Java游戏：检查交叉口和跳跃

Question

I need help with checking for intersections in a game I'm creating: When a character collides with a single obstacle on the screen all works as intended, but when multiple obstacles are added to the screen the character can only jump off of the last obstacle that is being checked for collision. The character still collides properly with the other obstacles (doesn't fall through, cant walk through) but can't jump off of them. Obs is an arraylist of obstacles. Ground is the boolean that determines if the character is allowed to jump.

public void checkIntersect(ArrayList<Obstacle> obs){
    for(Obstacle a: obs){


        if(a.getLeft().intersects(this.getRight())){
            if(getDx()>0){
                sidecollision=true;
                setDx(0);
                this.x-=1.5f;
            }
        } if (a.getRight().intersects(this.getLeft())){
                sidecollision = true;
                setDx(0);
                this.x+=1.5f;
        } if((a.getTop()).intersects(this.getBottom())){
            ground=true;
            setDy(0);
            this.y-=.10f;
        } else if(!(a.getTop()).intersects(this.getBottom())){ 
                ground = false;

                //return ground;        
        } if(a.getBottom().intersects(this.getTop())){
            ground=false;
            setDy(0);

            this.y+=.1f;
        }

    }
} 

and how collision is being checked on the game component:

bg.update(quote);
        win.fill(clear);
        bg.drawBG(win);
        for(Obstacle o: obs){
            o.draw(win);
            o.update(bg);
        }
        if(quote.isVisible()){

                quote.movedrawProtag(win, keys);
                quote.checkIntersect(obs);
        }

Answer 1

The most likely cause of your bug is subsequent calls to checkIntersect() overriding the value of ground . This results in the value of ground only reflecting the last call to checkIntersect() . To fix this bug, you should set ground to a default value of either true or false before making any calls to checkIntersect() . Then, modify the checkIntersect() method so that it can only set ground to the non-default value. When ground should be at its default value, it does not need to be set.

Do something like this. I'm using a default value of false .

public void checkIntersect(ArrayList<Obstacle> obs){
    for(Obstacle a: obs){


        if(a.getLeft().intersects(this.getRight())){
            if(getDx()>0){
                sidecollision=true;
                setDx(0);
                this.x-=1.5f;
            }
        } if (a.getRight().intersects(this.getLeft())){
                sidecollision = true;
                setDx(0);
                this.x+=1.5f;
        } if((a.getTop()).intersects(this.getBottom())){
            ground=true;
            setDy(0);
            this.y-=.10f;
        } else if(!(a.getTop()).intersects(this.getBottom())){ 
                // ground = false;

                //return ground;        
        } if(a.getBottom().intersects(this.getTop())){
            // ground=false;
            // setDy(0);

            // this.y+=.1f;
        }

    }
} 

When you check for collisions:

bg.update(quote);
        win.fill(clear);
        bg.drawBG(win);
        for(Obstacle o: obs){
            o.draw(win);
            o.update(bg);
        }

        // Set ground to its default value
        quote.ground = false;  

        if(quote.isVisible()){

                quote.movedrawProtag(win, keys);
                quote.checkIntersect(obs);
        }

        // If ground has not been set to true, do the default action
        if (quote.ground == false) {
            setDy(0);
            quote.y += .1f;
        }