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Bot ​

In this part of the tutorial we will make the botPaddle.

Setup ​

  1. Copy the userPaddle and rename it to botPaddle.
  2. Move the botPaddle to [0,0,-15.5] movedBotPaddle
  3. Change the color of the bot paddle to red colorChangeBotPaddle

Logic ​

We will update the movement.ts script to handle bot logic.

  1. To distinguish between the bot and the user, add a key auto to the props of the movement.ts file.
TypeScript
export const props = {
    speed: 5, // speed of movement
    auto: false, // automatic (true if this is the bot paddle)
};

  1. Tick the checkbox for auto in the component editor for botPaddle. botScript

  2. Update the movement.ts file to add the logic for the bot. Here we are assuming in advance that there will be a child of the rootGameObject called puck. We will try to get this objects position and then update the botPaddle's position bsed on this.

TypeScript
export const props = {
    speed: 1,//speed of movement
    auto: false,//automatic
};

export const init = (game, gameObject, {props}) => {
    let horizontal = 0;
    let vertical = 0;

    if(!props.speed)props.speed = 1;//use default speed if speed was not changed
    const updateLinVel = () => {//update linear velocity
        const rb = gameObject.components.rigidBody;
        if(!rb)return;
        rb.setLinvel({ x: horizontal* props.speed, y: vertical*props.speed, z: 0 }, true);
    };


    if(props.auto){// if this is the bot then set the speed automatically

        setInterval(() => {
            //get the puck rigidBody
            const puckRb = game.currentGameObject?.children?.puck?.components?.rigidBody;
            //get self rigidBody
            const selfRb = gameObject.components.rigidBody;
            //if any of the above is not initialized yet, return.
            if(!puckRb || !selfRb)return;
            //get the difference in positions and calculate the linear velocity
            const puckPos = puckRb.translation();
            const selfPos = selfRb.translation();
            horizontal = Math.sign(puckPos.x - selfPos.x);
            vertical = Math.sign(puckPos.y - selfPos.y);
            updateLinVel();
        }, 16);

    }else{// allow manuall control
        window.addEventListener('keydown', e => {
            if (e.repeat) { return }
            switch(e.code){
                case 'KeyA':
                    horizontal -= 1;
                    break;
                case 'KeyD':
                    horizontal += 1;
                    break;
                case 'KeyS':
                    vertical -= 1;
                    break;
                case 'KeyW':
                    vertical += 1;
                    break;
            };
            updateLinVel();
        })
    
        window.addEventListener('keyup', e => {
            switch(e.code){
                case 'KeyA':
                    horizontal += 1;
                    break;
                case 'KeyD':
                    horizontal -= 1;
                    break;
                case 'KeyS':
                    vertical += 1;
                    break;
                case 'KeyW':
                    vertical -= 1;
                    break;
            };
            updateLinVel();
        });
    }
}
  1. At this point there should be no visible difference in the game because there is no gameObject named puck inside the rootGameObject.
  2. Rename the cube to puck and you should see the botPaddle follow the puck falling down.