JP4983570B2 - Image processing apparatus and program - Google Patents

Description

  The present invention relates to an image processing apparatus and a program provided with a drawing processing function involving rotation processing.

  An image processing apparatus having a drawing processing function for mapping a sprite image in a frame memory is known. Some image processing apparatuses of this type have a function of rotating a sprite image during mapping. FIG. 5 is a flowchart showing an example of sprite rotation processing performed under the prior art.

In this rotation processing, the sprite pixel numbers SIZEX and SIZEY shown in FIG. 6 are used. Here, the number of pixels SIZEY is the number of pixels in the X direction (horizontal direction) of the area occupied by the sprite when projected without rotating the sprite on the pixel plane constituting the display screen, and the number of pixels SIZEY is the Y direction of the area. This is the number of pixels in the (vertical direction). In the rotation process, first, it is determined whether the number of pixels SIZEX in the X direction is an even number or an odd number (step S1). When the number of pixels SIZEX is an odd number, the X coordinates DAX, DBX, DCX, and DDX (see FIG. 6) of the vertices A, B, C, and D of the sprite in the pixel plane are calculated according to the following equation. (Step S2).
DAX = -SIZE / 2 + 0.5 (1)
DBX = −SIZEX / 2 + 0.5 (2)
DCX = SIZE / 2−0.5 (3)
DDX = SIZEEX / 2-0.5 (4)

On the other hand, if the number of pixels SIZEX is an even number, the X coordinates DAX, DBX, DCX, and DDX of the vertices A, B, C, and D of the sprite in the pixel plane are calculated according to the following equation (step S3).
DAX = -SIZE / 2 (5)
DBX = −SIZEX / 2 (6)
DCX = SIZE / 2-1 (7)
DDX = SIZEEX / 2-1 (8)

Next, it is determined whether the number of pixels SIZEY in the Y direction is an even number or an odd number (step S4). If the number of pixels SIZEY is an odd number, the Y coordinates DAY, DBY, DCY, and DDY of the vertices A, B, C, and D of the sprite in the pixel plane are calculated according to the following equation (step S5).
DAY = −SIZE / 2 + 0.5 (9)
DBY = SIZE / 2-0.5 (10)
DCY = SIZE / 2−0.5 (11)
DDY = -SIZE / 2 + 0.5 (12)

On the other hand, if the number of pixels SIZE is even, the Y coordinates DAY, DBY, DCY, and DDY of the vertices A, B, C, and D of the sprite in the pixel plane are calculated according to the following equation (step S6).
DAY = -SIZE / 2 (13)
DBY = SIZE / 2-1 (14)
DCY = SIZE / 2-1 (15)
DDY = -SIZE / 2 (16)

Then, a known rotational affine transformation is executed using the X and Y coordinates of the four vertices of the sprite thus obtained (step S7). Specifically, the sprite rotation angle θ and the X and Y coordinates of each vertex are substituted into the following equation to calculate the coordinates X ′ and Y ′ of each vertex after the sprite is rotated.
X ′ = X * COSθ + Y * SINθ (17)
Y ′ = Y * COSθ−X * SINθ (18)

Then, the image processing apparatus executes subsequent processing such as mapping processing. Here, in the mapping process, the sprite is set so that the positions of the four vertices of the sprite are the positions corresponding to the coordinates X ′ and Y ′ calculated as described above in the pixel plane constituting the display screen. When the image is projected onto the pixel plane, pixels in the pixel plane that will form the sprite image are obtained, and image data obtained by resampling the sprite image that has been rotated by these pixels is written into the frame memory. As a result, the sprite image after rotation is displayed on the display device. Note that image rotation processing using rotational affine transformation is disclosed in Patent Document 1, for example.
Japanese Patent Laid-Open No. 2007-80001

  By the way, in the conventional image processing apparatus described above, when at least one of the number of pixels in the horizontal direction and the vertical direction of the sprite is an even number, the center of rotational symmetry of the sprite is shifted or the vertex of the sprite is accompanied by the rotation. There was a problem that the rotation trajectory was blurred. Hereinafter, this problem will be described in detail with reference to FIG.

  First, for comparison, a case will be described where both the sprite pixel numbers SIZEX and SIZEY are odd numbers. In this case, since steps S2 and S5 in FIG. 5 are executed, the absolute values of the X coordinates of the four vertices are all equal, and the absolute values of the Y coordinates are also equal. In addition, the rotationally symmetrical center Q of the sprites for which the coordinates of the four vertices are determined in this way is 0 in each address in the X direction and the Y direction on the pixel plane as illustrated in FIG. 7A. It is located at the center of the pixel O (0, 0). As shown in FIG. 7B, the four vertices of the sprite in which the center Q of the rotational symmetry is arranged at the center of the pixel O (0, 0) have the same circular orbit in the pixel plane as the sprite rotates. Move along. As described above, when the number of pixels of the sprite SIZEX and SIZEY is an odd number, the problem of the rotational symmetry center shift and the rotation locus blurring does not occur.

