JP2005099313A - Image drawing method and image drawing system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image drawing method and an image drawing system capable of reducing the load on a CPU by extremely reducing trigonometric processing time in the rotation operation processing of a drawing object. <P>SOLUTION: In steps SB1, SB2, SB3 and SB4, the rotation state of the drawing object - whether it is necessary to rotate the object, whether the object is about to rotate, whether the rotation is to be continued - is judged. In steps SB5, SB6 and SB7, a rotation result table that is a trigonometric operation result corresponding to the rotation angle of the drawing object is selected. In the step SB8, the coordinates of the display position of the pixels of the drawing object after rotation is obtained and, in the step SB9, the pixels are drawn in a memory. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

    The present invention relates to an image drawing method and apparatus used for a game machine or the like.

  In a conventional image drawing apparatus, when rotating a drawing object, ω is an angular velocity of rotation, t is a display time interval of a frame, an angle is represented as θ = ω × t, and coordinates of pixels before the rotation are represented by (X, Y), the rotated pixel is (X ′, Y ′), the center coordinates of the rotation is (Rx, Ry), and the calculation is performed using the formula [Equation 1]. Here, in the prior art, the calculation of the trigonometric function in [Expression 1] is repeated every frame.

Furthermore, in the case where there are a plurality of drawing objects to be rotated in the frame, the number of operations of the trigonometric function corresponds to the product of these, so there is a problem that places a burden on the CPU (central processing unit).
In addition, what is described in patent document 1 is known as a technique which rotates the conventional figure.
JP-A-10-149440

  The present invention has been made in consideration of the above-described circumstances, and its purpose is to reduce the processing time of the trigonometric function in the rotation calculation processing of the drawing object, thereby reducing the load on the CPU. An object of the present invention is to provide an image drawing method and apparatus.

  The present invention has been made to solve the above-described problems, and the invention of claim 1 determines and obtains the coordinates of the display position of each pixel when the display object is rotated based on the attribute data. In an image drawing method for drawing a pixel after rotation in memory according to coordinates, values of sin nθ (n is a positive integer) and cos nθ are stored in a memory as a rotation angle table for a preset rotation angle θ. The attribute data includes the coordinates of the pixel after rotation when the rotation angle is set to 0 for each display frame and the pixel is rotated for each display frame. The image drawing method is characterized in that the calculation is performed using the rotation center coordinates and the data in the memory, and the pixel is drawn in the memory based on the calculation result.

  According to a second aspect of the present invention, in the image drawing method according to the first aspect, a plurality of types of rotation angle tables are provided in advance, table type data indicating a table type is set in the attribute data, and the table type data is The coordinates of the pixel after rotation are calculated using a rotation angle table to be indicated.

  According to a third aspect of the present invention, in the image drawing method according to the first or second aspect, a switching period is set in the attribute data, and the display frame is rotated each time the display frame is displayed by the number of the switching periods. The calculation of obtaining the coordinates of the pixel is executed, and the rotated pixel is drawn in a memory based on the calculation result.

  The invention according to claim 4 is an image drawing apparatus, wherein the coordinates of the display position of each pixel when the display object is rotated are obtained based on the attribute data, and the rotated pixel is determined according to the obtained coordinates. In an image drawing apparatus for drawing in a memory, a rotation angle table for storing values of sin nθ (n is a positive integer) and cos nθ for a preset rotation angle θ, and a rotation angle at the time of starting rotation are set to 0. , When the pixel is rotated with the rotation angle being θ, 2θ, 3θ,... For each display frame, the coordinates of the rotated pixel are the rotation center coordinates included in the attribute data and the rotation angle table. An arithmetic means for calculating using data, and a writing means for drawing a pixel in a memory based on an arithmetic result of the arithmetic means are provided.

  According to a fifth aspect of the present invention, in the image drawing apparatus according to the fourth aspect of the present invention, the rotation angle table includes a plurality of types, and the calculation unit is instructed by table type data indicating a table type included in the attribute data. The coordinates of the pixel after rotation are calculated using a rotation angle table.

