CAD drawing block rendering method and system based on CAD drawing block entity grouping

Abstract

The invention provides a CAD drawing block rendering method and system based on CAD drawing block entity grouping, relates to the technical field of computer image processing, and aims to render by adopting an entity grouping mode according to whether the range of the blocks exceeds the limit or not. The method does not depend on specific coordinate conversion, when the CAD drawing contains a plurality of block reference entities corresponding to the blocks, primitive data does not need to be created for the same sub-entity in the blocks for multiple times, only reference of the primitive data of the same sub-entity needs to be created, and the method is implemented in the mode that the current world coordinates of the camera are subtracted. According to the method, the generation speed of the block reference entity primitive data is greatly increased, and a finer complex curve can be displayed under the same CAD drawing display scale, so that the graph rendering precision and the vector primitive data generation efficiency are both considered.

Description

Technical Field

[0001] The present invention relates to the technical field of computer image processing, and more specifically, to a CAD drawing block rendering method and system based on CAD block entity grouping. Background Art

[0002] With the popularization of CAD technology and the improvement of computer hardware performance, CAD drawing block rendering technology has been widely used in architectural design, mechanical design and other fields.

[0003] CAD blocks are a general term for a group of graphic entities in CAD drawings, usually used as a template. In the block rendering process of CAD drawings, a crucial link is the conversion of the internal entity coordinates of the block to the world coordinates. However, when the result of this conversion process exceeds the accuracy range supported by the graphics display card, a series of problems will arise. Specifically, once the coordinates of the internal entity of the block exceed the accuracy limit of the graphics display card after being converted to world coordinates, the rendering accuracy will be significantly reduced. This means that the graphic elements that should have been clear and delicate may become blurred and distorted, losing the original design accuracy. In addition, this situation beyond the accuracy range may also cause abnormal graphics rendering. For example, the graphics may flicker, be misplaced or deformed, which seriously affects the presentation of the design effect. In extreme cases, it may even cause the CAD software to crash or fail to display the graphics normally, causing great trouble to the design work. Therefore, when performing CAD design, we must pay close attention to the conversion process of the internal entity coordinates of the block to ensure that the result is within the accuracy range of the graphics display card to ensure the rendering accuracy and normal display of the graphics.

[0004] At present, the industry has proposed a variety of methods to solve the problem of CAD block rendering accuracy. Taking the Open Design Alliance (ODA) as an example, when generating vector metadata, this method converts the internal entity coordinates of the block into world coordinates and subtracts the current world coordinates of the camera to reduce the risk of reduced rendering accuracy. However, this method will slow down the generation speed when there are many block references. Summary of the invention

[0005] In order to solve the problem that the current CAD block rendering method cannot take into account both the graphics rendering accuracy and the vector metadata generation efficiency, the present invention proposes a CAD drawing block rendering method and system based on CAD block entity grouping, which achieves a dual improvement in rendering accuracy and vector metadata generation efficiency.

[0006] In order to achieve the above technical effects, the technical solution of the present invention is as follows:

[0007] In a first aspect, the present application proposes a CAD drawing block rendering method based on CAD block entity grouping, comprising:

[0008] S1: Based on the block attribute information of the CAD block reference entity, determine the range of the block reference entity in the world coordinate system of the CAD drawing;

[0009] S2: Grouping all sub-entities of the block reference entity; the block reference entity includes a plurality of sub-entities to be rendered;

[0010] S3: traverse all sub-entities to be rendered. When traversing each sub-entity to be rendered, if the range exceeds the limit, generate metadata according to the sub-entity grouping result; if the range does not exceed the limit, generate metadata according to the coordinates of the current sub-entity, and finally obtain all metadata of the block reference entity;

[0011] S4: Render the metadata to the screen.

