KR101654865B1 - Apparatus, method and computer program for rendering image based on stroke - Google Patents

Abstract

A stroke-based image rendering apparatus includes a plurality of edge points that represent a stroke along a path and a plurality of edge points using a width of a normal and a stroke corresponding to each of the plurality of edge points, a boundary point generator configured to generate a boundary point; A mesh including at least one inner triangle and at least one boundary triangle corresponding to the stroke is created by using a middle point between each edge point, each boundary point and boundary points, A mesh generation unit configured to generate the mesh generation unit; And a rendering unit configured to render the mesh as an image. The apparatus divides the strokes generated continuously along the path into internal triangles and boundary triangles by means of curve rendering, so that the apparatus can easily draw vector graphics based on GPU (Graphic Processing Unit) Can be utilized.

Description

TECHNICAL FIELD [0001] The present invention relates to a stroke-based image rendering apparatus, a method and a computer program,

Embodiments are directed to a stroke based image rendering device, method and computer program, and more particularly, to input graphics for a vector graphics based GPU (Graphic Processing Unit) And a computer program capable of rendering a generated stroke as an image.

Vector graphics create digital images through points, straight lines, curves, polygons, and other objects based on a series of instructions or mathematical expressions to draw shapes placed in a given two- or three-dimensional space. In vector graphics, data about the shape to be rendered is created and stored in the form of a series of vector description statements. For example, vector graphics data includes locations of a series of points to be connected, instead of storing each bit for drawing a line, such as a conventional raster graphic, resulting in a smaller file size.

A central processing unit (CPU) -based vector graphic performs image rendering using the result of rasterizing the path data. However, CPU-based vector graphics use the CPU unnecessarily, and the quality of the resulting rendered image is poor. To solve these problems, researches on vector graphics based on GPU (Graphic Processing Unit) have been actively carried out in recent years, and IT corporations such as Google, Apple, and Nokia have developed GPUs for vector graphics We are making a lot of effort.

In order to render an image using GPU-based vector graphics, the polygon to be rendered must first be converted into a triangle mesh, which is a rendering unit of the GPU. However, when the data to be rendered is a stroke that is the result of the input event along the path, it is difficult to perform the rendering by the conventional vector graphic technique.

International Publication No. WO 2013/162136 United States Patent Application Publication No. US2007 / 0097123

According to an aspect of the present invention, there is provided a stroke-based image processing method capable of naturally rendering a stroke generated along an input event for vector graphics based on GPU (Graphic Processing Unit) A rendering device, a method, and a computer program.

A stroke-based image rendering apparatus according to an embodiment includes a plurality of edge points representing a stroke along a path, a width of a normal and a stroke corresponding to each of the plurality of edge points, A boundary point generator configured to generate a plurality of boundary points using the boundary point generator; A mesh including at least one inner triangle and at least one boundary triangle corresponding to the stroke is created by using a middle point between each edge point, each boundary point and boundary points, A mesh generation unit configured to generate the mesh generation unit; And a rendering unit configured to render the mesh as an image.

According to one embodiment, a stroke-based image rendering apparatus includes an input configured to receive stroke data including path data and a stroke width; And an edge point generating unit configured to generate the plurality of edge points from the stroke data.

In one embodiment, the boundary point generating unit is configured to generate, for each of the plurality of edge points, a pair of boundary points respectively located on both sides of the edge point on a normal line corresponding to the edge point.

In one embodiment, the plurality of edge points include a first edge point and a second edge point that are sequentially located along the traveling direction of the path. In this case, when the first normal line corresponding to the first edge point and the second normal line corresponding to the second edge point intersect with each other, the boundary point generating unit generates one of the boundary points corresponding to the second edge point, 1 normal line and the second normal line.

In one embodiment, the mesh generation unit includes an inner triangle generation unit configured to generate at least one intermediate point by connecting at least one of each edge point, each boundary point, and each intermediate point, ; And a boundary triangle generation unit configured to generate the boundary triangle including the boundary point and not meeting the path of the stroke by connecting at least one of each edge point, each boundary point, and each intermediate point.

In one embodiment, the boundary triangle generating unit may include a first vector from a vertex of the boundary triangle except the boundary point to a boundary point, and a second vector from the one vertex to a second vertex of the boundary triangle other than the boundary point, The type of the boundary triangle is determined to be concave or convex. At this time, the rendering unit is configured to render a part of the boundary triangle in a curved shape based on the type of the boundary triangle.

According to one embodiment, a stroke-based image rendering method includes generating a plurality of boundary points from a plurality of edge points representing a stroke along a path, using a width of a normal and a stroke corresponding to each of the plurality of edge points ; Generating a mesh including at least one inner triangle and at least one boundary triangle corresponding to the stroke using the midpoint between each edge point, each boundary point and the boundary points; And rendering the mesh as an image.

According to one embodiment, a stroke-based image rendering method includes the steps of: receiving stroke data including path data and a width of a stroke before the step of generating the plurality of boundary points; And generating the plurality of edge points from the stroke data.

In one embodiment, the step of generating the plurality of boundary points includes the step of generating, for each of the plurality of edge points, a pair of boundary points respectively located on both sides of the edge point on a normal line corresponding to the edge point do.

