A three-dimensional dynamic simulation modeling method for weft-knitted fabric

Abstract

This invention relates to a method for three-dimensional dynamic simulation modeling of weft-knitted fabrics. This invention utilizes computer graphics to rapidly establish a three-dimensional model of the weft-knitted product and achieve real-time dynamic simulation effects. Compared with existing methods, this method can achieve three-dimensional simulation of weft-knitted fabrics with loop structures and realize real-time dynamic effects, further demonstrating the realistic effect and state of the weft-knitted fabric. It solves the problem that current methods rely on texture mapping to achieve real-time dynamic display of weft-knitted fabrics.

Description

Technical Field

[0001] This invention relates to the field of fabric simulation, specifically a method for three-dimensional dynamic simulation modeling of weft-knitted fabrics. Background Technology

[0002] The design and development of weft-knitted products often have a long cycle, requiring the final woven product to provide a more intuitive understanding of its overall structural characteristics. Currently, most fabric modeling relies on texture mapping and lacks a realistic 3D structure of the loops. While typical weft-knitted fabrics feature loop structure modeling and simulation, this primarily focuses on simulating the loops on a single plane, with little discussion on 3D spatial surface modeling and simulation. Some models have achieved 3D spatial surface modeling and simulation, but these fail to capture the dynamic effects of weft-knitted fabrics in the real world and cannot adequately reflect their actual appearance in the display environment. Summary of the Invention

[0003] The technical problem to be solved by this invention is to address the above-mentioned shortcomings. This invention aims to use computer graphics methods to quickly establish a three-dimensional model of weft-knitted products and achieve real-time dynamic simulation effects.

[0004] To solve the above technical problems, the present invention adopts the following technical solution:

[0005] A method for three-dimensional dynamic simulation modeling of weft-knitted fabrics further includes the following steps:

[0006] Step 1: Construct a set of 3D vertex coordinates. Classify vertices according to their height. Group vertices with the same height into one group to obtain multiple groups. Each group represents a layer. All vertices in each layer are located on a circle, and the center of the circles in all layers is located on the central axis of the model.

[0007] Step 2: Take the group with the highest height as the first layer, randomly select a vertex from the first layer as the starting point, and sort all vertices in the current layer in a clockwise direction;

[0008] Step 3: Calculate the distance between all vertices in the next layer and all vertices in the previous layer. Set the index of each vertex in the next layer to match the index of the nearest vertex in the previous layer to obtain the index of all vertices in all layers.

[0009] Step 4: Take four adjacent points in two adjacent layers as a front mesh, and take the mesh directly behind the front mesh as the back mesh. The front mesh and the back mesh are symmetrical with respect to the central axis of the model. The four vertices of the front mesh and the back mesh are connected to form a mesh model of a coil.

[0010] Step 5: Based on the mesh model of each coil, determine the outline of each coil, complete the three-dimensional spatial modeling of the coil, and obtain the three-dimensional model of the weft-knitted fabric.

[0011] Step 6: Couple the three-dimensional model of the fabric with the spring mass model, and combine the yarn simulation algorithm to obtain the three-dimensional dynamic model of the weft-knitted fabric.

[0012] Furthermore, the specific method for obtaining the coil outline in step 5 is as follows:

[0013] Step 5.1: Let the four vertices of the front mesh of a coil be D1, D2, D3, D4, and the four vertices of the back mesh be D5, D6, D7, D8. Let the 12 control points of the coil outline be A, B, C, D, E, F, G, H, I, J, K. Then the formula for calculating the coordinates of the control points is as follows:

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[0025] dot i Let i be the coordinates of point i;

[0026] Step 5.2: Divide the control points into three groups, and use spline function interpolation to obtain the coordinates of the coil's shape points. Connect all control points and shape points sequentially using a smooth curve to obtain the outline of a coil. (The process is repeated in the original text.)

