CN103761376A - Two-dimensional DXF (drawing exchange file) format based three-dimensional realistic display method of parts - Google Patents

Abstract

The invention belongs to the technical field of image processing, and particularly relates to a two-dimensional DXF (drawing exchange file) format based three-dimensional realistic display method of parts. The three-dimensional realistic display method specifically includes the steps of 1), reading data of a bus and an axis in the DXF format; 2), structuring a rotating surface by utilizing the data read in the step 1); 2.1), calculating center coordinates of an arc by means of a circular arc cutting algorithm; 2.2), calculating the coordinates of the rotating surface by means of a rotation to formation algorithm; 2.2.1), subjecting a known curve to cross cutting; 2.2.2), subjecting points obtained from the cross cutting to lengthwise cutting; 3), performing lighting effect processing by means of a normal vector algorithm; 4), displaying a three-dimensional entity by means of OpenGL performance functions. Therefore, three-dimensional realistic display of the parts can be realized.

Description

Part three dimension realistic display packing based on two-dimentional DXF file layout

Technical field

The invention belongs to technical field of image processing, be specifically related to a kind of part three dimension realistic display packing based on two-dimentional DXF file layout.

Background technology

In the Design and manufacture of Practical Project part, the solid of revolution type part processing through turning and boring occupies very large proportion.In area of computer aided turning system of processing, main work is all carried out around this class part.This class figure is usually the X-Y scheme of being drawn by AutoCAD, and we are not easy to observe its 3-D solid structure.The file layout of AutoCAD acquiescence is DWG form, and this form AutoCAD corporate external is covert, and we cannot process it.

Computer graphics is rapid, the widely used new branch of science of development in recent years.It mainly studies principle, algorithm and the system of figure input, expression, conversion, Realistic Rendering technology, computing and tablet pattern.The newest research results of computer graphics is also widely applied in mechanical CAD/CAM field.Engineering technical personnel complete after the design of mechanical component, often wish to see the three-dimensional effect diagram of part at once, the understanding directly perceived, perceptual to its structure generation, and whether the structure, the design that are beneficial to evaluate product be reasonable.This just need to utilize the knowledge of computer graphics to carry out real graph visualization.But in the current widely used CAD/CAM system software of institute, real graph visualization function is only applied as one of functional module by some large softwares, and practical sense of reality software for display that can independent operating is also comparatively rare.

The generation of real graph visualization technology can be traced back to the mid-1960s, along with the development of computer technology and graphics and the appearance of raster display, add the increasing substantially of various computer hardware performances that comprises display-memory, make to need the generation of the photo realism graphic of magnanimity high-speed memory to become possibility.At present, real graph visualization technology has been widely used in the fields such as CAD/CAM, virtual manufacture, simulated training, Numerical Control Simulation.

In the Design and manufacture of Practical Project part, the solid of revolution type part processing through turning and boring occupies very large proportion.In area of computer aided turning system of processing, main work is all carried out around this class part.This class figure is usually the X-Y scheme of being drawn by AutoCAD, and we are not easy to observe its 3-D solid structure.The file layout of AutoCAD acquiescence is DWG form, and this form AutoCAD corporate external is covert, and we cannot process it.

Summary of the invention

The deficiency existing for prior art, the invention provides a kind of part three dimension realistic display packing based on two-dimentional DXF file layout.

The present invention takes to carry out as follows: the part three dimension realistic display packing based on two-dimentional DXF file layout is concrete

Step is as follows:

Step 1: the data of reading DXF file layout median generatrix and axis; In fact revolving parts graphical configuration is exactly

Know axis and bus, construct corresponding surface of revolution.

Step 2: utilize the data configuration surface of revolution reading in step 1;

Step 2.1: utilize circular arc cutting algorithm to calculate the central coordinate of circle of circular arc:

Step 2.2: utilize rotary forming algorithm to calculate the coordinate of surface of revolution:

Step 2.2.1: known curve is carried out to transverse cuts:

Step 2.2.2: the point to transverse cuts gained longitudinally cuts:

Step 3: that utilizes normal vector algorithm carries out lighting effect processing;

Step 4: utilize OpenGL power function to show 3D solid.

