[Flashcoders] BitmapData and setPixel();

[Claudia Barnal]

Hi everyone,

I’m having some math problems with a BitmapData and setPixel().
I’m using a for loop to calculate the different color values that should be 
assigned to a BitmapData, creating a gradient with a specific shape. Problem 
is that I can’t get the right combination of color and shape of the 
gradient.

In the sample code (which you can copy and paste and it will work straight 
away) I set two examples of the var p.

The first option has the shape that I want. The issue is that the colors 
that are in the top and bottom center (very dark green and very light green) 
should be in the corners of their respective top and bottom.

The second option has somewhat the color distribution that I want, but I 
doesn’t have the shape that I need. Here the curvature starts in the 
corners, but should be as in the first option.

I know it is a problematic question, but I would love to see your replies, 
as I have tried to solve this little problem for quite some time now.

Claudia Barnal

// CODE

var stageW:Number = 255;
var stageH:Number = 255;
var hStageMiddle:Number = Math.round((stageW / 2) + 1);
var bd:flash.display.BitmapData = new flash.display.BitmapData(stageW, 
stageH);


for (var x:Number = 0; x < hStageMiddle; x++)
{
        /*
        * OPTION1 RIGHT SHAPE, WRONG COLOR DISTRIBUTION
        * CURVE STARTS FROM TOP AND BOTTOM CENTER
        */
        var p:Number = Math.pow(1 - (x / hStageMiddle), 2);

        /*
        * OPTION2 WRONG SHAPE, RIGHT COLOR DISTRIBUTION
        * CURVE STARTS FROM THE CORNERS, WHICH IS WRONG
        */
        //var p:Number = Math.pow(2, 1 - (x / hStageMiddle));

        for (var y:Number = 0; y < stageH; y++)
        {
                var val1:Number = ((255 * y) / stageH);
                var val2:Number = ((val1 * (1 - p)) + (128 * p));
                var col:Number = (((val2 << 8) | 0) | 0);
                bd.setPixel(x, y, col);
                bd.setPixel(stageW - x, y, col);
        }
}


createEmptyMovieClip("bmp", 1);
bmp.attachBitmap(bd, 2);

// CODE END

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