If we have moving dot on square.In Manim we have the function move_along-path for this.However just to make myself understand how the updaters work,I considered the following problem:Suppose the dot is moving on the square(starting from any point on the square) and the square is rotating around its center.How can we trace the path followed by the moving dot.Any help would be greatly appreciated.I am absolutely new to manim and I do not have any idea how to do it
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I've got a project where I move objects around a canvas using pixi.js and GSAP. I'm using the GSAP MotionPath plugin to move the objects along an array on {x, y} coords.
I noticed some of my objects would snap to (0,0) after moving along the path.
here is a codepen showing the issue.
https://codepen.io/barrard/pen/LYyqJwo
The red square snaps back to (0,0) but the yellow box remains at the end of it's path.
The paths are very similar, but I can't understand why one works, and the other doesn't.
Any help is much appreciated, Thanks!
I'm trying to rotate a sphere around the center of another sphere, but I cannot make it work. I tried setActorLocation before and it also wouldn't work.
Any help would be very much appreciated.
main buleprint
RotateAround blueprint
I am currently building an Augmented Reality application and stuck on a problem that seem quite easy but is very hard to me ... The problem is as follow:
My device's camera is calibrated and detect a 2D marker (such as a QRCode). I know the focal length, the sensor's position, the distance between my camera and the center of the marker, the real size of the marker and the coordinates of the 4 corners of the marker and of it center on the 2D image I got from the camera. See the following image:
On the image, we know the a,b,c,d distances and the coordinates of the red dots.
What I need to know is the position and the orientation of the camera according to the marker (as represented on the image, the origin is the center of the marker).
Is there an easy and fast way to do so? I tried some method imagined by myself (using Al-Kashi's formulas), but this ended with too much errors :(. Could someone point out a way to get me out of this?
You can find some example code for the EPnP algorithm on this webpage. This code consists in one header file and one source file, plus one file for the usage example, so this shouldn't be too hard to include in your code.
Note that this code is released for research/evaluation purposes only, as mentioned on this page.
EDIT:
I just realized that this code needs OpenCV to work. By the way, although this would add a pretty big dependency to your project, the current version of OpenCV has a builtin function called solvePnP, which does what you want.
You can compute the homography between the image points and the corresponding world points. Then from the homography you can compute the rotation and translation mapping a point from the marker's coordinate system into the camera's coordinate system. The math is described in the paper on camera calibration by Zhang.
Here's an example in MATLAB using the Computer Vision System Toolbox, which does most of what you need. It is using the extrinsics function, which computes a 3D rotation and a translation from matching image and world points. The points need not come from a checkerboard.
I'm a newbie to KineticJS and have been going through the tutorials. I want to take an image that has a 'front' and rotate it a random number of degrees and then have it move forward a number of pixels/inches in that new direction.
I was able to use this rotation tutorial to rotate my image.
I see how to use transitionTo to send an image to an x/y coordinate.
I'm having trouble tying the two together. I feel like I need randomly generate e a new x/y coordinate and then determine the degree difference between where my image is pointing and a line drawn from the center of the image to the new x/y point.
Does anyone have any tips for doing something like this? How would one draw two lines from one point and determine the angle between them?
Thanks in advance.
You have to calculate the new coordinates thanks to the law of cosines.
http://en.wikipedia.org/wiki/Law_of_cosines
Once you have calculated the angle, you have to be careful because you will get an absolute angle.
Don't hesitate if you need more help. I also have to do this calculation using KineticJS.
Good luck !
The JS Math Object will be useful I guess : http://www.w3schools.com/jsref/jsref_obj_math.asp
I have struggled for the past 3 weeks trying to figure this out. If anyone could help me I would appreciate it so much.
I'm developing a game similar to Geometry Wars in where I have a triangle in the middle of the screen which you can move around.
The problem is I need the triangle to rotate and face toward the direction of the mouse curser. I don't need to worry about the z-axis per-say as I always have the camera in a fixed position (z=500) and I am treating the scene as a "2D scene" - all the action occurs on the z=0 plane.
Calculating the angle between the triangle and the mouse is elementary:
targetAngle = Math.atan2(mouseCoord.y-this.position.y, mouseCoord.x-this.position.x)
where this is the mesh.
The problem is that the mouseCoords are in standed Dom window format whilst the position of the triangle is in Three.js format.
Q) How would I convert the mouse coords to represent the coords on the z=0 plane where the triangle is?
I have tryed so many ways including ray intersection but nothing works ;(
Thank you all for your help and thank you so much for an amazing framework!!!!
I don't actually see the problem. use the THREE.vector3 with the z coord in 0. then use something like triangle.rotate(THREE.vector3(targetAngle,0,0) or something
I suspect your intersection isn't working because of a CSS offset by your canvas within the DOM.
If you need the triangle to look at something specific, you should simply be able to use the "lookAt" method of the triangle.
To have it look at the camera for example:
triangleMesh.lookAt(camera.position);