FillScanline algorithm

[Andreik 60]

I tried to write this function in autoit but I`m a bit confused about emptyStack(),push() and pop() functions. I know that exists this function in array udf but here seems to be different. For example how can I write this in autoit:

if(!push(x, y)) return;

This is the full code:

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void floodFillScanlineStack(int x, int y, int newColor, int oldColor)
{
    if(oldColor == newColor) return;
    emptyStack();
    
    int y1; 
    bool spanLeft, spanRight;
    
    if(!push(x, y)) return;
    
    while(pop(x, y))
    {    
        y1 = y;
        while(y1 >= 0 && screenBuffer[x][y1] == oldColor) y1--;
        y1++;
        spanLeft = spanRight = 0;
        while(y1 < h && screenBuffer[x][y1] == oldColor )
        {
            screenBuffer[x][y1] = newColor;
            if(!spanLeft && x > 0 && screenBuffer[x - 1][y1] == oldColor) 
            {
                if(!push(x - 1, y1)) return;
                spanLeft = 1;
            }
            else if(spanLeft && x > 0 && screenBuffer[x - 1][y1] != oldColor)
            {
                spanLeft = 0;
            }
            if(!spanRight && x < w - 1 && screenBuffer[x + 1][y1] == oldColor) 
            {
                if(!push(x + 1, y1)) return;
                spanRight = 1;
            }
            else if(spanRight && x < w - 1 && screenBuffer[x + 1][y1] != oldColor)
            {
                spanRight = 0;
            } 
            y1++;
        }
    }
}

Edited October 9, 2010 by Andreik

[Richard Robertson 186]

Considering we have no idea where those functions came from, how can we help you?

[Mat 364]

If you can get the definition for 'screenBuffer' then it would make life a lot easier (and 'h' as well while you're there)

I think that push adds a new item to screenBuffer, with the given x and y... Not sure though, as then it wants it as a color. emptyStack just resets the screenBuffer I think.

This is what I get sans pop and push. I guessed that screenBuffer is not anything like what I have it here as... But ah well.

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Global $screenBuffer[1][1]

Func floodFillScanlineStack($x, $y, $newColor, $oldColor)
    If $oldColor == $newColor Then Return
    emptyStack()

    Local $y1
    Local $spanLeft, $spanRight

    If Not push($x, $y) Then Return

    While pop($x, $y)
        $y1 = $y

        While ($y1 >= 0) And ($screenBuffer[$x][$y1] == $oldColor)
            $y1 -= 1
        WEnd
        $y1 += 1

        $spanLeft = 0
        $spanRight = 0

        While ($y1 < $h) And ($screenBuffer[$x][$y1] == $oldColor)
            $screenBuffer[$x][$y1] = $newColor;
            If (Not $spanLeft) And ($x > 0) And ($screenBuffer[$x - 1][$y1] == $oldColor) Then
                If Not push($x - 1, $y1) Then Return
                $spanLeft = 1
            ElseIf ($spanLeft) And ($x > 0) And ($screenBuffer[$x - 1][$y1] <> $oldColor) Then
                $spanLeft = 0
            EndIf

            If (Not $spanRight) And ($x < $w - 1) And ($screenBuffer[$x + 1][$y1] == $oldColor) Then
                If Not push($x + 1, $y1) Then Return
                $spanRight = 1
            ElseIf ($spanRight) And ($x < $w - 1) And ($screenBuffer[$x + 1][$y1] <> $oldColor) Then
                $spanRight = 0
            EndIf

            $y1 += 1
        WEnd
    WEnd
EndFunc   ;==>floodFillScanlineStack

; Reset the global array
Func emptyStack()
    ReDim $screenBuffer[1][1]
    $screenBuffer[0][0] = 0
EndFunc

Mat

[Andreik 60]

I forgot from where I get there code but after a quick search on google I got this:

http://www.student.kuleuven.be/~m0216922/CG/files/floodfill.cpp

So the missing part is this:

bool pop(int &x, int &y)
{
    if(stackPointer > 0)
    {
        int p = stack[stackPointer];
        x = p / h;
        y = p % h;
        stackPointer--;
        return 1;
    }    
    else
    {
        return 0;
    }   
}   
 
bool push(int x, int y)
{
    if(stackPointer < stackSize - 1)
    {
        stackPointer++;
        stack[stackPointer] = h * x + y;
        return 1;
    }    
    else
    {
        return 0;
    }   
}    

void emptyStack()
{
    int x, y;
    while(pop(x, y));
}

Now make more sense, I think I know how to write this is autoit.