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Using OpenGL C functions within Matlab using MEX

3 Ansichten (letzte 30 Tage)
Alla am 7 Jun. 2017
Bearbeitet: Alla am 23 Jul. 2018
Hello everyone I have been working on a 3D model using Matlab functions and after finishing it I was instructed to "refine" it and make it more realistic in addition to extracting and displaying depth information using OpenGL (C) functions, I have been looking into this for the last few days and it seems possible but I just can't seem to successfully get the simplest Mex files to work because of header problems and missing files and even when I compile the Mex file Matlab crashes when I call it, I want to start by simply compiling a MEX application which creates an OpenGL window, then I assume I'll have to redo the model using OpenGL functions and attempt to display the depth buffer.
I would appreciate any help I can get. Thanks.
EDIT01: Here is an example of a code that I compiled without any problems but crashes MATLAB when I attempt to run it.
#include "mex.h"
#define GL_VIEWPORT 0x0BA2
#define GL_DEPTH_COMPONENT 0x1902
#define GL_FLOAT 0x1406
void mexFunction(int nlhs, mxArray *plhs[], int nrhs, const mxArray *prhs[])
int viewport[4], i, x, y;
int colLen;
float *data;
double *matrix;
glGetIntegerv(GL_VIEWPORT, viewport);
data = (float*)malloc(viewport[2] * viewport[3] * sizeof(float));
glReadPixels(0, 0, viewport[2], viewport[3], GL_DEPTH_COMPONENT, GL_FLOAT, data);
plhs[0] = mxCreateNumericMatrix(viewport[3], viewport[2], mxDOUBLE_CLASS, mxREAL);
matrix = mxGetPr(plhs[0]);
colLen = mxGetM(plhs[0]);
for(x = 0; x < viewport[2]; ++ x) {
for(y = 0; y < viewport[3]; ++ y)
matrix[x * colLen + y] = data[x + (viewport[3] - 1 - y) * viewport[2]];
  9 Kommentare
li yang
li yang am 23 Jul. 2018
Hi Alaa,i am wondering if you have solved this problem
Alla am 23 Jul. 2018
Bearbeitet: Alla am 23 Jul. 2018
Helllo Li Yang, this was about a year ago, as I recall I could not use the MEX files because of the problems I described in the original question, I used this < OpenGL NI wrapper > OpenGL wrapper for a while and got decent results but it is quite restricted. I eventually moved on from using Matlab as a whole.

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Mark am 12 Okt. 2017
I found you need to run opengl in software mode and not hardware mode. Running the matlab command:
opengl software
before plotting does this. So now mexGetDepth runs without crashing Matlab, but it just plain doesn't work. The viewport never gets set to anything. It's always what I initialize it to before calling glGetIntegerv. If I call glGetError after glGetIntegerv I get 1282 which translates to "invalid command."


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