JP2010072808A - Drawing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a drawing device performing high-speed drawing, based on the targeted polygonal shape. <P>SOLUTION: A polygonal shape determination part 22 detects inflection points, based on apex data specifying a polygon to be drawn and determines whether the polygon is a y-monotonous polygon in which the y-axial coordinate is monotonously increased or monotonously decreased. When the polygon is the y-monotonous polygon, a triangular division part 23 internally divides the polygon into a plurality of triangles, based on the apex data to create triangular division data; and when the polygon is not the y-monotonous polygon, a stencil processing part 24 draws the polygon by a stencil method, based on the drawing order of apexes to create stencil data; and a mask formation part 25 forms a mask pattern for limiting a drawing part to a specific part, based on the triangular division data and stencil data created. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a drawing apparatus that creates drawing data representing a graphic to be displayed.

  Conventionally, it is determined whether or not the stencil method can be used according to the state of the memory resource detected in advance. Has proposed a drawing apparatus that selects and uses a method having a high processing speed from among a line segment division method or a triangulation method (see, for example, Patent Document 1). Further, a method of determining whether or not the polygon data is a concave polygon and dividing it into a convex polygon in advance if it is a concave polygon, and further performing triangulation from the convex polygon to draw is proposed (for example, Patent Document 2).

JP 2007-264989 A JP 2002-163665 A

  Since the conventional drawing apparatus is configured as described above, the problem of the memory resource is solved by determining whether to use the stencil method from the state of the memory resource detected in advance. There has been a problem that it is not possible to select an optimum drawing method for a rectangular state. In addition, when the stencil method is selected, the triangulation method is selected even in the case of a polygon that can perform higher-speed processing, which increases the processing load.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a drawing apparatus capable of performing high-speed drawing according to the target polygonal shape.

  The drawing apparatus according to the present invention detects an inflection point based on vertex data specifying a polygon to be drawn, and whether the polygon is a y monotone polygon whose Y-axis coordinate monotonously increases or decreases monotonously. A polygon shape determining unit for determining, and when the polygon is a y monotone polygon, a triangle dividing unit that generates triangulated data by dividing the polygon into a plurality of triangles based on the vertex data; When the polygon is not a monotonic polygon, the stencil processing unit generates the stencil data by drawing the polygon by the stencil method based on the drawing order of the vertices; The mask pattern is created by using a mask creation unit that creates a mask pattern that restricts a location to a specific location, and a bounding box that is a rectangle that circumscribes the polygon. A drawing unit that draws perform filling of the polygon from the top of the over emissions, in which and a display processing unit which outputs the rendered polygon to an external device.

  According to the present invention, the polygon shape determination unit detects an inflection point based on vertex data specifying a polygon to be drawn, and the polygon is a y monotone polygon whose Y-axis coordinate monotonously increases or decreases monotonously. If the polygon is a y-monotone polygon, the triangulation unit divides the polygon into a plurality of triangles based on the vertex data, and generates triangulation data. Since the stencil processing unit draws the polygon by the stencil method based on the drawing order of the vertices and generates stencil data when the square is not a monotonic polygon, the shape of the target polygon is determined. Then, it is possible to select a drawing processing method with the highest processing speed according to the shape.

Embodiment 1 FIG.
FIG. 1 is a block diagram showing a configuration of a drawing apparatus according to Embodiment 1 of the present invention.
The drawing apparatus 1 mainly includes a drawing processing unit 2 configured by a CPU (Central Processing Unit) or an MPU (Micro Processing Unit) and a memory 3 having a program 31. The drawing apparatus 1 is connected to a storage device 5 and a display device 6 via an I / O interface 4. The storage device 5 stores a plurality of polygon data for specifying polygons to be drawn. The display device 6 displays the polygon drawn by the drawing device 1 on a screen or the like.

  The drawing processing unit 2 includes a vertex data storage unit 21, a polygon shape determination unit 22, a triangulation unit 23, a stencil processing unit 24, a mask creation unit 25, a drawing unit 26, and a display processing unit 27. The vertex data storage unit 21 reads polygon data from the storage device 5 via the I / O interface 4 and acquires and stores each vertex coordinate of the polygon from this polygon data. The polygon shape determination unit 22 performs an inflection point detection process for determining whether or not the drawing target polygon has an inflection point using the vertex coordinates stored in the vertex data storage unit 21. If there is no inflection point, it is determined that the polygon is a monotone polygon, and the subsequent processing is branched to the triangulation method. On the other hand, if it has an inflection point, it is determined that the polygon is not monotonous, and the subsequent processing is branched to the stencil method.