In one embodiment, the plurality of edge points include a first edge point and a second edge point that are sequentially located along the traveling direction of the path. If the first normal line corresponding to the first edge point and the second normal line corresponding to the second edge point intersect with each other, the step of generating the pair of boundary points may include: And generating one of the boundary points at an intersection of the first normal line and the second normal line.

In one embodiment, the step of generating the mesh comprises: connecting the at least one of the respective edge points, each of the boundary points and each of the midpoints to create the internal triangle including the at least one midpoint and meeting the path of the stroke; And connecting the at least one of each edge point, each boundary point, and each intermediate point to generate the boundary triangle including the boundary point and not meeting the path of the stroke.

In one embodiment, the step of generating the boundary triangles may include: generating a first vector directed from one vertex of the boundary triangle except the boundary point to a boundary point, and a second vector directed to another vertex of the boundary triangle excluding the boundary point from the one vertex. And determining the type of the boundary triangle as concave or convex based on the vector product between the two vectors. At this time, rendering the mesh as an image includes rendering a part of the boundary triangle in a curved shape based on the type of the boundary triangle.

A computer program according to one embodiment may be written to the medium to perform the stroke-based image rendering method in combination with hardware.

According to an apparatus, a method, and a computer program for a stroke-based image rendering device according to an aspect of the present invention, strokes generated successively along an input event are referred to as an inner triangle and a boundary triangle), it can be rendered naturally by curve rendering. This rendering technique can be easily applied to vector graphics based on GPU (Graphic Processing Unit).

1 is a schematic block diagram of a stroke-based image rendering apparatus according to one embodiment.
2 is a schematic flow diagram of a stroke-based image rendering method according to one embodiment.
3A and 3B are images showing strokes.
Figures 4A-4D are images representing creating a plurality of edge points from a stroke along a path.
5A to 5C are images for explaining creation of a boundary point from an edge point.
Figs. 6A and 6B are images showing the boundary points generated from the edge points of Figs. 4C and 4D, respectively.
7A is an image showing creating an inner triangle and a boundary triangle corresponding to the strokes from the middle point between the edge point, the boundary point and the boundary points.
7B is an image showing the final image rendered from the inner triangle and the boundary triangle in FIG. 7A. FIG.
8 to 10 are still images showing the creation of an inner triangle and a boundary triangle corresponding to the strokes from the edge point, the boundary point and the midpoint.
11 and 12 are images showing the creation of an inner triangle and a boundary triangle corresponding to the folded strokes from the edge point, the boundary point and the midpoint.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

1 is a schematic block diagram of a stroke-based image rendering apparatus according to one embodiment.

Referring to FIG. 1, an image rendering apparatus according to the present embodiment includes a boundary point generator 30, a mesh generator 40, and a rendering unit 50. In one embodiment, the image rendering apparatus further comprises an input 10 and / or an edge point generator 20. The image rendering device according to embodiments may be entirely hardware, entirely software, or partially hardware, and may be partially software. For example, the image rendering apparatus may collectively refer to hardware having data processing capability and operating software for driving the hardware. The terms "unit," "system," and " device "and the like are used herein to refer to a combination of hardware and software driven by that hardware. For example, the hardware may be a data processing device comprising a GPU (Graphic Processing Unit) or other processor. Also, the software may refer to a running process, an object, an executable, a thread of execution, a program, and the like.

Each of the parts 10, 20, 30, 40, 50 constituting the image rendering apparatus according to the embodiments is not necessarily intended to refer to a separate component which is physically distinct. 1, the input unit 10, the edge point generation unit 20, the boundary point generation unit 30, the mesh generation unit 40, and the rendering unit 50 are shown as separate blocks separated from each other, Some or all of the input unit 10, the edge point generating unit 20, the boundary point generating unit 30, the mesh generating unit 40, and the rendering unit 50 may be integrated into one and the same device. Further, each of the units 10, 20, 30, 40, and 50 is a functionally separated device according to the operation performed in the computing device in which they are implemented, and does not necessarily mean a separate device separate from each other.

For example, the stroke-based image rendering apparatus according to embodiments may be implemented in a form integrated in a mobile device such as a smartphone, and may be operated using a GPU and a microprocessor on the mobile device , And provide the resultant for display on the display means of the mobile device. However, in another embodiment, at least one of the input unit 10, the edge point generating unit 20, the boundary point generating unit 30, the mesh generating unit 40, It may be implemented as a separate device that is physically separate. For example, each of the components 10, 20, 30, 40, 50 may be components that are communicatively coupled to one another in a distributed computing environment.

2 is a schematic flow diagram of an image rendering method according to one embodiment. An image rendering apparatus and method according to embodiments will be described in detail with reference to FIGS. 1 and 2. FIG.

First, the input unit 10 may receive stroke data corresponding to a stroke to be rendered as an image (S1). Stroke, as used herein, refers to data where an input event occurs along a path. 3A and 3B are images showing strokes, with reference to FIGS. 3 and 3B, a stroke is a pixel located within a predetermined width W from a path 300 along a path 300 defined by the user's input ). The user input defining the path 300 may be a touch input to a touch screen, a pen input, or the like. Path 300 may also include one or more segments of a Bezier Curve, a line, a free line, or other different types of lines.

