So, I am making a cutom PieChartView and now I want to hilight the piece of the chart I clicked on, however I don't know how to detect which piece of the pie chart I clicked on since the whole View is actually a square. Could anyone point me in the right direction?
Use atan2 to convert the vector with respect to the center of the chart into an angle. Turning that angle into a piece of the pie should be simple, but depends on how you represent your pie.
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I'm developing a game in libGDX, and the levels in my grid contains a grid actor which contains mirrors inside (see my game). The problem is that the grid is too big and I want to be able to see all the stage.
I'm using an OrthographicCamera and an ExtendViewport.
I tried using frustrum (I don't really know what it is): I create four BoundingBox (left, right, top and down) which are placed out of the grid. I set the camera position to the middle of the grid actor and i make a loop zooming the camera until the boxes are in the frustrum, but I don't know if it is the best solution...
I think you want to use a FitViewport, which will make sure you don't 'spill' off the screen.
FYI, the frustum is used to determine depth of your camera- how far it can see. I agree that that won't help you in this situation.
I am making a game with libGDX (with box2d) in which you drag and aim one circle body at another then release to fire. I would like to be able to predict the path of the second circle based on the aim of the first. very like 8 ball pool when aiming your shot.
I have been playing around with various trig solutions but i just cant get it to work at all! I have also been reading about ray casting in which I would cast a ray from the center of the first circle body in the direction i am aiming. this would tell me where the ray intersects the second circle body (if it does so) but it would not be correct as the circle fixture would not actually collide where they ray does because it obviously has a radius.
Is the trig solution the correct path or is there a simpler way to do this?
I'd like to set an angle on an image view and have that angle be generated randomly, and set the ancho point of the image view to the center of the android screen. After that I'd like the computer to generate a spot from a certain distance of the middle to the end of the screen on that angle and set a button to appear there. I'm not sure if eclipse has a quick automatic way to do that.
Thanks.
I've added a picture to help. I'd like the arrow to point to a random angle and then a button to appear on that angle but outside of the circle (the circle is imaginary just showing that it needs to appear outside of a certain distance from the center.
You can use setRotation method for rotate a view in android.
image.setRotation(90); // instead of 90 you can give your generated value.
// But make sure the value should be float.
image.setRotationX(90); // if you want rotate depends x axis
image.setRotationY(90); // if you want rotate depends y axis
also take a look on here
I hope this will help you.
I'm making a minecraft-inspired game through Java LWJGL, which is heavy into development already. However, I am not quite sure what method I would use to pick/highlight the nearest block in the exact center of the player's view frustum.
I am already storing frustum and positional data, which I could use.
I had a vague idea about using raycasting, but this seems to be unrelated based on what people have done with raycasting.
So which function or test would I use to determine this?
Raycasting will definitively work. You need to create a ray from the orientation of your camera and its position.
If your camera rotation matrix has no scale, the axis is the third column ( the z-axis ). Now depending on your convention, z axis may point to screen or to the world
I'm currently writing an application that actually acts as a "cut" tool for 3D meshes. Well, I had some problems with it now which I am clueless on how to solve, since it is my first application.
I have loaded a model from an object file onto the canvas, then on the same canvas, I use the mouse drag event to draw lines to define the cutting point.
Let us say I want to cut a ball into half and I draw the line in the middle. How do I detect the vertices of the ball under the line.
Secondly, if I rotate/translate the ball, would all the the vertices information change?
Think of what you'd do in the real world: You can't cut a ball with a line, you must use a knife (a line has no volume). To cut the ball, you must move the knife through the ball.
So what you're looking after is a plane, not a line. To get such a plane, you must use some 3D math. What you have is the canvas orientation and the "side view" of the plane (which looks like a line).
So the plane you're looking for is perpendicular to the canvas. A simple way to get such a plane is to take the canvas orientation and create a plane which has the same orientation and then rotate the plane around the line by 90°.
After that, you can visit all edges of your model and determine on which side of the plane they are. For this, determine on which side of the plane the end points of the edge are. Use the cross product. If they are on the same side (both results of the cross products will have the same sign), you can ignore the edge. Otherwise, you need to determine the intersection point of the edge and plane. Create new edges and connect them accordingly.
See this page for some background on the math. But you should find some helper methods for all this in your opengl library.
if I rotate / translate the ball, would all the the vertices information change
Of course.
It's not going to be that easy.
I assume the line you are drawing induces a plane which then cuts the sphere.
To do so, you have to calculate the intersecting area of the sphere and the plane.
This is not a trivial task and I suggest using an existing framework for this or if you really want to do this yourself, read about basic intersection problems to get a feeling for this kind of problem. This paper offers a good introduction to various intersection tests.
In general boundary represended volumes, as in your case, are difficult to handle when it comes to more advanced manipulations. Cutting a sphere in half is easy compared to burring a small hole into it. Sometimes it's better to use a volume representation, like tetrahedral meshes or CSG.
Regarding your second question, you shouldn't rotate or translate the sphere, rotate and translate the camera.