[0027] Furthermore, in step 6, in the spring-mass model, adjacent vertices are connected by structural springs, two vertices separated by one vertex in the horizontal and vertical directions are connected by bending springs, adjacent diagonal vertices in the oblique direction are linked by shear springs, and two diagonal vertices separated by one vertex in the oblique direction are connected by shear springs.

[0028] Compared with the prior art, the present invention, by adopting the above technical solution, has the following advantages:

[0029] Currently, most clothing simulations rely on texture mapping, which lacks realism and fails to preserve the details of the coils. Furthermore, most existing 3D simulation methods are static, lacking real-time dynamic effects and failing to adequately showcase the final appearance of the clothing. To address these issues, this invention proposes a method for 3D dynamic simulation of weft-knitted fabrics. This method establishes a coil model on a subdivided curved surface and utilizes a mesh-spring-mass coupling model to achieve 3D dynamic simulation of the weft-knitted fabric. This invention solves the problem of current weft-knitted fabric simulations being planar and lacking dynamic effects, resulting in more realistic simulations.

[0030] This invention proposes a mesh-spring mass coupling model in space, which couples the mesh model with the spring mass model in three-dimensional space to achieve a three-dimensional dynamic simulation effect for weft-knitted fabrics.

[0031] Given the characteristics of weft-knitted fabrics, it is often necessary to transmit more force in the diagonal direction to simulate the impact of real loop deformation on other structures. Therefore, to further adapt to actual conditions and obtain more realistic dynamic effects, based on the above analysis, an improvement has been made compared to the traditional quadrilateral spring-mass model. Shear springs are added between the spaced-out masses to allow the diagonal force of the masses to be transmitted to more distant masses, that is, to better transmit the deformation of the current loop in the diagonal direction.

[0032] Compared to the traditional quadrilateral spring-mass model, which uses shear springs only at adjacent nodes and cannot effectively transmit upward-sloping deformation forces to other coils, the improved model adds shear springs between alternate nodes. This allows upward-sloping forces to be transmitted more directly to other coils, ensuring both the realism of coil deformation and improving system stability.

[0033] The present invention will now be described in detail with reference to the accompanying drawings and embodiments. Attached Figure Description

[0034] Figure 1 This is a mesh model diagram of the coil;

[0035] Figure 2 This is a diagram showing the control point locations of the coil.

[0036] Figure 3 This is a diagram showing the location of the coil's type value points;

[0037] Figure 4 A mesh model diagram of a three-dimensional weft-knitted coil;

[0038] Figure 5 This is a diagram showing the location of a single coil in a three-dimensional weft-knitted coil mesh model.

[0039] Figure 6 This is a 3D model of the generated weft-knitted fabric.

[0040] Figure 7 This is a diagram of a spring-mass model.

[0041] Figure 8 This is a schematic diagram of a mesh-spring-mass coupling model.

[0042] Figure 9 This is a three-dimensional dynamic model of a weft-knitted fabric. Detailed Implementation

[0043] The principles and features of the present invention are described below with reference to the accompanying drawings. The examples given are only for explaining the present invention and are not intended to limit the scope of the present invention.

[0044] A method for three-dimensional dynamic simulation modeling of weft-knitted fabrics includes the following steps:

[0045] 1. Modeling of the coil

[0046] like Figure 1-3 As shown, a design coil model is established. This invention uses a mesh model to establish the coil model. The main approach is to determine the coordinates of the control points of the coil model using the four corner points of the mesh, and then obtain the coordinates of the coil's shape points through piecewise cubic spline interpolation. Unlike previous methods, since the control point coordinates are determined in three-dimensional space, the control points of the coil need to be represented using vectors, denoted as D1, D2, D3, D... 4， Determine the coordinates of the control points.

[0047] The three-dimensional coordinates of these 11 points AK are as follows:

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[0059] dot i D1 represents the coordinates of point i; D5, D6, D7, and D8 are the grid points relative to D1, D2, D3, and D4 in the subsequent grid-spring coupling model. Their function is to provide the direction vector for the backward deformation of the coil, thus completing the modeling of the coil in three-dimensional space.