[0012] Preferably, the block attribute information of the block reference entity in step S1 includes: block ID, block position, block translation, scaling size, and rotation angle; and the process of determining the range of the block reference entity in the world coordinate system of the CAD drawing includes:

[0013] S11: superimposing the coordinate range of each sub-entity in the block reference entity to obtain the coordinate range of the block reference entity, wherein the coordinate range of the block reference entity is defined by a point set consisting of a maximum coordinate and a minimum coordinate;

[0014] S12: according to the block translation, scaling, and rotation angle attributes, the coordinate range of the block reference entity is converted from the current local coordinate system to the world coordinate system to obtain a conversion matrix;

[0015] S13: Multiply the coordinate range of the block reference entity by the transformation matrix to obtain the range of the block reference entity in the world coordinate system of the CAD drawing.

[0016] Preferably, the manner of grouping all sub-entities of the block reference entity is a spatial clustering algorithm, and each obtained group contains a plurality of sub-entities.

[0017] Preferably, the manner of grouping all sub-entities of the block reference entity is: grouping based on the number of sub-entities and the positions of sub-entities, and each obtained group contains a plurality of sub-entities.

[0018] Preferably, the process of step S3 is specifically as follows:

[0019] S31: Read the sub-entity to be rendered;

[0020] S32: Determine whether the range exceeds the limit. If so, calculate the grouping conversion matrix according to the sub-entity grouping result, calculate the grouping coordinates of the sub-entity using the grouping conversion matrix, and execute step S33; otherwise, generate the image metadata using the coordinates of the current sub-entity, and execute step S34;

[0021] S33: Generate metadata using the grouping coordinates of the current sub-entity;

[0022] S34: Determine whether all sub-entities to be rendered are completely read. If so, obtain all metadata of the block reference entity and execute S4; otherwise, return to step S31.

[0023] Preferably, the determining whether the range exceeds the limit refers to determining whether the range accuracy of the block reference entity in the world coordinate system of the CAD drawing exceeds the display accuracy range of the graphics card.

[0024] Preferably, the process of calculating the group conversion matrix is:

[0025] Superimposing the coordinate range of each sub-entity in each group to obtain the overall coordinate range of each group, wherein the overall coordinate range of each group is defined by a point set consisting of a maximum coordinate and a minimum coordinate;

[0026] According to the tile translation, scaling, and rotation angle, the overall coordinate range of each group is converted from the current local coordinate system to the world coordinate system to obtain the group transformation matrix;

[0027] The expression for calculating the group coordinates of the sub-entity using the group transformation matrix is:

[0028] The group coordinates of the sub-entity = group transformation matrix * homogeneous coordinates of the coordinates.

[0029] Preferably, the process of step S4 is specifically as follows:

[0030] S41: Reading the metadata of the block reference entity, and transferring the transformation matrix of the block reference entity to the graphics card;

[0031] S42: Determine whether the range exceeds the limit. If so, transmit the group coordinates of the sub-entities to the graphics card and execute step S43; otherwise, execute step S44;

[0032] S43: Rendering the image metadata to the screen;

[0033] S44: Determine whether all the metadata are completely read, if so, complete the rendering; otherwise, return to S41.

[0034] In a second aspect, the present application proposes a computer-readable storage medium, which stores at least one computer instruction, and the instruction is loaded and executed by a processor to implement the steps performed in the CAD drawing block rendering method based on CAD block entity grouping.

[0035] In a third aspect, the present application proposes a CAD drawing block rendering system based on CAD block entity grouping, the system is used to implement the CAD drawing block rendering method based on CAD block entity grouping, including:

[0036] A block range calculation unit, based on the block attribute information of the CAD block reference entity, determines the range of the block reference entity in the world coordinate system of the CAD drawing;

[0037] An entity grouping unit, used for grouping all sub-entities of the block reference entity; the block reference entity includes a plurality of sub-entities to be rendered;

[0038] The metadata generating unit traverses all sub-entities to be rendered. When traversing each sub-entity to be rendered, if the range exceeds the limit, the metadata is generated according to the sub-entity grouping result; if the range does not exceed the limit, the metadata is generated according to the coordinates of the current sub-entity, and finally all the metadata of the block reference entity are obtained;

[0039] The rendering unit renders the image metadata to the screen.