  On the other hand, for example, when the number of sprite pixels SIZEX and SIZEY are both even numbers, steps S3 and S6 in FIG. 5 are executed, so that the absolute values of the X coordinates of the vertices A and B are X of the vertices C and D. The absolute value of the coordinates is larger by “1”, and the absolute values of the Y coordinates of the vertices A and D are larger by “1” than the absolute values of the Y coordinates of the vertices B and C. Then, the rotationally symmetrical center Q of the sprites whose coordinates of the four vertices are determined in this way is a rectangular shape that forms a boundary separating the pixel O (0, 0) from other pixels as shown in FIG. 7C. It will be located at the top left vertex. When the rotationally symmetrical center Q of the sprite is arranged at a position shifted from the center of the pixel in this way, as shown in FIG. Rotation around the center of (0, 0) causes a problem of deviation of the rotationally symmetrical center Q. In addition, since the absolute values of the X coordinates of the four vertices are not uniform and the absolute values of the Y coordinates are not uniform, the sprite rotation process causes a problem of fluctuation of the rotation trajectory of the four vertices of the sprite.

  The same applies when one of the sprite pixel numbers SIZEX and SIZEY is an even number. Also in this case, one of the absolute values of the X coordinates and the Y coordinates of the four vertices is not uniform. Therefore, the sprite rotates in a state where the rotationally symmetrical center Q is decentered with respect to the center of the pixel O (0, 0). More specifically, the rotationally symmetrical center Q of the sprite is rotated by drawing a circular orbit having a radius of 0.5 pixel pitch around the center of the pixel O (0, 0). A problem of misalignment occurs. In addition, since one of the absolute values of the X coordinate and the Y coordinate of the four vertices of the sprite is not uniform, there is a problem of blurring of the rotation locus of the four vertices of the sprite.

  The present invention has been made in view of the circumstances described above, and provides technical means for reducing the sprite's rotational symmetry center shift and blurring of the vertex's rotational trajectory in sprite drawing processing involving rotation processing. The purpose is to do.

  The present invention calculates the horizontal and vertical coordinates of the four vertices of the sprite based on the rotational symmetry center of the sprite based on the number of pixels in the horizontal and vertical directions of the sprite to be processed. The sprite was rotated around the rotationally symmetric center using the horizontal / vertical coordinates of the four vertices of the sprite obtained by the number of pixels / coordinate conversion means and the number of pixels / coordinate conversion means. Rotation processing means for calculating the horizontal and vertical coordinates of the four vertices of the sprite in the case, and in the pixel plane from the horizontal and vertical coordinates of the four vertices of the sprite obtained by the rotation processing means. Means for calculating the horizontal and vertical coordinates of the four vertices of the sprite after rotation; The coordinate correction processing for reducing the rotation of the center of rotational symmetry accompanying the rotation of the sprite after the rotation according to the combination of the odd / even number of pixels in the horizontal direction and the odd / even number of pixels in the vertical direction. Coordinate correction means applied to the horizontal and vertical coordinates of the four vertices of the sprite obtained by the processing means, and the rotation obtained by the coordinate correction means for each position of the four vertices of the sprite in the pixel plane When the sprite is projected onto the pixel plane so as to correspond to the coordinates of the four vertices of the later sprite, pixels in the pixel plane that will form the image of the sprite are obtained. And a mapping processing means for writing image data indicating the image of the sprite into a memory by using the pixels. The computer provides a program to function as the respective means.

  According to this invention, since the absolute values of the horizontal coordinates of the four vertices of the sprite obtained by the number of pixels / coordinate conversion means are aligned and the absolute values of the coordinates of the vertical direction are aligned, the sprite is rotated when the sprite is rotated. It is possible to eliminate the fluctuation of the rotation locus of the four vertices. Further, with respect to the horizontal and vertical coordinates of the four vertices of the sprite obtained by the rotation processing means, depending on the combination of the odd / even number of pixels in the horizontal direction of the sprite and the odd / even number of pixels in the vertical direction. Then, coordinate correction processing for reducing the shift of the rotationally symmetric center of the sprite after rotation is executed. Therefore, it is possible to reduce the shift of the rotationally symmetric center accompanying the rotation of the sprite.