In described step 1, the polyline providing with AutoCAD is described bus, by being set, line style identifies axis simultaneously, in entity joint, in LINE and LWPOLYLINE, there is respectively the information of axis and bus, in reading out data process, can according to the value of group code 0 and group code 6, search for the axis of line centered by line style, then according to file layout, read successively the starting point coordinate of axis; For polyline, first the polyline as bus according to the search of subclass mark value, then reads all apex coordinate values of polyline successively according to file layout.Through above, analyze and process, can be by the required data read-in programme of rotary forming, so that carry out next step data manipulation.

The detailed process of the central coordinate of circle (xo, yo) that calculates circular arc of described step 2.1 is as follows:

Order $l=\sqrt{\frac{{(c-a)}^2+{(d-b)}^2}{2}}$

Definition from camber

so h=l*bow

By figure intermediate cam relation, can be obtained: r ²-l ²=(r-h) ²

It is arc radius $r=\frac{h^2+l^2}{2\×h}$

Order $\mathrm{\ω}=\arctan \left(\frac{d-b}{c-a}\right)$

Camber line central coordinate of circle is:

$\left\{\begin{array}{c}\mathrm{xo}=\frac{a+c}{2}-(r-h)\×\sin \mathrm{\ω}\\ \mathrm{yo}=\frac{b+d}{2}+(r-h)\×\cos \mathrm{\ω}\end{array}\right.$

In formula: establish (a, b) for starting point coordinate, (c, d) is terminal point coordinate, l is the length of the string of (a, b) and (c, d) formation, and bow is camber, and h is action, and ω is the central angle that l is corresponding.The concrete cutting process of described step 2.2.1 is as follows: on bus, extract equably piecemeal several points, and their coordinate is deposited in to three two-dimensional array x[1, j], y[1, j], z[1, j].Counting of getting controlled by transverse cuts density in program, and transverse cuts density is higher, the solid figure bus that generates more close to former bus.

The concrete cutting process of described step 2.2.2 is as follows: after transverse cuts completes, the point of gained is carried out to three-dimensional rotation, and the rotational trajectory of each point is carried out to the calculating of interpolation point coordinate, the number of interpolation point is controlled by longitudinal cut capacity.Longitudinally cut capacity is higher, the solid figure xsect that generates more smooth, but equally also can cause data volume to increase.By transverse cuts operation, can obtain the coordinate points array x[1 on curve, j], y[1, j], z[1, j], if be longitudinally cut into and do the rotation of 360 ° around x axle, in order to obtain the coordinate of every bit formed n the point on rotational trajectory on curve, can establish rotation step-length is t=2 π/n, and rotational transform matrix is:

$T=\left[\begin{array}{ccc}1& 0& 0\\ 0& \cos t& -\sin \mathrm{<figure-callout\; id="0"\; label="t"\; filenames="HDA0000455268870000031.png"\; state="\{\{state\}\}">t</figure-callout>}\\ 0& \sin t& \cos t\end{array}\right]$

If the point on curve is (x, y, z), postrotational coordinate is:

[x ^*?y ^*?z ^*]＝[x?y?z]*T

? $\left\{\begin{array}{c}{x}^{*}=x\\ y^{*}=y\cos t+z\sin t\\ z^{*}=-y\sin t+z\cos t\end{array}\right.$

The concrete steps of described step 3 are as follows: calculate normal vector, required condition is three not coordinate figures of the point of conllinear, putting in order of they determined the direction of normal vector, in right hand space coordinates, establish known point A, B, C, coordinate figure be respectively (x _a, y _a, z _a), (x _b, y _b, z _b), (x _c, y _c, z _c), the normal vector of the plane of 3 formations of calculating, its algorithm is as follows:

First obtain vector

with

the method of utilizing space analysis geometry, the spatial description of planar process vector is $\left|\begin{array}{ccc}i& j& k\\ x_{\mathrm{AC}}& y_{\mathrm{AC}}& z_{\mathrm{AC}}\\ x_{\mathrm{BC}}& y_{\mathrm{BC}}& z_{\mathrm{BC}}\end{array}\right|$

Wherein $\left\{\begin{array}{c}{x}_{\mathrm{AC}}=x_A-x_C,y_{\mathrm{AC}}=y_A-y_C,z_{\mathrm{AC}}=z_A-z_C\\ x_{\mathrm{BC}}=x_B-x_C,y_{\mathrm{BC}}=y_B-y_C,z_{\mathrm{BC}}=z_B-z_C\end{array}\right.$

The matrix form that planar process vector space is described launches, and can obtain its mathematic(al) representation and be: (y _aCz _bC-z _aCy _bC) i+ (z _aCx _bC-z _bCx _aC) j+ (x _aCy _bC-x _bCy _aC) k.

