Thank you for your reply but I still do not understand how to cast the channel to the byte pointer. I will provide the snippet which is causing the performance issues. data = (unsigned char*)malloc(src_view.width()*src_view.height()*4); int i=0; for (int y=0; y < src_view.height(); y++) { for (int x=0; x < src_view.width(); x++) { data[i++] = get_color(src_view(x,y), boost::gil::red_t()); data[i++] = get_color(src_view(x,y), boost::gil::green_t()); data[i++] = get_color(src_view(x,y), boost::gil::blue_t()); data[i++] = get_color(src_view(x,y), boost::gil::alpha_t()); } } Later on "data" is passed to the OpenGL function which renders the textures. Unfortunately I find the gil doxygen documentation more confusing then helping. I hope it is clearer what I am trying to do with that image. In the case you have more questions shoot ahead, I am very frustrated because I am trying for days to solve that problem and most people seem to have very little knowledge of gil. Regards, Viktor -----Ursprüngliche Nachricht----- Von: boost-users-bounces@lists.boost.org [mailto:boost-users-bounces@lists.boost.org] Im Auftrag von Christian Henning Gesendet: Sonntag, 10. Januar 2010 19:36 An: boost-users@lists.boost.org Betreff: Re: [Boost-users] gil and OpenGL Hi there, depending on the memory layout of you could just cast the first channel of your first pixel into a byte pointer. BTW, what do you mean by color information? Regards, Christian On Sat, Jan 9, 2010 at 9:15 PM, <mailinglist@squarepx.com> wrote:

This is my first post in any mailinglist ever so i hope i am doing this right.

I successfully integrated the boost::gil module into my code to load some images and process their content so that I can display it as a texture in OpenGL.

My problem right now is the massive performance issue in retrieving the color information from the loaded image.

I am looping through every row and column and retrieve the red, green, blue and alpha color with the get_color method and push those values to a char array.

So I was wondering what the best approach would be to get the color information from the gil image into OpenGL or at least a char array.

Thanks in advance.

_______________________________________________ Boost-users mailing list Boost-users@lists.boost.org http://lists.boost.org/mailman/listinfo.cgi/boost-users

_______________________________________________ Boost-users mailing list Boost-users@lists.boost.org http://lists.boost.org/mailman/listinfo.cgi/boost-users

Viktor, here is a small snippet: rgba8_image_t img( 320, 240 ); rgba8_view_t v = view( img ); rgba8_pixel_t ppp = *v.begin(); unsigned char* data = &ppp[0]; Let me know if you have more questions. Regards, Christian On Sun, Jan 10, 2010 at 2:06 PM, <mailinglist@squarepx.com> wrote:

Thank you for your reply but I still do not understand how to cast the channel to the byte pointer.

I will provide the snippet which is causing the performance issues.

data = (unsigned char*)malloc(src_view.width()*src_view.height()*4); int i=0; for (int y=0; y < src_view.height(); y++) {    for (int x=0; x < src_view.width(); x++) {        data[i++] = get_color(src_view(x,y), boost::gil::red_t());        data[i++] = get_color(src_view(x,y), boost::gil::green_t());        data[i++] = get_color(src_view(x,y), boost::gil::blue_t());        data[i++] = get_color(src_view(x,y), boost::gil::alpha_t());    } }

Later on "data" is passed to the OpenGL function which renders the textures.

Unfortunately I find the gil doxygen documentation more confusing then helping.

I hope it is clearer what I am trying to do with that image. In the case you have more questions shoot ahead, I am very frustrated because I am trying for days to solve that problem and most people seem to have very little knowledge of gil.

Regards, Viktor

-----Ursprüngliche Nachricht----- Von: boost-users-bounces@lists.boost.org [mailto:boost-users-bounces@lists.boost.org] Im Auftrag von Christian Henning Gesendet: Sonntag, 10. Januar 2010 19:36 An: boost-users@lists.boost.org Betreff: Re: [Boost-users] gil and OpenGL

Hi there, depending on the memory layout of you could just cast the first channel of your first pixel into a byte pointer. BTW, what do you mean by color information?

Regards, Christian

On Sat, Jan 9, 2010 at 9:15 PM,  <mailinglist@squarepx.com> wrote:

...

This is my first post in any mailinglist ever so i hope i am doing this right.

I successfully integrated the boost::gil module into my code to load some images and process their content so that I can display it as a texture in OpenGL.

My problem right now is the massive performance issue in retrieving the color information from the loaded image.

I am looping through every row and column and retrieve the red, green, blue and alpha color with the get_color method and push those values to a char array.

So I was wondering what the best approach would be to get the color information from the gil image into OpenGL or at least a char array.

Thanks in advance.

_______________________________________________ Boost-users mailing list Boost-users@lists.boost.org http://lists.boost.org/mailman/listinfo.cgi/boost-users

_______________________________________________ Boost-users mailing list Boost-users@lists.boost.org http://lists.boost.org/mailman/listinfo.cgi/boost-users

_______________________________________________ Boost-users mailing list Boost-users@lists.boost.org http://lists.boost.org/mailman/listinfo.cgi/boost-users

Kenny Riddile wrote:

I do this to load GIL images as OpenGL textures and it works fine for me:

reinterpret_cast<const char*>( interleaved_view_get_raw_data(imageView) )

Also, I've noticed that OpenGL interprets the image data upside down, so I flip it prior to calling glTexImage2D using flipped_up_down_view. Flipping the image data seems to be common practice when loading OpenGL textures based on what I've read online.

Ruben Lopez wrote:

Kenny Riddile wrote:

...

Kenny Riddile wrote:

...

I do this to load GIL images as OpenGL textures and it works fine for me:

reinterpret_cast<const char*>( interleaved_view_get_raw_data(imageView) )

Also, I've noticed that OpenGL interprets the image data upside down, so I flip it prior to calling glTexImage2D using flipped_up_down_view. Flipping the image data seems to be common practice when loading OpenGL textures based on what I've read online. You can flip the image, but it is more efficient to flip the texture coordinates on Y (or T) axis. If you have a lot of texture coordinates, you can set a texture matrix (glMatrixMode(GL_TEXTURE)) that flips them on hardware.

Thanks! I was actually looking for a convenient way to flip all texture coordinates...I'm still somewhat unfamiliar with OpenGL. I see GLSL also gives me access to the texture matrices for each texture unit in the vertex shader, which is exactly what I need :)