Koali blog

I’m currently reading through a couple of tutorials on how to create a water effect I want. One of them starts with a blur function which is pretty easy to understand in concept but I wanted to see the result. So I wrote the formula in hydra.

kernel Blur{
    void evaluatePixel(in image4 src, out pixel4 dst){
        float2 coord = outCoord();
        float4 source = sampleNearest(src,coord);
        float4 source1 = sampleNearest(src,float2(coord.x+1.0,coord.y));
        float4 source2 = sampleNearest(src,float2(coord.x-1.0,coord.y));
        float4 source3 = sampleNearest(src,float2(coord.x,coord.y+1.0));
        float4 source4 = sampleNearest(src,float2(coord.x,coord.y-1.0));
        float4 final = (source+source1+source2+source3+source4)*0.2;
        dst = final;
    }
}

The code gets the pixel of the current pixel along with the top, right, bottom, left and then divides by 5 to find the average.
Flash already has an inbuilt blur filter but this was just to see the maths.

Loops are not supported when Hydra is used within flash, so I can’t think of a way that you could increase the blur via a parameter at the moment.

I decided to add frequency into my wiggle hydra example. Frequency adjusts the distance between a wave making wider or shorter waves. The old one only let you change the amplitude of the wave on the x and/or y.

kernel morph
{

parameter float xangle< minValue: 0.0;
    maxValue:10.0;
    defaultValue:5.0;
>;
parameter float frequency< minValue: 0.0;
    maxValue:2.0;
    defaultValue:1.0;
>;
parameter float yangle< minValue: 0.0;
    maxValue:10.0;
    defaultValue:0.0;
>;

    void evaluatePixel(in image4 src, out pixel4 dst)
    {
        float2 coord = outCoord();
        float xcoord = coord.x - sin(coord.y*frequency)*xangle;
        float ycoord = coord.y - sin(coord.x*frequency)*yangle;
        dst = sampleNearest(src,float2(xcoord,ycoord));
        if(dst.r==0.0&&dst.g==0.0&&dst.b==0.0){
           dst = sampleNearest(src,outCoord());
        }
    }
}