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37 lines
858 B
37 lines
858 B
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function BallSwing(fulcrumx, fulcrumy, ballx, bally, r){
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x = ballx - fulcrumx;
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y = bally - fulcrumy;
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this.poleLen = Math.sqrt(x*x + y*y);
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this.fx = fulcrumx;
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this.fy = fulcrumy;
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this.bx = ballx;
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this.by = bally;
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this.dx = 0;
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this.dy = 0;
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this.update = function(){
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x = this.bx - this.fx;
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y = this.by - this.fy;
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realLen = Math.sqrt(x*x + y*y);
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nx = x/realLen;
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ny = y/realLen;
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this.dy += 1;
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s = this.dx * nx + this.dy * ny;
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this.dx -= s*nx;
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this.dy -= s*ny;
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dlen = this.poleLen - realLen;
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this.dx += dlen * nx;
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this.dy += dlen * ny;
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this.bx += this.dx;
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this.by += this.dy;
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};
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this.draw = function(){
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line(this.fx, this.fy, this.bx, this.by)
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circle(this.bx, this.by, r)
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};
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}
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