Advantage of the present invention is: 1, because multiple typical three-dimensional CAD/CAM software product (AutoCAD, Pro-Engineer, Master CAM, CATIA, UG II, 3DSMAX) is all supported DXF file layout, so the application program based on this file layout exploitation has practicality widely.

2, utilize to known curve is carried out transverse cuts and longitudinally cuts and construct surface of revolution, by cut capacity, controlled the smoothness of the solid figure xsect that generates, thereby realized two-dimension graphic data to three-dimensional conversion.

3, the present invention utilizes real graph visualization choice of technology OpenGL as graphics package, realize a practical interactive real graph visualization, several functions below read graphic file mainly having been realized with OpenGL power function at this patent: form initialization, graphic plotting function, coordinate transform function, illumination and material setting, image and texture operation function, the functions such as line frame graph, surface model, body Model processing.Thereby by the setting of object material and light source, the lighting effect of simulate real world, reaches the object that the 3D solid computing machine sense of reality shows more exactly.By increasing atomizing effect and texture mapping, some special-effects that can realize entity show.

Accompanying drawing explanation

Fig. 1 is overview flow chart of the present invention;

Fig. 2 is circular arc cutting schematic diagram;

Fig. 3 longitudinally cuts schematic diagram;

Fig. 4 is that the sense of reality of figure of the present invention shows.

Embodiment

As shown in Figure 1 to Figure 3, the present invention takes to carry out as follows: the part based on two-dimentional DXF file layout is three-dimensional true

True feeling display packing, concrete steps are as follows:

Step 1: the data of reading DXF file layout median generatrix and axis; Revolving parts graphical configuration, is exactly in fact known axis and bus, constructs corresponding surface of revolution.

Step 2: utilize the data configuration surface of revolution reading in step 1;

Step 2.1: utilize circular arc cutting algorithm to calculate the central coordinate of circle of circular arc:

Step 2.2: utilize rotary forming algorithm to calculate the coordinate of surface of revolution:

Step 2.2.1: known curve is carried out to transverse cuts:

Step 2.2.2: the point to transverse cuts gained longitudinally cuts:

Step 3: that utilizes normal vector algorithm carries out lighting effect processing;

Step 4: utilize OpenGL power function to show 3D solid.

In described step 1, the polyline providing with AutoCAD is described bus, by being set, line style identifies axis simultaneously, in entity joint, in LINE and LWPOLYLINE, there is respectively the information of axis and bus, in reading out data process, can according to the value of group code 0 and group code 6, search for the axis of line centered by line style, then according to file layout, read successively the starting point coordinate of axis; For polyline, first the polyline as bus according to the search of subclass mark value, then reads all apex coordinate values of polyline successively according to file layout.Through above, analyze and process, can be by the required data read-in programme of rotary forming, so that carry out next step data manipulation.

The detailed process of the central coordinate of circle (xo, yo) that calculates circular arc of described step 2.1 is as follows:

Order $l=\sqrt{\frac{{(c-a)}^2+{(d-b)}^2}{2}}$

Definition from camber

so h=l*bow

By figure intermediate cam relation, can be obtained: r ²-l ²=(r-h) ²

It is arc radius $r=\frac{h^2+l^2}{2\&times;h}$

Order $\mathrm{\&omega;}=\arctan \left(\frac{d-b}{c-a}\right)$

Camber line central coordinate of circle is:

$\left\{\begin{array}{c}\mathrm{xo}=\frac{a+c}{2}-(r-h)\&times;\sin \mathrm{\&omega;}\\ \mathrm{yo}=\frac{b+d}{2}+(r-h)\&times;\cos \mathrm{\&omega;}\end{array}\right.$

In formula: establish (a, b) for starting point coordinate, (c, d) is terminal point coordinate, l is the length of the string of (a, b) and (c, d) formation, and bow is camber, and h is action, and ω is the central angle that l is corresponding.The concrete cutting process of described step 2.2.1 is as follows: on bus, extract equably piecemeal several points, and their coordinate is deposited in to three two-dimensional array x[1, j], y[1, j], z[1, j].Counting of getting controlled by transverse cuts density in program, and transverse cuts density is higher, the solid figure bus that generates more close to former bus.