  According to a sixth aspect of the present invention, in the image drawing device according to the fourth or fifth aspect, the attribute data includes a switching period, and the calculation means displays the display frame by the number of the switching periods. The calculation for obtaining the coordinates of the pixel after rotation is executed every time.

  According to the present invention, since the calculation result of the trigonometric function is prepared in the image drawing apparatus in advance and is used when drawing data is rotated, the burden on the host CPU can be reduced.

  Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing the configuration of the image drawing apparatus according to the present embodiment. In FIG. 1, reference numeral 11 denotes a character ROM (Read Only Memory) in which compressed image data of characters constituting a sprite is stored in a dot matrix format. Reference numeral 12 denotes a FIFO (First In First Out) memory in which the compressed image data of the sprite read from the character ROM 11 is temporarily stored.

  Reference numeral 13 denotes a decompression engine, which decompresses the compressed image data given from the character ROM 11 via the FIFO memory 12 and returns the image data to a pre-compression image data (color code or YUV format pixel value). Next, when the image data is a color code, the color code is converted into RGB (red, green, blue) color data by the color palette 14 and is transferred to the sprite buffer A or B on the two sides via the flip-flop 15. Write. When the decompressed image data is a pixel value in YUV (luminance / color difference) format, it is converted into RGB color data by the YUV decoder 16 and written into the sprite buffer A or B via the flip-flop 15. In this case, control data indicating which of the sprite buffers A and B is to be written is output from the decompression engine 13.

  A drawing engine 18 reads the RGB color data of the sprite from the sprite buffer A or B in accordance with an instruction from the controller 17, and refers to the rotation result table 20 based on the instruction data output from the controller 17 to the read RGB color data. Then, deformation processing such as rotation is performed, and then the RGB color data after the deformation processing is written to the address of the frame buffer 19 indicated by the position data output from the controller 17. The frame buffer 19 is composed of two banks and is alternately used as a drawing buffer and a display buffer.

  The controller 17 writes various instructions (sprite attribute data) output from the host CPU (not shown) and supplied via the CPU interface block 21 to the sprite attribute table 23 via the SRAM interface block 22 and the writing. The decompression engine 13 and the drawing engine 18 are controlled based on the sprite attribute data. Further, the controller 17 reads the RGB color data from the frame buffer 19 and outputs it to the display device (not shown) via the display interface block 24.

  Next, the drawing operation of the above-described embodiment will be described with reference to the flowchart shown in FIG. The flowchart of FIG. 2 shows an example in which N sprites are drawn in the frame buffer 19. Further, the process of the flowchart is performed in a frame cycle. In step SA1, the controller 17 in FIG. 1 sets one of the two banks of the frame buffer 19 for drawing and the other for display. That is, the bank that was used for drawing in the previous frame is set for display, and the bank that was used for display in the previous frame is set for drawing. Next, in step SA2 to step SA6, the controller 17 sequentially processes all the sprites shown in the sprite attribute table of FIG. 4 from the top.

  That is, the controller 17 first writes data “1” in the internal register SPNO (not shown) (step SA2). Next, the sprite attribute table 23 is accessed, and the attribute data corresponding to the data in the register SPNO (in this case “1”), that is, the attribute data of the sprite 1 is fetched (step SA3). Next, the character ROM 11 is accessed based on the address of the character of the sprite 1 indicated by the attribute data, and the character of the sprite 1 is read (step SA4). The read character is stored in the FIFO 12.

  Next, the controller 17 outputs a decompression instruction to the decompression engine 13, and then outputs the attribute data of the sprite 1 to the rendering engine 18 to instruct rendering (step SA5). The rendering engine 18 renders the RGB color data decompressed by the decompression engine 13 and written in the sprite buffers A and B, and performs rendering processing such as enlargement, reduction, and rotation indicated by the attribute data, and then is included in the attribute data. Based on the displayed display position data, the data is written into the drawing bank of the frame buffer 19. When the writing is completed, the controller 17 checks whether or not the data in the register SPNO is “N” (step SA6). If not, the data in the register SPNO is “ 1 "is added (step SA7), and the process returns to step SA3.

