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StL Data File Viewer

, 5 Mar 2003 CPOL
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A simple StereoLithography data file viewer.

Sample Image - StLViewer.jpg


StereoLithography(StL) is something that is widely used in CAD/CAM, RapidPrototyping etc. The concept is that any surface or solid is exported to StL format by data exchange packages after they are modeled in commercial CAD packages. This data consists of triangulated facets that approximate the surface of the solid. No topological or geometric information is exported. The surface is subdivided into small triangles. The approximation uses chordal deflection for curved surfaces to smoothen the surface. More the smoothening required, more number of smaller triangles are generated by subdivision resulting in larger size of data file. Now, along with triangles, their facet normals are also generated. The data is written both in ASCII and binary formats. The data in ASCII is written like this:

facet normal  0.000000e+000 -1.000000e+000  0.000000e+000
   outer loop
     vertex -1.499999e+002 -1.000000e+002  0.000000e+000
     vertex -1.500000e+002 -1.000000e+002  0.000000e+000
     vertex -1.500000e+002 -1.000000e+002 -5.000000e+001

The facet normal tells the three components of the facet normal followed by three vertices of one triangle, enclosed by the statements.

facet normal  0.000000e+000 -1.000000e+000  0.000000e+000



Thus all the triangles are written one after the other. This data can be then used as input for generating Rapid Prototype models as well as for NC toolpath generation. The Normal data helps to compute tool offsets etc.

Here, for displaying the data in the OpenGL viewer, I have written the code for reading the data and displaying each triangle using glBegin(GL_TRIANGLES) and the normals for lighting. The viewer and geometry coding is same as my earlier project CadSurf. You can read as many StL (ASCII only) files into the viewer zoom, pan, rotate the views, select the objects, change attributes like color and material. The viewer provides object oriented context menus. I.e., when you click the right mouse button in the view with no active selection, you get a context menu for setting the viewer attributes, whereas with StL object selected, you get menu for the object attributes. Some sample StL data is also provided in the Data folder of the project.

Please let me know your comments. Thank you.


This article, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)


About the Author

Engineer Tata Technologies Ltd
India India
Sharjith is a Mechanical Engineer with strong passion for Automobiles, Aircrafts and Software development.

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Comments and Discussions

AnswerRe: Unable to view the viewer after running the application Pin
Sharjith24-May-12 0:37
memberSharjith24-May-12 0:37 
GeneralRe: Unable to view the viewer after running the application Pin
Member 105096748-Jan-14 6:22
memberMember 105096748-Jan-14 6:22 
GeneralMy vote of 5 Pin
Volynsky Alex23-May-12 3:42
memberVolynsky Alex23-May-12 3:42 
QuestionSlicing Pin
ederson.nivel124-Apr-12 9:34
memberederson.nivel124-Apr-12 9:34 
QuestionSelection window on window 7 machine got distorted. Pin
singh96323-Apr-12 5:00
membersingh96323-Apr-12 5:00 
Questionflash screen appear while resizing window Pin
singh96323-Apr-12 4:54
membersingh96323-Apr-12 4:54 
QuestionRun-Time Check Failure #2 - Stack around the variable 'str' was corrupted. Pin
waterharbin1-Mar-12 2:33
memberwaterharbin1-Mar-12 2:33 
AnswerRe: Run-Time Check Failure #2 - Stack around the variable 'str' was corrupted. Pin
Sharjith1-Mar-12 11:59
memberSharjith1-Mar-12 11:59 
GeneralSTL Viewer Pin
cjellwood13-Feb-11 4:02
membercjellwood13-Feb-11 4:02 
GeneralRe: STL Viewer Pin
Sharjith13-Feb-11 5:54
memberSharjith13-Feb-11 5:54 
GeneralError [modified] Pin
sangar202023-Sep-10 18:21
membersangar202023-Sep-10 18:21 
GeneralRe: Error Pin
Sharjith24-Sep-10 7:28
memberSharjith24-Sep-10 7:28 
GeneralTell the path Pin
sangar202023-Sep-10 0:54
membersangar202023-Sep-10 0:54 
GeneralRe: Tell the path Pin
Sharjith23-Sep-10 4:42
memberSharjith23-Sep-10 4:42 
GeneralFatel error Pin
sangar202022-Sep-10 23:48
membersangar202022-Sep-10 23:48 
Questionfollowing message display in .net 2008? Pin
sangar202022-Sep-10 18:12
membersangar202022-Sep-10 18:12 
AnswerRe: following message display in .net 2008? Pin
Sharjith22-Sep-10 18:38
memberSharjith22-Sep-10 18:38 
GeneralDuplicated points removal Pin
M.Siyamalan3-May-10 18:56
memberM.Siyamalan3-May-10 18:56 
GeneralRe: Duplicated points removal Pin
Sharjith3-May-10 19:40
memberSharjith3-May-10 19:40 
QuestionHow to calculate angle between triangles Pin
nsivabalan202031-Mar-10 20:50
membernsivabalan202031-Mar-10 20:50 
AnswerRe: How to calculate angle between triangles Pin
Sharjith1-Apr-10 7:17
memberSharjith1-Apr-10 7:17 
GeneralUnable to open other stl file Pin
Member 460375414-Feb-10 20:12
memberMember 460375414-Feb-10 20:12 
GeneralStereolithography file (STL) edit Pin
nsivabalan202030-Nov-09 19:25
membernsivabalan202030-Nov-09 19:25 
GeneralWat knowledge should i must have to handle this task Pin
DevelopmentNoob21-Apr-09 17:58
memberDevelopmentNoob21-Apr-09 17:58 
GeneralIs there component out there that can recognize the demension of stl and iges files Pin
Member 14020139-Apr-09 5:56
memberMember 14020139-Apr-09 5:56 
AnswerRe: Is there component out there that can recognize the demension of stl and iges files Pin
Sharjith9-Apr-09 7:21
memberSharjith9-Apr-09 7:21 
Questionhow to convert CL data file to G codes/machine language Pin
dixitava8-Feb-09 23:37
memberdixitava8-Feb-09 23:37 
AnswerRe: how to convert CL data file to G codes/machine language Pin
Sharjith9-Feb-09 2:29
memberSharjith9-Feb-09 2:29 
GeneralRe: how to convert CL data file to G codes/machine language Pin
dixitava9-Feb-09 19:06
memberdixitava9-Feb-09 19:06 
thanku sir for immiediet response,

