How do I Instantiate Objects In Unity? - c#
I am making a top down game in Unity, how do I instantiate objects based on the players current position from the top of the camera view in Unity?
So far I have tried:
Instantiate(prefab, player.transform.position * 2 * Space.World)
but this didn't work. This just spawned objects from the center of the camera.
Space is simply an enum and has nothing to do with what you are trying! (Its purpose is to define the relative transform space for e.g. Transform.Rotate or Transform.Translate)
in that enum afaik
Space.World simply has the int value 0
Space.Self has the int value 1
so what you actually do is
Instantiate(prefab, player.transform.position * 2 * 0);
which equals
Instantiate(prefab, Vector3.zero);
which means the object is instantiated at World position 0,0,0.
Also using
Instantiate(prefab, player.transform.position * 2);
looks a bit strange. Are you sure you want to duplicate the actual position of the player? This would mean the spawned object is always on a line with the player and the World 0,0,0 and always double as far from the center as the player.
To me it sounds more like you rather want to spawn something in front of the player ... depending on the player's view direction (in topdown games usually player.transform.up or player.transform.right) so I guess what you are trying to do instead is something like
Instantiate(prefab, player.transform.position + player.transform.forward * 2);
which would instead spawn the object 2 Unity units in front of the player object
After your comment it sounds like instead you want to spawn the object at the player position on the X-axis but "over it" on the Y-axis so
Instantiate(prefab, player.transform.position + Vector3.Up * 2);
maybe you'll have to tweak the 2 depending how your player can move and how far it has to be to be "off screen". Alternatively you could also use a bit more complex using Camera.ScreenToWorldPoint
// get players position
var playerPos = player.transform.position;
// get camera's position
var cameraPos = Camera.main.transform.position;
// get difference on Z-axis
var cameraDistance = cameraPos.z - playerPos.z;
// Get the world 3d point for the upper camera border
// don't care about the X value
// and as distance we use the z-distance to the player
var cameraTopPoint = Camera.main.ScreenToWorldPoint(new Vector3(0, Camera.main.pixelHeight, cameraDistance);
// use the players X-axis position
cameraTopPoint.x = player.transform.x;
// to spawn it exactly on the Screen border above the player
Instantiate(prefab, cameraTopPoint);
// or to spawn it a bit higher
Instantiate(prefab, cameraTopPoint + Vector3.Up * 1);
Update
you said you want the prefab to be spawned on the "opposide" of the player position on the X axis.
If your Camera is static on world x=0 than this is actually quite simple:
cameraTopPoint.x = -player.transform.x;
If your camera is moving or not on x=0 than we have to calculate it already on the screen position level:
// get players position
var playerPos = player.transform.position;
// additionally convert the player position to screen space
var playerScreenPos = Camera.main.WorldToScreenPoint(playerPos);
var centerX = Camera.main.pixelWidth / 2.0f;
// get the difference between camera an player X (in screen space)
var differenceX = Mathf.Abs(playerScreenPos.x - centerX);
// here calculate the opposide side
var targetX = centerX + differenceX * (playerScreenPos.x < centerX ? 1 : -1);
// or alternatively if you want e.g. that the prefab always
// spawn with a bit of distance to the player even though he is very close
// to the center of the screen you could do something like
//var targetX = centerX + centerX / 2 * (playerScreenPos.x < centerX ? 1 : -1);
// Get the world 3d point for the upper camera border
// with the calculated X value
// and as distance we use the z-distance to the player
var cameraTopPoint = Camera.main.ScreenToWorldPoint(new Vector3(targetX, Camera.main.pixelHeight, playerScreenPos.z);
// to spawn it exactly on the Screen border above the player
Instantiate(prefab, cameraTopPoint);
// or to spawn it a bit higher
Instantiate(prefab, cameraTopPoint + Vector3.Up * 1);
Other Update
Ok so you want the prefab always spawn next to the player in a certain distance. The side depends on which side of the screen the player is so you could actually use the first approach again but just add the desired distance:
// Adjust this is the Inspector (in Unity units)
public float spawnDistanceToPlayer;
...
