Hi! I'm currently trying to get into game programming again and I'm having a bit of a problem at the moment. I'm trying to move a rectangle from point A to point B and it sort of works but the rectangle accelerate and deaccelerate instead of moving in a constant speed from A to B. Here's my code in its entirety:

Anyone know how to make the object move at a constant speed instead of accelerating/deaccelerate toward a position?

function love.load()
X = 30; -- initial X
Y = 30; -- initial Y
speed = 0.1;
end
function love.update( dt )
if (love.keyboard.isDown("right")) then
Xn = X + 128; -- destination X
Yn = Y + 45; -- destination Y
dX = Xn - X; -- deltaX
dY = Yn - Y; -- deltaY
distance = math.sqrt(dX^2 + dY^2); -- distance from A to B
moving = true;
end
if (moving == true) then
dX = Xn - X; -- update deltaX along path
dY = Yn - Y; -- update deltaY along path
X = X + dX * speed; -- update position
Y = Y + dY * speed; -- update position
if (math.sqrt(dX^2 + dY^2) > distance) then -- check whether object
X = Xn; -- has moved the entire
Y = Yn; -- distance
moving = false;
end
end
end
function love.draw()
love.graphics.setColor(0, 100, 100);
love.graphics.rectangle('fill', X, Y, 30, 30);
end

How do you use that method when moving a point from one place to another. in myexample, the distance from x1 to x2 is not the same as y1 to y2. I tried this:

That's because you compute dx and dy based on distance remaining. Thus your object is moving faster at the start and gradually slows down as it comes closer to the destination.

Oh yeah that's right, thanks for pointing that out Bluewolf.

I did a bit of extra research and found out that I need to normalize the vector before I can move the object along the line the way I want it. I rewrote it and now it works like I want it to:

function love.load()
X = 250; -- initial X
Y = 250; -- initial Y
speed = 500;
moving = false;
end
function love.update(dt)
if (moving == false) then
if (love.keyboard.isDown("down")) then moveto(X, Y + 32, 100) end
if (love.keyboard.isDown("up")) then moveto(X, Y - 32, 100) end
if (love.keyboard.isDown("left")) then moveto(X - 32, Y, 100) end
if (love.keyboard.isDown("right")) then moveto(X + 32, Y, 100) end
end
if (moving == true) then
X = X + dirX * speed * dt;
Y = Y + dirY * speed * dt;
if ( math.sqrt((X-oldX)^2 + (Y-oldY)^2) >= distance) then
X = newX;
Y = newY;
moving = false;
end
end
end
function love.draw()
love.graphics.setColor(0, 100, 100);
love.graphics.rectangle('fill', X-15, Y-30, 30, 60);
end
function moveto(movex,movey,movespeed)
oldX = X;
oldY = Y;
newX = movex;
newY = movey;
dX = newX - oldX;
dY = newY - oldY;
distance = math.sqrt(dX^2 + dY^2);
dirX = dX / distance;
dirY = dY / distance;
speed = movespeed;
moving = true;
end