The stroke data received by the input unit 10 may include the path data and the stroke width. The path data corresponds to path 300 in FIG. 3A, and the width of the stroke may be determined at regular intervals along path 300 based on user input defining path 300. For example, when a user moves his or her hand from point A to point B on the screen while holding a finger on the touch screen, the movement path of the finger from point A to point B corresponds to the path data. In addition, the width of the stroke is defined based on the speed at which the user's finger moves or the strength of the touch input. For example, in the area where the user quickly moves the finger, the width of the stroke is small in the area where the finger is moved slowly. In the area where the strength of the touch input is weak, the stroke width is small and the strength of the touch input is strong The width of the stroke can be increased.

The edge point generating unit 20 can generate a plurality of edge points from the stroke data (S2). The edge points are arranged at regular intervals on the path of the stroke, and each edge point is connected to a leading edge between them. For each edge point, the width of the corresponding stroke is specified. Figures 4A and 4B show path data 410 and 420 and Figures 4C and 4D show a plurality of edge points 411 and 421, respectively, generated from the path data of Figures 4A and 4B.

The boundary point generating unit 30 receives the information of the edge points from the edge point generating unit 20 and can generate a plurality of boundary points based on the received information. In this specification, a boundary point is a point for defining an outline of a stroke, and is generated by using the width of a normal line and a stroke corresponding to each edge point from each edge point located on the path of the stroke. In the present specification, the tangent of each edge point is defined by the following equation (1) using the positions of adjacent edge points in the sequentially arranged edge points. In this specification, the normal of each edge point is perpendicular to the above- It is defined as a straight line. The boundary points may be generated on both sides of the edge point so as to be spaced apart from the corresponding edge point by 1/2 of the stroke width corresponding to the edge point while being positioned on the normal line corresponding to each edge point.

5A is an image for explaining generating a boundary point from an edge point according to an embodiment.

은 해당 에지점과 인접하여 위치한 V_{n -1} 및 V_{n +1} 에 기초하여 다음 수학식 1에 의해 정의된다.Referring to FIG. 5A, the edge points include sequentially arranged edge points V _{n -1} , V _n, and V _{n +1} , and the direction in which the edge points of the edge points increase corresponds to the stroke direction of the stroke. At this time, a process of generating a boundary point corresponding to the edge point V _n will be described. First, the tangent of the edge point V _n

Is defined by the following equation (1) based on V _{n -1} and V _{n +1} located adjacent to the edge point.

과 수직한 직선(즉, 에지점 V_n 의 법선)상에 생성된다. 경계점 VL_n 및 VR_n 각각으로부터 V_n까지의 거리는 V_n에 대응되는 스트로크의 폭(W)의 1/2이다. 즉, VL_n 및 V_n 사이의 거리는 W/2 이며, 마찬가지로 V_n 및 VR_n 사이의 거리도 W/2 이다. 이상의 과정을 각 에지점에 대하여 반복함으로써, 각 에지점에 대응되는 한 쌍의 경계점 VL_n 및 VR_n (n은 임의의 자연수)이 생성될 수 있다. 본 명세서에서, 대응되는 에지점에 대하여 경로의 진행 방향에 대해 좌측에 위치한 경계점(예컨대, VL_n)은 좌측 경계점으로도 지칭되며, 대응되는 에지점에 대하여 경로의 진행 방향에 대해 우측에 위치한 경계점(예컨대, VR_n)은 우측 경계점으로도 지칭된다. 이와 같이 생성된 경계점들은, 스트로크의 메쉬에서 경계 삼각형(boundary triangle)의 구성을 위하여 사용되며 이는 상세히 후술한다.The edge points have respective stroke width values corresponding to them. Using the width W of the stroke corresponding to the edge point V _n , the pair of boundary points VL _n and VR _n are tangent to the edge point V _n

(I.e., the normal of the edge point V _n ). The distance from each of the boundary points VL _n and VR _n to V _n is 1/2 of the width W of the stroke corresponding to V _n . That is, the distance between VL _n and V _n is W / 2, and the distance between V _n and VR _n is also W / 2. By repeating the above process for each edge point, a pair of boundary points VL _n and VR _n (n is an arbitrary natural number) can be generated. In this specification, a boundary point (for example, VL _n ) located on the left side with respect to the traveling direction of the path with respect to the corresponding edge point is also referred to as a left boundary point, and a boundary point (E.g., VR _n ) is also referred to as the right border point. The boundary points thus generated are used for constructing the boundary triangle in the mesh of the stroke, which will be described in detail later.

5B and 5C are images for explaining generating boundary points from edge points according to another embodiment.

Referring to FIG. 5B, in the process of generating the boundary points of the respective edge points in the manner described above with reference to FIG. 5A, the normal line of the leading edge point V _n among the sequentially arranged edge points is located adjacent to V _n And the normal line of the trailing edge point V _{n +1} . At this time, when the boundary point generating portion edge point VL _n corresponding to V _n feature points _n VL, _n VR, and the edge point V _{n + 1} corresponding to _+1, are each generated as shown in Fig. 5b the VR _{n + 1,} the rendered image The boundary of the stroke becomes non-smooth. To solve this problem, in one embodiment, the trailing edge boundary point V _n VR _n the leading edge point V _n normal to the trailing edge point of the normal line V of the _{n + 1 + 1} corresponding to ₊₁ as shown in Figure 5c As shown in FIG. However, this is an exemplary one, and in another embodiment the movement process may be omitted.