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a block diagram showing a configuration of an image processing apparatus according to an embodiment of the present invention. As shown in FIG. 1, the image processing apparatus according to the present embodiment includes a CPU 1, a sprite memory 2, a drawing processing unit 3, a frame memory 6, a display control unit 7, and a display device 8. . Here, the frame memory 6 is a memory for storing image data to be displayed on the display device 8, and is constituted by a RAM or the like. The display control unit 7 repeats the control of displaying the image data stored in the frame memory 6 on the display device 8 for each vertical scanning period of a certain time length. The display device 8 is composed of, for example, a liquid crystal panel and its driving device.

  The sprite memory 2 is a memory for storing image data of sprites such as game characters, and is constituted by a ROM, for example. The drawing processing unit 3 is a device that executes drawing processing for reflecting sprite image data stored in the sprite memory 2 to display target image data in the frame memory 6 in accordance with an instruction from the CPU 1.

  The drawing processing unit 3 in the present embodiment has a rotation processing function for rotating a sprite and writing the image data into the frame memory 6 in accordance with an instruction from the CPU 1. The drawing processing unit 3 includes a coordinate calculation unit 4 and a mapping processing unit 5 as means for realizing the rotation processing function.

  Here, the coordinate calculation unit 4 receives instructions from the CPU 1 regarding the number of pixels in the X direction SIZEX, the number of pixels in the Y direction YSIZEY, and the rotation angle θ of the sprite to be drawn, and rotates the sprite by the angle θ in the pixel plane. This is means for calculating the X and Y coordinates of the four vertices A, B, C and D.

  The mapping processing unit 5 is means for executing mapping processing. In this mapping processing, the mapping processing unit 5 uses the CPU 1 to send the location information (for example, the center position of the sprite) indicating the address of the image data of the sprite to be drawn in the sprite memory 2 and the position of the sprite in the pixel plane. And the X and Y coordinates in the pixel plane of the four vertices of the sprite after rotation are received from the coordinate calculation unit 4. Then, the mapping processing unit 5 projects the sprite after rotation onto the pixel plane so that the positions of the four vertices of the sprite correspond to the X and Y coordinates calculated by the coordinate calculation unit 4. Each pixel in the pixel plane that will form the sprite image is obtained. Then, the image data of the sprite to be drawn is read from the sprite memory 2, and the image data of each pixel in the pixel plane constituting the rotated sprite image is calculated using the image data. The position of the image data is adjusted so that the sprite occupies the position indicated by the arrangement information, and the image data after the position adjustment is written in the frame memory.

  In the present embodiment, the coordinate calculation unit 4 includes a pixel number / coordinate conversion unit 41, a rotation processing unit 42, and a coordinate correction unit 43. FIG. 2 is a diagram showing processing contents executed by each unit of the coordinate calculation unit 4.

The pixel number / coordinate conversion unit 41 executes the pixel number / coordinate conversion process shown in FIG. In this pixel number / coordinate conversion process, the number of pixels SIZEX and SIZEY in the X direction and Y direction of the sprite to be processed is used, and the rotationally symmetrical center Q of the sprite is set in the X plane address and Y direction in the pixel plane. Coordinates DAX, DBX, DCX and DDX in the X direction of the four vertices A, B, C, D of the sprite when positioned at the center of the pixel O (0, 0) whose address is all 0 Each coordinate DAY, DBY, DCY, and DDY is calculated by the following equation.
DAX = -SIZE / 2 + 0.5 (19)
DAY = -SIZE / 2 + 0.5 (20)
DBX = −SIZEX / 2 + 0.5 (21)
DBY = SIZE / 2-0.5 (22)
DCX = SIZE / 2−0.5 (23)
DCY = SIZEY / 2-0.5 (24)
DDX = SIZEX / 2-0.5 (25)
DDY = -SIZE / 2 + 0.5 (26)

The rotation processing unit 42 executes the rotation process shown in FIG. In this rotation process, the coordinates DAX, DBX, DCX and DDX in the X direction of the four vertices of the sprite obtained by the pixel number / coordinate conversion process and the coordinates DAY, DBY, DCY and DDY in the Y direction are used, and the pixel O When the sprite is rotated by an angle θ around the center of (0, 0), the X-direction coordinates DAX_ROT, DBX_ROT, DCX_ROT and DDX_ROT and the Y-direction coordinates DAY_ROT, DBY_ROT, DCY_ROT and DDY_ROT of the four vertices of the sprite It calculates according to the following rotation affine transformation formula.
DAX_ROT = DAX / COSθ + DAY / SINθ (27)
DAY_ROT = DAY · COSθ−DAX · SINθ (28)
DBX_ROT = DBX · COSθ + DBY · SINθ (29)
DBY_ROT = DBY · COSθ−DBX · SINθ (30)
DCX_ROT = DCX · COSθ + DCY · SINθ (31)
DCY_ROT = DCY · COSθ−DCX · SINθ (32)
DDX_ROT = DDX · COSθ + DDY · SINθ (33)
DDY_ROT = DDY · COSθ−DDX · SINθ (34)

