# How to run cgx in batch mode and create screenshots **URL:** \ **Category:** CalculiX GraphiX\ **Created:** [September 11, 2023, 10:18am UTC](https://calculix.discourse.group/t/how-to-run-cgx-in-batch-mode-and-create-screenshots/1807 "2023-09-11T10:18:30Z")\ **Posts on this page:** 9\ **Page:** 1
**Author:** ![Megidd](https://yyz2.discourse-cdn.com/free1/user_avatar/calculix.discourse.group/megidd/32/1875_2.png) [@Megidd](https://calculix.discourse.group/u/Megidd)\ **Post date:** [September 11, 2023, 10:18am UTC](https://calculix.discourse.group/t/how-to-run-cgx-in-batch-mode-and-create-screenshots/1807/1 "2023-09-11T10:18:30Z")
# Background I have studied the [documentation](http://www.dhondt.de/cgx_2.21.pdf) section B.14 about how to run cgx in batch mode. But I cannot figure out a problem. I have this FBD file: ```auto # Change file name to the job name you used. read C:\Users\m3\AppData\Local\Temp\result-layer0-to-layer3.frd capt "Layer 0 to 3" # Data set number depends on how may things you saved! ds 2 e 7 gonly off rot y frame hcpy png right gonly on rot r 90 frame hcpy png front rot r 90 frame hcpy png left rot r 90 frame hcpy png back rot y rot u 90 frame hcpy png top rot d 180 frame hcpy png bottom quit ``` # Good case When I run this FBD file like this, everything is fine: ```bash cgx_STATIC.exe -b C:\Users\m3\AppData\Local\Temp\shot-710971079.fbd ``` The PNG files are stored next to CGX executable as expected: ![2023-09-11 13_39_13-net48](https://global.discourse-cdn.com/free1/uploads/calculix/original/2X/2/26698f41ff5843fd264ad26c365dd604006ea27a.png) And the CGX logs are: ```auto on a Windows 10 machine, nodename ADMINISTRATOR, release 10, version 10.0 19041, machine 8664 The win HOME was detected:C:\Users\m3 parameters:3 arguments:2 GL_MAX_EVAL_ORDER:32, mesh threads:1 C:\Users\m3\AppData\Local\Temp\shot-710971079.fbd opened reading file # Change file name to the job name you used. file:C:\Users\m3\AppData\Local\Temp\result-layer0-to-layer3.frd opened reading frd format MODEL NAME: record: 1UModel: 3D model Date: 2023-Sep-11 UTC record: 1UUSER record: 1UDATE 11.september.2023 record: 1UTIME 13:12:17 record: 1UHOST record: 1UPGM CalculiX record: 1UVERSION Version 2.20 record: 1UCOMPILETIME Sat Apr 1 21:09:13 2023 record: 1UDIR record: 1UDBN record: 1UMAT 1RESIN record: 2C 2362 1 reading Nodes 2362 nodes reallocated record: 3C 5651 1 reading Elements 5651 elements reallocated record: 1PSTEP 1 1 1 record: 100CL 101 1.000000000 2362 0 1 1 reading Dataset No:1 gen lc[0] ncomps:4 ncomps:3 nvals:3 record: 1PSTEP 2 1 1 record: 100CL 101 1.000000000 2362 0 1 1 reading Dataset No:2 gen lc[1] ncomps:6 ncomps:6 nvals:6 record: 1PSTEP 3 1 1 record: 100CL 101 1.000000000 2362 0 1 1 reading Dataset No:3 gen lc[2] ncomps:1 ncomps:1 nvals:1 record: 9999 gtol calculated:8.495190e-05 ready # Data set number depends on how may things you saved! 2 L 101 1.000000 STRESS Mises Extremal values from displayed mesh-entities: max:1.165530e-03 at node:1790 min:0.000000e+00 at node:1 2 L 101 1.000000 STRESS Mises Extremal values from displayed mesh-entities: max:1.165530e-03 at node:1790 min:0.000000e+00 at node:1 2 L 101 1.000000 STRESS Mises Extremal values from displayed mesh-entities: max:1.165530e-03 at node:1790 min:0.000000e+00 at node:1 2 L 101 1.000000 STRESS Mises Extremal values from displayed mesh-entities: max:1.165530e-03 at node:1790 min:0.000000e+00 at node:1 create right.png ready 2 L 101 1.000000 STRESS Mises