On May 3, 2006, at 10:14 AM, [EMAIL PROTECTED] wrote:
Hi
Anyone been able to use the convolution filter to create realistic
motion blur effects?
I do not believe a convolution operation cannot perform a zoom and
spin blur alone. Those need to be performed separately on every
single pixel in an image. You can get a similar result from
transforming the bitmap using a transformation matrix that's offset
from the center of the zoom or spin, rotating or scaling the copied
bitmap and overlaying the pixels onto the original.
Motion blur can be done to an extent. The problem that you will find
is that it doesn't work for fast curved motion. Slower curved motion
it works fine.
The code below is what I posted on my now-defunct site shiftedPixels.
It's a simplified method to do motion blur by using sampled locations
and linearly interpolating filter-applied copies of the source.
A better choice would be to use a spline-based sampling system on
your object and motion blur along points of the spline using a surve
or slerp method. Of course, doing so will be much slower due to point-
on-curve routines.
cheers,
Jon
// --------------------------------------------------------
// Temporal Anti-aliasing (motion blur)
// jon bradley, 2005
//
// Create a movie clip on your stage named "src".
// Copy the following code in the first frame.
// Set the frame rate of your file high, like 120.
// --------------------------------------------------------
import flash.display.BitmapData;
import flash.filters.*;
import flash.geom.*;
_quality = "medium";
src.startDrag(true);
Mouse.hide();
src._visible = false;
// set up the filters:
colorM = new ColorMatrixFilter
([1,0,0,0,0,0,1,0,0,0,0,0,1,0,0,0,0,0,0.4,0]);
blurFilter = new BlurFilter(5, 5, 1);
src.cacheAsBitmap = true;
var blurImg:BitmapData = new BitmapData(550, 400, true, 0xFFFFFF);
blurImg.transparent = false;
var blurClip:MovieClip = createEmptyMovieClip("blurClip", 99947);
blurClip.attachBitmap(blurImg, 0);
blurClip.cacheAsBitmap = true;
var rect = new flash.geom.Rectangle(0,0,Stage.width, Stage.height);
var pt = new flash.geom.Point(0,0);
// Linear interpolation to get points between object position points
// A more accurate choice would be to use spline interpolation based on
// a motion path of the object - of course this will run much slower.
function lerp(t,a,b)
{
return a+t*(b-a);
}
var x = _xmouse;
var y = _ymouse;
function updateBlur()
{
var m = src.transform.matrix;
var xa = _xmouse;
var dx = Math.sqrt(Math.abs(xa*xa - x*x));
var ya = _ymouse;
var dy = Math.sqrt(Math.abs(ya*ya - y*y));
blurFilter.blurX = dx/20;
blurFilter.blurY = dy/20;
var i = 15;
var t = 1/i;
while (i--)
{
m.tx = lerp( (i+1)*t, xa, x);
m.ty = lerp( (i+1)*t, ya, y);
blurImg.draw(src,m);
}
blurImg.applyFilter(blurImg, rect, pt, colorM);
blurImg.draw(src,m);
blurImg.applyFilter(blurImg, rect, pt, blurFilter);
x = _xmouse;
y = _ymouse;
}
// Pprocessor intensive - stick with onEnterFrame
// blurInterval = setInterval(updateBlur,0);
onEnterFrame = function()
{
src._x = _xmouse;
src._y = _ymouse;
updateBlur();
}
// END CODE
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