I have a project on Unity where I have a 2D space world, where a player (spaceship) is influenced by the gravitational pull of the surrounding planets. But I'm using Newton's law for gravity (F=G*((M*m)/r^2)), and the problem with this is that the gravitational pull will be active throughout the whole level.
So I'm using the Sphere of influence to get a limit as to where the gravity would stop influencing the spaceship, and to do this it requires me to have the radius of the Planet.
The problem is that my Planets don't all have the same size (or "scale"), but the prefabs do. So the CircleCollider component has a radius of 1.5 referring to the original scale. No matter the scale, it stays the same, even when I rescale it manually, the collider gets bigger with it in the scene view, but the value is the same.
So let's say I have Planet1 with a scale of (20,20,20), and Planet2 with a scale of (10,10,10). They have different scales, but their CircleCollider has a value of 1.5, even though it is clearly twice as big in the scene view.
I've looked everywhere and I still haven't found a way of adjusting the CircleCollider.radius value to the scale of the Planet.
I don't necessarily need to get the CircleCollider radius, but just the Planet radius.
So, as I understood colliders visually are correct size so they will work correctly but you trying to get its value and it is returning some kind of local value. So just multiply it by scale!
Vector3 scl = gameObject.transform.scale();
float colliderRadius = radius*scl;
Note: I dont have Unity opened so it is more like pseudo-code.
Related
I've create a movement script that moves a character (ship) in a topdown view.
Gravity is disabled, but the rest of the settings i left mostly alone.
I'm applying a constant force in the forward or backward direction (local, so relative to the character NOT the world). This however causes some movement in other directions if the character is rotated for some reason.
Debug.Log(nameof(force) + force);
rigidBody2D.AddRelativeForce(force);
Lets me explain with pictures.
Starting point:
Moving forward somewhat (works okay):
Back to starting point (stopping game, starting anew)
And then i manually change the rotation to -90 in the inspector.
I then move forward somewhat.
As we can see since the rotation is -90, moving forward in relative to the character (AddRelativeForce(..)) causes it to move to the right on the screen.
The X position increments accordingly.
However, also the Y component changes, the character gets velocity in this direction, even though i apply no force in that direction - which we can see in the output.
How can I move my character with force without this issue?
Edit:
Here are the project files. Runs under the latest unity 2020.1.14f1. The logic mentioned here is located in MoveExecuteSystem. I use a small ECS framework: https://github.com/Leopotam/ecs
https://wetransfer.com/downloads/b86dfb27b4388b85ac4fef285d87b39520201124193329/00af66
Take into account that AddRealtiveForce adds the force in the local coords system. If the force vector has got always the same value, the outcome is going to be different depending on the rotational position of the entity.
To solve this, you need to apply the force such as: Vector3 force = myShip.forward * forceValue where force value can be an int or a float.
It can be myShip.up or myShip.right depending on what you want. My point is that with the .forward, .up or .right you always will apply the force according to the instant local coordinate system rotational position.
EDIT:
This question seems deeper than I thought, I made the trial in a project myself, and actually there are variations in the position when you apply force only when the object is rotated. Had a quick look and don't know why this is. Seem to be a precisión thinh regarding the rotations of the physics the rigidbody uses under the hood.
I tried to remove the friction which I thought might be also cause of the problem but seems not possible. +1 to this question and lookig forward to know the answer.
EDIT2:
Bounciness and friction can be set to 0 if a new physics material 2d is created, but the issue persists.
You can freeze position in determined axis as a solution, but this does not explain the position variation problem.
In my code, I use OnTriggerExit to detect when an object leaves a previous cube's space, and then create another cube. However, because of delta time, the cube gets placed slightly late creating these varied size gaps:
How do I get rid of them, and position the cube properly?
I am pretty sure I need to interpolate, but I am not sure exactly what/how to do it. If needed, I have the last cube, last frame and current transforms, as well as current speed (in Vector3 form). Thanks!
When you leave, set this cube's position to lastCube.position + size_offset, where size_offset is however big your cubes are in the direction that they're moving.
You already have a reference to the previous cube (due to the OnTriggerExit supplying you with a reference to the other collider, from which you can get the needed Transform).