Here, inflection points, connection points, y-monotonic polygons, and non-y-monotonic polygons will be described with reference to FIGS. FIG. 2 is a diagram showing inflection points and connection points in a polygon. FIG. 3 (a) shows a polygon that is monotonous in y and FIG. 3 (b) is a diagram showing a polygon that is not monotonic in y.
First, inflection points are points where adjacent points located on both sides of the target vertex are both located above the target vertex in the Y-axis direction and the internal angle of the target vertex is 180 ° or more (joint point), and adjacent points. Both points are points located below the target vertex in the Y-axis direction, and the internal angle of the target vertex is 180 ° or more (separation point).

In the example of FIG. 2, when the target vertex is A ₃ , the adjacent points (A ₂ , A ₄ ) located on both sides of A ₃ are both positioned below A _{3 in the} Y-axis direction, and the inner angle of A ₃ Since A is 180 ° or more, A ₃ is determined to be an inflection point. When the target vertex is A ₁₀ , the adjacent points (A ₉ , A ₁₁ ) located on both sides of A ₁₀ are both positioned above A _{10 in the} Y-axis direction, and the internal angle of A ₁₀ is 180 ° or more. Therefore, A ₁₀ is determined to be an inflection point. On the other hand, if the target vertex set to A _1, the adjacent point located on both sides of _{A 1 (A 2, A 11} ) is, A ₂ is positioned downward with respect to A ₁ in the Y-axis direction, A ₁₁ is upwardly Since the inner angle is 180 ° or less, A ₁ is determined not to be an inflection point but to be a connection point.

Next, y-monotone polygons and non-y-monotone polygons will be described with specific examples.
The y-monotonic polygon is a polygon that does not have an inflection point and whose Y-axis coordinate monotonously increases or decreases monotonously. For example, as shown in FIG. 3A, a vertex that takes the maximum value of the Y-axis coordinate When going from B ₁ to the vertex B ₅ that takes the minimum value, it is a polygon that always goes downward or horizontally without rising in the Y-axis direction. On the other hand, a polygon that is not monotonous with Y is a point that rises in the Y-axis direction when moving from the vertex B ₁ that takes the maximum value of the Y-axis coordinates to the vertex B ₅ that takes the minimum value, as shown in FIG. A polygon having (B ₃ ′, B ₄ ′).

  Based on the determination result of the polygon shape determination unit 22, the triangulation unit 23 repeats the process of forming a diagonal line toward another stacked vertex using one vertex of the polygon to be drawn as a point of interest. Triangulation data is generated by dividing a square into a plurality of triangles. The stencil processing unit 24 draws a triangle formed according to the drawing order of the vertexes of the polygon based on the determination result of the polygon shape determination unit 22 to generate stencil data. The mask creating unit 25 creates a figure mask pattern based on the triangulation data input from the triangulation unit 23 and the stencil data input from the stencil processing unit 24, and stores the mask pattern in the stencil buffer 25a.

  Here, the mask pattern restricts the drawing part of the figure to a specific part. With this mask pattern, even if the entire figure is painted, only a drawable portion can be drawn. FIG. 4 shows a specific example of the mask pattern. (A) is a mask pattern having a star-shaped figure, and (b) shows a color buffer for filling the figure. By passing the color buffer of (b) through the mask pattern of (a), a star shape filled with the color of the color buffer as shown in (c) can be drawn.

  The drawing unit 26 fills a polygon to be drawn through a mask pattern stored in the stencil buffer 25a. The display processing unit 27 performs display processing on the polygonal drawing data painted in the drawing unit 26.

Next, the operation of the drawing apparatus 1 will be described. FIG. 5 is a flowchart showing the operation of the drawing apparatus according to the first embodiment.
When execution of the program 31 in the memory 3 is started in the drawing device 1, the vertex data storage unit 21 of the drawing processing unit 2 reads and acquires the necessary number of polygon data from the storage device 5 (step ST1). In this operation description, it is assumed that one piece of polygon data is acquired. Further, the vertex data storage unit 21 acquires and stores the vertex coordinates (V1 to Vn) of the polygon to be drawn based on the acquired polygon data (step ST2).