Thereafter, the drawing process for sprites 2 to N is performed by the same process as described above. The outline of the drawing process described above is the same as that of a conventional drawing apparatus.
Next, a sprite rotation process performed in the drawing engine 18 that is unique to this embodiment will be described in detail.
In this embodiment, in the sprite rotation process, the host CPU does not calculate sin and cos as in the prior art, but uses the data in the rotation result table 20 prepared in advance.

That is, in this embodiment, as shown in FIG. 3, the unit of rotation is two types of eight divisions or four divisions of one rotation. Then, sin 45 °, sin 90 °,..., Sin 315 °, cos 45 °, cos 90 °,... Cos 315 ° are calculated and stored in advance in the rotation result table 20 as an 8-part table. The values of sin 90 °, sin 180 °, sin 270 °, cos 90 °, cos 180 °, and cos 270 ° are stored as a 4-partition table.
On the other hand, in the sprite attribute table, as shown in FIG.
Rotation flag Table type (8 divisions / 4 divisions)
4 cycles of rotation period are stored.

Conventionally, as the rotation control data, sin θ, cos θ, and the rotation center are stored in the sprite attribute table, and the host CPU calculates sin θ and cos θ for each sprite and writes them in the attribute table.
Now, the drawing engine 18 rotates the sprite for the sprite having the rotation flag “1” by the processing described below based on the rotation control data, and draws the sprite in the frame buffer 19. FIG. 5 is a diagram showing a display example, and Δt indicates a frame interval. In the figure, (A) is a display example by eight divisions, and the image is switched every two frames (switching cycle = 2). Similarly, (B) is a display example by 8 divisions, and an image is switched every frame (switching cycle = 1). (C) is a display example by four divisions, and the image is switched every frame (switching cycle = 1). In such a display, the sprite (A) rotates the slowest, the sprite (B) rotates at an intermediate speed, and the sprite (C) rotates the fastest.

Next, the process of the rotation process described above in the drawing engine 18 will be described with reference to the flowchart shown in FIG.
The drawing engine 18 first checks the rotation flag in the sprite attribute table supplied from the controller 17. When the sprite rotation flag becomes “1” for the first time, it is determined that rotation has started (step SB1), and “0” is written in an internal register CNT (not shown) (step SB2). Next, the table type of the sprite attribute data is checked (step SB5). If 8-division is designated, the process proceeds to step SB6. If 4-division is designated, the process proceeds to step SB7.
In step SB6,
INT (CNT / switching cycle)
INT (): Value obtained by cutting off the decimal part of the calculation result in parentheses
CNT: Data in register CNT
Switching period: The calculation of the data stored in the sprite attribute table is performed, and then the values of sin θ and cos θ are read from the 8-part table of the rotation result table 20 based on the calculation result. For example, when CNT = 3 and the switching cycle = 2, INT = 1, and values of sin 45 ° and cos 45 ° are read from the rotation result table 20. Similarly, when INT = 2, values of sin 90 ° and cos 90 ° are read from the rotation result table 20, and when INT = 7, values of sin 315 ° and cos 315 ° are read from the rotation result table 20.

Similarly, in step SB7, the above calculation is performed, and then the values of sin θ and cos θ are read from the four-division table of the rotation result table 20 based on the calculation result. For example, when CNT = 3 and the switching cycle = 2, values of sin 90 ° and cos 90 ° are read from the rotation result table 20.
Next, when proceeding to step SB8, based on the values of sin θ and cos θ described above and the coordinates (Rx, Ry) of the rotation center read from the sprite attribute table, the above-described calculation of [Equation 1] is performed. The coordinates (X ′, Y ′) of the rotated pixel are obtained, and then, in step SB9, the RGB color data is written into the drawing bank of the frame buffer 19 in accordance with the obtained coordinates (X ′, Y ′). .
Note that (X, Y) is obtained based on data indicating the display coordinates of the sprite as the sprite attribute data (the coordinates of the upper left pixel).
The processes in steps SB8 and SB9 described above are performed for all pixels constituting the sprite.

