I am in need of a way to obtain the pixel coordinates of a rect transform.
x position where 0 is the left of the screen and y position where 0 is the bottom of the screen.
You want to use Camera.WorldToScreenPoint.
Convert the object origin.
Convert the object origin+width.
Convert the object origin+height.
Your pixel coords are Array[origin.x, origin.y, origin.x+width, origin.y+height]
In 3d there are not pixels. Only a units in unity 3d.
float x = transform.x;
float y = transform.y;
You will get units in x, y.
If you working with textures you might use Texture2D, it has some methods for pixel working.
Related
I am trying to calculate circular motion (orbit) around an object. The code i have gives me a nice circular orbit around the object. The problem is that when i rotate the object, the orbit behaves as though the object were not rotated.
I've put a really simple diagram below to try and explain it better. The left is what i get when the cylinder is upright, the middle is what i currently get when the object is rotated. The image on the right is what i would like to happen.
float Gx = target.transform.position.x - ((Mathf.Cos(currentTvalue)) * (radius));
float Gz = target.transform.position.z - ((Mathf.Sin(currentTvalue)) * (radius));
float Gy = target.transform.position.y;
Gizmos.color = Color.green;
Gizmos.DrawWireSphere(new Vector3(Gx, Gy, Gz), 0.03f);
How can i get the orbit to change with the objects rotation? I have tried multiplying the orbit poisition "new Vector3(Gx,Gy,Gz)" by the rotation of the object:
Gizmos.DrawWireSphere(target.transform.rotation*new Vector3(Gx, Gy, Gz), 0.03f);
but that didn't seem to do anything?
That is happening because you are calculating the vector (Gx, Gy, Gz) in world space coordinates, where the target object's rotations are not taken in consideration.
One way to solve your needs is to calculate this rotation using the target object's local space coordinates, and then convert them to world space coordinates. This will correctly make your calculations consider the rotation of the target object.
float Gx = target.transform.localPosition.x - ((Mathf.Cos(currentTvalue)) * (radius));
float Gz = target.transform.localPosition.z - ((Mathf.Sin(currentTvalue)) * (radius));
float Gy = target.transform.localPosition.y;
Vector3 worldSpacePoint = target.transform.TransformPoint(Gx, Gy, Gz);
Gizmos.color = Color.green;
Gizmos.DrawWireSphere(worldSpacePoint, 0.03f);
Notice that instead of target.transform.position, which retrieves the world space coordinates of the given transform, I am doing the calculations using the target.transform.localPosition, which retrieves the local space coordinates of the given transform.
Also, I am calling the TransformPoint() method, which converts the coordinates which I have calculated in local space to its corresponding values in world space.
Then you might safely call the Gizmos.DrawWireSphere() method, which requires world space coordinates to work correctly.
so the quest is this, I got an ARPointCloud with a bunch of 3d points and I'd like to select them based on a 2d frame from the perspective of the camera / screen.
I was thinking about converting the 2d frame to a 3d frustum and check if the points where the 3d frustum box, not sure if this is the ideal method, and not even sure how to do that.
Would anyone know how to do this or have a better method of achieving this?
Given the size of the ARKit frame W x H and the camera intrinsics we can create planes for the view frustum sides.
For example using C++ / Eigen we can construct our four planes (which pass
through the origin) as
std::vector<Eigen::Vector3d> _frustumPlanes;
frustumPlanes.emplace_back(Eigen::Vector3d( fx, 0, cx - W));
frustumPlanes.emplace_back(Eigen::Vector3d(-fx, 0, -cx));
frustumPlanes.emplace_back(Eigen::Vector3d( 0, fy, cy - H));
frustumPlanes.emplace_back(Eigen::Vector3d( 0, -fy, -cy));
We can then clip a 3D point by checking its position against the z < 0
half-space and the four sides of the frustum:
auto pointIsVisible = [&](const Eigen::Vector3d& P) -> bool {
if (P.z() >= 0) return false; // behind camera
for (auto&& N : frustumPlanes) {
if (P.dot(N) < 0)
return false; // outside frustum plane
}
return true;
};
Note that it is best to perform this clipping in 3D (before the projection) since points behind or near the camera or points far outside
the frustum can have unstable projection values (u,v).