  The polygon shape determination unit 22 reads the corner vertex coordinate information (V1 to Vn) stored in the vertex data storage unit 21 in step ST2, and detects an inflection point based on the read coordinate information (step ST3). . Further, based on the detection result in step ST3, it is determined whether or not the polygon to be drawn is a y monotone polygon (step ST4). When it is determined in step ST4 that the polygon is a y-monotone polygon because no inflection point is detected, the polygon data is output to the triangle division unit 23 and the triangle division method is performed (step ST5). . On the other hand, when an inflection point is detected in step ST4 and it is determined that it is not a y monotone polygon, the polygon data is output to the stencil processing unit 24, and stencil processing is performed (step ST6). Details of the triangulation method processing and the stencil method processing will be described later.

  Based on the triangulation data generated in step ST5 and the stencil data generated in step ST6, the mask creating unit 25 generates a polygonal mask pattern to be drawn and stores it in the stencil buffer 25a (step ST7). . The drawing unit 26 performs painting using the mask pattern stored in step ST7, and draws a polygon to be drawn (step ST8). The display processing unit 27 performs display processing on the polygonal drawing data drawn in step ST8, outputs the data to the display device 6 via the I / O interface 4, and outputs the data to a display or the like (step ST9). The process ends.

Next, details of the triangulation method processing will be described with reference to FIGS. FIG. 6 is a flowchart showing the operation of the triangulation unit of the drawing apparatus according to the first embodiment. The details of the triangulation method processing ST5 shown in FIG. 5 are described in detail. FIG. 7 is an explanatory diagram showing a specific example of the triangulation method process.
First, the operation of the triangulation unit will be described according to the flowchart of FIG.
The triangulation unit 23 sorts the array of the vertices of the polygon to be drawn in descending order of the Y-axis coordinates (step ST11). Two vertices from the top of the vertex array sorted in step ST11 are stacked in an internal memory (not shown) or the like (step ST12). The attention point Pn is set as the third vertex (n = 3) from the top (step ST13).

  A diagonal line that can be formed inside the polygon is drawn from the attention point Pn (n = 3) toward the vertex stacked in step ST12 (step ST14). Next, it is determined whether or not all the polygons are divided into triangles (step ST15). If it is determined in step ST15 that the entire polygon cannot be divided into triangles, all the vertices not divided in step ST14 are stacked (step ST16), and the point of interest Pn is shifted by one (n = n + 1) (step ST17), returning to the process of step ST14, the process described above is repeated. On the other hand, if it is determined in step ST15 that the entire polygon has been divided into triangles, the triangle division method processing is terminated, and the process proceeds to step ST7 in the main flow of FIG.

Next, a specific operation of the triangulation unit will be described using the polygon shown in FIG. 7 along the flow of the flowchart of FIG.
First, as step ST11, the array of each vertex of the polygon is sorted in the descending order of the Y-axis coordinates, that is, in the order of vertices C ₁ , C ₂ , C ₃ , C ₄ , C ₅ , C ₆ , C ₇ . As steps ST12 and ST13, the vertices C ₁ and C ₂ for two vertices from the top of the sorted vertex array are stacked, and the attention point Pn is set as the _third vertex C ₃ from the top (Pn = C ₃ ). From point of interest C ₃ as step ST14, pulling the diagonal can be formed inside the polygon towards the vertex C ₁ and C ₂ which are stacked in step ST12. In step ST15, it is determined whether or not the entire polygon has been divided into triangles.

In the example of FIG. 7, there are polygons C ₂ C ₃ C ₄ C ₅ C ₆ C ₇ that are not all divided into triangles, so that vertices C ₄ , C ₅ , C ₆ that were not divided in step ST12 as step ST16. , C ₇ are stacked. Also, be shifted one target point C ₃ as step ST17 is set to C _4, newly formed inside the polygon towards the vertex C _5, C _6, C _7, which is stacked at Step ST14' Draw a diagonal line that you can. In step ST15 ′, it is determined again whether or not the entire polygon has been divided into triangles.

