I'm working on a car drift game, which I want to make skid marks with using the pen.
I created a circle, radius 25 around the car that I am using as a reference for where the tires would be, and I need to get the tire sprite to follow the back end of car according to its rotation. I'm trying to adapt the formulas x'= xcosθ−ysinθ, y'= xsinθ+ycosθ but I don't know how to do it.
I set the initial x value as 0 and the y value as -25, but I know this is wrong because it doesn't stay the same when the car is moved and rotated.
Here is my project:
https://scratch.mit.edu/projects/535410396/
I got the solution from a user of the Scratch Forums. For the x value:
CarX-25*sin(CarRotation)
For the y value:
CarY-25*cos(CarRotation)
Related
I'm attempting to write a bouncing ball game using flame in flutter. To detect collisions the onCollision and onCollisionStart methods are provided. What I had hoped is that onCollisionStart would give a precise location when two objects first hit each other. However, instead it gives a list of positions indicating where the two objects overlap after the first game-tick when this happens (i.e. onCollisionStart is called at the same time as onCollision, but is not called a second time if the same two objects are still colliding on the next tick).
This is illustrated in the attached picture. The collision points are marked with red dots. If the ball were moving downwards, then the ball would have hit the top of the rectangle and so should bounce upwards. However, if the ball were moving horizontally, then its first point of contact would have been the top left corner of the box, and the ball would bounce upwards and to the left.
If I want to work out correct angle that the ball should fly off, then I would need to do some clever calculations to work out the point that the ball first started hitting the other object (those calculations would depend on the precise shape of the other object). Is there some way to work out the point at which the two objects first started colliding? Thanks
What you usually need for this is the normal of the collision, but unfortunately we don't have that for the collision detection system yet.
We do have it in the raytracing system though, so what you could do is send out a ray and see how it will bounce and then just bounce the ball in the same way.
If you don't want to use raytracing I suggest that you calculate the direction of the ball, which you might already have, but if you don't you can just store the last position and subtract it from the current position.
After that you need to find the normals of the edges where the intersection points are.
Let's say the ball direction vector is v, and the two normal vectors are n1 and n2.
Calculate the dot product (this is build in to the vector_math library) of the ball direction vector and each of the normal vectors:
dot1 = v.dot(n1)
dot2 = v.dot(n2)
Compare the results of the dot products:
If dot1 > 0, n1 is facing the ball.
If dot2 > 0, n2 is facing the ball.
After that you can use v.reflect(nx) to get the direction where your ball should be going (where nx is the normal facing the ball).
Hopefully we'll have this built-in to Flame soon!
I have a player object that controls like the ship in Asteroids, using speed and direction. This object is fixed in the middle of the screen, but can rotate. Movement of this object is a visual illusion as other objects move past it.
I need to get x and y coordinates of this player object, from an origin of (0, 0) at room start. x and y do not provide this info as the object does not move. Does anyone know how I can get 'fake coordinates', based on the speed and direction?
One thing to make sure is that you're not just getting x and y on their own, as that will get the current object's x and y position. Instead, make sure to reference the object you're trying to get. For example:
var objectX = myShip.x;
var objectY = myShip.y;
show_debug_message("x: " + string(objectX));
show_debug_message("y: " + string(objectY));
I think you are thinking about it wrong. You do not need "fake coordinates". Real coordinates are fine. Give the ship and asteroids/enemies whatever coordinates and velocity vectors you want; randomly generate them if the game is like Asteroids.
The coordinates do not have to be fake; it is just that when you render in your game loop, you render a particular frame of reference. If the origin is the center of the screen, when you paint an object at (x,y) paint it as though it were at (x - ship_x, y - ship_y) -- including the ship, which will be at (0,0). If you wanted to make rotation relative to the ship too, you could do the same thing with rotation.
Now, you have your question tagged as game-maker. I have no idea if game-maker lets you control how sprites are painted like this. If not then you need to maintain the real coordinates as separate properties of objects and let the official (x,y) coordinates be relative to the ship. The trouble with this is that you will have to update all of the objects everytime the ship moves. But like I said I don't know how GameMaker works -- if it is a problem maybe ask a question more specific to GameMaker.
You'll need to think what you'll use to move the ship around, but then use that code on different variables.