  The coordinate correction unit 43 executes the coordinate correction process shown in FIG. In this coordinate correction process, the X-direction coordinates DAX_ROT, DBX_ROT, DCX_ROT and DDX_ROT and the Y-direction coordinates DAY_ROT, DBY_ROT, DCY_ROT and DDY_ROT of the four vertices of the sprite obtained by the rotation process are rotated on the pixel plane. The coordinates DAX_ROT ′, DBX_ROT ′, DCX_ROT ′ and DDX_ROT ′ in the X direction of the four vertices and the coordinates DAY_ROT ′, DBY_ROT ′, DCY_ROT ′ and DDY_ROT ′ in the Y direction are calculated. At that time, in the coordinate correction process, the shift of the rotationally symmetric center Q accompanying the rotation of the sprite is reduced in accordance with the combination of the odd / even number of pixels SIZEX in the X direction and the odd / even number of pixels SIZEY in the Y direction. Correction is performed on the X-direction coordinates DAX_ROT, DBX_ROT, DCX_ROT and DDX_ROT and the Y-direction coordinates DAY_ROT, DBY_ROT, DCY_ROT and DDY_ROT of the four vertices of the sprite obtained by the rotation process.

  Specifically, when the number of pixels in the X direction SIZEX and the number of pixels in the Y direction SIZEY are both odd numbers, the correction value ROT_ADJX in the X direction and the correction value ROT_ADJY in the Y direction are both set to zero. When the number of pixels in the X direction SIZEX and the number of pixels in the Y direction SIZEY are both even numbers, the correction value ROT_ADJX in the X direction and the correction value ROT_ADJY in the Y direction are both set to 0.5. Further, when the number of pixels in the X direction SIZEX is an odd number and the number of pixels in the Y direction SIZEY is an even number, the correction value ROT_ADJX in the X direction is set to the absolute value Abs (SINθ) / 2 of SINθ / 2, and the Y direction The correction value ROT_ADJY is an absolute value Abs (COSθ) / 2 of COSθ / 2. Further, when the number of pixels in the X direction SIZEX is an even number and the number of pixels in the Y direction SIZEY is an odd number, the correction value ROT_ADJX in the X direction is Abs (COSθ) / 2, and the correction value ROT_ADJY in the Y direction is Abs. (SINθ) / 2.

In the coordinate correction process, the X-direction coordinates DAX_ROT ′, DBX_ROT ′, DCX_ROT ′ and DDX_ROT ′ of the four vertices of the sprite after rotation in the pixel plane and the Y-direction coordinates DAY_ROT ′ and DBY_ROT ′ are determined according to the following formula. , DCY_ROT ′ and DDY_ROT ′ are calculated.
DAX_ROT '= DAX_ROT-ROT_ADJX (35)
DAY_ROT '= DAY_ROT-ROT_ADJY (36)
DBX_ROT ′ = DBX_ROT−ROT_ADJX (37)
DBY_ROT ′ = DBY_ROT−ROT_ADJY (38)
DCX_ROT ′ = DCX_ROT−ROT_ADJX (39)
DCY_ROT ′ = DCY_ROT−ROT_ADJY (40)
DDX_ROT ′ = DDX_ROT−ROT_ADJX (41)
DDY_ROT ′ = DDY_ROT−ROT_ADJY (42)

  The mapping processing unit 5 performs the above-described mapping processing using the X and Y coordinates of the four vertices of the sprite after correction obtained in this way. The above is the details of the image processing apparatus according to the present embodiment.

  Next, a specific example is given and operation | movement of this embodiment is demonstrated. FIG. 3 shows the operation of this embodiment when the number of pixels SIZEX in the X direction of the sprite is an even number 2m (m is an integer) and the number of pixels SIZE in the Y direction is an even number 2n (n is an integer). Shows the operation of the present embodiment when the number of pixels in the X direction SIZEX is an even number 2m (m is an integer) and the number of pixels SIZEY in the Y direction is an odd number 2n + 1 (n is an integer). More specifically, FIGS. 3 (a), (b), (c) and (d) and FIGS. 4 (a), (b), (c) and (d) show that the rotation angle θ in this embodiment is The position in the pixel plane of the sprite after the coordinate correction process in each case of 0 °, 90 °, 180 °, and 270 ° is shown. 3 (a) ′, (b) ′, (c) ′ and (d) ′ and FIGS. 4 (a) ′, (b) ′, (c) ′ and (d) ′, they are indicated by broken lines. The figure shows the position of the sprite in the pixel plane after the rotation process and before the coordinate correction process. In FIGS. 3A ', (b)', (c) ', and (d)', etc., the sprite after the coordinate correction processing is shown as a solid line in order to make the movement of the sprite position before and after the coordinate correction processing easier to understand. Is indicated by