In the example of FIG. 7, there are polygons C ₂ C ₃ C ₄ C ₅ that cannot be divided into all triangles. Therefore, vertices C ₂ and C ₃ that are not divided in step ST16 are stacked as step ST16 ′. Also, by shifting one point of interest C ₄ Step ST17' set to C _5, can be formed inside the polygon towards the vertex C _2, C ₃ newly stacked in step ST14'' Draw a diagonal line. In step ST15 ″, it is determined whether or not all the polygons are divided into triangles. In the example of FIG. 7, since all the polygons can be divided into triangles, the triangulation process ends.

Next, details of the stencil method processing will be described with reference to FIGS. FIG. 8 is a flowchart showing the operation of the stencil processing unit of the drawing apparatus according to the first embodiment, and details the contents of the stencil method processing ST6 shown in FIG. FIG. 9 is an explanatory diagram showing a specific example of the stencil method processing.
First, the operation of the stencil processing unit will be described with reference to the flowchart of FIG.
The stencil processing unit 24 registers the top vertex of the array of vertices of the polygon to be drawn as the start point Pf (step ST21). A triangle is formed by drawing a diagonal line from the start point Pf registered in step ST21 to each other vertex (step ST22). Only the portion where the triangle formed in step ST22 overlaps an odd number of times is set as a drawable region (step ST23), the stencil method processing is ended, and the processing proceeds to step ST7 of the main flow of FIG.

Next, the specific operation of the stencil processing unit will be described using the polygon shown in FIG. 9 along the flow of the flowchart of FIG.
First, in step ST21, it registers the head of the vertex D ₁ as a starting point Pf of the sequences of each vertex of the polygon. Step ST22, the other vertex D ₂ from the starting point D1 form a triangle pull the diagonal with respect to D _10. Specifically, (a) triangle “D ₁ D ₂ D ₃ ”, (b) triangle “D ₁ D ₃ D 4”, (c) triangle “D ₁ D ₅ D ₆ ”, (d) triangle “D ₁ ”. D ₆ D ₇ ”, (e) triangle“ D ₁ D ₈ D ₉ ”, and (f) triangle“ D ₁ D ₉ D ₁₀ ”are formed.

As step ST23, only the portion where the triangle formed in step ST22 overlaps an odd number of times, that is, the triangles “D ₁ D ₂ D ₃ ” and “D ₁ D ₉ D ₁₀ ” where the triangles overlap an even number of times All other triangles except for are used as the drawable area, and the process ends. By the processing from step ST21 to step ST23, the star-shaped drawing area shown in (f) can be obtained.

  As described above, according to the first embodiment, it is determined whether or not the polygon to be drawn is a y-monotone polygon, and the polygon drawing processing is performed by the triangulation method processing or the stencil method processing based on the determination result. Since the polygonal shape determining unit 22 that branches into the polygonal shape is provided, the fastest drawing processing method can be selected in accordance with the polygonal shape.

  Also, many current mobile phones, car navigation systems, and the like have 3D graphics hardware, and the triangulation method and stencil method according to the first embodiment are supported by this 3D graphics function. It is possible to use an accelerator for 3D graphics of a mobile phone or a car navigation system.

Embodiment 2. FIG.
In the stencil method process shown in the first embodiment, an unnecessary filled portion is generated outside the target polygon to be drawn in the process of step ST22 in the flowchart of FIG. A specific example will be described. When the polygon shown in FIG. 10A is subjected to the stencil method of Embodiment 1, the polygon E ₁ E ₂ E ₃ E ₄ E ₅ E ₆ E ₇ is filled. In addition, useless painting processing occurs in the three triangular portions “E ₁ E ₂ E ₃ ”, “I ₁ E ₄ E ₅ ”, and “E ₁ E ₆ E ₇ ” outside the polygon.

  In the second embodiment, a configuration for suppressing useless painting processing in the above-described stencil method processing will be described. FIG. 11 is a block diagram illustrating a configuration of a drawing apparatus according to the second embodiment. The drawing apparatus 1 is provided with a centroid calculating unit 24a in addition to the stencil processing unit 24 shown in the first embodiment. In the following, the same or corresponding parts as the components of the drawing apparatus 1 according to the first embodiment are denoted by the same reference numerals as those used in the first embodiment, and the description thereof is omitted or simplified.