I don't think this is strictly deltatime,s fault. Physisc engine has its on timestep, and if the velocity is x, the object will travel x*dt per physics step. So, by the time the next round of triggers is fired, the object is already penetrating. You could either use a rigidbody (easier but may not give expected results), or check penetration depth with that collider and offset that
I'm asking a question that has been asked a million times before, but I still haven't found a good answer after going through these and also resorting to other sites:
How to rotate a graphic over global axes, and not to local axes?
rotating objects in opengl
How to rotate vertices exactly like with glRotatef() in OpenGL?
Rotate object about 3 axes in OpenGL
Rotate an object on its own axes in OpenGL
Is it possible to rotate an object around its own axis and not around the base coordinate's axis?
OpenGL Rotation - Local vs Global Axes
Task is relatively simple, I am making an sensor module with accelerometer and gyro onboard, and I need to display rotation.
I have a 3D model of the object in STL format, I've made an STL parser and I can visualise the object perfectly well.
When I try to rotate it I get all kinds of strange results.
I am using SharpGL (the Scene component).
I tried to write an "effect" that (for now) is controlled with 3 separate trackbars, but this will be the data from the sensors.
I wanted to do it as an effect because (in theory) I could have more objects in the scene and I only need to rotate a specific one (and also for educational purposes as I am relatively new to OpenGL).
I tried to rotate the object using quaternions, multiplying them and generating a rotation matrix, then applying gl.MultMatrix(transformMatrix.AsColumnMajorArray).
I also tried gl.Rotate(angleX, 1, 0, 0) (and similar for Y and Z axes).
Depending on the order of quaternion multiplication or gl.Rotate(...) statements, I would get the object to rotate about the local axis (first), something weird (second), and the "world" third. For example, if I did it with quaternions qX*qY*qZ and got the rotation matrix from that, I would get (I think) the rotations about a local X, "arbitrary" Y, and the world Z axes.
The part I cannot understand is that when I apply gl.Rotate(dx, 1, 0, 0) (and others for Y and Z rotations) inside the trackbar's Scroll event, the entire scene rotates about the X, Y, and Z axes and in that order, and exactly as I expected the rotation to happen.
My only issue with this approach is that the entire scene rotates. So if I (hypothetically) wanted to draw a room around the object, the whole room would rotate too, which is not what I want.
I will post any code requested, but I feel there is too much and the aforementioned links have similar code to what I have.
At the end of the day, I want my object (Polygon in SharpGL terms) to rotate about its own axes (or about the "world" axes, but be consistent).
EDIT:
I've placed the project in my dropbox: https://goo.gl/1LzNhn
If someone wants to look at it, any help will be greatly appreciated.
In the MainForm, the TbRotXYZScroll function has trackbar code and the Rotation class is where the problem resides (or so I think).
Rotate X, Y, and Z by say 45 degrees in that order. All seems to work great. Now rotate X, Y, and Z further by another 30 or so degrees, try to visualise about which axis the rotation is happening as you rotate...
X seems to be always world and Z seems to be always local, while Y is something in between (changing the order of rotation changes this).
Going into TbRotXYZScroll function and changing method to 2 does what I want (except the rotation of the entire scene). Tried quaternions and they produce the exact same result, so I must be doing something wrong...
Changing it to 1 produces similar result, but that is applying the rotation to the polygons alone (not what's being rendered as that includes local coordinate axes too).
At the end of the day, I want my object (Polygon in SharpGL terms) to
rotate about its own axes (or about the "world" axes, but be
consistent).
I think this answer you put in your question is somehow explaining the situation. In order to perform rotation around object axis:
1. Perform Translation/Rotation to your object and make the object axis overlap with one of base axis (x,y or z)
2. Perform your rotation
3. Revert your object back to its original position. (simply revert the translation/rotations at step1)
Note: While doing that, one thing you should consider is openGL apply transformations from the reverse order.
Example :
glRotatef(90,1,0,0);
glTranslatef(-5,-10,5);
drawMyObject();
In this case, opengl will first translate your object and then rotate. So while writing your transformations consider that. Here is my answer that may give you an idea.
I am testing out some ideas in Unity where a player can walk around a circle while staying on it (so the circle has its own gravity) and also being oriented properly. This game is currently being done in 2D, so all objects are sprites.
I do hope I can explain myself properly. Please ask if you need any further clarification...