FIG. 6A is an image showing the boundary points 611 and 612 generated from the edge point 411 of FIG. 4C by the above-described process, FIG. 6B is an image showing the boundary points 611 and 612 generated from the edge point 421 of FIG. (621, 622).

Referring again to FIGS. 1 and 2, the mesh generation unit 40 includes a triangle, which is a rendering unit of the GPU, using a middle point between edge points, boundary points, and boundary points, (S4, S5). The mesh generation unit 40 includes an inner triangle generation unit 41 for generating an inner triangle of a stroke (S4) and a boundary triangle generation unit 42 for generating a boundary triangle of the stroke (S5) . The boundary triangle in this specification is for drawing the outer portion of the stroke and includes at least one boundary point. Further, the inner triangle in this specification is for drawing an inner portion except the outer portion of the stroke, and includes at least one midpoint and meets at least partly with the path of the stroke.

7A is an image showing creation of an inner triangle and a boundary triangle corresponding to a stroke from an edge point, a boundary point and a middle point. Referring to FIG. 7A, in the mesh generation unit according to an embodiment, The operation of the unit will be described in detail.

Referring to FIGS. 1 and 7A, the mesh generator 40 may first generate a midpoint between boundary points corresponding to adjacent edge points. That is, as the midpoint between the edge points and edge point V _n feature points VL _n V _{n -1 n -1} of the boundary point VL, it is possible to generate the ML _{n -1.} In the same manner, the midpoint MR _{n -1} between the boundary points VR _{n -1} and VR _n , the midpoint ML _n between the boundary points VL _n and VL _{n +1} , the midpoint MR _n between the boundary points VR _n and VR _{n +} Can be generated.

The boundary triangle generation unit 42 may generate one or more boundary triangles by connecting adjacent points from each boundary point. For example, a boundary triangle 710 is defined with the boundary point VL _n and the intermediate points ML _n-1 and ML _n adjacent thereto as three vertexes. Similarly, a boundary triangle 720 is defined with the boundary point VR _n and the intermediate points MR _{n -1} and MR _n adjacent thereto as three vertexes. In one embodiment, the boundary triangle generation unit 42 determines the type of the boundary triangles 710 and 720 as either convex or concave. This kind is a vector product between a first vector from one vertex except for a border point in boundary triangles 710 and 720 to the border point and a second vector from the one vertex to another vertex except for the border point ≪ / RTI >

이 제1 벡터에 해당되며, ML_{n -1}로부터 경계점이 아닌 다른 꼭지점 ML_n을 향하는 벡터

가 제2 벡터에 해당된다. 이때, 전술한 두 벡터의 벡터 곱

은 z 축 방향에서 음의 크기를 갖는다. 따라서, 경계 삼각형(710)의 종류는 볼록에 해당된다. Specifically, a direction perpendicular to the first and second vectors (perpendicular to the drawing) is defined as a z-axis, and a direction projecting forward from the drawing is defined as a positive direction on the z-axis. In this case, in the case of the boundary triangle including the left boundary point (also referred to as the left boundary triangle in this specification), when the magnitude of the vector product of the first and second vectors along the z-axis direction is 0 or a negative value, If the size is a positive value, the boundary triangle is determined as a concave. Taking the boundary triangle 710 as an example, a vector from the vertex ML _{n -1} of the boundary triangle 710 that is not the boundary point to the boundary point VL _n

Corresponds to the first vector, and a vector from ML _{n -1} to a vertex ML _n other than the boundary point

Corresponds to the second vector. At this time, the vector product of the two vectors

Has a negative magnitude in the z-axis direction. Therefore, the type of the boundary triangle 710 corresponds to the convexity.

이 제1 벡터에 해당되며, MR_{n -1}로부터 경계점이 아닌 다른 꼭지점 MR_n을 향하는 벡터

가 제2 벡터에 해당된다. 이때, 제1 및 제2 벡터의 벡터 곱

은 z 축 방향에서 음의 크기를 가지므로, 경계 삼각형(720)의 종류는 오목에 해당된다.On the other hand, in the case of the boundary triangle including the right boundary point (also referred to as the right boundary triangle in this specification), the type of boundary triangle is determined in a manner opposite to the left boundary triangle. That is, if the magnitude of the vector product of the first and second vectors along the z-axis direction is 0 or a negative value, the boundary triangle is determined to be concave, and if the size is positive, the boundary triangle is determined to be convex. For example, in the boundary triangle 720, a vector from the vertex MR _{n -1} of the boundary triangle 720 that is not the boundary point to the boundary point VR _n

Corresponds to the first vector, and a vector from MR _{n -1} to a vertex MR _n other than the boundary point

Corresponds to the second vector. At this time, the vector products of the first and second vectors

Has a negative magnitude in the z-axis direction, so that the kind of the boundary triangle 720 corresponds to the concave.

The types of the boundary triangles 710 and 720 determined as concave or convex are used to draw a curved shape of an area in the boundary triangles 710 and 720 by applying a predetermined shader in a rendering process to be described later. The curve rendering process will be described in detail later.