Extremal values from displayed mesh-entities: max:1.165530e-03 at node:1790 min:0.000000e+00 at node:1 2 L 101 1.000000 STRESS Mises Extremal values from displayed mesh-entities: max:1.165530e-03 at node:1790 min:0.000000e+00 at node:1 2 L 101 1.000000 STRESS Mises Extremal values from displayed mesh-entities: max:1.165530e-03 at node:1790 min:0.000000e+00 at node:1 create front.png ready 2 L 101 1.000000 STRESS Mises Extremal values from displayed mesh-entities: max:1.165530e-03 at node:1790 min:0.000000e+00 at node:1 2 L 101 1.000000 STRESS Mises Extremal values from displayed mesh-entities: max:1.165530e-03 at node:1790 min:0.000000e+00 at node:1 create left.png ready 2 L 101 1.000000 STRESS Mises Extremal values from displayed mesh-entities: max:1.165530e-03 at node:1790 min:0.000000e+00 at node:1 2 L 101 1.000000 STRESS Mises Extremal values from displayed mesh-entities: max:1.165530e-03 at node:1790 min:0.000000e+00 at node:1 create back.png ready 2 L 101 1.000000 STRESS Mises Extremal values from displayed mesh-entities: max:1.165530e-03 at node:1790 min:0.000000e+00 at node:1 2 L 101 1.000000 STRESS Mises Extremal values from displayed mesh-entities: max:1.165530e-03 at node:1790 min:0.000000e+00 at node:1 2 L 101 1.000000 STRESS Mises Extremal values from displayed mesh-entities: max:1.165530e-03 at node:1790 min:0.000000e+00 at node:1 create top.png ready 2 L 101 1.000000 STRESS Mises Extremal values from displayed mesh-entities: max:1.165530e-03 at node:1790 min:0.000000e+00 at node:1 2 L 101 1.000000 STRESS Mises Extremal values from displayed mesh-entities: max:1.165530e-03 at node:1790 min:0.000000e+00 at node:1 create bottom.png ready ``` # Bad case But when running the CGX with the `-bg` parameter to run it in batch mode: ```auto cgx_STATIC.exe -bg C:\Users\m3\AppData\Local\Temp\shot-710971079.fbd ``` No PNG image is created. The CGX logs are: ```auto on a Windows 10 machine, nodename ADMINISTRATOR, release 10, version 10.0 19041, machine 8664 The win HOME was detected:C:\Users\m3 parameters:3 arguments:2 C:\Users\m3\AppData\Local\Temp\shot-710971079.fbd opened reading file # Change file name to the job name you used. file:C:\Users\m3\AppData\Local\Temp\result-layer0-to-layer3.frd opened reading frd format MODEL NAME: record: 1UModel: 3D model Date: 2023-Sep-11 UTC record: 1UUSER record: 1UDATE 11.september.2023 record: 1UTIME 13:12:17 record: 1UHOST record: 1UPGM CalculiX record: 1UVERSION Version 2.20 record: 1UCOMPILETIME Sat Apr 1 21:09:13 2023 record: 1UDIR record: 1UDBN record: 1UMAT 1RESIN record: 2C 2362 1 reading Nodes 2362 nodes reallocated record: 3C 5651 1 reading Elements 5651 elements reallocated record: 1PSTEP 1 1 1 record: 100CL 101 1.000000000 2362 0 1 1 reading Dataset No:1 gen lc[0] ncomps:4 ncomps:3 nvals:3 record: 1PSTEP 2 1 1 record: 100CL 101 1.000000000 2362 0 1 1 reading Dataset No:2 gen lc[1] ncomps:6 ncomps:6 nvals:6 record: 1PSTEP 3 1 1 record: 100CL 101 1.000000000 2362 0 1 1 reading Dataset No:3 gen lc[2] ncomps:1 ncomps:1 nvals:1 record: 9999 gtol calculated:8.495190e-05 ready # Data set number depends on how may things you saved! 2 L 101 1.000000 STRESS Mises Extremal values from displayed mesh-entities: max:1.165530e-03 at node:1790 min:0.000000e+00 at node:1 ``` # Question I studied the documentation but I could not figure out why with `-bg` parameter, CGX won’t create the PNG files. I have to run CGX in batch mode since I’m going to run it by another program to create the PNG files. I don’t want the user of the other program to observe the pop-up of the CGX graphic window. ---
**Author:** ![Megidd](https://yyz2.discourse-cdn.com/free1/user_avatar/calculix.discourse.group/megidd/32/1875_2.png) [@Megidd](https://calculix.discourse.group/u/Megidd)\ **Post date:** [September 11, 2023, 11:15am UTC](https://calculix.discourse.group/t/how-to-run-cgx-in-batch-mode-and-create-screenshots/1807/2 "2023-09-11T11:15:28Z")
Adding the command `stack on` to the FBD file didn’t help. ---