  If both the number of pixels SIZEX and SIZEY are even numbers, SIZEX = 2m, and SIZEY = 2n, the number of pixels / coordinate conversion process is obtained by substituting SIZEX and SIZEEY into the above formulas (19) to (26). The absolute values of the X coordinates of the four vertices are all m-0.5, and the absolute values of the Y coordinates of the four vertices are all n-0.5. The coordinates of the four vertices calculated in this way are obtained when the center Q of the sprite's rotational symmetry is positioned at the center of the pixel O (0, 0) in the pixel plane, as shown in FIG. It corresponds to the coordinates of the four vertices of the sprite. In the rotation processing in the present embodiment, when the sprite rotationally symmetrical center Q is positioned at the center of the pixel O (0,0) and the sprite is rotated by the angle θ, the pixel O (0,0) The coordinates DAX_ROT, DBX_ROT, DCX_ROT and DDX_ROT in the X direction and the coordinates DAY_ROT, DBY_ROT, DCY_ROT and DDY_ROT in the Y direction of the four vertices viewed from the center of the image are calculated.

  In the coordinate correction process, both the X-direction correction value ROT_ADJX and the Y-direction correction value ROT_ADJY are set to 0.5. Then, the X-direction coordinates DAX_ROT ′, DBX_ROT ′, DCX_ROT ′ and DDX_ROT ′ and the Y-direction coordinates DAY_ROT ′, DBY_ROT ′, DCY_ROT of the four vertices after correction are calculated by the calculations of the above equations (35) to (42). 'And DDY_ROT' are calculated.

  As shown in FIGS. 3A to 3D, the coordinates of these four vertices are the upper left vertex of a rectangle that is a boundary separating the origin pixel O (0, 0) from other pixels in the pixel plane. This is the coordinates of the four vertices of the sprite when the rotationally symmetrical center Q of the sprite is positioned. FIGS. 3A to 3D show the sprite arrangement state in each of the rotation angles θ of 0 °, 90 °, 180 °, and 270 °, but in the case of other rotation angles. The coordinates of the four vertices obtained by the calculations of the above equations (35) to (42) are sprites at the upper left vertex of the rectangle that is the boundary separating the origin pixel O (0, 0) from other pixels. Are the coordinates of the four vertices of the sprite when the rotationally symmetrical center Q is located.

  As described above, in the present embodiment, when both the number of pixels SIZEX and SIZEY are an even number, the pixel plane always has an upper left vertex of a rectangle that is a boundary separating the pixel O (0, 0) from other pixels. The sprite can be rotated by positioning the rotationally symmetrical center Q. Therefore, when the sprite is rotated, there is no shake at the center of rotational symmetry, and the rotation locus is not shaken.

  Next, a case where the number of pixels in the X direction SIZEX is an even number 2m and the number of pixels in the Y direction SIZEY is an odd number 2n + 1 will be described. In this case, the contents of the pixel number / coordinate conversion process and the rotation process are basically the same as the case where both the pixel numbers SIZEX and SIZEY are even numbers. That is, when the sprite is rotated by the angle θ by positioning the center Q of the rotational symmetry of the sprite at the center of the pixel O (0, 0) through the pixel number / coordinate conversion process and the rotation process, the pixel O The coordinates DAX_ROT, DBX_ROT, DCX_ROT and DDX_ROT in the X direction of the four vertices viewed from the center of (0, 0) and the coordinates DAY_ROT, DBY_ROT, DCY_ROT and DDY_ROT in the Y direction are obtained.

  However, when the number of pixels SIZEX in the X direction is an even number 2m and the number of pixels SIZEY in the Y direction is an odd number 2n + 1, the mode of coordinate correction processing is different from the case where both the number of pixels SIZEX and SIZEY are even numbers. It will be a thing. Further details are as follows.

  First, when both the number of pixels SIZEX and SIZEY are even numbers, the rotationally symmetrical center Q of the sprite after rotation forms a boundary that separates the pixel O (0, 0) from other pixels at any rotation angle θ. It is located at the top left corner of the rectangle (see FIGS. 3A to 3D).

