Question

Basically I want to move my enemy from one position to another.

There starting position is not a problem… neither is the place where they are suppose to go.

The problem lies with the how they get there. With the code I wrote they just teleport off the map.

So I am not even going to post it. Using triangles… what would be the most efficient way to get them from point A to point B?

Lets say point A is 10, 10; and point B is 123, 349. But there is also the chance that A will be B and B will be A. So it also has to deal with negatives.

Now the last thing that complicates the matter is that it moves between 1 and 5 pixels every time it repaints… so if it goes over the position I am not sure how to check to see if its in the general area.

Thanks! Btw I don’t need full code… just IDEAS!!! I can code myself. Thank you!!!

current code:

                if (enemyList.length > 0) {
                for (int[] x : enemyList) {
                    double changeX;
                    double changeY;
                    //if already in spot, anounce it
                    if (x[0] == x[2] && x[1] == x[3]) {
                        x[2] = -1;
                        x[3] = -1;
                    }
                    //if anounced generate new spot of interest
                    if (x[2] == -1 || x[3] == -1) {
                        x[2] = generateRandom(0, 550);
                        x[3] = generateRandom(0, 400);
                    }
                    //find distance from target and move there
                    int _y = x[1] - x[3];
                    int _x = x[0] - x[2];
                    if (_x > _y) {
                        changeX = _x / _y;
                        changeY = _y / _y;
                    } else {
                        changeY = _y / _x;
                        changeX = _x / _x;
                    }
                    changeY = changeY * generateRandom(0, 10);
                    changeX = changeX * generateRandom(0, 10);
                    //change physical position
                    x[0] += (int) changeX;
                    x[1] += (int) changeY;
                }
            }

Answer 1

Based on the code it looks like your enemy will sort of wiggle to its destination in maybe a curved fashion, but it’s hard to tell just by inspection. Maybe you just need to swap your source and destination because it looks like you may just have it backwards:

int _y = x[3] - x[1];
int _x = x[2] - x[0];

Is this what you intended, or should it make a beeline?

speed = 5; // "pixels" per frame
deltaX = destX - sourceX;
deltaY = destY - sourceY;
distance = sqrt(deltaX^2 + deltaY^2);

moveX = speed / distance * deltaX;
moveY = speed / distance * deltaY;

newX = sourceX + moveX;
newY = sourceY + moveY;

I used similar triangles to calculate moveX and moveY. Note the square root is slow, but that may be ok for your purposes… once you have it working, there are ways to optimize out the square root.