JPH0737109A - Line texture generation method - Google Patents

Abstract

PURPOSE:To set apparent texture patterns to be constant without depending on the inclination of a vector. CONSTITUTION:When the texture patterns are plotted at corresponding inclination angles, texture patterns which apparently become the same texture patterns are stored in texture pattern memories 12-1 to 12-n corresponding to respective inclination angles as data. The respective texture pattern memories 12-1 to 12-n are referred to by addresses obtained by counting a dot clock by a counter 10, and enable signals obtained as data as a result are inputted to n 1 selector 14. The n 1 selector 14 inputs angle information showing the inclination angle of the vector from an SEL terminal and selects one enable signal. Since the enable signal is that showing the texture pattern deformed in accordance with the inclination angle of the vector, it is prevented that the apparent texture pattern changes in accordance with the inclination angle of the vector.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a line texture generating method for generating a line texture by an enable signal synchronized with a dot clock when drawing a vector by digital differential analysis (DDA).

[0002]

2. Description of the Related Art When writing (drawing) a vector on a frame memory of a display device, DDA is executed using the starting point coordinates and the ending point coordinates of the vector. DD
As is well known, A is a method in which start point coordinates and end point coordinates are initially given, and coordinate values of respective dots on a frame memory which should form a vector are generated at a predetermined timing. When generating the coordinate value of each dot, the DDA considers the tilt angle of the vector determined by the start point coordinate and the end point coordinate. For example, as shown in FIG. 3, when P1 is given as the start point and P8 is given as the end point, the dots P2 to P7 forming the vector are determined so as not to be greatly separated from the straight line connecting the start point P1 and the end point P8. At this time, the X coordinate (X address of the frame memory) and the Y coordinate (Y address of the frame memory) of each dot P1 to P8 are generated in synchronization with the dot clock (Dot Clock). In the following figures, the horizontal direction is X and the vertical direction is Y.
Coordinates.

When a line texture, for example, a broken line or a dash-dotted line, is generated by using such a method, an enable signal for permitting / prohibiting drawing is used. This enable signal is, for example, a signal synchronized with the dot clock as shown in FIG. 4, and takes an H value at the drawing timing of a dot to be drawn and an L value at the drawing timing of a dot that should not be drawn. When the enable signal has an H value, the dot is drawn, and when the enable signal has an L value, it is not drawn. Therefore, the line texture is generated with the line texture pattern determined by the enable signal.

The enable signal is generated by a circuit as shown in FIG. 5, for example. The circuit shown in this figure comprises a counter 10 and a texture pattern memory 12.

The counter 10 is a counter for counting the dot clocks having the above-mentioned predetermined frequency, and the count value of the dot clocks by the counter 10 is supplied to the texture pattern memory 12 as an address. The texture pattern memory 12 is a memory that stores, as data, a texture pattern of a line texture to be generated. When the count value of the counter 10 is given as an address to the texture pattern memory 12, the line pattern pattern to be generated, that is, an enable signal corresponding to the texture pattern is output from the texture pattern memory 12 as data. This enable signal is supplied to the gate after DDA,
As a result, the permission / prohibition control of drawing each dot is executed.

[0006]

However, when the line texture is generated by such a method, even if the line texture is generated by the same texture pattern, different textures are generated depending on the inclination angle of the vector to be drawn. The problem that it looks like a pattern occurs. For example, as shown in FIG. 6, as compared with the case of drawing a vector in the A direction, 45 in the A direction.
° When drawing a vector in the B direction, which is a different direction,
The texture pattern looks 1.414 times longer.

The present invention has been made to solve the above problems, and an object of the present invention is to prevent an apparent difference in line texture due to an inclination angle of drawing.

[0008]

In order to achieve such an object, the line texture generating method of the present invention uses a vector of a vector to be drawn such that a texture pattern is apparently constant regardless of the inclination angle of the vector. It is characterized in that a texture pattern is selected according to the tilt angle and an enable signal representing the selected texture pattern is generated.

According to the enable signal generating method of the present invention, a plurality of texture pattern memories are used corresponding to a plurality of kinds of tilt angles, and the texture patterns stored in advance in the respective texture pattern memories correspond to the corresponding tilt angles. These texture patterns are different texture patterns that appear to be the same texture pattern when the vector is drawn at an angle, and one of the enable signals output from each of the plurality of texture pattern memories depends on the tilt angle of the vector to be drawn. It is characterized by selecting by.

Further, the enable signal generating circuit of the present invention has a plurality of types of texture pattern memories so that different texture patterns which are apparently the same texture pattern when the vectors are drawn at the corresponding tilt angles are stored. And a means for selecting one of the enable signals respectively output from the plurality of texture pattern memories according to the tilt angle of the vector to be drawn. .

[0011]

In the line texture generating method of the present invention, the enable signal is generated according to the inclination angle of the vector to be drawn. Therefore, when performing the drawing control using this enable signal, it is possible to perform the control so that the apparent texture pattern becomes constant regardless of the inclination angle of the vector. This prevents an apparent difference in the texture pattern due to the vector inclination angle.

Further, in the enable signal generating method and circuit of the present invention, a plurality of texture pattern memories are used corresponding to a plurality of kinds of tilt angles. Different texture patterns are stored in the texture pattern memory. Each texture pattern is
The patterns have the same texture pattern when they are drawn at the corresponding tilt angles. Further, in the present invention, one of the enable signals respectively output from the plurality of texture pattern memories is selected according to the inclination angle of the vector to be drawn. Therefore, according to the present invention, when the drawing control of each dot is performed using the enable signal generated and output, the apparent texture pattern becomes constant regardless of the inclination angle of the vector.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the present invention will be described below with reference to the drawings. The same components as those of the conventional example shown in FIGS. 3 to 6 are designated by the same reference numerals and the description thereof will be omitted.