  On the other hand, when the number of pixels SIZEX in the X direction is an even number and the number of pixels SIZEY in the Y direction is an odd number, the position of the rotational symmetry center Q of the sprite after rotation differs depending on the rotation angle θ. It will be a thing. For example, when the rotation angle θ is 0 ° and 180 °, the rotationally symmetrical center Q of the sprite after rotation is the pixel O (0, 0) in the pixel plane as shown in FIGS. ) Must be positioned at the center point of the left side of the rectangle, which is the boundary separating the other pixels. In each of the rotation angles θ of 90 ° and 270 °, the rotationally symmetrical center Q of the sprite after rotation is the pixel O (0, 0, 0 in the pixel plane as shown in FIGS. 4B and 4D. 0) must be located at the center point of the upper side of the rectangle which is the boundary separating the other pixels.

  This is because, in sprite rendering processing without rotation, sprites having an even number of pixels in the X direction SIZEX and an odd number of pixels in the Y direction SIZEY are shown in FIGS. 4 (a) and 4 (c). Are arranged on the pixel plane, and the sprite having the odd number of pixels SIZEX in the X direction and the even number of pixels SIZEY in the Y direction is arranged on the pixel plane as shown in FIGS. 4B and 4D. This is because the arrangement method of the center Q of the rotational symmetry of the sprite is matched with the drawing process of the sprite accompanying the rotation. As described above, by arranging the sprite rotationally symmetrical center Q in the same manner for the sprite drawing processing without rotation and the sprite drawing processing with rotation, several advantages can be obtained. First, when a sprite placed on the pixel plane by a drawing process with rotation and a sprite placed on the pixel plane by a drawing process without rotation are mixed, the positional relationship between both sprites is intended. Easy to do. In addition, when drawing is performed when rotation starts from a state in which the sprite is not rotating, it is possible to avoid a discontinuous change in the position of the sprite when the sprite starts rotating.

  For the above reasons, when the number of pixels SIZEX in the X direction is an even number and the number of pixels SIZEY in the Y direction is an odd number, the position that the rotational symmetry center Q of the sprite after rotation should take is the rotation angle θ. It will be different. Therefore, in the coordinate correction process in this case, the correction amounts ROT_ADJX and ROT_ADJY are changed according to the rotation angle θ. Specifically, the correction value ROT_ADJX in the X direction is Abs (COSθ) / 2, and the correction value ROT_ADJY in the Y direction is Abs (SINθ) / 2, and is corrected by the calculations of the above equations (35) to (42). The coordinates DAX_ROT ′, DBX_ROT ′, DCX_ROT ′ and DDX_ROT ′ in the X direction of the subsequent four vertices and the coordinates DAY_ROT ′, DBY_ROT ′, DCY_ROT ′ and DDY_ROT ′ in the Y direction are calculated.

Here, for each of θ = 0 °, 90 °, 180 °, and 270 °, the correction value ROT_ADJX = Abs (COSθ) / 2 and the correction value ROT_ADJY = Abs (SINθ) / 2 are calculated as follows. become.
θ = 0 ° ROT_ADJX = 0.5 ROT_ADJY = 0
θ = 90 ° ROT_ADJX = 0 ROT_ADJY = 0.5
θ = 180 ° ROT_ADJX = 0.5 ROT_ADJY = 0
θ = 270 ° ROT_ADJX = 0 ROT_ADJY = 0.5

  Accordingly, the X-direction coordinates DAX_ROT ′, DBX_ROT ′, DCX_ROT ′ and DDX_ROT ′ obtained by the coordinate correction processing and the Y-direction coordinates DAY_ROT ′, DBY_ROT ′, DCY_ROT ′ and DDY_ROT ′ indicate four positions of the sprite. When the vertex is positioned, the sprite arrangement in each case of θ = 0 °, 90 °, 180 °, and 270 ° is as shown in FIGS. 4 (a), 4 (b), 4 (c), and 4 (d).

  In addition, the sprite arrangement at rotation angles θ other than 0 °, 90 °, 180 °, and 270 ° maintains continuity with the sprite arrangement in each of θ = 0 °, 90 °, 180 °, and 270 °. It will be drunk.

  First, when the rotation angle θ changes from 0 ° to 90 °, the correction value ROT_ADJX = Abs (COSθ) / 2 in the X direction draws a cosine curve from 0.5 to 0 as the angle θ increases. The correction value ROT_ADJY = Abs (SINθ) / 2 in the Y direction continuously increases in a sine curve from 0 to 0.5 as the angle θ increases. For this reason, the position of the rotationally symmetrical center Q of the sprite is along the circumference of the radius 0.5 pixel pitch around the center of the pixel O (0, 0) while the rotation angle θ changes from 0 ° to 90 °. Thus, the pixel O (0, 0) moves from the center of the left side of the rectangle, which is the boundary with the other pixels, to the center of the upper side.