The concrete cutting process of described step 2.2.2 is as follows: after transverse cuts completes, the point of gained is carried out to three-dimensional rotation, and the rotational trajectory of each point is carried out to the calculating of interpolation point coordinate, the number of interpolation point is controlled by longitudinal cut capacity.Longitudinally cut capacity is higher, the solid figure xsect that generates more smooth, but equally also can cause data volume to increase.By transverse cuts operation, can obtain the coordinate points array x[1 on curve, j], y[1, j], z[1, j], if be longitudinally cut into and do the rotation of 360 ° around x axle, in order to obtain the coordinate of every bit formed n the point on rotational trajectory on curve, can establish rotation step-length is t=2 π/n, and rotational transform matrix is:

$T=\left[\begin{array}{ccc}1& 0& 0\\ 0& \cos t& -\mathrm{<figure-callout\; id="0"\; label="sin\; t"\; filenames="HDA0000455268870000031.png"\; state="\{\{state\}\}">sin</figure-callout>}t\\ 0& \sin t& \cos t\end{array}\right]$

If the point on curve is (x, y, z), postrotational coordinate is:

[x ^*?y ^*?z ^*]＝[x?y?z]*T

? $\left\{\begin{array}{c}{x}^{*}=x\\ y^{*}=y\cos t+z\sin t\\ z^{*}=-y\sin t+z\cos t\end{array}\right.$

The concrete steps of described step 3 are as follows: calculate normal vector, required condition is three not coordinate figures of the point of conllinear, putting in order of they determined the direction of normal vector, in right hand space coordinates, establish known point A, B, C, coordinate figure be respectively (x _a, y _a, z _a), (x _b, y _b, z _b), (x _c, y _c, z _c), the normal vector of the plane of 3 formations of calculating, its algorithm is as follows:

First obtain vector

with

the method of utilizing space analysis geometry, the spatial description of planar process vector is $\left|\begin{array}{ccc}i& j& k\\ x_{\mathrm{AC}}& y_{\mathrm{AC}}& z_{\mathrm{AC}}\\ x_{\mathrm{BC}}& y_{\mathrm{BC}}& z_{\mathrm{BC}}\end{array}\right|$

Wherein $\left\{\begin{array}{c}{x}_{\mathrm{AC}}=x_A-x_C,y_{\mathrm{AC}}=y_A-y_C,z_{\mathrm{AC}}=z_A-z_C\\ x_{\mathrm{BC}}=x_B-x_C,y_{\mathrm{BC}}=y_B-y_C,z_{\mathrm{BC}}=z_B-z_C\end{array}\right.$

The matrix form that planar process vector space is described launches, and can obtain its mathematic(al) representation and be: (y _aCz _bC-z _aCy _bC) i+ (z _aCx _bC-z _bCx _aC) j+ (x _aCy _bC-x _bCy _aC) k.

As shown in Figure 4, the present invention utilizes OpenGL power function mainly to realize following several functions to read graphic file: form initialization, graphic plotting function, coordinate transform function, illumination and material setting, image and texture operation function, the functions such as line frame graph, surface model, body Model processing.Thereby by the setting of object material and light source, the lighting effect of simulate real world, reaches the object that the 3D solid computing machine sense of reality shows more exactly.By increasing atomizing effect and texture mapping, some special-effects that can realize entity show.

Claims (5)

1. the part three dimension realistic display packing based on two-dimentional DXF file layout, is characterized in that: concrete steps are as follows:

Step 1: the data of reading DXF file layout median generatrix and axis;

Step 2: utilize the data configuration surface of revolution reading in step 1;

Step 2.1: utilize circular arc cutting algorithm to calculate the central coordinate of circle of circular arc:

Step 2.2: utilize rotary forming algorithm to calculate the coordinate of surface of revolution:

Step 2.2.1: known curve is carried out to transverse cuts:

Step 2.2.2: the point to transverse cuts gained longitudinally cuts:

Step 3: that utilizes normal vector algorithm carries out lighting effect processing;

Step 4: utilize OpenGL power function to show 3D solid.

2. the part three dimension realistic display packing based on two-dimentional DXF file layout according to claim 1, it is characterized in that: in described step 1, the polyline providing with AutoCAD is described bus, by being set, line style identifies axis simultaneously, in entity joint, in LINE and LWPOLYLINE, there is respectively the information of axis and bus, in reading out data process, can according to the value of group code 0 and group code 6, search for the axis of line centered by line style, then according to file layout, read successively the starting point coordinate of axis; For polyline, first the polyline as bus according to the search of subclass mark value, then reads all apex coordinate values of polyline successively according to file layout.

