Writing to screen buffer.

[h3ro]

Hallo,

I am using a API which does not have any setPixel() functions, instead it just has a long array. Im trying to make my own setPixel() function, but im not really sure im doing it the right way.

This is how I try to set the color of a pixel:

#define SCREEN_WIDTH	768
#define SCREEN_HEIGHT	512
#define BYTES_PER_PIXEL	4

// yPos and xPos are integers.
// Is this the correct calculation?
int pixelOffset = BYTES_PER_PIXEL * ((yPos *  SCREEN_WIDTH)) + xPos);

screen[pixelOffset ] = 255;
screen[pixelOffset +1] = 255;
screen[pixelOffset +2] = 255;
//screen[pixelOffset +3] = 255; Alpha channel, not used

Thanks for your time

[matsp]

Looks OK to me - assuming of course you have the right byte-order and the pixels are organized in a linear order.

--
Mats

[mike_g]

I am using a API which does not have any setPixel() functions, instead it just has a long array. Im trying to make my own setPixel() function, but im not really sure im doing it the right way.

Does your code work and produce the expected output?
Or are you having problems with it?
What API are you using?
Screen should be and unsigned character array, you probably already have it as such.
If you arent drawing white pixels then your byte ordering is the wrong way around.
If the code does not compile it could be that the screen is an object and the actual image buffer is contained within it.
Your pixel offset calculation should be correct

[h3ro]

Thanks for the help.

The API is called HAPI, it made by at teacher at the University. The problem had to do with the really really stupid way i was drawing pixels to the screen.

[Adak]

Thanks for the help.

The API is called HAPI, it made by at teacher at the University. The problem had to do with the really really stupid way is was drawing pixels to the screen.

So HAPI is making you SAD. There's an irony for ya!