[0060] 2. Modeling of curved surface coils

[0061] like Figure 4-6 As shown, based on the principle of coil modeling, as long as there are four points in space resembling a quadrilateral, a coil model can be constructed in space based on the mesh model. Therefore, for the simulated weft-knitted fabric, a quadrilateral surface subdivision is constructed in space to build a mesh model in space.

[0062] This invention employs a subdivision surface method to construct a three-dimensional spatial mesh model of the weft-knitted coils. The constructed spatial mesh model is as follows: Figure 4 As shown. To more easily illustrate the model's structure, the mesh model in the diagram was not finely subdivided during surface subdivision. (From...) Figure 4 As can be seen, for a three-dimensional surface in space, the spatial surface can be reconstructed by subdividing it into quadrilaterals.

[0063] The mass points of the mesh model in this invention are constructed from a pre-designed mesh model file, which consists of vertex coordinates and vertex numbers. To facilitate the calculation of coil control points, the vertices in the pre-designed mesh model file need to be analyzed and calculated after its construction. To simplify the calculation, the method described herein requires all mass points to be uniformly distributed across n layers, facilitating the subsequent establishment of the coil model and the spring-mass system.

[0064] For constructing the vertex set D = {d1, d2, d3, ... d...} i First, read the height h of all points h = {h1, h2, h3, ... h}. j}, perform height analysis and judgment, and group points with similar heights into a set H.t ={H1, H2, H3, ... H t}, construct a mesh model and a spring mass model between adjacent sets of points.

[0065] After dividing the area into circles for each layer, the points on adjacent circles need to be mapped one-to-one to construct the mesh model. The method used is to randomly select points in the first layer, H1. Rearrange all point numbers clockwise from the starting point, and calculate the distance DIS between each point and the points in the previous layer of circular point set:

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[0067] Where m is the number of points on each layer of circles.

[0068] Choose the closest point Starting from the second layer H2, rearrange all point numbers clockwise, and calculate, analyze, and reorder the circle points of all layers according to the above method.

[0069] The reordered points can then be used to easily construct mesh models and spring-mass models. For the starting point of a single grid and Forming a single grid.

[0070] like Figure 5 As shown, after determining the sequence number of each layer of points, given the coordinates of D1, D2, D3, and D4, the coordinates of D5, D6, D7, and D8 can be found through the sequence number. For example, D1 is the first ring point with sequence number m. There are 70 points in a ring with sequence numbers 0-70, so the corresponding point D6 should be m+70 / 2. If m+70 / 2 is greater than 70, then the sequence number of D6 is m+70 / 2-70.

[0071] 3. Simulation and real-time dynamic effects

[0072] This invention proposes a mesh-spring mass coupling model in space, which couples the mesh model with the spring mass model in three-dimensional space to achieve a three-dimensional dynamic simulation effect for weft-knitted fabrics.

[0073] Given the characteristics of weft-knitted fabrics, it is often necessary to transmit more force in the diagonal direction to simulate the impact of real loop deformation on other structures. Therefore, to further adapt to actual conditions and obtain more realistic dynamic effects, based on the above analysis, an improvement was made compared to the traditional quadrilateral spring-mass model. Shear springs were added between the spaced-out masses to allow the diagonal force on the masses to be transmitted to more distant masses, thus better transmitting the deformation of the current loop diagonally. The before and after improvements are shown below. Figure 7As shown, the left figure is a traditional quadrilateral spring-mass model, and the right figure is the spring-mass model of the present invention.

[0074] Compared to the traditional quadrilateral spring-mass model, which uses shear springs only at adjacent nodes and cannot effectively transmit upward-sloping deformation forces to other coils, the improved model adds shear springs between alternate nodes. This allows upward-sloping forces to be transmitted more directly to other coils, ensuring both the realism of coil deformation and improving system stability.