It appeared that I succeeded with my idea until I noticed something odd.
So as expected, the player moves around the circle without falling off (custom gravity worked just fine) and its Z rotation is affected as it aligns itself with a direction:
// Align code:
// We reverse the direction so the object is standing up the right way.
private void Update()
{
transform.up = -(planet.position - transform.position);
}
It works... mostly. However, when the player object's rotation Z naturally reaches 180, it appears to flip horizontally (like a mirror effect) and then it returns to normal as rotation Z leaves 180. The visual flip happens because for some reason the object's Y becomes 180 at the same time too. At no other point does X or Y change in regards to rotation. Only Z. So the moment Z hits 180, Y is affected and the moment we leave Z 180, Y returns to 0.
I'm happy to provide a quick video of it happening in-game if anybody needs some visual understanding of what's going on.
The visibility of this bug tends to rely on how fast you're moving around the circle. If you're moving fast enough, you can probably skip over 180 and not see it happen at all, however if you move slow enough there's no denying it's there. It's also problematic for the fact that I simply make the camera a child of the player so when the player flips, so does the camera causing the entire scene to flip which can look extremely glitchy for a player to see.
I really have no idea how to tackle this issue as I have no clue why it would do such a thing. At every other rotation value it behaves just fine. It's only at Z = 180 (so the object is exactly upside down) does it decide to rotate in the wrong ways.
EDIT: Changed tag to Unity3D
It's probably because of converting quaternions (which is what's actually used internally for rotations) to euler angles for display. Can you try to use Quaternion.Slerp to rotate?
It might be that my math is rusty or I'm just stuck in my box after trying to solve this for so long, either way I need your help.
Background: I'm making a 2d-based game in C# using XNA. In that game I want a camera to be able to zoom in/out so that a certain part of objects always are in view. Needless to say, the objects move in two dimensions while the camera moves in three.
Situation: I'm currently using basic trigonometry to calculate which height the camera should be at for all objects to show. I also position the camera between those objects.
It looks something like this:
1.Loop through all objects to find the outer edges of our objects : farRight, farLeft, farUp, farDown.
2.When we know what the edges of what has to be shown are, calculate the center, also known as the camera position:
CenterX = farLeft + (farRight - farLeft) * 0.5f;
CenterY = farUp + (farDown - farUp) * 0.5f;
3.Loop through our edges to find the largest value compared to our camera position, thus the furthest distance from the center of screen.
4.Using the largest distance-value we can easily calculate the needed height to show all of those objects (points):
float T = 90f - Constants.CAMERA_FIELDOFVIEW * 0.5f;
float height = (float)Math.Tan(MathHelper.ToRadians(T)) * (length);
So far so good, the camera positions itself perfectly based on the calculations.
Problem:
a) My rendering target is 1280*720 with a Field of View of 45 degrees, so one always sees a bit more on the X-axis, 560 pixels more actually. This is not a problem per se but more one that on b)...
b) I want the camera to be a bit further out than it is, so that one sees a bit more on what is happening beyond the furthest point. Sure, this happens on the X-axis, but that is technically my flawed logic's result. I want to be able to see more on both the X- and Y-axis and to control this behavior.
Question
Uhm, so to clarify. I would like to have some input on a way to make the camera position itself, creating this state:
Objects won't get closer than say... 150 pixels to the edge of the X-axis and 100 pixels to the edge of the Y-axis. To do this the camera shall position itself along the Z-axis so that the field of view covers it all.
I don't need help with the coding, just the math and logic of calculating the height of my camera. As you probably can see, I have a hard time wrapping this inside my head and even harder time trying to explain it to you.
If anyone out there has been dealing with this or is just better than me at math, I'd appreciate whatever you have to say! :)
Don't you just need to add or subtract 150 or 100 pixels (depending on which edge you are looking at) to each distance measurement in your loop at step 3 and carry this larger value into length at step 4? Or am I missing something.
I can't explore this area further at the moment, but if anyone is having the same issue but is not satisfied by provided answer there is another possibility in XNA.
ViewPort.Unproject()
This nifty feature converts a screen space coordinate to a world space one.
ViewPort.Project()
Does the opposite thing, namely converting world space to screen space. Just thought that someone might want to go further than me. As much as my OCD hates to leave things not perfect, I can't be perfectioning this... yet.