  In the drawing process for the next frame, the process proceeds again to step SB1 described above. If the sprite is not started to rotate, the process proceeds to step SB3. In step SB3, it is checked whether or not the rotation flag is “1”. If the rotation flag is “0”, the rotation process is terminated. On the other hand, if “1”, “1” is added to the data in the register CNT (step SB4). And it progresses to the process after step SB5 mentioned above.

  As described above, the embodiments of the present invention have been described in detail with reference to the drawings, but the specific configuration is not limited to these embodiments, and includes design changes and the like within a scope not departing from the gist of the present invention. It is. For example, in the present embodiment, the rotation result table is obtained by dividing 360 degrees into four equal parts and eight equal parts, but it may be divided more finely.

It is a block diagram which shows the structure of the image drawing apparatus by one Embodiment of this invention. It is a flowchart which shows schematic operation | movement of the embodiment. It is a figure for demonstrating the rotation process in the embodiment. It is a structural diagram of the sprite attribute table 23 in the same embodiment. It is a figure which shows an example of the rotation process in the embodiment. It is a flowchart which shows the flow of the rotation process in the embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 ... Character ROM, 12 ... FIFO memory, 13 ... Decompression engine, 14 ... Sprite color palette, 15 ... Flip flop, 16 ... Sprite YUV decoder, 17 ... Controller, 18 ... Drawing engine, 19 ... Frame buffer, 20 ... Rotation result Table, 21 ... CPU interface block, 22 ... SRAM interface block, 23 ... Sprite attribute table, 24 ... Display interface block

Claims (6)

In the image drawing method of obtaining the coordinates of the display position of each pixel when the display object is rotated based on the attribute data, and drawing the rotated pixel in the memory according to the obtained coordinates.
The values of sin nθ (n is a positive integer) and cos nθ are stored in a memory as a rotation angle table for a preset rotation angle θ.
The attribute data includes the coordinates of the pixel after rotation when the rotation angle is set to 0 for each display frame and the pixel is rotated for each display frame. Calculated using the rotation center coordinates and the data in the memory,
An image drawing method, wherein a pixel is drawn in a memory based on the calculation result.   A plurality of types of rotation angle tables are provided in advance, table type data indicating the table type is set in the attribute data, and the coordinates of the rotated pixel are calculated using the rotation angle table specified by the table type data. The image drawing method according to claim 1.   A switching period is set in the attribute data, and a calculation for obtaining the coordinates of the rotated pixel is executed every time the display frame is displayed by the number of the switching periods, and the rotated pixel is stored in the memory based on the calculation result. The image drawing method according to claim 1, wherein drawing is performed. In the image drawing device for obtaining the coordinates of the display position of each pixel when the display object is rotated based on the attribute data, and drawing the rotated pixel in the memory according to the obtained coordinate.
A rotation angle table for storing values of sin nθ (n is a positive integer) and cos nθ for a preset rotation angle θ;
The attribute data includes the coordinates of the pixel after rotation when the rotation angle is set to 0 for each display frame and the pixel is rotated for each display frame. Calculation means for calculating using the rotation center coordinates and data in the rotation angle table;
Writing means for drawing a pixel in a memory based on a calculation result of the calculation means;
An image drawing apparatus comprising:   A plurality of types of rotation angle tables are provided, and the calculation means calculates the coordinates of the rotated pixel using the rotation angle table indicated by the table type data indicating the table type included in the attribute data. The image drawing apparatus according to claim 4. 5. The attribute data includes a switching cycle, and the calculation means executes a calculation for obtaining coordinates of a pixel after rotation every time the display frame is displayed by the number of the switching cycles. The image drawing apparatus according to claim 5.

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