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Posted: Fri May 18, 2007 11:32 am
by zsouthboy
Shit my original notes were scratched on a napkin (I wish I were joking)
I'll have to grab that .asp file to get the offsets for you.
at least its an easy format though.
Posted: Fri May 18, 2007 11:46 am
by zsouthboy
Okay, lemme start from the top:
I didn't comment my code with what each code offset does, unfortunately - but this should help you.
fileSize=(width * height * 3) + 54
'this is the file size in bytes, for our 24-bit dib
bitmapDataSize=(width * height * 3)
'this is the actual bitmap data size in bytes
Here's the header (you can probably figure it out, but each chr() returns a byte, and &h makes the data passed to it hexidecimal):
chr(&h42) + chr(&h4D) + *4 bytes here for fileSize* + chr(&h00) + chr(&h00) + chr(&h00) + chr(&h00) + chr(&h36) + chr(&h00) + chr(&h00) + chr(&h00) + chr(&h28) + chr(&h00) + chr(&h00) + chr(&h00) + *4 bytes here for image width in pixels* + *4 bytes here for image height in pixels* + chr(&h01) + chr(&h00) + chr(&h18) + chr(&h00) + chr(&h00) + chr(&h00) + chr(&h00) + chr(&h00) + *4 bytes here for bitmapDataSize* + chr(&h00) + chr(&h00) + chr(&h00) + chr(&h00) + chr(&h00) + chr(&h00) + chr(&h00) + chr(&h00) + chr(&h00) + chr(&h00) + chr(&h00) + chr(&h00) + chr(&h00) + chr(&h00) + chr(&h00) + chr(&h00) + *image data goes here, scanlines in reverse order. 1 byte R, 1 byte G, 1 byte B. padded to DWORD boundaries if your width isn't divisible by 4*
To create a simple 24-bit bitmap, with no wierd settings, that will do.
I remember parts of the header, specifying for example the offset to the beginning of the image data, but that's not important for this exercise - i built it into the header code.
If this doesn't make sense, tell me.
Posted: Fri May 18, 2007 9:18 pm
by arneoog
Can't say I understood much of that, sorry
How does it write the information??
where does it do it? No 'for loops' at all?
Heh.. It proably works, and works good,
but I can't understand how it is doing it, at all... (except the two first lines
)
...
Posted: Fri May 18, 2007 11:15 pm
by zsouthboy
You know how to do simple file IO in C++?
Create a handle to a new file.
Next, we prepare the header data for your bmp file.
The header is going to be 54 bytes long, for a standard 24-bit uncompressed bmp file.
Write the following to the new file you just created:
Code: Select all
424D
*4 bytes here for fileSize*
000000003600000028000000
*4 bytes here for image width in pixels*
*4 bytes here for image height in pixels*
0100180000000000
*4 bytes here for bitmapDataSize*
00000000000000000000000000000000
With me so far? That takes care of the header of the file.
To finish, simply write, line by line, the contents of the generated framebuffer, into the file next. Remember to write the lines in reverse order, or the image will be upside down when viewed elsewhere.
Possible example:
Code: Select all
for (int i=0, i < imageHeight, i++)
{
for (int j=0, j < imageWidth, j++)
{
'pseudo-code - i obviously don't know what your functions look like
bmpWriter.AddPixel(framebuffer.getValue(i, j));
}
}
Is that more clear?
Posted: Fri May 18, 2007 11:47 pm
by arneoog
I am probably to new to C++ to understand this
I am trying, but I can't make sense this bmp stuff
Code: Select all
FILE *f;
int filesize = 54 + 3*WIDTH*HEIGHT;
unsigned char bmpfileheader[14] = {'B','M', 0,0,0,0, 0,0, 0,0, 54,0,0,0};
unsigned char bmpinfoheader[40] = {40,0,0,0, 0,0,0,0, 0,0,0,0, 1,0, 24,0};
bmpfileheader[ 2] = (unsigned char)(filesize );
bmpfileheader[ 3] = (unsigned char)(filesize>> 8);
bmpfileheader[ 4] = (unsigned char)(filesize>>16);
bmpfileheader[ 5] = (unsigned char)(filesize>>24);
bmpinfoheader[ 4] = (unsigned char)( WIDTH );
bmpinfoheader[ 5] = (unsigned char)( WIDTH>> 8);
bmpinfoheader[ 6] = (unsigned char)( WIDTH>>16);
bmpinfoheader[ 7] = (unsigned char)( WIDTH>>24);
bmpinfoheader[ 8] = (unsigned char)( HEIGHT );
bmpinfoheader[ 9] = (unsigned char)( HEIGHT>> 8);
bmpinfoheader[10] = (unsigned char)( HEIGHT>>16);
bmpinfoheader[11] = (unsigned char)( HEIGHT>>24);
f = fopen("C:/ti_img01.bmp","wb");
fwrite(bmpfileheader,1,14,f);
fwrite(bmpinfoheader,1,40,f);
//Set pixels
for(int y = 0; y < HEIGHT; y++){
for(int x = 0; x < WIDTH; x++){
if(pixel[x][y] == '1'){
printf("#");
}else{
printf("·");
}
//WHAT THE FUCK!!!???
