Forgotten Coder craziest idea

[jonnin]

that is not too advanced. you just flip the rows. row max and row zero exchange.
just draw it the way the tool wants it, and flip your iteration.

for(rows = maxrow; rows; rows--)  //if maxrow is the size, you need -1 here
  for(cols = 0; cols <= maxcol; cols++)  //if maxcol is the size, use < not <= here
   {
      img[rows][cols] = pixeldata; //its correct to think top down here, but its filling it bottom up
    }

what-if you had a top down and a bottom up then?  adding a top-down source to copy from:
for(rows = maxrow; rows; rows--)  //if maxrow is the size, you need -1 here
  for(cols = 0; cols <= maxcol; cols++)  //if maxcol is the size, use < not <= here
   {
      img[rows][cols] = topdown[maxrow-row][cols];
    }

it may be faster to have an extra iteration variable for maxrow-row that goes 0-maxrow.
but that is code tweaking, the logic is identical.

[forgottencoder]

Hi jonnin

The problem is that memory_buffer uses has origin (0,0) the bottom left corner of screen. I want to pass (0,0) to top left corner of screen with a formula. No success so far. Memory buffer is continuos. Your go through with a pointer. Doesn't have rows or columns.

p - pointer to buffer memory
x,y - coords
*4 = 4 bytes per color in buffer memory


p += y * 4 * buffer_width;
p += x * 4;


This formula will start your pixels origin from bottom left corner. I want it to start on top left corner of screen.

Note: thanks for your code

[jonnin]

Doesn't have rows or columns.

you can make a 1-d to 2-d.
the standard formula is:
oned[desired row* number_cols + desired_col];
that is C/C++ memory layout.

a different and more complex mapping for going over it your way is doable. But its inefficient: you will go much faster iterating it forward as it is in memory. And the subtraction costs a bit too.

what you do is take the above formula and do what I did in the code above to revere the rows.
so instead of desired_row you get (maxrow-desired_row) I think, or something like that.

[mbozzi]

My memory buffer starts putting pixels from bottom left corner, line by line, all the way up on screen. It's bottom top. I want to start on top left corner moving down. Struggling with a working formula for that.

Let GDI do this by creating a top-down bitmap.
https://docs.microsoft.com/en-us/windows/win32/directshow/top-down-vs--bottom-up-dibs
Essentially you have to negate the height of the bitmap in the bitmapinfo structure.

Also make sure to choose 32 bits-per-pixel so that exactly zero bytes of padding are required after the end of a scan line. Row stride (the offset from the start of one scan line to the next) must be a multiple of four. Moreover the start of each scan line must be aligned on a 4-byte boundary.

[Duthomhas]

If you use the windows memory functions to get space for the bitmaps you are guaranteed a DWORD alignment, but honestly, the C and C++ memory managers should do that for you on Windows as well, unless you fiddle with some compiler flags to turn that off.

[forgottencoder]

Hi jonin

Thanks for tip.

[forgottencoder]

Hi mbozzi

Thanks for tip. Made some ajustments in my code. And now i have a superfast putpixel function. More fast than W32 SetPixel.

This line will change mode to top-down in bitmap (negative height)

buffer_bitmap_info.bmiHeader.biHeight= - buffer_height;

[forgottencoder]

Hi Duthomhas

Thanks for tip. I am using VirtualAlloc to alocate memory.


buffer_memory = VirtualAlloc(0,buffer_size,MEM_RESERVE|MEM_COMMIT,PAGE_READWRITE);

[forgottencoder]

Hi guys

Finally i have a name for library. I call it TURBOSCREEN.

Trying to setup a forum for it with PHPBB. Another strugling BIG LOL.

Working on a color system like SFML for my pixels on screen. An idea i got from here.

My system will be like

ts::Color::RED



Note: ts = turboscreen :)