[0040] Compared with the prior art, the technical solution of the present invention has the following beneficial effects:

[0041] The present invention proposes a CAD drawing block rendering method and system based on CAD block entity grouping. According to whether the block range exceeds the limit, the entity grouping method is used for rendering in a targeted manner. Compared with the rendering method of converting the coordinates of the entity inside the block to the world coordinates and subtracting the world coordinates of the current camera, the present invention does not rely on a specific coordinate conversion implementation. When the CAD drawing contains multiple block reference entities corresponding to the block, it is not necessary to create metadata for the same sub-entity in the block multiple times. Only a reference to the metadata of the same sub-entity needs to be created, which greatly speeds up the generation speed of the block reference entity metadata. Moreover, at the same CAD drawing display scale, more sophisticated complex curves can be displayed. Therefore, the present invention takes into account both the graphics rendering accuracy and the vector metadata generation efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 A schematic diagram showing a flow chart of a CAD drawing block rendering method based on CAD block entity grouping proposed in an embodiment of the present invention;

[0043] Figure 2A schematic diagram showing a flow chart of determining the range of a block reference entity in a CAD drawing world coordinate system proposed in an embodiment of the present invention;

[0044] Figure 3 A schematic diagram showing a process of obtaining all metadata of a block reference entity proposed in an embodiment of the present invention;

[0045] Figure 4 A schematic diagram showing a process of rendering image metadata onto a screen according to an embodiment of the present invention;

[0046] Figure 5 A structural composition diagram of a CAD drawing block rendering system based on CAD block entity grouping proposed in an embodiment of the present invention. DETAILED DESCRIPTION

[0047] The drawings are for illustrative purposes only and should not be construed as limiting the present patent;

[0048] In order to better illustrate the present embodiment, some parts of the drawings may be omitted, enlarged or reduced, and do not represent the actual size;

[0049] It is understandable to those skilled in the art that descriptions of certain well-known contents in the drawings may be omitted.

[0050] The technical solution of the present invention is further described below in conjunction with the accompanying drawings and embodiments.

[0051] The positional relationships described in the drawings are only for illustrative purposes and should not be construed as limiting the present patent;

[0052] Example 1

[0053] like Figure 1 As shown, this embodiment proposes a CAD drawing block rendering method based on CAD block entity grouping, comprising the following steps:

[0054] S1: Based on the block attribute information of the CAD block reference entity, determine the range of the block reference entity in the world coordinate system of the CAD drawing;

[0055] S2: Grouping all sub-entities of the block reference entity; the block reference entity includes a plurality of sub-entities to be rendered;

[0056] S3: traverse all sub-entities to be rendered. When traversing each sub-entity to be rendered, if the range exceeds the limit, generate metadata according to the sub-entity grouping result; if the range does not exceed the limit, generate metadata according to the coordinates of the current sub-entity, and finally obtain all metadata of the block reference entity;

[0057] S4: Render the metadata to the screen.

[0058] The following is an explanation of the relevant content: (1) Entity: In CAD drawings, a line, a circle, a picture, etc. is called an entity, which can be translated into entity or object in English. An entity has multiple attributes. For example, a line entity has geometric attributes such as the start point and the end point, and style attributes such as color value and line width. A circle entity has geometric attributes such as the center position and radius, and style attributes such as color value and line width. (2) Block reference entity: As mentioned above, a straight line, a circle, etc. is an entity. However, if you want to add a complex object to a CAD drawing, such as a street lamp, the symbol of a street lamp is composed of multiple straight lines and circles. It is impossible to draw these straight lines and circles every time. Therefore, these straight lines and circles are combined into a street lamp template. This template is called a block in CAD. The lines and circles in the block are called sub-entities of the block. These templates are then referenced in the drawing. For example, if there are multiple street lamps on a road, then references to the street lamp block (template) are inserted at different locations, and the same street lamps will be displayed at different locations on the road. These references to the street lamp block (template), like a straight line, a circle, etc., are also an entity. A straight line is called a straight line entity, and a circle is called a circle entity. Then the street lamp is called a block reference entity.

