VisClient/org/hfbk/vis/TransitionViewpoint.java

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/*
 * Created on 25.04.2008
 */
package org.hfbk.vis;

import org.lwjgl.util.vector.Vector3f;

public class TransitionViewpoint extends Viewpoint {
        Viewpoint fromView, toView;
        
        float speed=1f, transition=0;

        
        public TransitionViewpoint(Viewpoint viewpoint, Viewpoint viewpoint2, float speed) {
                this.fromView=viewpoint;
                this.toView=viewpoint2;
                this.speed=speed;
        }
        
        public boolean checkArrived(){
                return transition>=1;
        }
        
        //linear interpolation
        float ipol(float a, float b, float t){
                return a*(1-t)+b*t;
        }
        
        //angular interpolation
        float aipol(float a, float b, float t){
                float pi=(float)Math.PI;
                if (Math.abs(a-b)>Math.PI){
                        a=(a+pi)%(2*pi);
                        b=(b+pi)%(2*pi);                        
                        return (a*(1-t)+b*t + pi)%(2*pi);                       
                }else
                        return a*(1-t)+b*t;
        }
        
        
        void render(float dt) {
                transition+=dt*speed;
                float ftrans=(float)Math.sin((transition-.5f)*Math.PI)/2+.5f;
                
                angle=    aipol( fromView.angle, toView.angle,ftrans);
                elevation=aipol( fromView.elevation, toView.elevation,ftrans);
                Vector3f.add(
                        (Vector3f)new Vector3f(fromView).scale(1-ftrans),
                        (Vector3f)new Vector3f(toView).scale(ftrans),   
                        this
                );
                
                super.render(dt);
        }       
}

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