is cleared to 0 before drawing the figure, the sign bit is "0" at this time, and by reversing it, it becomes "1".
It becomes Pa.

As a result, the sign bit 1 in the line memory for the Y coordinate of the drawing start point of the arbitrary figure. The X coordinate becomes 0. And the final vector of the arbitrary figure, points B and O in Figure 8 (a)
When drawing the vector between, when it reaches point 0, it becomes point 0. as shown in the figure. It connects α.

When determining the displacement in the Y coordinate direction of the first vector of an arbitrary figure, instead of comparing it with the previous vector, in the case of the first vector, the Y coordinate direction to be compared is kept constant. Even if you set the value to , it is impossible to specify the direction in which the first vector of an arbitrary figure is drawn, so it is better if the vector is in the same direction as the set direction. , if it is in the opposite direction, a problematic phenomenon will occur, and in the end it is no different from comparing with the previous vector, and there is no solution.

Problem 2> Draw a figure like the one shown in Figure 8 (b) at point 0. C,B.

There is no problem if you draw points A and O in that order, but as shown in the same figure, point 0. If A, B, C, O are drawn in order, point O9
It connects α. The reason is as follows.

In the embodiment described with reference to FIGS. 1 and 2, no line memory operation is performed at point A. Next, when drawing between points A and B, the vector Y
The displacement in the coordinate direction changes from the horizontal direction to the downward direction.

In this case, since it is determined that the displacement in the Y coordinate direction has been reversed, the sign bit in the line memory for the Y coordinate of point A is inverted, that is, set to "1". When drawing between points 0.0, point 0 and point A are on the same horizontal line, and the line memories for these two points are the same, so when point O is reached, O9α is connected.

In order to solve the second two problems, perform the following operations.

First, a flag (hereinafter referred to as the first starting point flag) is provided to determine whether it is the drawing start point of an arbitrary figure, and this flag is set immediately before drawing the figure.When drawing a vector, this flag is set. Problem 1 can be solved by determining whether the sign bit is set and not inverting the sign bit if it is set. In principle, this flag is cleared after the judgment has been made.

Next, in FIG. 8 (b), the first starting point flag is set to point 0 according to the principle. It will be cleared after determining whether it is set or not when drawing between A, but as shown in the figure, the first vector from the drawing start point (vector between points 0 and A) ) is Y=a (a is a constant), that is, in the case of a horizontal vector, the first starting point flag is not cleared even after determining whether it is set, and the next vector is also horizontal. In other words, the first starting point flag remains set while the first and subsequent vectors are horizontal vectors, and when a non-horizontal vector appears for the first time,
Clear it after determining whether this flag is set when drawing that vector.

By performing this operation, point A in Figure 8 (b)
, B, since the first starting point flag is set, the sign bit in the line memory for the Y coordinate of point A is no longer inverted and becomes "1", and points 0 .
Even if you reach point 0 when drawing between 0 and 0, the point 0. Since there is no connection between α, this problem is also solved.

All the operations described so far are performed when drawing each vector of an arbitrary figure, and they are also
By performing filling based on sign bit detection in Figure 1), accurate filling of all shapes is achieved.

The control flow of the sign bit operation as explained above is summarized in FIG. 9.

FIG. 9 shows steps 81 to 311 as shown in the figure.
There is no need to explain this further.

Moreover, such an operation flow can be easily realized by software in the CPU.

[Effects of the Invention] FIG. 10 is an explanatory diagram showing the process of filling processing according to the present invention. In Figure 10 (a), the starting point (XO, Y
However, according to the present invention, if drawing is performed one dot at a time on the Y coordinate, the drawing starts from the lowest position (O) in the Y coordinate direction.
xt, , YL) and turns upward from there, the required section is filled in as each dot is drawn in the Y-coordinate direction, so the figure drawing starts at the first stage.
The process progresses as shown in FIG. 0 (b), and when the curve tit drawing is completed, the filling is also completed accurately as shown in FIG. 10 (c), so the figure drawing is completed in one process. Moreover, unlike conventional drawing processing, there is no need to read data written in the drawing memory dot by dot and compare it with the current drawing data, so there is an advantage that the fill-in drawing processing is speeded up.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of a filling circuit that executes filling processing according to the present invention, FIG. 2 is a flowchart showing the operation flow of the filling circuit shown in FIG. 1, and FIG. FIG. 4 is an explanatory diagram showing the process of drawing processing using the conventional method. FIG. 4 is an explanatory diagram of the operating principle of the present invention. FIG. 5 is an explanatory diagram of the operation of the sign bit. FIG. FIG. 7 is an explanatory diagram of the mode of operation of input pit; FIG. 8 is an explanatory diagram of other inconveniences that may occur when the present invention is implemented without operation of the sign bit; FIG. 9 is a chart showing the control flow of the sign bit operation according to the present invention, and FIG. 10 is an explanatory diagram showing the process of filling processing according to the present invention. Description of symbols 1... Drawing Y coordinate generation circuit, 2... Drawing X coordinate generation circuit, 3... Line memory, 4... Line memory address data control circuit, 5... Comparator, 6...
・Line memory control circuit, 7... sign bit system? i
lQ path, 8... line memory input data register, 9
...Latch, 10...CPU, 11...Graphic. Agent Patent Attorney Akio Namiki

Claims (1)

[Claims] 1) A closed area filling display method that draws a closed curve on a display surface according to drawing data given by X and Y coordinates, and displays the closed area inside the curve by filling it with a specific color, Among the X and Y coordinates that make up the drawing data, prepare a memory in which to write the X coordinate and sign bit using the Y coordinate as the address, and first write a column in the memory to write the X coordinate and a column to write the sign bit. Clear all to zero, and when the drawing data as the starting point data of the closed curve is given, while performing the drawing process, look at the sign bit column of the memory whose address is the Y coordinate of the starting point data, and write it there. If 1 is not set in , write the X coordinate in the X coordinate field and set 1 in the sign bit field, then receive the next drawing data and proceed to its processing, and write the memory whose address is the Y coordinate of the start point data. Look at the sign bit field and if 1 is set there, read out the X coordinate that was already written in the , to move on to the filling process between both X coordinates (during which the Y coordinate is constant), and after that, receive the next drawing data and proceed to that process. A closed area filling display method characterized in that when the closed curve is drawn by returning to the starting point data, the filling process for the closed area inside the closed curve is also completed. 2) In the closed area filling display method according to claim 1, the closed curve starting from the starting point data and returning to the starting point data is displayed as a succession of vectors, [1] Each vector (horizontal curve whose Y coordinate value is constant) When drawing a vector (excluding vectors), save the direction of the drawn vector, compare it with the direction of the vector immediately before drawing the vector (excluding horizontal vectors whose Y coordinate value is constant), and When it is determined that a reversal of the drawing direction of the coordinates has occurred, the sign bit in the line memory for the Y coordinate data of the starting point of the vector processed for drawing is changed to 0 if it was previously 1, and 0 if it was 0. [2] At the drawing start point of the closed curve, a special flag bit is prepared in advance to indicate this, and this bit is set. If you look at the special flag bit corresponding to the start point of [3] However, while the first drawing vector from the drawing start point of the closed curve and the following drawing vectors are horizontal vectors, the special flag bit is cleared in principle. , even after determining that the special flag bit is set in the process of [2] above, the special flag bit is not cleared, and when a non-horizontal vector appears, after the above-mentioned necessary determination, the special flag bit is not cleared. A closed area filling display method characterized by clearing the special flag bit.