[0059] In this embodiment, based on the block attribute information of the CAD block reference entity, the range of the block reference entity in the world coordinate system of the CAD drawing is determined, and according to whether the block range exceeds the limit, the entity grouping method is used for rendering in a targeted manner. Compared with the rendering method of converting the coordinates of the entity inside the block to the world coordinates and subtracting the world coordinates of the current camera, the method proposed in this embodiment does not rely on a specific coordinate conversion implementation. When the CAD drawing contains multiple block reference entities corresponding to the block, it is not necessary to create metadata for the same sub-entity in the block multiple times. Only a reference to the metadata of the same sub-entity needs to be created, which greatly speeds up the generation speed of the block reference entity metadata. Moreover, at the same CAD drawing display scale, more refined complex curves can be displayed. Therefore, both the graphics rendering accuracy and the vector metadata generation efficiency are taken into account.

[0060] Example 2

[0061] In this embodiment, the block attribute information of the block reference entity includes: block ID, block position, block translation, scaling, rotation angle, and other block attribute information; see Figure 2 , the process of determining the extent of a block reference entity in the CAD drawing world coordinate system includes:

[0062] S11: superimposing the coordinate range of each sub-entity in the block reference entity to obtain the coordinate range of the block reference entity, wherein the coordinate range of the block reference entity is defined by a point set consisting of a maximum coordinate and a minimum coordinate;

[0063] S12: according to the block translation, scaling, and rotation angle attributes, the coordinate range of the block reference entity is converted from the current local coordinate system to the world coordinate system to obtain a conversion matrix;

[0064] S13: Multiply the coordinate range of the block reference entity by the transformation matrix to obtain the range of the block reference entity in the world coordinate system of the CAD drawing.

[0065] In this embodiment, all sub-entities of the block reference entity are grouped using a spatial clustering algorithm, and each obtained group contains several sub-entities. Grouping can also be performed based on the number of sub-entities and the location of the sub-entities, and each obtained group contains several sub-entities. This embodiment uses a spatial clustering algorithm to group all sub-entities of the block reference entity. For complex block definitions containing a large number of sub-entities, a spatial clustering algorithm can help simplify their organization, making block reference entities easier to manage and maintain. By grouping sub-entities using a spatial clustering algorithm, the required sub-entity set can be quickly located, thereby improving the search and editing efficiency during the design process. In addition, during the CAD drawing process, if a sub-entity set with the same attributes needs to be inserted multiple times, the required block reference entity can be quickly generated through a clustering algorithm, reducing the workload of repeated drawing and editing.

[0066] Figure 3 The schematic diagram of the process of obtaining all metadata of a block reference entity of the present invention is shown, and the process of step S3 is specifically as follows:

[0067] S31: Read the sub-entity to be rendered;

[0068] S32: Determine whether the range exceeds the limit. If so, calculate the grouping conversion matrix according to the sub-entity grouping result, calculate the grouping coordinates of the sub-entity using the grouping conversion matrix, and execute step S33; otherwise, generate the image metadata using the coordinates of the current sub-entity, and execute step S34;

[0069] S33: Generate metadata using the grouping coordinates of the current sub-entity;

[0070] S34: Determine whether all sub-entities to be rendered are completely read. If so, obtain all metadata of the block reference entity and execute S4; otherwise, return to step S31.

[0071] In this embodiment, there are many sub-entities to be rendered. When step S31 reads the sub-entities to be rendered, each of all the sub-entities may be read in sequence. After reading each sub-entity, step S32 is executed. In step S32, the determination of whether the range exceeds the limit refers to determining whether the range accuracy of the block reference entity in the world coordinate system of the CAD drawing exceeds the display accuracy range of the graphics card. For example, in OpenGL ES, the maximum accuracy supported by vertex coordinate data is the 32-bit floating point type in the IEEE 754 standard. When the coordinate value exceeds this range, the vertex data of the graphics card will be calculated incorrectly.