i will do it earliest and will send you the file.

thanku so much.

GeneralRe: how to convert CL data file to G codes/machine language Pin
dixitava11-Feb-09 18:07
memberdixitava11-Feb-09 18:07 
GeneralRe: for which controller Pin
dixitava11-Feb-09 18:09
memberdixitava11-Feb-09 18:09 
QuestionHow can I contact you? Pin
jemmyell12-Dec-08 7:13
memberjemmyell12-Dec-08 7:13 
AnswerRe: How can I contact you? Pin
Sharjith15-Dec-08 4:47
memberSharjith15-Dec-08 4:47 
General[Message Deleted] Pin
avajja17-Oct-08 19:02
memberavajja17-Oct-08 19:02 
GeneralRe: How to View STL file in BINARY format Pin
Sharjith23-Oct-08 6:34
memberSharjith23-Oct-08 6:34 
Questionthanks in advance Pin
garyzhg18-Jul-08 23:44
membergaryzhg18-Jul-08 23:44 
QuestionGenport I/O initialitazion failure Pin
Vinod_code25-Sep-07 0:03
memberVinod_code25-Sep-07 0:03 
Generaldimension of stl Pin
saisp22-Jul-07 21:42
membersaisp22-Jul-07 21:42 
QuestionRe: dimension of stl Pin
Sharjith23-Jul-07 6:51
memberSharjith23-Jul-07 6:51 
AnswerRe: dimension of stl [modified]-pls i need ur help Pin
saisp24-Jul-07 17:28
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QuestionProblem Building Pin
dspantha29-Jan-07 15:54
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vickys24-Jan-07 12:42
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vickys24-Jan-07 12:42
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tulip.sun7-Feb-07 22:45
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Questiontrouble building Pin
mea3616-Jan-07 7:31
membermea3616-Jan-07 7:31 
QuestionI am very interested in the topological relation of triangles [modified] Pin
hyzhujc4-Dec-06 20:38
memberhyzhujc4-Dec-06 20:38 
AnswerRe: I am very interested in the topological relation of triangles Pin
Sharjith18-Dec-06 4:15
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GeneralNC & RP code Pin
harshalmsrsas19-Nov-06 23:14
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AnswerRe: NC & RP code Pin
Sharjith18-Dec-06 4:07
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GeneralI want to use OpenGL with STL From Robotic 6 axis Pin
aluntum15-Feb-06 9:25
memberaluntum15-Feb-06 9:25 

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