On the other hand, the inner triangle generating unit 41 may connect one or more inner triangles by connecting adjacent points from each intermediate point. The inner triangle 730 is generated with the intermediate points ML _{n -1} and MR _{n -1} and the boundary point VR _n in FIG. 7A as vertices, and the inner triangle 730 is generated with the intermediate points ML _{n -1} and ML _n and the boundary point VR _n as vertices, The inner triangle 750 is generated with the intermediate points ML _n and MR _n and the boundary point VR _n as vertexes. However, this is illustrative, and the manner of dividing the stroke data into one or more inner triangles may be different from that shown. Various methods of creating an inner triangle from the points for mesh generation are well known in the art, and therefore a detailed description thereof will be omitted herein.

In the same manner as described above, a mesh of strokes including a boundary triangle and an inner triangle is generated (S6). Since the generated mesh is a triangle, which is a rendering unit of the GPU, the rendering unit 50 can draw the stroke by rendering the mesh as an image (S7). In rendering, the rendering unit 50 applies a solid shader to the inner triangle so that the entire inner triangle is rendered as an image, while the curve shader is applied to the boundary triangle, Only some areas are rendered as images.

In the case of the boundary triangle 710 corresponding to the convex in FIG. 7A, only the area between the side facing the boundary point VL _n and the curve is converted into a convex shape image. In the case of a triangle boundary 720 corresponding to the recess is, including the boundary points (VR _n) it is switched only the area between the boundary point _(n VR) and curve to an image of a concave shape. As a result, a natural curved image can be finally obtained as shown in FIG. 7B. For the rendering of the boundary triangle curves, see Charles Loop and Jim Blinn (Siggraph 2005) entitled " Resolution Independent Curve Rendering using Programmable Graphics Hardware ", and US Patent Application Publication No. US 2007/0097123 Since the present invention is well known in the technical field of the present invention, detailed description will be omitted in order to clarify the gist of the present invention.

8 to 10 are still images showing the creation of an inner triangle and a boundary triangle corresponding to the strokes from the edge point, the boundary point and the midpoint.

Referring to FIG. 8, FIG. 8 shows a stroke of a symmetrical form as shown in FIGS. 7A and 7B. A boundary triangle 810 is defined with the boundary point VL _n and the intermediate points ML _{n -1} and ML _n adjacent thereto as three vertexes. Likewise, the boundary triangle 820 is defined with the boundary point VR _n and the intermediate points MR _{n -1} and MR _n adjacent thereto as three vertexes.

, 및 ML_{n -1}로부터 경계점이 아닌 다른 꼭지점 ML_n을 향하는 제2 벡터

의 벡터 곱

은 z 축 방향(즉, 도면에 수직한 방향)에서 양의 크기를 갖는다. 따라서, 경계 삼각형(810)의 종류는 오목에 해당된다. 한편, 경계 삼각형(820)은 우측 경계 삼각형이며, 경계점이 아닌 경계 삼각형(820)의 꼭지점 MR_{n -1}로부터 경계점 VR_n을 향하는 제1 벡터

, 및 MR_{n -1}로부터 경계점이 아닌 다른 꼭지점 MR_n을 향하는 제2 벡터

의 벡터 곱

은 z 축 방향에서 양의 크기를 갖는다. 따라서, 경계 삼각형(720)의 종류는 볼록에 해당된다. The boundary triangle 810 is a left boundary triangle, and the first vector from the vertex ML _{n -1} of the boundary triangle 810 that is not the boundary point to the boundary point VL _n

, And ML _{n -1} to a vertex ML _n other than the boundary point,

Vector product of

Has a positive magnitude in the z-axis direction (i.e., the direction perpendicular to the drawing). Therefore, the type of the boundary triangle 810 corresponds to the concave. On the other hand, the boundary triangle 820 is the right boundary triangle, and the first vector from the vertex MR _{n -1} of the boundary triangle 820 that is not the boundary point to the boundary point VR _n

, And a second vector from the MR _{n -1} to a vertex MR _n other than the boundary point

Vector product of

Has a positive magnitude in the z-axis direction. Therefore, the type of boundary triangle 720 corresponds to the convexity.

Meanwhile, the inner triangles 830, 840, and 850 can be generated in the same manner as described above with reference to FIG. 7A.

The stroke can be drawn by rendering the mesh composed of the boundary triangles 810 and 820 and the inner triangles 830, 840 and 850 generated as described above as an image. In carrying out the rendering, boundary triangle 810 so that the recess, including the boundary points (VL _n), and switching only the area between the boundary point (VL _n) and curved in the image of a concave shape, border triangles 820 is convex So that only the area between the sides facing the boundary point VR _n and the curve is converted into a convex shape image. The above process can be easily understood by those skilled in the art from the above description with reference to FIGS. 7A and 7B, and thus detailed description will be omitted in order to avoid duplication of description.

Referring to Fig. 9, Fig. 9 shows a stroke including only a convex boundary triangle with the width of the stroke partially widened. A boundary triangle 910 is defined with the boundary point VL _n and the intermediate points ML _{n -1} and ML _n adjacent thereto as three vertexes. Likewise, a boundary triangle 920 is defined with the boundary point VR _n and the intermediate points MR _{n -1} and MR _n adjacent thereto as three vertices.