[0072] In step S32, the process of calculating the group conversion matrix is:

[0073] Superimposing the coordinate range of each sub-entity in each group to obtain the overall coordinate range of each group, wherein the overall coordinate range of each group is defined by a point set consisting of a maximum coordinate and a minimum coordinate;

[0074] According to the tile translation, scaling, and rotation angle, the overall coordinate range of each group is converted from the current local coordinate system to the world coordinate system to obtain the group transformation matrix.

[0075] The expression for calculating the group coordinates of the sub-entity using the group transformation matrix is:

[0076] The group coordinates of the sub-entity = group transformation matrix * homogeneous coordinates of the coordinates.

[0077] Here, the homogeneous coordinates of the coordinates are the homogeneous coordinates of the coordinates of the sub-entity. For example, if the coordinates of a sub-entity are (x, y, z), then the homogeneous coordinates are (x, y, z, 1.0).

[0078] In this embodiment, the process of rendering the image metadata onto the screen in step S4 is specifically as follows:

[0079] S41: Reading the metadata of the block reference entity, and transferring the transformation matrix of the block reference entity to the graphics card;

[0080] S42: Determine whether the range exceeds the limit. If so, transmit the group coordinates of the sub-entities to the graphics card and execute step S43; otherwise, execute step S44;

[0081] S43: Rendering the image metadata to the screen;

[0082] S44: Determine whether all the metadata are completely read, if so, complete the rendering; otherwise, return to S41.

[0083] Example 3

[0084] This embodiment proposes a computer-readable storage medium, in which at least one computer instruction is stored. The instruction is loaded and executed by a processor to implement the steps performed in the CAD drawing block rendering method based on CAD block entity grouping described in Embodiment 1 and Embodiment 2.

[0085] Example 4

[0086] This embodiment proposes a CAD drawing block rendering system based on CAD block entity grouping, the system comprises: Figure 5 As shown, the CAD drawing block rendering method based on CAD block entity grouping described in Example 1 and Example 2 includes:

[0087] A block range calculation unit, based on the block attribute information of the CAD block reference entity, determines the range of the block reference entity in the world coordinate system of the CAD drawing;

[0088] An entity grouping unit, used for grouping all sub-entities of the block reference entity; the block reference entity includes a plurality of sub-entities to be rendered;

[0089] The metadata generating unit traverses all sub-entities to be rendered. When traversing each sub-entity to be rendered, if the range exceeds the limit, the metadata is generated according to the sub-entity grouping result; if the range does not exceed the limit, the metadata is generated according to the coordinates of the current sub-entity, and finally all the metadata of the block reference entity are obtained;

[0090] The rendering unit renders the image metadata to the screen.

[0091] The embodiments are merely examples for clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the embodiments here. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the claims of the present invention.

Claims

1. A CAD drawing block rendering method based on CAD block entity grouping, characterized in that: include: S1: Based on the block attribute information of the CAD block reference entity, determine the range of the block reference entity in the world coordinate system of the CAD drawing; S2: Grouping all sub-entities of the block reference entity; the block reference entity includes a plurality of sub-entities to be rendered; S3: traverse all sub-entities to be rendered. When traversing each sub-entity to be rendered, if the range exceeds the limit, generate metadata according to the sub-entity grouping result; if the range does not exceed the limit, generate metadata according to the coordinates of the current sub-entity, and finally obtain all metadata of the block reference entity; S4: Render the metadata to the screen.

2. The CAD drawing block rendering method based on CAD block entity grouping according to claim 1, characterized in that: The block attribute information of the block reference entity in step S1 includes: block ID, block position, block translation, scaling size, and rotation angle; the process of determining the range of the block reference entity in the CAD drawing world coordinate system includes: S11: superimposing the coordinate range of each sub-entity in the block reference entity to obtain the coordinate range of the block reference entity, wherein the coordinate range of the block reference entity is defined by a point set consisting of a maximum coordinate and a minimum coordinate; S12: according to the block translation, scaling, and rotation angle attributes, the coordinate range of the block reference entity is converted from the current local coordinate system to the world coordinate system to obtain a conversion matrix; S13: Multiply the coordinate range of the block reference entity by the transformation matrix to obtain the range of the block reference entity in the world coordinate system of the CAD drawing.