Normally, you'll update the x or y if you want to move the ship, but since you're not going to do that, simply use a custom variable that replaces the x and y value (like posx or posy), and use them on the code that would otherwise be used to move the ship around.
I am getting started with Unity and am just trying to get my head around the units. What are these units? It seems they are their own 'quantity' and to treat 2 units as 2 times the value of 1 unit.
Anyway - I am trying to workout how to optimally calculate transforms to objects sit exactly where I want them to.
In my scene I have a terrain and a cylinder as so:
As you can see my cylinder is floating. I want the cylinder to sit perfectly on top of the terrain.
My terrain is at the following transform: 0,0,0 and scale 0,0,0 (not sure how to tell it's dimensions yet).
My cylinder is part of a new object, as so:
My FirstPersonPlayer is at transform: 85.9,2.165,51.8 and scale 1,1,1. My Cylinder is at 'localposition' 0,0,0 and local scale 1.2,1.8,1.2
Now - the transform of FirstPersonPlayer on the y axis appears to be what I need to correct.
Currently it is set to 2.165 and is floating a bit above the terrain.
Through manually shifting it, around 1.85 looks about right - but I want to know how to calculate that, rather than doing a finger in the air 'that looks about right'.
Can anyone help me? (Before you suggest using gravity etc , I actually am, but don't want the player falling as soon as they start, however slight that may look or feel.
Many thanks,
As per #Nikola Dimitroff the answer is:
You don't have to compute anything, hold Shift + Control and drag the object. Every game engine ever made calls this "Snap to Ground"
I appreciate and agree with the other comments.
Swift beginner struggling with moving a scene node in ARkit in response to the device motion.
What I want to achieve is: First detect the floor plane, then place a sphere on the floor. From that point onwards depending on the movement of the device, I want to move the sphere along its x and z axis to move it around the floor of the room. (The sphere once created needs to be in the center of the device screen and locked to that view)
So far I can detect the floor and place a node no problem. I can use device motion to obtain the device attitude (pitch, roll and yaw) but how to translate these values into meaningful x, y, z positions that I can update my node with?
Are there any formulas or methods that are used to calculate such information or is this the wrong approach? I would appreciate a link to some info or an explanation of how to go about this. Also I am unsure how to ensure the node would be always at the center of the device screen.
so, as far as I understood you want to have a following workflow:
Step 1. You create a sphere on a plane (which is already done)
Step 2. Move the sphere with respect to the camera's horizontal plane (i.e. along its x and z axis to move it around the floor of the room depending on the movement of the device)
Assuming that the Step 1 is done, what you can do:
Get the position of the camera and the sphere
This should be first called within the function that is invoked after sphere creation (be it a tapGestureRecognizer(), touchesBegan(), etc.).
You can do it by calling position property of SCNNode for sphere and for camera position and/or orientation by calling sceneView.session.currentFrame's .camera.transform which contains all necessary parameters about current position of the camera
Move the sphere as camera moves
Having the sphere position on the Scene and the transformation matrix of the camera, you can find the distance relation between them. Here you can find a good explanation of how exactly you can do it
After you get those things you should implement a proper logic within renderer(_:didUpdate:for:) to obtain continuous lock of the ball with respect to the camera position
If you are interested about the math behind it, you can kick off by reading more about transformation matrices which is a big part of Image Processing and many other areas
Hope that this will help!
I want to create 2d game. The game is similar to the Scale Puzzle. I've already created nearly all the functionality. Only the last remains.
.
This is example.
And that's how I draw shapes.
.
I click inside a white square, and after 1 seconds a square is drawn regardless of the position of the ball. (x,y).
Square is created programmatically, and it is added to the parent element "SquaresList" with name New Game Object.
How can i do, so that the violet field becomes larger, and in the middle of the screen.
I made it so that for every 3 clicks, "SquaresList" increases Scale by 0.25f, and get negative position of the ball. Example:
SquareList.transform.position = new Vector2(-ball.pos.x, -ball.pos.y)
This does not work correctly.
What options can be? (intersections, find the max/min point, math formulas) ?
Hi NoName :) Your method
SquareList.transform.position = new Vector2(-ball.pos.x, -ball.pos.y)
would work perfectly if your object does not inherit other objects and there positions. To fix this make sure that you reset the position of all other game objects that you use as containers.