, 및 ML_{n -1}로부터 경계점이 아닌 다른 꼭지점 ML_n을 향하는 제2 벡터

의 벡터 곱

은 z 축 방향(즉, 도면에 수직한 방향)에서 음의 크기를 갖는다. 따라서, 경계 삼각형(910)의 종류는 볼록에 해당된다. 한편, 경계 삼각형(920)은 우측 경계 삼각형이며, 경계점이 아닌 경계 삼각형(920)의 꼭지점 MR_{n -1}로부터 경계점 VR_n을 향하는 제1 벡터

, 및 MR_{n -1}로부터 경계점이 아닌 다른 꼭지점 MR_n을 향하는 제2 벡터

의 벡터 곱

은 z 축 방향에서 양의 크기를 갖는다. 따라서, 경계 삼각형(920)의 종류도 볼록에 해당된다. The boundary triangle 910 is a left boundary triangle, and the first vector from the vertex ML _{n -1} of the boundary triangle 910 that is not the boundary point to the boundary point VL _n

, And ML _{n -1} to a vertex ML _n other than the boundary point,

Vector product of

Has a negative magnitude in the z-axis direction (i.e., the direction perpendicular to the drawing). Therefore, the type of boundary triangle 910 corresponds to the convexity. On the other hand, the boundary triangle 920 is a right boundary triangle, and the first vector from the vertex MR _{n -1} of the boundary triangle 920 that is not the boundary point to the boundary point VR _n

, And a second vector from the MR _{n -1} to a vertex MR _n other than the boundary point

Vector product of

Has a positive magnitude in the z-axis direction. Therefore, the type of boundary triangle 920 also corresponds to the convexity.

On the other hand, the middle point ML _{n -1, n -1} MR and ML to a _n in the vertex is within the triangle 930 is generated by the midpoint MR _{n -1, n} ML and MR _n vertices to another within the triangle ( 940) are generated.

The stroke can be drawn by rendering the mesh composed of the boundary triangles 910 and 920 and the inner triangles 930 and 940 generated as described above as an image. The boundary triangles 910 and 920 correspond to the convex so that only the region between the sides facing the boundary points VL _n and VR _n included in the boundary triangles 910 and 920 is convex To the image of the form. As a result, a stroke in the form of widening in the vicinity of the edge point V _n can be rendered in a natural curve shape.

Referring now to FIG. 10, FIG. 10 shows a stroke that includes only a concave boundary triangle with the width of the stroke being partially narrowed. A boundary triangle 1010 is defined with the boundary point VL _n and the intermediate points ML _{n -1} and ML _n adjacent thereto as three vertexes. Similarly, a boundary triangle 1020 is defined with the boundary point VR _n and the intermediate points MR _{n -1} and MR _n adjacent thereto as three vertexes.

, 및 ML_{n -1}로부터 경계점이 아닌 다른 꼭지점 ML_n을 향하는 제2 벡터

의 벡터 곱

은 z 축 방향(즉, 도면에 수직한 방향)에서 양의 크기를 갖는다. 따라서, 경계 삼각형(1010)의 종류는 오목에 해당된다. 한편, 경계 삼각형(1020)은 우측 경계 삼각형이며, 경계점이 아닌 경계 삼각형(1020)의 꼭지점 MR_{n -1}로부터 경계점 VR_n을 향하는 제1 벡터

, 및 MR_{n -1}로부터 경계점이 아닌 다른 꼭지점 MR_n을 향하는 제2 벡터

의 벡터 곱

은 z 축 방향에서 음의 크기를 갖는다. 따라서, 경계 삼각형(1020)의 종류도 오목에 해당된다. Boundary triangle 1010 is the left border triangles, and the first vector directed toward the border point VL _n from the vertex of the boundary ML _{n -1} triangle 1010, a non-boundary point

, And ML _{n -1} to a vertex ML _n other than the boundary point,

Vector product of

Has a positive magnitude in the z-axis direction (i.e., the direction perpendicular to the drawing). Therefore, the type of the boundary triangle 1010 corresponds to the concave. On the other hand, the boundary triangle 1020 is the right boundary triangle, and a first vector from a vertex MR _{n -1} of the boundary triangle 1020, a non-boundary pixels toward the border point VR _n

, And a second vector from the MR _{n -1} to a vertex MR _n other than the boundary point

Vector product of

Has a negative magnitude in the z-axis direction. Therefore, the type of the boundary triangle 1020 corresponds to the concave.

On the other hand, the middle point ML _{n -1, n -1} MR and VR border point to the vertex _n to be within the triangle 1030 is created, the intermediate point and the boundary points ML _{n -1 n} VL, _n VR inside the triangle to the apex ( 1040) is generated. Further, an inner triangle 1050 is generated with vertexes of the boundary points VL _n , VR _n and the middle point ML _n , and the boundary points VR _n And the middle point ML _n and MR _n as vertexes, the inner triangle 1060 is generated.

The stroke can be drawn by rendering the mesh composed of the boundary triangles 1010 and 1020 and the inner triangles 1030, 1040, 1050, and 1060 generated as described above as an image. In carrying out the rendering, border triangles only the concave region between the (1010, 1020) is because both of the concave boundary points including the feature points (VL _n, VR _n) included in each of (VL _n, VR _n) and curve . As a result, a stroke in the form of a narrowing width in the vicinity of the edge point V _n can be rendered in a natural curve shape.

11 is an image showing creating an inner triangle and a boundary triangle corresponding to the folded strokes from the edge point, the boundary point and the midpoint.