3. The CAD drawing block rendering method based on CAD block entity grouping according to claim 1, characterized in that: The method of grouping all sub-entities of the block reference entity is a spatial clustering algorithm, and each obtained group contains a number of sub-entities.

4. The CAD drawing block rendering method based on CAD block entity grouping according to claim 1, characterized in that: The manner of grouping all sub-entities of the block reference entity is: grouping based on the number of sub-entities and the positions of sub-entities, and each obtained group contains a plurality of sub-entities.

5. The CAD drawing block rendering method based on CAD block entity grouping according to claim 1, characterized in that: The specific process of step S3 is: S31: Read the sub-entity to be rendered; S32: Determine whether the range exceeds the limit. If so, calculate the grouping conversion matrix according to the sub-entity grouping result, calculate the grouping coordinates of the sub-entities using the grouping conversion matrix, and execute step S33; Otherwise, the coordinates of the current sub-entity are used to generate the graphic element data, and step S34 is executed; S33: Generate metadata using the grouping coordinates of the current sub-entity; S34: Determine whether all sub-entities to be rendered are completely read. If so, obtain all metadata of the block reference entity and execute S4; otherwise, return to step S31.

6. The CAD drawing block rendering method based on CAD block entity grouping according to claim 5, characterized in that: The determination of whether the range exceeds the limit refers to determining whether the range accuracy of the block reference entity in the world coordinate system of the CAD drawing exceeds the display accuracy range of the graphics card.

7. The CAD drawing block rendering method based on CAD block entity grouping according to claim 5, characterized in that: The process of calculating the group transition matrix is: Superimposing the coordinate range of each sub-entity in each group to obtain the overall coordinate range of each group, wherein the overall coordinate range of each group is defined by a point set consisting of a maximum coordinate and a minimum coordinate; According to the tile translation, scaling, and rotation angle, the overall coordinate range of each group is converted from the current local coordinate system to the world coordinate system to obtain the group transformation matrix; The expression for calculating the group coordinates of the sub-entity using the group transformation matrix is: The group coordinates of the sub-entity = group transformation matrix * homogeneous coordinates of the coordinates.

8. The CAD drawing block rendering method based on CAD block entity grouping according to claim 2, characterized in that: The specific process of step S4 is: S41: Reading the metadata of the block reference entity, and transferring the transformation matrix of the block reference entity to the graphics card; S42: Determine whether the range exceeds the limit, if so, transmit the grouping coordinates of the sub-entities to the graphics card, and execute step S43; Otherwise, execute step S44; S43: Rendering the image metadata to the screen; S44: Determine whether all the metadata are completely read, if so, complete the rendering; otherwise, return to S41.

9. A computer-readable storage medium, characterized in that: The storage medium stores at least one computer instruction, which is loaded and executed by the processor to implement the steps performed in the CAD drawing block rendering method based on CAD block entity grouping as described in any one of claims 1 to 8.

10. A CAD drawing block rendering system based on CAD block entity grouping, characterized in that: The system is used to implement the CAD drawing block rendering method based on CAD block entity grouping according to any one of claims 1 to 8, comprising: A block range calculation unit, based on the block attribute information of the CAD block reference entity, determines the range of the block reference entity in the world coordinate system of the CAD drawing; An entity grouping unit, used for grouping all sub-entities of the block reference entity; the block reference entity includes a plurality of sub-entities to be rendered; The metadata generating unit traverses all sub-entities to be rendered. When traversing each sub-entity to be rendered, if the range exceeds the limit, the metadata is generated according to the sub-entity grouping result; if the range does not exceed the limit, the metadata is generated according to the coordinates of the current sub-entity, and finally all the metadata of the block reference entity are obtained; The rendering unit renders the image metadata to the screen.

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