**Author:** ![rsmith](https://yyz2.discourse-cdn.com/free1/user_avatar/calculix.discourse.group/rsmith/32/1684_2.png) [@rsmith](https://calculix.discourse.group/u/rsmith)\ **Post date:** [September 11, 2023, 7:10pm UTC](https://calculix.discourse.group/t/how-to-run-cgx-in-batch-mode-and-create-screenshots/1807/3 "2023-09-11T19:10:23Z")
> [@Megidd](#): > > I studied the documentation but I could not figure out why with `-bg` parameter, CGX won’t create the PNG files. I’m not sure if it is in the documentation, but it is tied to the way `cgx` works. Basically (and I’m skimping over a lot here) the 3D API that CalculiX GraphicX uses (OpenGL) renders the 3D scene to a “frame buffer”, a piece of memory to store a 2D pixel image. The `hcpy` function basically copies the image from the frame buffer and saves it to a file. If you use `-bg` there is no screen to render to, so no image. Now, OpenGL does support off-screen rendering but it’s not automatic, the programmer has to explicitly program that to make it work. And if you’re rendering off-screen, how big should the image be? ---
**Author:** ![Megidd](https://yyz2.discourse-cdn.com/free1/user_avatar/calculix.discourse.group/megidd/32/1875_2.png) [@Megidd](https://calculix.discourse.group/u/Megidd)\ **Post date:** [September 12, 2023, 9:57am UTC](https://calculix.discourse.group/t/how-to-run-cgx-in-batch-mode-and-create-screenshots/1807/4 "2023-09-12T09:57:20Z")
Right ✅ I’m reading the CGX version 2.21 source code. I see that `HCPY` calls `createHardcopy()` function that calls `getTGAScreenShot()` function that calls `glutSetWindow()` function and `SaveTGAScreenShot()` function that is calling `glReadPixels()` function like this: ```c /* This will save a screen shot to a file. */ void SaveTGAScreenShot(char *filename, int w, int h) { char *imageData; imageData = (char *)malloc(sizeof(char) * w * h * 4); glReadPixels(0, 0, w, h,GL_RGBA,GL_UNSIGNED_BYTE, (GLvoid *)imageData); WriteTGA(filename,w,h,imageData); // release the memory free(imageData); } ``` I’m going to research further 📚 ---
**Author:** ![Megidd](https://yyz2.discourse-cdn.com/free1/user_avatar/calculix.discourse.group/megidd/32/1875_2.png) [@Megidd](https://calculix.discourse.group/u/Megidd)\ **Post date:** [September 12, 2023, 10:11am UTC](https://calculix.discourse.group/t/how-to-run-cgx-in-batch-mode-and-create-screenshots/1807/5 "2023-09-12T10:11:51Z")
By the way, CGX source code sometimes considers the Windows OS by: ```c #ifdef WIN32 sprintf (buffer, "move /y \"%s\" \"%s.fbb\"", datin, setname ); #else sprintf (buffer, "mv %s %s.fbb", datin, setname ); #endif ``` But there are many places that Windows OS is not considered at all, like this case: ```c void getTGAScreenShot(int nr) { //... sprintf( buffer, "rm -f *__.tga %s",DEV_NULL); // ... } ``` Now I understand why I had to copy `rm.exe` and `mv.exe` from `C:\cygwin64\bin` next to my CGX executable 🙂 ---