I have a rectangle in 3D space that I need to project to 2D to the screen.
The camera is orthographic, so I figured - can I just set the Z coordinates of the 4 points of the rectangle to 0, so they would splat on the screen?
When I rotate a rectangle on the Y axis for instance, since the camera is orthographic - all I see is the rectangle in front of me getting narrower, because the X and Y components are being altered(along with the Z component).
But if I set the Z to 0 and leave the X and Y, it would still look the same on the orthographic camera.
The question is - is this a viable method? Are there cases where it breaks?
Yes, for building orthographic projection onto OXY plane it is enough to set z=0.
matrix is
(1 0 0 0)
(0 1 0 0)
(0 0 0 0)
(0 0 0 1)
When you rotate origin-centered axis-aligned rectangle about axis Y, it's projection will change width, but height remains the same.
Example: right top corner has coordinates (1, 1, 0). After rotation about Y-axis by angle Fi, it has 3d coordinates (Cos(Fi), 1, Sin(Fi)) and screen coordinates (Cos(Fi), 1)
I have a transform which is being rotated around the X axis. But while transferring this rotation to another transform, i want it to do the exact same rotation. But then around the Z axis.
However, this rotation is not a "rotation" it is just a transform which rotation gets edited from the outside. So i have to rotate the original transform to match the 2nd transform, but take the rotation into account.
Axis in below images: RED = X, GREEN = Y, BLUE = Z
Rotation original:
Rotation it should have after:
What would be the correct way to go about this frame by frame?
Thanks in advance,
Smiley
I can give you an answer that solves the general problem of changing the rotation from one axis to another.
Each transform object has a transform.localRotation property that represents the orientation of the transform, relative to the parent's orientation. If the transform has no parent, than this orientation is relative to World Space.
Quaternion is the data type used to represent rotations, and it has a useful method called ToAngleAxis.
float angle;
Vector3 axis;
transform.localRotation.ToAngleAxis(out angle, out axis);
Will set the variables angle and axis to the angle and axis of localRotation. The out part means that you're passing in a variable meant to be set by the function, rather than to be used as input.
In this case, the angle variable is the part you want to actually use. If you use Quaternion.AngleAxis, providing this angle value and your desired axis, you'll get a new rotation that will match your desired parameters.
For example: To change any rotation of transform1 to a Z-axis rotation on transform2, you would use
float angle;
float axis;
transform1.localRotation.ToAngleAxis(out angle, out axis);
transform2.localRotation = Quaternion.AngleAxis(angle, Vector3.forward);
Hope this helps
How to rotate a 3d game object around its center point in unity 3d.
Just use bounds.center from the renderer
Vector3 position = myGameObject.GetComponent<Renderer>().bounds.center;
myGameObject.transform.RotateAround(position, rotationVector, degreesPerSecond * Time.deltaTime);
where rotationVector is your rotation axis (Vector3)
The two common ways to rotate an object are
The rotate attribute in the transform. Using this one you can set the exact coordinates for the target object rotation. However, you'll have to manage the smoothness by yourself if you want to make animations and the values are given through Quaternion type. I recommend to use the static method Quaternion.Euler so you can pass values in a X, Y, Z. The example below set the object to turn 90 degrees clockwise in the Y axis:
transform.rotation = Quaternion.Euler (0, 90, 0);
The second approach uses the Rotation method in the same transform attribute. This method allow you to pass the amount of degrees in which object will rotate and already accept X, Y and Z coordinates instead Quaternion.
The example below rotate the object 1 degree clockwise in the Y axis:
transform.Rotate (0, 1, 0);
To best understand the difference between both methods, if you use the first one in an Update method you'll see the object static rotated 90 degrees in the Y axis. The second example used in an Update will make the object spin clockwise in the Y axis (too fast).
use
Transform.rotation
look here for Examples/Documentation :
Unity Script Reference