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Compile error

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sethjackson:
Hi I get this error

error: incompatible types in assignment of `int' to `unsigned char*[((unsigned int)((int)imageSize))]'

with this code......


--- Code: (cpp) ---if (image.HasAlpha())
{
        unsigned long imageSize = image.GetWidth() * image.GetHeight() * 4;
        unsigned char* imageData = image.GetData();
        unsigned char* imageAlpha = image.GetAlpha();
        unsigned char* data[imageSize];

        for (unsigned long index = 0; index < imageSize; index += 4)
        {
            memcpy(data, imageData, 3);

            imageData += 3;

            memcpy(data + 3, imageAlpha, 1);

            imageAlpha++;

            data += 4;
        }

        gluBuild2DMipmaps(GL_TEXTURE_2D, GL_RGBA, image.GetWidth(), image.GetHeight(),
                          GL_RGB, GL_UNSIGNED_BYTE, data);
}

--- End code ---


Help me please...... Sorry for the beginner question? I just don't get it I used to do stuff like increaseing the ptr with += all the time.....

EDIT:

Let me say that it fails on the line


--- Code: (cpp) ---data += 4;

--- End code ---

 :P

sethjackson:
Ok I fixed it now could someone tell me why this works???


--- Code: (cpp) ---*(data) += 4;

--- End code ---

polygon7:
Hi,
this should work

--- Code: ---if (image.HasAlpha())
{
        unsigned long imageSize = (image.GetWidth() * image.GetHeight())  << 2;
        unsigned char* imageData = image.GetData();
        unsigned char* imageAlpha = image.GetAlpha();
        unsigned char* data[imageSize];
 
        for (unsigned long index = 0; index < imageSize; index += 4)
        {
            memcpy(data, imageData, 3);
 
            imageData += 3;
 
            memcpy(data + 3, imageAlpha, 1);
 
            ++imageAlpha;
 
           (*data) += 4;
        }
 
        gluBuild2DMipmaps(GL_TEXTURE_2D, GL_RGBA, image.GetWidth(), image.GetHeight(),
                          GL_RGB, GL_UNSIGNED_BYTE, data);
}
--- End code ---
// Edit: Ah, you're faster :P

--- Code: ---char* array[size]
--- End code ---
is the same as
--- Code: ---char** array
--- End code ---

sethjackson:
 :lol: :lol: Read my post above. Exactly why does it work though? Thanks.  :D

Michael:

--- Quote from: sethjackson on February 05, 2006, 10:40:22 pm --- :lol: :lol: Read my post above. Exactly why does it work though? Thanks.  :D

--- End quote ---

You tried to assign an int to an unsigned char*. This does not work for sure. What do did is to de-reference the pointer. Then it works.

Why you cast before int and then unsigned int?

Anyway, do not use C-cast style. This is not a good idea in C++. You should use C++ cast style or better no cast at all (if possible).

Best wishes,
Michael

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