Referring to Fig. 11, the path from the edge point V _n to V _{n + 1} is bent with respect to the path from the edge point V _{n -1} to V _n . Since the stroke fills the pixels located within a predetermined width from the path, when the angle? Of the path is less than 90 degrees, a stroke is folded and overlapped around the bent portion. In such a folded stroke, an edge point V _n corresponding to the bent portion is located at the outer edge of the stroke together with the boundary point, and a boundary triangle is defined using the edge point and the boundary point.

In other words, the boundary triangle 1110 is defined by the boundary _{n VL,} and thus adjacent the midpoint ML _{n -1} and the edge points V _n with three vertices. In addition, a boundary triangle 1120 is defined with the boundary point VR _n and the edge point V _n and the intermediate point ML _n adjacent thereto as three vertexes. When the stroke is folded, that is, when the angle formed by the path from the edge point V _n to V _{n +1} to the edge point V _n-1 to V _n is less than 90 degrees, the edge point V _The boundary triangles including _n are all convex. That is, the boundary triangle 1110 and the boundary triangle 1120 are convex boundary triangles.

On the other hand, the inner triangle is defined using the midpoint and the edge point. At this time, since the stroke is folded, an intermediate point MR _n located after the bending point may exist inside the triangle generated by using other intermediate points and / or edge points. In one embodiment, whether or not the intermediate point is present inside a triangle connecting other midpoints and / or edge points is determined by determining whether the intermediate point is within a triangle connected to another intermediate point and / Can be determined using the relative positions of the intermediate points. The above determination is performed by the internal triangle generation unit 41, and more specifically, as described below.

In Fig. 11, the path was bent to the right with respect to the advancing direction of the stroke. At this time, the last intermediate point MR _n-1 located at the right of the path in the bending direction and located before the bending point from the first intermediate point ML _n located after the edge point V _n located at the left side of the path, Define connected line segments. At this time, a triangle formed by connecting intermediate points and / or edge points having different intermediate points after the bending, through the relative positions of the first intermediate point MR _n located at the right side of the bending direction and located after the bending point and the above- It is possible to judge whether or not it exists inside. ML _n And MR _{n -1} is an axis perpendicular to the line segment, and the direction adjacent to the path on the axis is a positive direction, ML _n And the shortest distance D from the line segment connecting MR _{n -1} to MR _n has a positive value, it can be seen that MR _n is located inside the triangle connecting the other points.

If it is determined that MR _n is located inside the triangle connecting the other points, the inner triangle generation unit 41 generates an inner triangle using other midpoints except MR _n . That is, the middle point ML _{n -1, n -1} and MR edge to the point V _n to the vertex is within the triangle 1130 is produced, the middle point MR _{n -1,} to the ML _n and V _n edge points as vertices inside A triangle 1140 is generated. The mesh generation and rendering process using the inner triangle and the boundary triangle are the same as the corresponding processes of the above-described embodiments, and thus a detailed description thereof will be omitted.

12 is another image showing creating an inner triangle and a boundary triangle corresponding to the folded strokes from the edge point, the boundary point and the midpoint.

12 differs from the example shown in Fig. 11 in the stroke progress speed. That is, in the example shown in FIG. 11, the last right boundary point MR _n exists inside the triangle generated by the other points. However, in the example of FIG. 12, the stroke progresses at a higher speed and the last right boundary point MR _n is generated by the other points It exists outside the triangle. This point is, similarly to that described above with reference to Figure 11, ML _n And the code of the shortest distance from the line segment connecting MR _{n -1} to MR _n . ML _n And MR _{n -1} is an axis perpendicular to the line segment, and the direction adjacent to the path on the axis is a positive direction, ML _n And the shortest distance (D) from the line segment connecting MR _{n -1} to MR _n is negative. Thus, it can be seen that MR _n is not located inside the triangle connecting the other points.

If it is determined that MR _n is located outside the triangle connecting the other points, the inner triangle generation unit 41 generates an inner triangle using MR _n as a vertex together with other intermediate points. That is, the middle point ML _{n -1, n -1} and MR edge to the point V _n to the vertex is within the triangle 1230 is produced, the middle point MR _{n -1,} to the ML _n and V _n edge points as vertices inside A triangle 1240 is generated, and the midpoints MR _{n -1} , ML _n And MR _n as the vertexes, the inner triangle 1250 is generated.

On the other hand, with reference to FIG. 11, one that boundary point VL _n, in the same way the middle above points ML _n-1 and the edge points boundary to the V _n in the vertex triangle 1210, and, the boundary points VR _n, the edge points V _n, and the intermediate point A boundary triangle 1220 having vertex ML _n is defined. The types of the two boundary triangles 1210 and 1220 are all convex. Using the boundary triangles 1210 and 1220 and the inner triangles 1230, 1240 and 1250 generated as described above, the mesh generation and rendering process can be performed in the same manner as the corresponding processes of the above-described embodiments.

The operations according to the stroke-based image rendering apparatus and method according to the embodiments described above can be implemented, at least partially, in a computer program and recorded in a computer-readable recording medium. The computer-readable recording medium includes all kinds of recording apparatuses in which data that can be read by a computer is stored. Examples of the computer-readable recording medium include a ROM, a RAM, a CD-ROM, a magnetic tape, a floppy disk, an optical data storage device, and the like, and a carrier wave (for example, And the like. The computer readable recording medium may also be distributed over a networked computer system so that computer readable code is stored and executed in a distributed manner. In addition, functional programs, codes, and code segments for implementing the present embodiment may be easily understood by those skilled in the art to which this embodiment belongs.

