Read Color of a Pixel

[floorball92]

Hi, I have a Problem. I want to know, if it' s possible to read the color of an spezific pixel. I mean, i have the pixel 10*10 and want to know, if he is pink ( only an example ).

Is there a function in OSl, I mean, that I' ve read something like this somewhere, but I could' t find it. If it' s not on OSL, can someone give me a way to do this job with normal SDK??

Floorball92

ps: like last time to, sorry for my bad english xD

[floorball92]

I read a bit in the documentation and found something. I was very happy and wantet direktly try it, so I' ve made this Code:

//The main library OSLib
#include <oslib/oslib.h>
 
//The callbacks
PSP_MODULE_INFO("OSLib Sample", 0, 1, 1);
PSP_MAIN_THREAD_ATTR(THREAD_ATTR_USER | THREAD_ATTR_VFPU);
 
OSL_IMAGE *bg;

int main()
{
	//Initialization of the library
	oslInit(0);
 
	//Initialization of the graphic mode
	oslInitGfx(OSL_PF_8888, 0);
 
	//Initialization of the text console
	oslInitConsole();
 
	bg = oslLoadImageFile("bg.png", OSL_IN_RAM, OSL_PF_5551);
	
	//Display text on the screen
	oslPrintf("%s", oslGetImagePixelAdr(bg,10,10));
 
	//Wait a keystroke
	oslWaitKey();
	
	//Leaving the program
	oslEndGfx();
	oslQuit();
	return 0;
}

I was very schocked, the only damn Thing i Get were soome unidentified Symbols.

What' s wrong with this??

[daaa57150]

Have you tried this?

Code PHP:

//Get a 32 bit (OSL_PF_8888) color for the pixel at x, y, whatever its pixelformat is.
pixel = oslConvertColorEx(yourImage->palette, OSL_PF_8888, yourImage->pixelFormat, oslGetImagePixel(yourImage, x, y)); 


I haven't but it's certainly what you're looking for.
If you want to know if that pixel is pink (255,0,255) just see if
pixel==RGB(255,0,255)

[floorball92]

Do I have to insert something for pixelformat and palette ??

[daaa57150]

Envoyé par floorball92

Do I have to insert something for pixelformat and palette ??

yes, it's those of your osl_image...

Code PHP:

bool answer=false;
OSL_IMAGE *theimage=oslLoadImageFile("theimage.png", OSL_IN_RAM, OSL_PF_8888);
OSL_COLOR pixel=oslConvertColorEx(theimage->palette, OSL_PF_8888, theimage->pixelFormat, oslGetImagePixel(theimage, 10, 10)); 
if(pixel==RGB(255,0,255))
    answer=true; 


and there you have your answer, telling you if the pixel (10, 10) is pink.
Again, I haven't tested, but that would be my first try.

[floorball92]

This works perfect, thank you so much

[Brunni]

Are you sure you need to do that? The drawbuffer (= the screen) is itself an image, you can get it by oslGetDrawBuffer(). So you could read the pixel that way.
But beware that because the GPU may be drawing at the moment you read the pixel (i.e. the drawing is not finished) you may not get the right color. So, before reading anything on the screen, always ensure that the drawing is finished with a former oslSyncDrawing call

[fiorello]

Envoyé par Brunni

Are you sure you need to do that? The drawbuffer (= the screen) is itself an image, you can get it by oslGetDrawBuffer(). So you could read the pixel that way.
But beware that because the GPU may be drawing at the moment you read the pixel (i.e. the drawing is not finished) you may not get the right color. So, before reading anything on the screen, always ensure that the drawing is finished with a former oslSyncDrawing call

but my collision map isn't drawed, it is just loaded into memory and i don't want to load two color, big png file, map would be better.