**Author:** ![Megidd](https://yyz2.discourse-cdn.com/free1/user_avatar/calculix.discourse.group/megidd/32/1875_2.png) [@Megidd](https://calculix.discourse.group/u/Megidd)\ **Post date:** [September 12, 2023, 11:01am UTC](https://calculix.discourse.group/t/how-to-run-cgx-in-batch-mode-and-create-screenshots/1807/6 "2023-09-12T11:01:02Z")
The CGX version 2.21 source code indicates that `inpformat` variable is set to `0` in the case of `-bg` mode: ```c else if( compare( argv[j], "-bg", 3 ) == 3 ) { // ... inpformat=0; // ... } ``` And then, screenshot creation is skipped altogether if `inpformat` is set to `0` like this: ```c void createHardcopy( int selection, char *filePtr ) { if(!inpformat) return; // ... } ``` Also here: ```c void getTGAScreenShot(int nr) { if(!inpformat) return; // ... } ``` ---
**Author:** ![rsmith](https://yyz2.discourse-cdn.com/free1/user_avatar/calculix.discourse.group/rsmith/32/1684_2.png) [@rsmith](https://calculix.discourse.group/u/rsmith)\ **Post date:** [September 12, 2023, 5:43pm UTC](https://calculix.discourse.group/t/how-to-run-cgx-in-batch-mode-and-create-screenshots/1807/7 "2023-09-12T17:43:08Z")
> [@Megidd](#): > > But there are many places that Windows OS is not considered at all Maybe send a patch to Klaus Wittig? > [@Megidd](#): > > screenshot creation is skipped altogether if `inpformat` is set to `0` With OpenGL it is possible to set up an off-screen render context. So it _could_ probably be done. Although I don’t know if that functionality is available on all platforms that `cgx` runs on. The question then is also how big to make that image? That should probably be made configurable as well. ---
**Author:** ![Megidd](https://yyz2.discourse-cdn.com/free1/user_avatar/calculix.discourse.group/megidd/32/1875_2.png) [@Megidd](https://calculix.discourse.group/u/Megidd)\ **Post date:** [September 12, 2023, 8:52pm UTC](https://calculix.discourse.group/t/how-to-run-cgx-in-batch-mode-and-create-screenshots/1807/8 "2023-09-12T20:52:21Z")
> [@rsmith](#): > > Maybe send a patch to Klaus Wittig? Good idea 👍 > [@rsmith](#): > > With OpenGL it is possible to set up an off-screen render context. So it _could_ probably be done. Thanks. I’m going to research that 📚 > [@rsmith](#): > > Although I don’t know if that functionality is available on all platforms that `cgx` runs on. Maybe just Windows OS is enough for me at this point. > [@rsmith](#): > > The question then is also how big to make that image? That should probably be made configurable as well. Right ✅ The window size should be configured. ---
**Author:** ![rgre](https://avatars.discourse-cdn.com/v4/letter/r/dec6dc/32.png) [@rgre](https://calculix.discourse.group/u/rgre)\ **Post date:** [September 22, 2023, 11:02am UTC](https://calculix.discourse.group/t/how-to-run-cgx-in-batch-mode-and-create-screenshots/1807/9 "2023-09-22T11:02:44Z")
If it is an option, maybe you can run cgx on a Linux machine and use the virtual frame buffer Xvfb. This allows to run graphical applications without a screen attached. It has come in handy for me in the past, although I have not tested with cgx. It should be than as easy as running ‘xvfb-run cgx -b [frd]’ If you run into issues with OpenGL, you may find some pointers on Stackoverflow: [opengl es - GLX offscreen rendering in headless system - Stack Overflow](https://stackoverflow.com/questions/75680223/glx-offscreen-rendering-in-headless-system) I’m not aware of similar options for Windows though… Edit: just tried, using Xvfb works for me on Linux.