  The center-of-gravity calculation unit 24a of the stencil processing unit 24 calculates the center of gravity of the polygon using each vertex coordinate of the drawing target polygon. The stencil processing unit 24 performs the stencil method processing by setting the center of gravity of the polygon calculated by the center of gravity calculating unit 24a as a start point.

Next, the operation of the stencil processing unit of the drawing apparatus according to the second embodiment will be described. FIG. 12 is a flowchart showing the processing operation of the stencil processing unit according to the second embodiment, which will be described below with reference to this flowchart.
The centroid calculating unit 24a of the stencil processing unit 24 calculates the centroid from each vertex coordinate of the polygon to be drawn (step ST31). The stencil processing unit 24 registers the center of gravity calculated in step ST31 as the start point Pf (step ST32). Further, a diagonal line is drawn from the start point Pf registered in step ST32 to each other vertex to form a triangle (step ST22). Only the portion where the triangle formed in step ST22 overlaps an odd number of times is set as a drawable region (step ST23), the stencil method processing is ended, and the processing proceeds to step ST7 of the main flow of FIG.

FIG. 10B shows a specific example in the case where the stencil processing unit according to the second embodiment is processed along the flow of the flowchart of FIG.
If the stencil method processing shown in FIG. 12 is applied to the polygon E ₂ ′ E _{3 ′} E _{4 ′} E _{5 ′} E ₆ ′ E ₇ ′ E ₈ ′ with the center of gravity V1 ′ as the starting point Pf, it is generated outside the polygon. There are only two unnecessary filled portions of triangles “I ₂ E ₂ ′ E ₃ ′” and “I ₁ E ₅ ′ E ₆ ′”. Compared with the stencil method processing of the first embodiment shown in FIG. 10A, unnecessary filled portions are reduced, and the processing burden can be reduced.

  As described above, according to the second embodiment, the stencil processing unit 24 is provided with the centroid calculating unit 24a that calculates the centroid of the polygon, and the stencil processing is performed using the calculated centroid of the polygon as a starting point. Since it is configured, it is possible to reduce the memory load when creating a mask pattern for stencil processing, and it is possible to perform drawing at higher speed.

Embodiment 3 FIG.
Also in the third embodiment, a configuration for suppressing useless painting processing in stencil processing will be described. FIG. 13 is a block diagram illustrating a configuration of a drawing apparatus according to the third embodiment. The drawing apparatus 1 is provided with a bounding box midpoint calculation unit 24b in addition to the stencil processing unit 24 shown in the first embodiment. In the following, the same or corresponding parts as the components of the drawing apparatus 1 according to the first embodiment are denoted by the same reference numerals as those used in the first embodiment, and the description thereof is omitted or simplified.

  First, the bounding box will be described with reference to FIG. (A) is a mask pattern indicating a polygon to be drawn, (b) is a color buffer for filling the entire display screen, and (c) is a color buffer for a bounding box. Normally, when drawing is performed using the mask pattern (a), the mask pattern (a) is painted using the color buffer (b). However, the area that needs to be actually painted is only the range of the polygon formed in the mask pattern, and can be entirely covered by this polygonal area.

  Therefore, the maximum rectangle and the minimum value in the X-axis and Y-axis directions are stored in advance for the polygon formed in the mask pattern, and the minimum rectangle that can contain the polygon using the maximum and minimum values. By using the color buffer formed by (1), that is, the bounding box, it is possible to suppress the waste of painting. In the third embodiment, the unnecessary filling process of the stencil method process is suppressed using the area information of the bounding box.

  The bounding box midpoint calculation unit 24b calculates the midpoint of the bounding box using the maximum value and the minimum value in the X-axis and Y-axis directions of the bounding box that is the smallest rectangle that encloses the polygon to be drawn. The stencil processing unit 24 sets the midpoint of the bounding box calculated by the bounding box midpoint calculation unit 24b as a start point and performs stencil processing.