[0075] To achieve more realistic dynamic effects, this project combines a spatial mesh model with an improved spring-mass model to construct a coupled mesh-spring-mass model. As shown in the figure, each vertex of a subdivided quadrilateral in space is coupled to a mass point of the spring-mass model. Based on these mass points, a three-dimensional spring-mass model can be easily constructed. A schematic diagram of the resulting mesh-spring-mass coupled model is shown below. Figure 8 As shown.

[0076] In a spatial 3D mesh model, improvements are made to the local aspects of the spring-mass model, such as... Figure 8 As shown in the black box, to achieve coupling with the mesh model, the spring-mass model needs to remain in a closed state in space, just like the mesh model. In the spatial mesh model, adjacent corner points are connected by structural springs, spaced-apart corner points are connected by bending springs, springs in the diagonal direction are linked by shear springs, and spaced-apart corner points in the diagonal direction are connected by shear springs. All corner points are treated as mass points and constructed into a three-dimensional spring-mass model. In this model, the mass points are primarily affected by the elastic force of the springs and the force of gravity.

[0077] like Figure 9 As shown, after constructing the coil model using a spatial grid-spring mass model, a three-dimensional simulation of the weft-knitted coil is achieved using a yarn simulation algorithm.

[0078] The above description provides examples of the preferred embodiments of the present invention. Parts not detailed herein are common knowledge to those skilled in the art. The scope of protection of the present invention is determined by the claims. Any equivalent modifications based on the technical teachings of the present invention are also within the scope of protection of the present invention.

Claims

1. A method for three-dimensional dynamic simulation modeling of weft-knitted fabrics, characterized in that, Includes the following steps: Step 1: Construct a set of 3D vertex coordinates. Classify vertices according to their height. Group vertices with the same height into one group to obtain multiple groups. Each group represents a layer. All vertices in each layer are located on a circle, and the center of the circles in all layers is located on the central axis of the model. Step 2: Take the group with the highest height as the first layer, randomly select a vertex from the first layer as the starting point, and sort all vertices in the current layer in a clockwise direction; Step 3: Calculate the distance between all vertices in the next layer and the starting point in the previous layer. Select the point in the next layer that is closest to the starting point in the previous layer as the starting point of that layer, and rearrange all point numbers clockwise. Obtain the index of all vertices in all layers; Step 4: Take four adjacent points in two adjacent layers as a front mesh, and take the mesh directly behind the front mesh as the back mesh. The front mesh and the back mesh are symmetrical with respect to the central axis of the model. The four vertices of the front mesh and the back mesh are connected to form a mesh model of a coil. Step 5: Based on the mesh model of each coil, determine the outline of each coil, complete the three-dimensional spatial modeling of the coil, and obtain the three-dimensional model of the weft-knitted fabric; Step 6: Couple the mesh model with the spring mass model in three-dimensional space, and combine the yarn simulation algorithm to obtain a three-dimensional dynamic model of the weft-knitted fabric; The specific method for obtaining the coil outline in step 5 is as follows: Step 5.1: Let the four vertices of the front mesh of a coil be D1, D2, D3, D4, and the four vertices of the back mesh be D5, D6, D7, D8. Let the 11 control points of the coil outline be A, B, C, D, E, F, G, H, I, J, K. Then the formula for calculating the coordinates of the control points is as follows: ； ； ； ； ； ； ； ； ； ； ； dot i Let i be the coordinates of point i; Step 5.2: Divide the control points into three groups, and use spline function interpolation to obtain the coordinates of the coil's shape points. Use a smooth curve to connect all the control points and shape points in sequence to obtain the outline of a coil. In step 6, each vertex of the subdivided quadrilateral in the mesh model is coupled to the mass point of the spring mass model. Adjacent vertices in the mesh model are connected by structural springs. Two vertices separated by one vertex in the horizontal and vertical directions are connected by bending springs. Adjacent diagonal vertices in the diagonal direction are connected by shear springs. Two diagonal vertices separated by one vertex in the diagonal direction are connected by shear springs.

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