While the invention has been shown and described with reference to certain embodiments thereof, it will be understood by those skilled in the art that various changes and modifications may be made therein without departing from the spirit and scope of the invention as defined by the appended claims. However, it should be understood that such modifications are within the technical scope of the present invention. Accordingly, the true scope of the present invention should be determined by the technical idea of the appended claims.

Claims (13)

Wherein the stroke data is configured to receive stroke data including path data and a stroke width defined by a user input, the width of the stroke being determined at regular intervals based on a user input defining the path data;
An edge point generating unit configured to generate a plurality of edge points from the stroke data;
A boundary point generation unit configured to generate a plurality of boundary points from the plurality of edge points using a normal line corresponding to each of the plurality of edge points and a width of the stroke;
A mesh generation unit configured to generate a mesh including at least one inner triangle and at least one boundary triangle corresponding to a stroke using an intermediate point between each edge point, each boundary point, and boundary points; And
And a rendering unit configured to render the mesh as an image,
Wherein the mesh generation unit comprises:
The boundary triangle including the boundary points and not meeting the paths of the strokes is generated by connecting at least one of the edge points, the respective boundary points, and the respective intermediate points, And a boundary triangle generation unit configured to determine the type of the boundary triangle as a concave or a convex based on a vector product between a vector and a second vector directed to another vertex of the boundary triangle excluding the boundary point from the one vertex. Based image rendering device.
delete The method according to claim 1,
The boundary-
And to generate, for each of the plurality of edge points, a pair of boundary points respectively located on both sides of the edge point on a normal corresponding to the edge point.
The method of claim 3,
The plurality of edge points including a first edge point and a second edge point sequentially located along a traveling direction of the path,
Wherein the boundary point generation unit generates one of boundary points corresponding to the second edge point when the first normal line corresponding to the first edge point and the second normal line corresponding to the second edge point intersect with each other, And at the intersection of the first normal and the second normal.
The method according to claim 1,
Wherein the mesh generation unit comprises:
Further comprising an internal triangle generation unit configured to concatenate at least one of each edge point, each boundary point, and each intermediate point to generate the internal triangle including at least one midpoint and meeting the path of the stroke, .
The method according to claim 1,
Wherein the rendering unit is configured to render a portion of the boundary triangle in a curved shape based on the type of the boundary triangle.
The method comprising the steps of: receiving stroke data including path data and stroke width defined by user input, the stroke width being determined at regular intervals based on user input defining the path data; ;
Generating a plurality of edge points from the stroke data
Generating a plurality of boundary points from the plurality of edge points by using a normal line corresponding to each of the plurality of edge points and a width of the stroke;
Generating a mesh including at least one inner triangle and at least one boundary triangle corresponding to the stroke using the midpoint between each edge point, each boundary point and the boundary points; And
Rendering the mesh as an image,
Wherein the generating the mesh comprises:
Connecting the at least one of each edge point, each boundary point, and each intermediate point to generate the boundary triangle including the boundary point and not meeting the path of the stroke; And
Based on a vector product between a first vector from a vertex of one of the boundary triangles excluding a boundary point to a boundary point and a second vector from the one vertex to another vertex of the boundary triangle excluding the boundary point, And determining a concave or convex shape of the stroke-based image.
delete 8. The method of claim 7,
Wherein the generating of the plurality of boundary points comprises:
And for each of the plurality of edge points, generating a pair of boundary points respectively located on both sides of the edge point on a normal corresponding to the edge point.
10. The method of claim 9,
The plurality of edge points including a first edge point and a second edge point sequentially located along a traveling direction of the path,
Wherein the step of generating the pair of boundary points comprises the steps of: when a first normal line corresponding to the first edge point and a second normal line corresponding to the second edge point intersect with each other, And creating one at the intersection of the first normal and the second normal.
8. The method of claim 7,
Wherein the generating the mesh comprises:
Further comprising connecting the at least one of the respective edge points, each of the boundary points, and each of the intermediate points to create the internal triangle that includes at least one midpoint and meets the path of the stroke.
8. The method of claim 7,
Wherein rendering the mesh as an image comprises rendering a region of the interior of the bounding triangle in a curve shape based on the type of the boundary triangle.
A computer program stored on a medium coupled to hardware for executing a stroke-based image rendering method,
The stroke-based image rendering method includes:
The method comprising the steps of: receiving stroke data including path data and stroke width defined by user input, the stroke width being determined at regular intervals based on user input defining the path data; ;
Generating a plurality of edge points from the stroke data
Generating a plurality of boundary points from the plurality of edge points by using a normal line corresponding to each of the plurality of edge points and a width of the stroke;
Generating a mesh including at least one inner triangle and at least one boundary triangle corresponding to the stroke using the midpoint between each edge point, each boundary point and the boundary points; And
Rendering the mesh as an image,
Wherein the generating the mesh comprises:
Connecting the at least one of each edge point, each boundary point, and each intermediate point to generate the boundary triangle including the boundary point and not meeting the path of the stroke; And
Based on a vector product between a first vector from a vertex of one of the boundary triangles excluding a boundary point to a boundary point and a second vector from the one vertex to another vertex of the boundary triangle excluding the boundary point, Wherein the step of determining the concavity or convexity comprises:
Computer program.

Images