  Next, when the rotation angle θ changes from 90 ° to 180 °, the correction value ROT_ADJX = Abs (COSθ) / 2 in the X direction is a cosine curve from 0 to 0.5 as the angle θ increases. The correction value ROT_ADJY = Abs (SINθ) / 2 in the Y direction continuously decreases while drawing a sine curve from 0.5 to 0 as the angle θ increases. For this reason, the position of the rotationally symmetrical center Q of the sprite is along the circumference of the radius 0.5 pixel pitch around the center of the pixel O (0, 0) while the rotation angle θ changes from 90 ° to 180 °. The pixel O (0, 0) moves from the center of the upper side of the rectangle, which is the boundary with the other pixels, to the center of the left side.

  The same applies to the following. When the rotation angle θ is continuously changed, the position of the rotationally symmetrical center Q of the sprite has a period of 180 ° with a radius of 0. It reciprocates along a 5-pixel pitch arc.

  As described above, in this embodiment, when the number of pixels SIZEX in the X direction of the sprite is an even number and the number of pixels SIZEY in the Y direction is an odd number, the center Q of the rotational symmetry of the sprite accompanying the rotation The gap cannot be eliminated. However, if the sprite is rotated once, under the prior art, the rotationally symmetrical center Q of the sprite makes one turn along a circle having a radius of 0.5 pixel pitch. The center Q of symmetry only reciprocates in a section corresponding to a quarter of a circle having a radius of 0.5 pixel pitch. As described above, in the present embodiment, the shift of the rotationally symmetrical center Q of the sprite can be made smaller than in the prior art. In this embodiment, the absolute values of the X-direction coordinates of the four vertices of the sprite are aligned and the absolute values of the Y-direction coordinates of the four vertices are also aligned during the rotation process. There is no problem of shaking.

  When the number of pixels SIZEX in the X direction of the sprite is an odd number and the number of pixels SIZEY in the Y direction is an even number, in the coordinate correction process, Abs (SINθ) / 2 is used as the correction value ROT_ADJX, and Abs is used as the correction value ROT_ADJY. COSθ) / 2 is used. Except for this point, the processing contents when the number of pixels SIZEX in the X direction of the sprite is an odd number and the number of pixels SIZEY in the Y direction are an even number are as follows. And the same processing contents as those when the number of pixels SIZEY in the Y direction is an odd number.

  When the number of pixels SIZEX in the X direction of the sprite is an odd number and the number of pixels SIZEY in the Y direction is an odd number, 0 is used as the correction values ROT_ADJX and ROT_ADJY in the coordinate correction process. Accordingly, as in the prior art, it is possible to rotate the sprite without causing the problem of the rotational symmetry center Q shift and the fluctuation of the rotation trajectory of the four vertices.

  As described above, according to the present embodiment, when the sprite is rotated and drawn, the shift of the rotational symmetry center Q of the sprite is eliminated or reduced, and the rotation locus of the four vertices is not shaken. You can rotate the sprite.

Although one embodiment of the present invention has been described above, the present invention may have other embodiments. For example:
(1) The coordinate calculation unit 4 including the pixel number / coordinate conversion unit 41, the rotation processing unit 42, and the coordinate correction unit 43, and the mapping processing unit 5 are dedicated hardware for performing the processing described in the above embodiment. However, it may be a drawing application program that causes a computer to execute such processing.
(2) The correction values ROT_ADJX and ROT_ADJY used in the coordinate correction process may not be Abs (SINθ) / 2 or Abs (COSθ) / 2. The correction values ROT_ADJX and ROT_ADJY may be calculated by using an appropriate θ function that changes in the range of 0.5 to 0 instead of Abs (SINθ) / 2 or Abs (COSθ) / 2.

1 is a block diagram illustrating a configuration of an image processing apparatus according to an embodiment of the present invention. It is a figure which shows the processing content of the pixel number / coordinate conversion part 41, the rotation process part 42, and the coordinate correction | amendment part 43 of the coordinate calculating part 4 in the embodiment. It is a figure which shows operation | movement when the pixel number SIZEX of the X direction of a sprite and the pixel number SIZEY of a Y direction are both even numbers in the same embodiment. It is a figure which shows operation | movement when the pixel number SIZEX of the X direction of a sprite is an even number in the same embodiment, and the pixel number SIZEY of a Y direction is an odd number. It is a flowchart which shows the content of the drawing process accompanying rotation of the conventional sprite. It is a figure explaining the pixel number of a sprite, and the coordinate of 4 vertices. It is a figure which shows the rotation condition of the sprite in the conventional drawing process.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... CPU, 2 ... Sprite memory, 3 ... Drawing processing part, 6 ... Frame memory, 7 ... Display control part, 8 ... Display apparatus, 4 ... Coordinate calculation part, 5 ... Mapping processing part , 41... Pixel number / coordinate conversion unit, 42... Rotation processing unit, 43.

