Jump to content
  • Advertisement
Sign in to follow this  
amerigo14

Maintaining speed with touch path

This topic is 2469 days old which is more than the 365 day threshold we allow for new replies. Please post a new topic.

If you intended to correct an error in the post then please contact us.

Recommended Posts

I'm currently making a game similar to the airport controller games already available but I'm having a bit of difficulty keeping the same speed with a path. When the plane is initialised, it is given a velX and velY value that changes the position of the plane, but when the user touches the plane, a vector of points is created that set the position of the plane. My question is, how can I keep the plane moving at the same speed as it was set, instead of just moving from point to point at whatever speed the path is created?

Share this post


Link to post
Share on other sites
Advertisement
Whatever you do will end up being very specific to your game logic.

Perhaps a rolling average or weighted spline of point distances to come up with your velocity ? Or if the velocity should be kept current, you would not need to do anything other than follow the curve.

Share this post


Link to post
Share on other sites
Sorry I think I was a bit unclear about my intentions. My plane has a velX and velY value that is added to the position to move it. When a path is created I'm having an issue moving the plane along to the next point. I tried :

double theta = Math.atan2(pathPoints.firstElement().y-posY, pathPoints.firstElement().x - posX);

velX=(float) (magnitude * Math.sin(theta));
velY=(float) (magnitude * Math.cos(theta));

but this results in the plane moving in a straight line away from the point, in the opposite direction. I also tried doing posY-velY but this resulted in the plane flying in a circle. What am I doing wrong?

Share this post


Link to post
Share on other sites

double theta = Math.atan2(nextY - posY, nextX - posX); //calculate the angle of the next coordinate relative to the current position
velX = magnitude*Math.cos(theta); //calculate the velocity of X given using the angle of theta and magnitude of the total velocity
velY = magnitude*Math.sin(theta); //calculate the velocity of Y given using the angle of theta and magnitude of the total velocity

currX+=velX*(timeElapsed); //add the velocity to the currentX
currY+=velY*(timeElapsed); //add the velocity to the currentY

Share this post


Link to post
Share on other sites

Sorry I think I was a bit unclear about my intentions. My plane has a velX and velY value that is added to the position to move it. When a path is created I'm having an issue moving the plane along to the next point. I tried :

double theta = Math.atan2(pathPoints.firstElement().y-posY, pathPoints.firstElement().x - posX);

velX=(float) (magnitude * Math.sin(theta));
velY=(float) (magnitude * Math.cos(theta));

but this results in the plane moving in a straight line away from the point, in the opposite direction. I also tried doing posY-velY but this resulted in the plane flying in a circle. What am I doing wrong?


With this code snippet, you are doing a redundant euclidean -> polar -> euclidean conversion. It is simpler and faster to just work with 2D vectors as follows:

// Unnormalized direction vector to move to.
velX = pathPoints.firstElement().x - posX;
velY = pathPoints.firstElement().y - posY;
float length = velX*velX + velY*velY;
float desiredVelocity = x;
if (length <= desiredVelocity*desiredVelocity)
{
// distance to target is shorter than our velocity. We have arrived to our target, what to do?
// Immediately snap to target, or take next waypoint instead?
return;
}

// Scale the velocity to the desired length.

length = 1.0f / Sqrt(length);
velX *= length * desiredVelocity;
velY *= length * desiredVelocity;


However, if I understand correctly, you are moving your plane through a set of waypoints. In that case, just going linearly from waypoint to waypoint will look jaggy, and instead, you will be looking to use a smooth curve with arc length parametrization. At least, that's what the flight control games on Android and iPad are doing.

Share this post


Link to post
Share on other sites
Sign in to follow this  

  • Advertisement
×

Important Information

By using GameDev.net, you agree to our community Guidelines, Terms of Use, and Privacy Policy.

GameDev.net is your game development community. Create an account for your GameDev Portfolio and participate in the largest developer community in the games industry.

Sign me up!