[Mesa3d-users] Capture Window pixel values using glReadPixels

[Srimal J. <sr...@gm...>]

Hi

I'm new to mesa(and OpenGL) .

I need to get the pixel values of whats rendered on screen (window) to a
text file for an Image Recognition Application.

First I tried to just print the values on screen using this code:

        GLvoid* data;
        data = (GLvoid *) malloc (1024*768);
        glReadPixels (0,0,1024,768,GL_RED, GL_UNSIGNED_BYTE, data);
        for(int i=0; i<1024*768; i++)
        cout << data[i];
        free(data);

But it gives this error:

$ make
g++ -Wall -o render main.cpp -lglut
main.cpp: In function ‘void drawScene()’:
main.cpp:154: error: pointer of type ‘void *’ used in arithmetic
main.cpp:154: error: ‘GLvoid*’ is not a pointer-to-object type
make: *** [render] Error 1


Am I missing something here?

Is there a better way to do this?

Thanks in advance

Srimal.
~
Srimal Jayawardena
BSc (Engineering), BIT, MIET
PhD Student, Australian National University.

Phone(Offilce): 0011 612 6125 1771
Phone(Home): 0011 612 6125 5413

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http://srimal.sri-lankan.net/
http://srimal-techdiary.blogspot.com/