algorithmic Zoom calculation help rmmv?

[Jonforum]

Would anyone have the right math formula to calculate the zoom in rpg maker mv?
I need one based on the mouse position.

const SM_S = SceneManager._scene;
const mapZoom = SM_S._spriteset._tilemap.scale;

    function wheel_(event) {//TODO: zoom system
        if(event.wheelDeltaY>0){
            mapZoom.x+=0.05;
            mapZoom.y+=0.05;
            $gameMap._displayX+=0.05
            dX+=0.05;
        }else{
            mapZoom.x-=0.05;
            mapZoom.y-=0.05;
            $gameMap._displayX-=0.05
            dX-=0.05;
        }
    };

thank

 

[Poryg]

I have tried to deal with zoom, but always failed in the end However, maybe it'd be more appropriate to use $gameMap._displayX+= Math.floor (0.05 * Graphics.boxWidth) multiplied by 1 or -1 depending on which half of the screen your mouse is.
Same for the Y direction.

 

[Jonforum]

Someone explain to me a trick that seems logical to me, it remains for me more than to apply it.
Ideally I would like something a little more mathematical.
The idea is to remember coordinates of certain point on screen, and then restore them.

class myCamera extends PIXI.Container {
       constructor {
              super();
              memCoord = new PIXI.Point();
           memCoord2 = new PIXI.Point();
       }

   public pushPivot(pos) {
       this.toLocal(pos, null, this.memCoord);
   }

   public popPivot(pos) {
       this.toLocal(pos, null, this.memCoord2);
       this.pivotTarget.x -= this.memCoord2.x - this.memCoord.x;
       this.pivotTarget.y -= this.memCoord2.y - this.memCoord.y;
   }
}
//declare scale somewhere. you can do it in camera too.
var scale = 1.0;
...
//zoom in
const mousePos = renderer.interaction.mouse.global;
stage.camera.pushPivot(mousePos);

scale *= 1.1;
camera.scale.set(scale);

stage.camera.popPivot(mousePos);

 

[Jonforum]

ho yess, finaly, no need to touch the $gameMap._displayX

    memCoord = new PIXI.Point();
    memCoord2 = new PIXI.Point();
    function pushPivot(pos) {
        SM_S._spriteset._tilemap.toLocal(pos, null, memCoord);
    }
    function popPivot(pos) {
        SM_S._spriteset._tilemap.toLocal(pos, null, memCoord2);
        SM_S._spriteset._tilemap.pivot.x -= memCoord2.x - memCoord.x;
        SM_S._spriteset._tilemap.pivot.y -= memCoord2.y - memCoord.y;
    }
    function wheel_(event) {//TODO: zoom system
        setMouseXY();
        const mousePos = new PIXI.Point(mX,mY);
        pushPivot(mousePos);
        if(event.wheelDeltaY>0){
            mapZoom.x+=0.1
            mapZoom.y+=0.1
        }else{
           mapZoom.x-=0.1;
           mapZoom.y-=0.1;
        }
        popPivot(mousePos);
    };

 

[hiddenone]

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