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Thread: glReadPixels GL_RGBA returning ARGB pixels instead

  1. #1
    Junior Member Newbie
    Join Date
    Jun 2012
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    11

    glReadPixels GL_RGBA returning ARGB pixels instead

    Calling the next instruction to get the viewport pixels. I am expecting the pixels to be in RGBA format, but instead I get ARGB pixels. Is there something wrong or the be set prior to glReadPixels? (note: written in NDK, Android)

    void getViewPortPixels(const unsigned int x, const unsigned int y, const unsigned int width, const unsigned int height, unsigned int* output)
    {
    glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
    glPixelStorei(GL_PACK_ALIGNMENT, 1);
    glReadPixels(x, y, width, height, GL_RGBA, GL_UNSIGNED_BYTE, (void*)output);
    }

  2. #2
    Super Moderator OpenGL Guru
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    Feb 2000
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    Montreal, Canada
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    4,264
    ------------------------------
    Sig: http://glhlib.sourceforge.net
    an open source GLU replacement library. Much more modern than GLU.
    float matrix[16], inverse_matrix[16];
    glhLoadIdentityf2(matrix);
    glhTranslatef2(matrix, 0.0, 0.0, 5.0);
    glhRotateAboutXf2(matrix, angleInRadians);
    glhScalef2(matrix, 1.0, 1.0, -1.0);
    glhQuickInvertMatrixf2(matrix, inverse_matrix);
    glUniformMatrix4fv(uniformLocation1, 1, FALSE, matrix);
    glUniformMatrix4fv(uniformLocation2, 1, FALSE, inverse_matrix);

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