# How to create a good fractal zoom?

**URL:** <https://discourse.processing.org/t/how-to-create-a-good-fractal-zoom/33217>\
**Category:** Coding Questions\
**Created:** [November 1, 2021, 9:29am UTC](https://discourse.processing.org/t/how-to-create-a-good-fractal-zoom/33217 "2021-11-01T09:29:30Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![CodeMasterX](https://yyz2.discourse-cdn.com/flex036/user_avatar/discourse.processing.org/codemasterx/32/2942_2.png) [@CodeMasterX](https://discourse.processing.org/u/CodeMasterX)\
**Post date:** [November 1, 2021, 9:29am UTC](https://discourse.processing.org/t/how-to-create-a-good-fractal-zoom/33217/1 "2021-11-01T09:29:30Z")

</div>

Hi!  
I created a mandelbrot set explorer, with which, you can zoom into the fractal if you use the mouse wheel. But I can’t seem to get the mouse wheel zoom working correctly. What can I do to fix it?

Right now, both zoom and position shift aren’t working smoothly and can behave weirdly. I tried using mouse selection to zoom, but it worked even worse. Do you have any ideas / examples I could look at?

> **My current code**
>
> ```auto
> PGraphics gen;
> int iter = 250;
> color clr[] = new color[iter];
> float scale = 200;
> 
> float offx=0,offy=0;
> int genQ, lq = 10;
> 
> boolean useSquare = true;
> 
> void setup() {
> size(600,600);
> //fullScreen();
> colorMode(HSB);
> rectMode(CORNERS);
> float m = 0.95;
> for(int i = 0; i < iter; i++) clr[i] = color(pow(m,i)*255,255,255);
> clr[iter-1] = #000000;
> gen = createGraphics(width,height);
> stroke(255);
> strokeWeight(3);
> offx = width*0.5;
> offy = height*0.5;
>   
> generate(iter);
> }
> void draw() {
> image(gen,0,0);
> if(frameCount%100==0 && genQ < iter) {
> generate(iter);
> }
> }
> void generate(int q) {
> genQ = q;
>   
> gen.beginDraw();
> gen.loadPixels();
>   
> for(int i = 0; i < width; i++) for(int j = 0; j < height ; j++) {
> complex point = getPosC(i,j,offx,offy,scale);
> complex mover = new complex(point.re, point.im);
> int it;
> for(it=0; it < q-1 && inBounds(mover); it++) {
> mover.setValueC(z2pc(mover,point));
> }
> gen.pixels[i+j*width] = clr[it];
> }
> gen.updatePixels();
> gen.endDraw();
> }
> 
> void mouseWheel(MouseEvent event) { //HERE
> float e = -event.getCount();
>   
> float mox = (width*0.5-mouseX)/(width*0.5), moy = (height*0.5-mouseY)/(height*0.5);
>   
> //offx-=(mouseX-width*0.5)*0.25*e;
> //offy-=(mouseY-height*0.5)*0.25*e;
>   
> offx+=mox*abs(mox)*width*e;
> offy+=moy*abs(moy)*height*e;
>   
> if(e>0) {
> scale*=1.1;
> } else {
> scale/=1.1;
> }
> generate(lq);
> }
> 
> boolean inBounds(complex c) {
> if(useSquare) return( abs(c.re)<2 && abs(c.im)<2 );
> else return( pow(c.re,2)+ pow(c.im,2) < 4 );
> }
> 
> //COMPLEX NUMBERS--------------------------------------------------------------------------------
> class complex {
> float re, im;
> complex(float re, float im) {
> this.re = re;
> this.im = im;
> }
> void setValue(float re, float im) {
> this.re = re;
> this.im = im;
> }
> void setValueC(complex c) {
> this.re = c.re;
> this.im = c.im;
> }
> }
> //COMPLEX CALCULATIONS ----------------------------------------------------------------------
> complex csum(complex z, complex w) {
> return new complex(z.re+w.re,z.im+w.im);
> }
> complex cmult(complex z, complex w) {
> return new complex(w.re*z.re - w.im*z.im, w.re*z.im + z.re * w.im);
> }
> complex csq(complex z) {
> return cmult(z,z);
> }
> complex z2pc(complex z, complex c) { //z^2+c
> return csum(csq(z),c);
> }
> //VALUE ASSIGNMENT ---------------------------------------------------------------------------
> complex getPosC(float x, float y, float xoff, float yoff, float scl) {
> return new complex((x-xoff)/scl,(y-yoff)/scl);
> }
> 
> ```

 ![image](https://canada1.discourse-cdn.com/flex036/uploads/processingfoundation1/original/2X/1/1ab71a5a9e963686a2e0696dfc50155b3172953d.png)