// get players position
var playerPos = player.transform.position;
// additionally convert the player position to screen space
var playerScreenPos = Camera.main.WorldToScreenPoint(playerPos);
var centerX = Camera.main.pixelWidth / 2.0f;
// Get the world 3d point for the upper camera border
// with the calculated X value
// and as distance we use the z-distance to the player
var cameraTopPoint = Camera.main.ScreenToWorldPoint(new Vector3(playerScreenPos.x, Camera.main.pixelHeight, playerScreenPos.z);
// now add or reduce spawnDistanceToPlayer
// depending on which side of the screen he is
cameraTopPoint.x += spawnDistanceToPlayer * (playerScreenPos.x < centerX ? 1 : -1);
// OR if your camera sits static on X=0 anyway you also could compare
// the player position directly without calculating in screenspace:
cameraTopPoint.x += spawnDistanceToPlayer * (playerPos.x < 0 ? 1 : -1);
// to spawn it exactly on the Screen border above the player
Instantiate(prefab, cameraTopPoint);
// or to spawn it a bit higher
Instantiate(prefab, cameraTopPoint + Vector3.Up * 1);
Typed on smartphone so might not be "copy-paste-able" ;)
Related
Need to rotate object on z axis to point at/look at mouse on xy plane
I am making a 3d side scroller. need to rotate gun on z axis to face mouse on x,y plane. This is What I have so far. Tried lookat and angle. They sort of worked but would not point correctly. only half of the screen. I just think I am missing something.
void FixedUpdate()
{
screenPosition = Input.mousePosition;
screenPosition.z = 1; //mainCamera.nearClipPlane + 1;
worldPosition = mainCamera.ScreenToWorldPoint(screenPosition);
worldPosition.z = 0;
//Angle?????
transform.rotation = Quaternion.Slerp(rb.transform.rotation,
Quaternion.Euler(0,0,angle), 0.7f);
}
In order to get the angle there is no need to convert to world space. Indeed actually it is way easier to go the other way round and convert your objects position into screen space. Then you can simply use the Mathf.Atan2 on the pixel space delta var mousePosition = Input.mousePosition; var objectScreenPosition = mainCamera.WorldToScreenPoint(rb.position); var direction = mousePosition - objectScreenPosition; // No need to normalize btw var angle = Mathf.Atan2(direction.x, direction.y) * Mathf.Rad2Deg; // since this seems to be a rigidbody I would rather use this rb.MoveRotation(Quaternion.Slerp(rb.rotation, Quaternion.Euler(0, 0, angle), 0.7f); // NOTE: Or in case your rb is actually Rigidbody2D then rather simply rb.MoveRotation(Mathf.Lerp(rb.rotation, angle, 0.7f));
How do I make Rigidbody2D.MovePosition move a gameobject in local space?
I found a way to find what the title says for Rigidbody but not for Rigidbody2D, since the original method involves using Transform.TransformDirection(), which only functions on Vector3 while Rigidbody2D.MovePosition functions on Vector2. I essentially need a bullet to move forward, with two more bullets moving forward but rotated at a 45 degree angle difference. How would i go about doing this?
