Fixed Panning

        initialize_pan_and_zoom: function(){

            EDITOR.PIXI_APPLICATION.stage.interactive = true;

            on_wheel(EDITOR.PIXI_APPLICATION.renderer, EDITOR.PIXI_APPLICATION.stage);

            function on_wheel(renderer, stage){
                renderer.view.addEventListener("wheel", function(e) {
                    //let zoom_in = e.deltaY < 0 ? true : false;
                    let zoom_in = e.deltaY < 0; //simplified
                    let zoom_factor;
                    if (zoom_in) {
                        zoom_factor = 1.1;
                    } else {
                        zoom_factor = (1/1.1);
                    }

                    //zoom
                    stage.scale.x *= zoom_factor;
                    stage.scale.y *= zoom_factor;

                    //center on cursor
                    let mouse_loc = renderer.plugins.interaction.eventData.data.global;
                    stage.x -= (mouse_loc.x - stage.x) * (zoom_factor - 1);
                    stage.y -= (mouse_loc.y - stage.y) * (zoom_factor - 1);

                    correct(renderer, stage);

                    renderer.render(stage);
                    e.preventDefault();
                });
            }


            EDITOR.PIXI_APPLICATION.renderer.view.addEventListener("mousedown", function(e) {
                if(e.which == 3){
                    EDITOR.CURRENT_MOUSE_LOCATION = EDITOR.PIXI_APPLICATION.renderer.plugins.interaction.eventData.data.global;
                    EDITOR.PAN_LOCATION = [
                        EDITOR.CURRENT_MOUSE_LOCATION.x,
                        EDITOR.CURRENT_MOUSE_LOCATION.y
                    ];
                    EDITOR.PIXI_APPLICATION.ticker.add(apply_pan);
                    e.preventDefault();
                }
            });


            EDITOR.PIXI_APPLICATION.renderer.view.addEventListener("mouseup", function(e) {
                if(e.which == 3) {
                    EDITOR.CURRENT_MOUSE_LOCATION = EDITOR.PIXI_APPLICATION.renderer.plugins.interaction.eventData.data.global;
                    EDITOR.PAN_LOCATION = [
                        EDITOR.CURRENT_MOUSE_LOCATION.x,
                        EDITOR.CURRENT_MOUSE_LOCATION.y
                    ];
                    EDITOR.PIXI_APPLICATION.ticker.remove(apply_pan);
                    e.preventDefault();
                }
            });

            function apply_pan(){
                let NEW_MOUSE_LOCATION = EDITOR.PIXI_APPLICATION.renderer.plugins.interaction.eventData.data.global;
                let LAST_PAN_LOCATION = EDITOR.PAN_LOCATION;
                let diff_x = NEW_MOUSE_LOCATION.x - LAST_PAN_LOCATION[0];
                let diff_y = NEW_MOUSE_LOCATION.y - LAST_PAN_LOCATION[1];
                EDITOR.PAN_LOCATION = [NEW_MOUSE_LOCATION.x, NEW_MOUSE_LOCATION.y];
                EDITOR.PIXI_APPLICATION.stage.x += diff_x;
                EDITOR.PIXI_APPLICATION.stage.y += diff_y;
                correct(
                    EDITOR.PIXI_APPLICATION.renderer,
                    EDITOR.PIXI_APPLICATION.stage
                );
            }

            function correct(renderer, stage) {
                //keep in frame
                stage.x = Math.min(0, stage.x);
                stage.y = Math.min(0, stage.y);

                //keep width in bounds
                let visible_width = (renderer.width * stage.scale.x) + stage.x;
                if (visible_width < renderer.view.width) {
                    stage.x = Math.min(0, renderer.view.width - (renderer.width * stage.scale.x));
                    if (stage.x == 0) {
                        stage.scale.x = renderer.view.width / renderer.width;
                    }
                }

                //keep height in bounds
                let visible_height = (renderer.height * stage.scale.y) + stage.y;
                if (visible_height < renderer.view.height) {
                    stage.y = Math.min(0, renderer.view.height - (renderer.height * stage.scale.y));
                    if (stage.y == 0) {
                        stage.scale.y = renderer.view.height / renderer.height;
                    }
                }

                //keep aspect ratio
                if (stage.scale.y != stage.scale.x) {
                    stage.scale.x = Math.max(stage.scale.x, stage.scale.y);
                    stage.scale.y = Math.max(stage.scale.x, stage.scale.y);
                }
            }
        }