FIG. 1 shows a configuration of an enable signal generating circuit according to an embodiment of the present invention, and FIG. 2 shows a line texture generating method realized by using this circuit.

As shown in FIG. 1, the circuit of this embodiment has n (12-1 to 12-1) texture pattern memories 12.
12-n). Each texture pattern memory 1
2-1 to 12-n have the same texture pattern,
The texture pattern deformed according to the inclination angle of the vector to be drawn is stored as data. Therefore,
When the texture pattern memories 12-1 to 12-n are referred to by using the count value of the counter 10 as an address, the enable signals output as data from the texture pattern memories 12-1 to 12-n have different patterns. . Also, the texture pattern memory 12-
An n → 1 selector 14 is provided at the subsequent stage of 1 to 12-n. The n → 1 selector 14 inputs angle information indicating a tilt angle of a vector to be drawn from a SEL terminal, and selectively outputs any enable signal according to the input angle information.

Consider, for example, the case where a vector is drawn in the A direction as shown in FIG. The texture pattern corresponding to the tilt angle in the direction A, that is, 0, is stored in any of the plurality of texture pattern memories 12-1 to 12-n (for example, 12-1). Assuming that the enable signal read out as data (that is, the texture pattern corresponding to the inclination angle of 0) is a signal as shown by the enable signal A in FIG. 2, the texture pattern of the vector drawn along the A direction is 5 The texture pattern has individual drawing, four non-drawing, and one drawing. On the other hand, the texture pattern having an inclination angle of 45 ° corresponding to the B direction is the texture pattern memory 12 described above.
The enable signal stored in any of -1 to 12-n (for example, 12-3) and read as data from the texture pattern memory 12-3 is a pattern represented by the enable signal B in FIG. Then, the pattern of the vector drawn along the B direction is a pattern of four drawing, three non-drawing, and one drawing.

When the two types of line textures thus obtained are compared, the apparent texture patterns are substantially the same. That is, no apparent texture pattern difference as shown in FIG. 6 occurs. The feature of this embodiment is that the texture pattern memory 12
A plurality of texture patterns are provided and each texture pattern memory 12 has a uniform texture pattern.
The texture patterns to be stored in -1 to 12-n are set.

Therefore, according to the present embodiment, when the line texture is generated, the texture pattern which is apparently the same can be obtained regardless of the inclination angle of the vector.

[0019]

As described above, according to the line texture generating method of the present invention, the enable signal is generated according to the inclination angle of the vector to be drawn, and the enable / disable of each dot is determined using this enable signal. Since the line texture is controlled, the texture pattern becomes apparently constant regardless of the inclination of the vector when the line texture is generated.

Further, according to the enable signal generating method and circuit of the present invention, a plurality of texture pattern memories are used, and the texture patterns stored in the respective texture pattern memories are apparently the same when drawn at the corresponding inclination angles. Since the texture pattern is a texture pattern of, the apparent texture pattern is changed to the vector inclination by selecting one of the enable signals output from each texture pattern memory according to the inclination angle of the vector to be drawn. It will be constant regardless. Therefore, by using the enable signal generated in this way to control whether or not each dot can be drawn,
It is possible to realize suitable line texture generation.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of an enable signal generating circuit according to an embodiment of the present invention.

FIG. 2 is a diagram showing an example of a line texture in this embodiment.

FIG. 3 is a diagram for explaining drawing of a vector by DDA.

FIG. 4 is a diagram showing a method of realizing a texture pattern using an enable signal.

FIG. 5 is a block diagram showing a configuration of an enable signal generation circuit according to a conventional example.

FIG. 6 is a diagram showing a problem in the related art.

[Explanation of symbols]

 10 counters 12-1 to 12-n texture pattern memory 14 n → 1 selector

Claims (3)

[Claims] 1. A coordinate value of each dot forming the vector is generated by performing a digital differential analysis of the vector using the start point coordinate and the end point coordinate, and based on the generated coordinate value and in synchronization with a dot clock. When drawing each dot, the line texture generation method that generates line texture by synchronizing with the dot clock and controlling the drawing enable / disable by the enable signal that represents the texture pattern is apparently constant regardless of the tilt angle of the vector. A line texture generating method, wherein a texture pattern is selected in accordance with a tilt angle of a vector to be drawn so as to form a texture pattern, and an enable signal representing the selected texture pattern is generated. 2. A texture pattern of a vector to be drawn is stored in advance in a series of addresses on the texture pattern memory as data, the texture pattern memory is referred to in the order of addresses, and the data output from the texture pattern memory is obtained. In the enable signal generating method for outputting as an enable signal indicating whether or not each dot of the vector can be drawn, a plurality of texture pattern memories are used corresponding to a plurality of kinds of tilt angles, and are stored in advance in each texture pattern memory. The texture patterns are different texture patterns that appear to be the same texture pattern when a vector is drawn at a corresponding tilt angle, and one of the enable signals output from each of the plurality of texture pattern memories. Is selected according to the inclination angle of the vector to be drawn. 3. A texture pattern memory in which a texture pattern of a vector to be drawn is stored in advance in a series of addresses as data, and means for counting dot clocks and referring to the texture pattern memory in the order of addresses using the count values. In the enable signal generation circuit that outputs the data output from the texture pattern memory as an enable signal indicating whether or not each dot of the vector is drawn, the texture pattern that is apparently the same when the vector is drawn at the corresponding tilt angle In order to store different texture patterns that are different from each other, a plurality of texture pattern memories are provided corresponding to a plurality of tilt angles, and one of the enable signals output from the plurality of texture pattern memories is drawn. You Enable signal generating circuit comprising means for selecting according to the inclination angle of the feeder vector.