魚眼レンズ風に画像変換する

genFishEyePicture.js

function genFishEyePicture(srcImageData) {
    //
    var width = srcImageData.width;
    var height = srcImageData.height;
    
    var kk=width*0.5;
    var ll=height*0.5;
    
    var destImageData = ctx.createImageData(width,height);
    console.log(destImageData.width+","+destImageData.height);
    for(var y = 0; y < height; y++) {
        for(var x = 0; x < width; x++) {
            targetPixel = (width*y+x)*4;
            var dx=(x-kk);
    		var dy=(y-ll);
    		var aa=Math.atan2(dy,dx);
    		var rr=hypot(dy,dx);
    		var rs=rr*rr/hypot(kk,ll);
    		var px=Math.floor(kk+rs*Math.cos(aa));
    		var py=Math.floor(ll+rs*Math.sin(aa));
            //console.log(px+","+py);
            destPixel = (width*py+px)*4;
            /*
            destImageData.data[destPixel+0] = srcImageData.data[targetPixel+0];
            destImageData.data[destPixel+1] = srcImageData.data[targetPixel+1];
            destImageData.data[destPixel+2] = srcImageData.data[targetPixel+2];
            destImageData.data[destPixel+3] = srcImageData.data[targetPixel+3];
*/
            destImageData.data[targetPixel+0] = srcImageData.data[destPixel+0];
            destImageData.data[targetPixel+1] = srcImageData.data[destPixel+1];
            destImageData.data[targetPixel+2] = srcImageData.data[destPixel+2];
            destImageData.data[targetPixel+3] = srcImageData.data[destPixel+3];

        }
    }
    var destCs = document.createElement('canvas');
    destCs.width = width;
    destCs.height = height;
    ctx = destCs.getContext('2d');
    ctx.putImageData(destImageData,0,0);
    document.body.appendChild(destCs);
}