Splitting BMPs

If you write your own custom loading function then it''s relativly simple.

It''s like linar memory access.

Hey I had to do this once too I did a small tile engine and such but now I''m trying to experiment on BSP''s and see how that works for settings like castles in rpgs and caves and such but I might go back and work on my tile engine again since I liked it heres my modification off Nehe''s .tga loader basically its the same thing though

TextureImage::Extract(int x, int y, int ex_width, int ex_height) { unsigned char *src = NULL,*dest = NULL, *dest2; unsigned int type = GL_RGBA; int bytes_per_pixel = bpp/8; unsigned int id; dest = new unsigned char[ex_width * ex_height * bytes_per_pixel]; memset(dest,0,sizeof(dest)); x = x * (ex_width); y = y * (ex_height); src = buffer + (y * (width * bytes_per_pixel) + (x * bytes_per_pixel)); dest2 = dest; for(int index = 0; index < ex_height; index++) { memcpy(dest2, src, (ex_width * bytes_per_pixel)); dest2 += (ex_width * bytes_per_pixel); src += (width * bytes_per_pixel); } glGenTextures(1, &id); glBindTexture(GL_TEXTURE_2D, id); if(bpp == 24) type = GL_RGB; glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR); gluBuild2DMipmaps(GL_TEXTURE_2D, type, ex_width, ex_height, type, GL_UNSIGNED_BYTE,dest); free(dest); dest2=NULL; src = NULL; return(id); }

you can mess around with that as long as you have the buffer saved that you read in it works so like in your class keep like a unsigned char *buffer; where all the image data is kept only thing that is weird on this that I havent figured out really why it is is that lets say you have a 2 rows of cells and 3 colums
1 2 3
4 5 6
the cell 4 is located at 0,0 so you would call the function like
Extract(0,0,32,32) //if the tiles are 32x32 and that will give you the image of cell 4 if you want cell 1 you call Extract(0,1,32,32) yeah its weird like taht but I havent figured out why it does it...if anyone knows please tell