Your question reminded me of a game I made for a game jam a while ago so I checked the code, and it seems I used Quaternion.AngleAxis to rotate the bullets. I'm assuming you have a reference to the prefab you want to clone (in this example, it's projectilePrefab), as well as a firePoint Transform that represents the position you want to shoot from and the rotation of the middle projectile. // Middle Bullet GameObject mBullet = Instantiate(projectilePrefab, firePoint.position, firePoint.rotation); var mRb = mBullet.GetComponent<Rigidbody2D>(); middleRb.AddForce(mRb.transform.up * velocity, ForceMode2D.Impulse); // Left Bullet GameObject lBullet = Instantiate(projectilePrefab, firePoint.position, firePoint.rotation); // Rotate here lBullet.transform.up = Quaternion.AngleAxis(-45, Vector3.forward) * firePoint.transform.up; var lRb = lBullet.GetComponent<Rigidbody2D>(); lRb.AddForce(lBullet.transform.up * velocity, ForceMode2D.Impulse); // Right Bullet GameObject rBullet = Instantiate(projectilePrefab, firePoint.position, firePoint.rotation); // Rotate here rBullet.transform.up = Quaternion.AngleAxis(45, Vector3.forward) * firePoint.transform.up; var lRb = lBullet.GetComponent<Rigidbody2D>(); lRb.AddForce(lBullet.transform.up * velocity, ForceMode2D.Impulse); Let me know if you run into any issues with this code, I can't test it right now.
I'm assuming you have a bullet prefab, and that you are instantiating 3 bullets at once, but want 2 of them to be at -45 and 45 degrees respectively. //bullet is whatever prefab you have var bl = Instantiate(bullet); var bl = Instantiate(bullet); bl.transform.rotation = //Set rotation here to 45 deg var bl = Instantiate(bullet); bl.transform.rotation = //Set rotation here to -45 deg
Between Vector2 and Vector3 exists an implicit conversion and vise versa. Both types can more or less be used exchangeable which will either create a Vector3 where z is simply 0 or create a Vector2 only using the x and y and simply ignoring the z. You can simply pass a Vector3 as parameter to Rigidbody2D.MovePosition and it will implicitly convert it to a Vector2 ignoring the Z component.
How can i set an offset on my Enemy script so he can easy take a shoot
So i have a small code in my 2d game in unity that if my enemy's y position equal to my player's y position, then my Enemy will shoot a bullet, the thing is right now my enemy need exactly position to take a shoot, so is there anyway that i can add and offset to get this easier
if (target.position.y == boss.position.y)
{
Shoot();
}
You can simply find the distance between two values by doing |x - y|
var targetPosition = target.position.y;
var enemyPosition = boss.position.y;
var offSet = 3f;
var shouldShoot = Mathf.Abs(targetPosition - enemyPosition) <= offSet;
if(shouldShoot) {
Shoot();
}
how to only transform.position the x position and not also the y c# unity
I need help with changing one of my c# scripts. I have created 2d sprite buttons in unity that have a box collider on and use the OnMouseDown() function. I have a c# script to make the buttons follow the player and to offset them so that they aren't on top of the player. But when my player jumps, the y and x position of the buttons change as well, so the buttons 'jump' aswell. I need to keep the coords.y = playerTransform.position.y; and offset because the button needs to be offset. I would like for the position of the buttons to change on the x axis but not the y. Here is my code: Vector3 coords = transform.position; //stores the current camera position in coords coords.x = playerTransform.position.x; // set coords to be equal to the current players x coordinate coords.y = playerTransform.position.y; coords.x += offsetX; coords.y += offsetY; transform.position = coords; //set the cameras position to be equal to coords
transform.Translate(new Vector3(playerTransform.x + offsetX, 0, 0)); This takes less code and adds the Vector3 that you pass in to transform.position. Just set the coordinates that you don't want to change to 0.
