This is the piece of code I am using to make the bird jump, but it's not even close to making a jump like flappy bird.it goes up on touch, ut does not fall like gravity is pulling it. Infact, after a couple of seconds, it looks like the bird is at its initial position as well as the jump position(two birds on screen), what can I do to fix this?
function Play: whenTouched()
self.touchStarted= true
x,y = self.myAnim:getPosition()
if self.touchStarted then
speed = -16
self.touchStarted = false
end
y = y + speed;
speed = speed + 2
self.myAnim:setPosition(x,y)
end
This is the equation you're looking for perhaps
http://www.school-for-champions.com/science/gravity_equations_upward_velocity.htm#.U60pj42SyDQ
Not sure how much math you have so If you need more help say so
Related
So I made a game, made a map, and everything is working fine. The problem is I made a very dumb collision system that worked first, but I am running into problems.
I am using player's X and Y positions to draw character, and using players tileX and tileY (x/32 and y/32) to detect collision. Heres a picture which explains my problem:
The Red box is players tileX and tileY cordinate.
Player still moves beyound the wall where the collision should happen.
The TileX doesnt let increases/decreases happen if they collide with a solid tile, BUT player's X and Y (sprite) still moves beyond that box for 31 more pixels. I have no idea how to fix this. My player image is not centered, its drawn on the top-right corner.
This is the current code im using:
for i=1, #lsx_map1 do
if math.floor(player.fx/32) == lsx_map1[i] and math.floor(player.fy/32) == lsy_map1[i] then
player.speedx = 0
player.speedy = 0
print("COLISSION DETECTED ON "..player.x.." "..player.y)
else
print(colVar)
colVar = colVar+1
end
end
if colVar == #lsx_map1 then
player.x = player.fx
player.y = player.fy
end
lsx_map1 is the number of solid tiles, and colVar should equal to that number if collision doesnt happen. In case collision happens, that number doesnt increase by one, and then nothing happens. Ask for any more details you need if you want to help me but you need more information.
Any help or tips would be appreciated. Thank you.
I'm trying to code a Pong game on Lua using the framework Love2D with some extra features. Among others, I want curves to occur. In order to do so, I'm trying to implement the trajectory of horizontally launched projectiles. I have a ball table with a position attribute for x (ball.x) and another for y (ball.y). I, also, have a an attribute for the x velocity (ball.dx) and another for the y velocity (ball.dy). Finally, I have an acceleration variable (gravity)
In my game, if the paddle moves and the ball hits it, the ball should follow and horizontal curve. In order to create my curves, I want to change the y-axis velocity on each frame in order to make my ball move in an arc across the screen. The main issue that I have is that I don't know how to change this velocity in each frame in order to create the expected arc. The most recent attempt that I made was to create a while loop like the following code. However, it creates an infinite loop. Can someone enlighten me please?
Clarification:
-Player.x and player.y are the player coordinate
-Player2.x and Player2.y are the opponent coordinate
-This piece of code is inside another if statement detecting a collision. It is inside the love.update(dt) function.
Thank you so much!
if love.keyboard.isDown("up") and distanceBetween(ball.x,ball.y,player.x,player.y)>30 then
ball.dy=0
while CollisionDetector(ball.x,player2.x,ball.y,player2.y, player2.width,player2.height,ball.size)==false or ball.x>0 or ball.y-20>0 or ball.y+20<love.graphics.getHeight() do
ball.dy=ball.dy+gravity*dt
ball.y=ball.y+ball.dy
end
end
I believe the snippet you've provided is a part of love.update function. (At least it should be.) That function is supposed to perform a single step of the game at a time and return. It is not supposed to handle the whole flight in a single call.
In your particular case, while loop expects the ball to move, but that is not something that will happen until the loop and encompassing function end.
In general, to simulate ongoing processes you'll have to store the information about such process. For example, if you want gravity be dependent on the paddle movement direction, then you'll have to modify the corresponding variable and store it between the call.
In your code, there are multiple other design flaws that make it do not what you think it should do. With some functions and code parts left to be implemented by yourself, the code outline would look as follows:
function collides(ball,player)
return (ball.x,player.x,ball.y,player.y, player.width,player.height,ball.size)
end
function love.update(dt)
handle_paddle_movements()
--handle the ball-paddle interaction
if collides(ball,player1) or collides(ball,player2) then
ball.dx=-ball.dx
if love.keyboard.isDown("up") then
--store the info you need to know about the interaction
ball.d2y = -gravity
else if love.keyboard.isDown("down")
ball.d2y = gravity
else
ball.d2y = 0
end
end
handle_the_wall_collision()
--ball movement code should be separate from collision handling
--concrete equations can be whatever you want
ball.x = ball.x+ball.dx*dt
ball.dy = ball.dy + ball.d2y * dt
ball.y = ball.y + ball.dy * dt
end
My code for physics in my game is this:
-- dt = time after each update
self.x = math.floor(self.x + math.sin(self.angle)*self.speed*dt)
self.y = math.floor(self.y - math.cos(self.angle)*self.speed*dt)
-- addVector(speed,angle,speed2,angle2)
self.speed,self.angle = addVector(self.speed,self.angle,g,math.pi)`
when it hits the ground, the code for it to bounce is :
self.angle = math.pi - self.angle
self.y = other.y - self.r`
the function addVector is defined here:
x = math.sin(angle)*speed + math.sin(angle2)*speed2
y = math.cos(angle)*speed + math.cos(angle2)*speed2
v = math.sqrt(x^2 + y^2)
a = math.pi/2 - math.atan(y,x)
return v,a
but when I place a single ball in the simulation without any drag or elasticity, the height of the ball after each bounce keeps getting higher. Any idea what may be causing the problem?