Next, the operation of the stencil processing unit of the drawing apparatus according to Embodiment 3 will be described. FIG. 15 is a flowchart showing the processing operation of the stencil processing unit according to the third embodiment, which will be described below with reference to this flowchart.
The bounding box midpoint calculator 24b of the stencil processing unit 24 calculates the midpoint of the bounding box that is the smallest rectangle that encloses the polygon to be drawn (step ST41). The stencil processing unit 24 registers the midpoint of the bounding box calculated in step ST41 as the start point Pf (step ST42). Further, a triangle is formed by drawing a diagonal line from the start point Pf registered in step ST42 to each other vertex (step ST22). Only the portion where the triangle formed in step ST22 overlaps an odd number of times is set as a drawable region (step ST23), the stencil method processing is ended, and the processing proceeds to step ST7 of the main flow of FIG.

  As described above, according to the third embodiment, the stencil processing unit 24 is provided with the bounding box midpoint calculating unit 24b that calculates the midpoint of the bounding box that is the smallest rectangle that contains the polygon to be drawn. Since the stencil processing is performed with the calculated midpoint of the bounding box as the starting point, the memory load at the time of mask pattern generation in the stencil method processing can be reduced, and higher-speed drawing can be performed.

  However, it cannot be said that the configuration of the third embodiment can be efficiently filled as compared with the configuration in which the stencil processing is performed using the polygonal center of gravity of the second embodiment. However, since the configuration of the third embodiment uses data used for filling a target polygon, there is an advantage that no setup cost is required.

It is a block diagram which shows the structure of the drawing apparatus which concerns on Embodiment 1 of this invention. It is explanatory drawing which shows an inflection point. It is explanatory drawing which shows the figure which is y monotone and a figure which is not y monotone. It is a figure which shows the drawing method of the drawing apparatus which concerns on Embodiment 1 of this invention. It is a flowchart which shows operation | movement of the drawing apparatus which concerns on Embodiment 1 of this invention. It is a flowchart which shows operation | movement of the triangulation part of the drawing apparatus which concerns on Embodiment 1 of this invention. It is an example which shows the triangulation method process of the drawing apparatus which concerns on Embodiment 1 of this invention. It is a flowchart which shows operation | movement of the stencil process part of the drawing apparatus which concerns on Embodiment 1 of this invention. It is an example which shows the stencil system process of the drawing apparatus which concerns on Embodiment 1 of this invention. It is an example which shows the stencil system process of the drawing apparatus which concerns on Embodiment 2 of this invention. It is a block diagram which shows the structure of the drawing apparatus which concerns on Embodiment 2 of this invention. It is a flowchart which shows operation | movement of the stencil process part of the drawing apparatus which concerns on Embodiment 2 of this invention. It is a block diagram which shows the structure of the drawing apparatus which concerns on Embodiment 3 of this invention. It is explanatory drawing which shows a bounding box. It is a flowchart which shows operation | movement of the stencil process part of the drawing apparatus which concerns on Embodiment 3 of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Drawing apparatus, 2 Drawing process part, 3 Memory, 4 I / O interface, 5 Storage apparatus, 6 Display apparatus, 21 Vertex data storage part, 22 Polygon shape determination part, 23 Triangular division part, 24 Stencil process part, 24a Center-of-gravity calculation unit, 24b Bounding box midpoint calculation unit, 25 Mask creation unit, 25a Stencil buffer, 26 drawing unit, 27 Display processing unit, 31 program.

Claims (3)

A polygon shape determination unit that detects an inflection point based on vertex data specifying a polygon to be drawn, and determines whether the polygon is a y monotone polygon whose Y-axis coordinate monotonously increases or decreases; ,
A triangulation unit that divides the polygon into a plurality of triangles based on the vertex data to generate triangulation data when the polygon is a y monotone polygon;
A stencil processing unit for generating stencil data by drawing the polygon by a stencil method based on a drawing order of vertices when the polygon is not a y monotone polygon;
Based on the triangulation data and the stencil data, a mask creation unit that creates a mask pattern that restricts a drawing location to a specific location;
Using a bounding box that is a rectangle circumscribing the polygon, a drawing unit that fills and draws the polygon from above the mask pattern;
And a display processing unit that outputs the drawn polygon to an external device.   The stencil processing unit includes a centroid calculating unit that calculates a centroid of a polygon to be drawn based on vertex data, and performs the stencil method drawing by setting the calculated centroid as a starting point of a drawing order. The drawing apparatus according to claim 1.   The stencil processing unit includes a midpoint calculation unit that calculates a midpoint of the bounding box, and performs the stencil method drawing by setting the calculated midpoint as a start point of a drawing order. Drawing device.

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