如何创建漩涡/漩涡效果? [英] How to create whirlpool/vortex effect?

问题描述

我试图在作为传感器的圆形体上制作涡流效果.我一直在寻找这个，我寻找的所有示例都是用 C++ 或 Objective C 编写的，我似乎翻译得不好.

Im trying to make a Vortex effect on a Circle Body that is a Sensor. I've been looking for this and all examples i look for are in C++ or Objective C and i dont seem to translate them well.

当我的对象碰撞时，它会调用 beginContact(..) 并设置一个标志，以便我可以调用 bodyToUpdate.applyForce(...);

when my objects collition, it calls beginContact(..) and it sets a flag so that i can call bodyToUpdate.applyForce(...);

 public void beginContact(Contact contact) {
             setColliding(true);
 }

 //updating collition every frame
 public void act(){
     if (colliding) {
        ball.getBody().applyForce(....);

 }

如何计算每帧施加的力使其成为漩涡?

how to calculate the amount of force to apply every frame to make it a vortex?

所以我现在让物体直接进入漩涡的中心，但没有旋转"

so i now have the object going straight to the center of the vortex, but no "spin"

public void act() {
    if (colliding) {
        ball.getBody().setLinearVelocity(0, 0);

        ball.getBody().applyForce((portal.getBody().getPosition().x - ball.getBody().getPosition().x) * i,
                (portal.getBody().getPosition().y - ball.getBody().getPosition().y) * i,
                ball.getBody().getPosition().x, ball.getBody().getPosition().y, true);

        i++;
    } else
        i = 10;
}

推荐答案

你想实现一个切向力，其大小向涡流中心增加.

You want to implement a tangential force with a magnitude that increases towards the center of the vortex.

这是一些伪代码.

radialVector = objectPosition - vortexPosition;
tangentialVector = radialVector.perpendicularVector();

if (radialVector.length() < vortexRadius) {

    // Swirl faster when near the center of the vortex.
    // Max tangential force when distance from center is 0.
    // Min tangential force when distance from center is vortexRadius.
    forceMagnitude = map(radialVector.length(), vortexRadius, 0, minTangentialForce, maxTangentialForce);
    force = forceMagnitude * tangentialVector.normalize();
    object.applyForce(force);

}

这是显示矢量分量的图像:

Here's an image that shows the vector components:

要创建漩涡效果，当物体靠近中心时，应增加径向 (Fr) 和切向 (Ft) 力.

To create a whirlpool effect there should be increasing radial (Fr) and tangential (Ft) forces as the object moves closer to the center.

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