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Unfortunately I need more help again. I´m trying to do a pixel perfect collision function but I can´t get passed a simple maths problem. I need to figure out the x and y position of a pixel of a sprite. I have the x position and y position of the sprite and I know it´s width and height. I have the image that the sprite uses stored in a memblock. I now need to think up some maths that gives me the pixel´s position given the height, width and size of the sprite. I use a for next loop like this to check the sprites colour and get the pixel´s x and y values:

xsize1=sprite width(sprite1) : ysize1=sprite height(sprite1)

xsize1*ysize1=size1 : xsize2*ysize2=size2
memsize=(size1*4)+12

for imageloop=12 to memsize step 4
if memblock byte(1,imageloop)=255

pixelposx=
pixelposy=
endif
next imageloop

Basically if imageloop=12 then the pixel´s position is the same as the sprites position. If imageloop=16 (step 4) then the pixels x position is one greater than the sprite and it´s y value stays the same and so on and so fourth. How do I tell the computer the rules? Any ideas? If you want me to explain anything more clearly don´t hesitate to say so.
You help is appreciated

P.S: Thank you Freddix for your pixel perfect collision function which I´m basing mine on.

Wouldn't you need two loops - one to check the x-pos and one for the y-position? Like

for loop_y = 0 to height
for loop_x = 0 to width

if pixel is white then pixel_x=loop_x
if pixel is white then pixel_y=loop_y

next loop_x
next loop_y

That would check every pixel from left to right for every row from top to bottom.

Sorry if that's not what you meant.

Thank you!! If I could somehow tie your idea to mine it might work. Right. I´ve got alot of programming to do.