Edit: self.r is the radius, self.x and self.y are the position of the centre of the ball.
Your Y axis is increasing downward and decreasing upward.
Making self.y = math.floor(..) moves your ball a bit upward every frame.
The solution is to store your coordinates with maximal precision.
You could make new variable y_for_drawing = math.floor(y) to draw the ball at pixel with integer coordinates, but your main y value must have fractional part.
I’ve managed to get your code to run and reproduce the behavior you are seeing. I also find it difficult to figure out the issue. Here’s why: movement physics involves position, which is affected by a velocity vector, which in turn is affected by an acceleration vector. In your code these are all there, but are in no way clearly separated. There are trig functions and floor functions all interacting in a way that makes it difficult to see what role they are playing in the final position calculation.
By far the best and easiest-to-understand tutorial to help you implement basic physics lime this is The Nature of Code (free to read online, with interactive examples). As an exercise I ported most of the early exercises into Lua. I would suggest you see how he clearly separates the position, velocity and acceleration calculations.
As an experiemnt, increase g to a much higher number. When I did that, I noticed the ball would eventually settle to the ground, but of course the bouces were too fast and it didnt bounce in a way that seems natural.
Also, define other.y - it doesnt seem to affect the bouncing issue, but just to be clear on what that is.
I might be stupid or something. But, I'm having a hard time with this. I usually find examples of code but it just confuses me. Unfortunately there isn't any good tutorial for this. I been using Lua for almost a year so I kinda have experience. Help would be extremely appreciate!
Basically I want to learn how to make rectangle jump up and then go back down.
For a single block that you control, you essentially need to store it's gravity and figure out a nice acceleration for it.
currentGravity = 0;
gravity = 1;
Then in the loop, you have to check if it's on ground using some collision detection. You want to add the gravity acceleration to currentGravity:
currentGravity = currentGravity + gravity
Then, you add it to the current y axis of the block:
YAxis = YAxis + currentGravity
Once you land, make sure to set gravity to 0. Also be sure to keep setting it to 0 to ensure you don't fall through the ground (as you kept adding to gravity no matter what.)
if not inAir() then
currentGravity = 0
end
And, of course, to jump, set currentGravity to a negative number (like 20) (if that's how you made the gravity work.)
Here's a collision detection function I made for Love2D:
function checkCollision(Pos1,Size1,Pos2,Size2)
local W1,H1,W2,H2 = Size1[1]/2,Size1[2]/2,Size2[1]/2,Size2[2]/2
local Center1,Center2 = {Pos1[1]+W1,Pos1[2]+H1},{Pos2[1]+W2,Pos2[2]+H2}
local c1 = Center1[1]+(W1) > Center2[1]-W2
local c2 = Center1[1]-(W1) < Center2[1]+W2
local c3 = Center1[2]+(H1) > Center2[2]-H2
local c4 = Center1[2]-(H1) < Center2[2]+H2
if (c1 and c2) and (c3 and c4) then
return true
end
return false
end
It assumes the position you gave it is the center of the block. If the box is rotated it won't work. You'll have to figure out how to make it work with walls and the like. And yes, it's ugly because it's very old. :p
I'm new to Corona and looking for a little help manipulating moving objects:
Basically I want a set up where when I can click on a moving object, a dialog box will pop up giving me the option to change the speed of the object and the vector of travel. I'm pretty sure I can figure out the event handling and the dialog but I'm stuck on simply changing the direction of travel to the new vector
in a simple example, I have a rect moving up the screen as follows:
obj1 = display.newRect(500, 800, 10, 40)
transition.to(obj1,{x=500, y = 100, time = 40000})
I know I can change the speed by adjusting the time, but if I use
obj1:rotate(30)
to turn the object 30 degrees, how do I make it travel in the new direction?
Should I be using physics - linear impulse for example, instead of transitions?
Apologies if this is a stupid question but I have searched without success for a solution.
This sounds like what you are trying to do. You would have to modify bits to fit your code but this is a working example. So if you copy it to a new main.lua file and run it you can see how it works. (Click to rotate obj).
local obj = display.newRect(50,50, 10, 40)
local SPEED = 1
local function move(event)
obj.x = obj.x + math.cos(math.rad(obj.rotation)) * SPEED
obj.y = obj.y + math.sin(math.rad(obj.rotation)) * SPEED
end
local function rotate(event)
obj.rotation = obj.rotation + 45
end
Runtime:addEventListener("enterFrame", move)
Runtime:addEventListener("tap", rotate)
Basically I used the "enterFrame" event to 'move' the rectangle, by recalculating the x and y of the objects location using its rotation (which is easy enough to modify) every frame.