Claims (5)

Number of pixels / coordinates for calculating the horizontal and vertical coordinates of the four vertices of the sprite based on the rotational symmetry center of the sprite, based on the number of horizontal and vertical pixels of the sprite to be processed Conversion means;
Using the horizontal and vertical coordinates of the four vertices of the sprite obtained by the number of pixels / coordinate conversion means, the four vertices of the sprite when the sprite is rotated around the rotational symmetry center. Rotation processing means for calculating horizontal and vertical coordinates;
Means for calculating the horizontal and vertical coordinates of the four vertices of the sprite after rotation in the pixel plane from the horizontal and vertical coordinates of the four vertices of the sprite obtained by the rotation processing means; In the calculation process, the shift of the rotational symmetry center accompanying the rotation of the sprite after the rotation is reduced in accordance with the combination of the odd / even number of pixels in the horizontal direction and the odd / even number of pixels in the vertical direction. Coordinate correction means for performing coordinate correction processing on the horizontal and vertical coordinates of the four vertices of the sprite obtained by the rotation processing means;
The sprite is projected onto the pixel plane so that the positions of the four vertices of the sprite in the pixel plane correspond to the coordinates of the four vertices of the sprite after rotation obtained by the coordinate correction means. And a mapping processing means for obtaining pixels in the pixel plane that will constitute the sprite image and writing image data indicating the sprite image in the memory by using the pixels. Image processing device.   In the coordinate correction process, the coordinate correction unit is configured to perform horizontal processing at the four vertices of the sprite obtained by the rotation processing unit when both the horizontal pixel number and the vertical pixel number of the sprite are even numbers. The image processing apparatus according to claim 1, wherein correction processing is performed to shift each coordinate in the direction and the vertical direction by 0.5 pixel pitch.   In the coordinate correction process, when only one of the number of pixels in the horizontal direction and the number of pixels in the vertical direction of the sprite is an even number, the coordinate correction unit rotates the rotation by a correction amount corresponding to the rotation angle θ of the sprite. The image processing apparatus according to claim 1 or 2, wherein the horizontal and vertical coordinates of the four vertices of the sprite obtained by the processing means are shifted.   In the coordinate correction process, when the number of pixels in the horizontal direction of the sprite is an even number and the number of pixels in the vertical direction is an odd number, the coordinate correction unit is configured to obtain the sprite obtained by the rotation processing unit. The horizontal coordinates of the four vertices are shifted by the absolute value of COSθ / 2 and the vertical coordinates are shifted by the absolute value of SINθ / 2. The number of pixels in the horizontal direction of the sprite is an odd number, and the vertical coordinates are vertical. When the number of pixels in the direction is an even number, the horizontal coordinates of the four vertices of the sprite obtained by the rotation processing means are shifted by an absolute value of SINθ / 2, and the vertical coordinates are set to COSθ / 2. The image processing apparatus according to claim 3, wherein the image processing apparatus is shifted by an absolute value. Computer
Number of pixels / coordinates for calculating the horizontal and vertical coordinates of the four vertices of the sprite based on the rotational symmetry center of the sprite, based on the number of horizontal and vertical pixels of the sprite to be processed Conversion means;
Using the horizontal and vertical coordinates of the four vertices of the sprite obtained by the number of pixels / coordinate conversion means, the four vertices of the sprite when the sprite is rotated around the rotational symmetry center. Rotation processing means for calculating horizontal and vertical coordinates;
Means for calculating the horizontal and vertical coordinates of the four vertices of the sprite after rotation in the pixel plane from the horizontal and vertical coordinates of the four vertices of the sprite obtained by the rotation processing means; In the calculation process, the shift of the rotational symmetry center accompanying the rotation of the sprite after the rotation is reduced in accordance with the combination of the odd / even number of pixels in the horizontal direction and the odd / even number of pixels in the vertical direction. Coordinate correction means for performing coordinate correction processing on the horizontal and vertical coordinates of the four vertices of the sprite obtained by the rotation processing means;
The sprite is projected onto the pixel plane so that the positions of the four vertices of the sprite in the pixel plane correspond to the coordinates of the four vertices of the sprite after rotation obtained by the coordinate correction means. In this case, the pixel plane in the pixel plane that constitutes the sprite image is obtained, and the pixel functions as a mapping processing unit that writes image data indicating the sprite image in a memory. Program to do.

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