}
printf("\n");
}
fclose(f);
All of this, except the loop parts is something I just copyed and pasted..
It does save a .bmp file with all the info, but not the image, obviously
Code: Select all
bmpWriter.AddPixel(framebuffer.getValue(i, j));
Does not work.. I have just been using arrays for x/y info storing, is that okay?
pixel[x][y] and img[x][y][(r,g,b)]
Arg...
EDIT:
Hand drawn replica of one of my results:
Posted: Sat May 19, 2007 2:45 am
by arneoog
Posted: Sat May 19, 2007 7:03 am
by zsouthboy
Nice antialiasing!
Well, your frustrations at least convey to me your skill level in C++
I don't have time for indepth fix, but here:
Code: Select all
FILE *f;
int filesize = 54 + 3*WIDTH*HEIGHT;
unsigned char bmpfileheader[14] = {'B','M', 0,0,0,0, 0,0, 0,0, 54,0,0,0};
unsigned char bmpinfoheader[40] = {40,0,0,0, 0,0,0,0, 0,0,0,0, 1,0, 24,0};
bmpfileheader[ 2] = (unsigned char)(filesize );
bmpfileheader[ 3] = (unsigned char)(filesize>> 8);
bmpfileheader[ 4] = (unsigned char)(filesize>>16);
bmpfileheader[ 5] = (unsigned char)(filesize>>24);
bmpinfoheader[ 4] = (unsigned char)( WIDTH );
bmpinfoheader[ 5] = (unsigned char)( WIDTH>> 8);
bmpinfoheader[ 6] = (unsigned char)( WIDTH>>16);
bmpinfoheader[ 7] = (unsigned char)( WIDTH>>24);
bmpinfoheader[ 8] = (unsigned char)( HEIGHT );
bmpinfoheader[ 9] = (unsigned char)( HEIGHT>> 8);
bmpinfoheader[10] = (unsigned char)( HEIGHT>>16);
bmpinfoheader[11] = (unsigned char)( HEIGHT>>24);
f = fopen("C:/ti_img01.bmp","wb");
fwrite(bmpfileheader,1,14,f);
fwrite(bmpinfoheader,1,40,f);
//Set pixels
for(int y = 0; y < HEIGHT; y++){
for(int x = 0; x < WIDTH; x++){
if(pixel[x][y] == '1'){
//printf("#");
//00FF00 is RGB(0, 255, 0) - draw a Green pixel basically
fwrite(0x00FF00, 1, 3, f);
}else{
printf("·");
}
//WHAT THE FUCK!!!???
}
//printf("\n");
}
fclose(f);
Now try. You weren't actually writing the results into your image file
Note that your intended image will be upside down, and paint.exe (which is the program I used to test my output
) might display it oddly if your width isn't divisible by 4. The .bmp spec specifies that image data be padded to DWORD boundaries.
I'm actually quite surprised, arne - I assumed you were a much more experienced coder than I
Posted: Sat May 19, 2007 7:07 am
by Kram1032
In php, that may be the case, but he hasn't got the possibility to use C++, since a very short time back
Posted: Sat May 19, 2007 7:42 am
by arneoog
Ah, thanks!
It is writing green to the file!
Heh.. I've been messing with C/C++ for maybe two months
But PHP for a year and a half, I think..
Posted: Sat May 19, 2007 8:21 am
by zsouthboy
So post an image then
Posted: Sat May 19, 2007 8:29 am
by arneoog
Okay!
Posted: Sat May 19, 2007 9:45 am
by DaveC
Nice work, Arne. Great to see the progress
Posted: Sun May 20, 2007 2:06 am
by arneoog
Thanks, Dave
I made a simple "rotate animation" with it
AVI | MP4
It took like 0.5 sec to generate and save 35 images
I have some bad normal issues
I will fix the, hehe.
Also, what exactly does this "error" mean?
Code: Select all
10 [main] a 2104 _cygtls::handle_exceptions: Error while dumping state (probably corrupted stack)
Segmentation fault (core dumped)
It's seems to be an error Cygwin print beacuse I have to many variables or something
This limits me to 320x240 images, and not very big models...
Posted: Sun May 20, 2007 4:10 am
by zsouthboy
I've never used cygwin. You get the error when you try to write an image over a certain size?
Why are you using cygwin - IIRC its a *nix layer for windows, right? if your program is just using stdio.h you don't need it.
Or are you more familiar with *nix programming and are using it because of that?
Posted: Sun May 20, 2007 4:12 am
by Kram1032
he's using it, 'cause Deus told him to use it