3. the part three dimension realistic display packing based on two-dimentional DXF file layout according to claim 1, is characterized in that: the detailed process of the central coordinate of circle (xo, yo) that calculates circular arc of described step 2.1 is as follows:

Order $l=\sqrt{\frac{{(c-a)}^2+{(d-b)}^2}{2}}$

Definition from camber

so h=l*bow

By figure intermediate cam relation, can be obtained: r ²-l ²=(r-h) ²

It is arc radius $r=\frac{h^2+l^2}{2\&times;h}$

Order $\mathrm{\&omega;}=\arctan \left(\frac{d-b}{c-a}\right)$

Camber line central coordinate of circle is:

$\left\{\begin{array}{c}\mathrm{xo}=\frac{a+c}{2}-(r-h)\&times;\sin \mathrm{\&omega;}\\ \mathrm{yo}=\frac{b+d}{2}+(r-h)\&times;\cos \mathrm{\&omega;}\end{array}\right.$

In formula: establish (a, b) for starting point coordinate, (c, d) is terminal point coordinate, l is the length of the string of (a, b) and (c, d) formation, and bow is camber, and h is action, and ω is the central angle that l is corresponding.

4. the part three dimension realistic display packing based on two-dimentional DXF file layout according to claim 1, it is characterized in that: the concrete cutting process of described step 2.2.1 is as follows: on bus, extract equably piecemeal several points, and their coordinate is deposited in to three two-dimensional array x[1, j], y[1, j], z[1, j].

5. the part three dimension realistic display packing based on two-dimentional DXF file layout according to claim 1, it is characterized in that: the concrete cutting process of described step 2.2.2 is as follows: after transverse cuts completes, point to gained carries out three-dimensional rotation, and the rotational trajectory of each point is carried out to the calculating of interpolation point coordinate: by transverse cuts operation, can obtain the coordinate points array x[1 on curve, j], y[1, j], z[1, j], if be longitudinally cut into and do the rotation of 360 ° around x axle, in order to obtain the coordinate of every bit formed n the point on rotational trajectory on curve, can establish rotation step-length is t=2 π/n, rotational transform matrix is:

$T=\left[\begin{array}{ccc}1& 0& 0\\ 0& \cos t& -\sin t\\ 0& \sin t& \cos t\end{array}\right]$

If the point on curve is (x, y, z), postrotational coordinate is:

[x ^*?y ^*?z ^*]＝[x?y?z]*T

? $\left\{\begin{array}{c}{x}^{*}=x\\ y^{*}=y\cos t+z\sin t\\ z^{*}=-y\sin t+z\cos t\end{array}\right.$

5, the part three dimension realistic display packing based on two-dimentional DXF file layout according to claim 1, it is characterized in that: the concrete steps of described step 3 are as follows: calculate normal vector, required condition is three not coordinate figures of the point of conllinear, putting in order of they determined the direction of normal vector, in right hand space coordinates, establish known point A, B, C, coordinate figure be respectively (x _a, y _a, z _a), (x _b, y _b, z _b), (x _c, y _c, z _c), the normal vector of the plane of 3 formations of calculating, its algorithm is as follows:

First obtain vector with

the method of utilizing space analysis geometry, the spatial description of planar process vector is $\left|\begin{array}{ccc}i& j& k\\ x_{\mathrm{AC}}& y_{\mathrm{AC}}& z_{\mathrm{AC}}\\ x_{\mathrm{BC}}& y_{\mathrm{BC}}& z_{\mathrm{BC}}\end{array}\right|$

Wherein $\left\{\begin{array}{c}{x}_{\mathrm{AC}}=x_A-x_C,y_{\mathrm{AC}}=y_A-y_C,z_{\mathrm{AC}}=z_A-z_C\\ x_{\mathrm{BC}}=x_B-x_C,y_{\mathrm{BC}}=y_B-y_C,z_{\mathrm{BC}}=z_B-z_C\end{array}\right.$

The matrix form that planar process vector space is described launches, and can obtain its mathematic(al) representation and be: (y _aCz _bC-z _aCy _bC) i+ (z _aCx _bC-z _bCx _aC) j+ (x _aCy _bC-x _bCy _aC) k.

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