How to calculate the (proper) transformation matrix between two frames (axial systems) in Unity3D
For a project in Unity3D I'm trying to transform all objects in the world by changing frames. What this means is that the origin of the new frame is rotated, translated, and scaled to match the origin of the old frame, then this operation is applied to all other objects (including the old origin). For this, I need a generalized, 3-dimensional (thus 4x4) Transformation-Matrix. I have looked at using Unity's built-in Matrix4x4.TRS()-method, but this seems useless, as it only applies the Translation, Rotation & Scale to a defined point. What I'm looking for, is a change of frames, in which the new frame has a different origin, rotation, AND scale, with regards to the original one. To visualize the problem, I've made a small GIF (I currently have a working version in 3D, without using a Matrix, and without any rotation): https://gyazo.com/8a7ab04dfef2c96f53015084eefbdb01 The values for each sphere: Origin1 (Red Sphere) Before: Position (-10, 0, 0) Rotation (0,0,0) Scale (4,4,4) After: Position (10, 0, 0) Rotation (0,0,0) Scale (8,8,8) - Origin2 (Blue Sphere) Before: Position (-20, 0, 0) Rotation (0,0,0) Scale (2,2,2) After: Position (-10, 0, 0) Rotation (0,0,0) Scale (4,4,4) - World-Object (White Sphere) Before: Position (0, 0, 10) Rotation (0,0,0) Scale (2,2,2) After: Position (30, 0, 20) Rotation (0,0,0) Scale (4,4,4) Currently I'm simply taking the Vector between the 2 origins, scaling that to the difference between the two origins, then applying that on top of the new position of the original (first) origin. This will of course not work when rotation is applied to any of the 2 origins. // Position in original axes Vector3 positionBefore = testPosition.TestPosition - origin.TestPosition; // Position in new axes Vector3 positionAfter = (positionBefore * scaleFactor) + origin.transform.position; What I'm looking for is a Matrix that can do this (and include rotation, such that Origin2 is rotated to the rotation Origin1 was in before the transformation, and all other objects are moved to their correct positions). Is there a way to do this without doing the full calculation on every Vector (i.e. transforming the positionbefore-Vector)? It needs to be applied to a (very) large number of objects every frame, thus it needs to be (fairly) optimized. Edit: Scaling will ALWAYS be uniform.
There might be other solutions but here is what I would do
Wrap your objects into the following hierarchy
WorldAnchorObject
|- Red Sphere
|- Blue Sphere
|- White Sphere
Make sure the WorldAnchorObject has
position: 0,0,0
rotation: 0,0,0
localScale: 1,1,1
position/rotate/scale the Spheres (this will now happen relative to WorldAnchorObject)
Now all that is left is to transform the WorldAnchorObject -> it will move, scale and rotate anything else and keeps the relative transforms intact.
How exactly you move the world anchor is your thing. I guess you want to allways center and normalize a certain child object. Maybe something like
public void CenterOnObject(GameObject targetCenter)
{
var targetTransform = targetCenter.transform;
// The localPosition and localRotation are relative to the parent
var targetPos = transform.localPosition;
var targetRot = targetTransform.localRotation;
var targetScale = targetTransform.localScale;
// First reset everything
transform.position = Vector3.zero;
transform.rotation = Quaternion.Idendity;
transform.localScale = Vector3.one;
// set yourself to inverted target position
// After this action the target should be on 0,0,0
transform.position = targetPos * -1;
// Scale yourself relative to 0,0,0
var newScale = Vector3.one * 1/targetScale.x;
ScaleAround(gameObject, Vector3.zero, newScale);
// Now everything should be scaled so that the target
// has scale 1,1,1 and still is on position 0,0,0
// Now rotate around 0,0,0 so that the rotation of the target gets normalized
transform.rotation = Quaternion.Inverse(targetRotation);
}
// This scales an object around a certain pivot and
// takes care of the correct position translation as well
private void ScaleAround(GameObject target, Vector3 pivot, Vector3 newScale)
{
Vector3 A = target.transform.localPosition;
Vector3 B = pivot;
Vector3 C = A - B; // diff from object pivot to desired pivot/origin
float RS = newScale.x / target.transform.localScale.x; // relative scale factor
// calc final position post-scale
Vector3 FP = B + C * RS;
// finally, actually perform the scale/translation
target.transform.localScale = newScale;
target.transform.localPosition = FP;
}
Now you call it passing one of the children like e.g.
worldAnchorReference.CenterOnObject(RedSphere);
should result in what you wanted to achieve. (Hacking this in on my smartphone so no warranties but if there is trouble I can check it as soon as I'm with a PC again. ;))
Nevermind.. Had to apply the rotation & scale to the Translation before creating the TRS D'Oh