Move object left and right in ARKit session - ios

How to move an object left and right in ARKit scene without changing its Y-axis, if its in the air then it doesn't change that and just move left and right in screen?

This will be a very general example, I could get more specific if you make your question more detailed or give an example of what you are trying to do.
Lets say you want the object to just move on it's x-axis and you had an object of type SCNNode called selectedObject, you could do something like this
selectedObject.position = SCNVector3Make(value, selectedObject.position.y, selectedObject.position.z)
In this case, you can provide the value you want for the x axis position while maintaining the position the object has on the y and z axes.

Related

Work out world coordinates relative to position and rotation of an object in lua

I am trying to make a new tool for the tabletop simulator community based on my "pack up bag". The Packup Bag is a tool that remembers world position and rotation of objects you place inside it, so you can then place them back in the same positions and rotations they came from when "unpacking the bag".
I have been trying to modify this so it spits things out in a relative position and rotation to the bag, instead of using hardcoded world coordinates. The idea here is that players can sit at any location at the table, pick the faction bag they wish to play.. drop it on a known spot marked for them and press the place and it will populate contents of the bag relative to its location.
Now I have gotten some of this worked out... I am able to get the bag to place relative in some ways .. but I am finding it beyond my maths skills to work out the modifications of the transforms.
Basically I have this part working..
The mod understands relative position to the bag
The mod understands relative rotation to the bag
BUT.. the mod dose not understand relative position AND rotation at the same time.... I need someway to modify the position data relative to the rotational data... but can not work out how.
See this video....
https://screencast-o-matic.com/watch/cFiOeYFsyi
As you can see as I move the bag around the object is placed relative to it.... but if I rotate the bag, the object has the correct rotation but I need math to work out the correct position IF it is rotated. You can see it is just getting placed in the same position it was as if there was no rotation... as I haven't worked out how to code it to do this.
Now I have heard of something called "matrix math" but I couldn't understand it. I'm a self taught programmer of only a few months after I started modding TTS.
You can kinda understand what I mean I hope.. In the video example, when I rotate the bag, the object should be placed with the correct rotation but the world position needs to be changed.
See this Example to see relative rotation ....
https://screencast-o-matic.com/watch/cFiOeZFsyq
My code dose this by remembering the self.getPostion() of the bag and the obj.Position() of the object getting packed up.. it then dose a self - obj and stores that value for the X and Y position. It also remembers if it is negative or position and then when placing it uses the self.postion() and adds or subtracts the adjustment value. Same for rotation.
Still I do not know what ot go from here.. I have been kinda hurting my head on this and thought maybe some of you math guys might have a better idea on how to do this.
: TL;DR :
So I have
bag.getPosition() and obj.getRotation()
bag.getRotation(0 and obj.getRotation()
These return (x,y,z}
What math can I use to find the relative position and rotation of the objects to the bag so if I rotate the bag. The objects come out of it in a relative way...
Preferably in LUA.. thank you!
I'd hope you've found the answer by now, but for anyone else finding this page:
The problem is much simpler than what you're suggesting - it's basic right triangle trigonometry.
Refer to this diagram. You have a right triangle with points A, B, and C, where C is the right angle. (For brevity, I'll use abbreviations opp, adj, and hyp.) The bag is at point A, you want the object at point B. You have the angle and distance (angle A and the length of the hyp, respectively), but you need the x,y coordinates of point B relative to point A.
The x coord is the length of adj, and y coord is the length of opp. As shown, the formulas to calculate these are:
cos(angle A) = adj/hyp
sin(angle A) = opp/hyp
solving for the unknowns:
adj = hyp * cos(angle A)
opp = hyp * sin(angle A)
For your specific use, and taking into account the shift in coordinate system x,y,z => x,z,y:
obj_x_offset = distance * math.cos(bag.getRotation().y)
obj_z_offset = distance * math.sin(bag.getRotation().y)
obj_x_position = bag.getPosition().x + obj_x_offset
obj_z_position = bag.getPosition().z + obj_z_offset
Diagram source:
https://www.khanacademy.org/math/geometry/hs-geo-trig/hs-geo-modeling-with-right-triangles/a/right-triangle-trigonometry-review

ios-charts - Changing Y axis value by a drag and drop

I am using ios-charts library to draw charts on a swift2 app. I am wondering if, for a given X value, I can change its Y associated value by a drag and drop gesture on the chart.
If this is not possible on this library, is it possible to do such a thing using another library?
technically you can. Every time you scroll/zoom the chart, it will trigger a redraw, so everything is redrawing, you can decide your own logic how you want the y axis value changed.
It has two parts:
In computeAxisValues in y axis renderer, the y axis labels(values) are determined. Then in renderAxisLabels, it is drawn using the calculated values.
So you can take a look at these functions and implement your logic. Note, it's your responsibility to make sure what you are doing is valid in your scenario, because if something weird happens, you may not get support on github, because it's not a bug, and sometimes not easy to answer.

Convert Scene's (x, y) to screen's (x, y)

I have an application built with SceneKit that is currently displaying several nodes. I can figure out which node is pressed and want to use that to make a label appear below the Node that was touched. Now, when I set the label's center the following way...
nameLabel.center = CGPointMake(CGFloat(result.node.position.x), CGFloat(result.node.position.y+20)
…it appears in the upper left corner since the node is on (1, 0). What I figured is that the sceneView's (0, 0) is in the center of the screen while the actual physical display's (0, 0) is in the top left corner.
Is there a way to convert the two different numbers into each other? (I could hardcode since I know where the Node's are or create a separate label for each Node but that is not really a perfect solution.)
Thanks in advance :)
You can use the projectPoint: method:
var projected = view.projectPoint(result.node.position))
//projected is an SCNVector3
//projected.x and y are the node's position in screen coordinates
//projected.z is its depth relative to the near and far clipping planes
nameLabel.center = CGPointMake(CGFloat(projected.x), CGFloat(projected.y+20)

How to detect the coordinates of a custom UIView on CPTPlotspace?

In my App, I am using Coreplot to draw a CPTScatterPlot. Now i want to do a scanner on the chart and this animation of UIView (a line) should be like a Line aligned with Y-axis and travels through x=0 to whatever the last value of x is.
I want to perform an action based on the y value while this custom UIView (scanner) travels.
Any help would be appreciated.
Thanks,
i have something similar in an app of mine, the way i went about it was to add a bar graph on top of the scatter plot, i used that bar graph to represent the line that tracks the user's touch.
then i have a UIView that is overlaid on the plot and tracks the scatter plot touches and displays details of the point being touched.
if you just want to display a line, adding a bar graph is probably the easiest, then you don't have to worry about plot space coordinates vs superview coordinates.
the bar graph data source is only returning a value for the location the user is touching, with a height to match the size of the scatter plot.
the quick version is you can use handlePlotTouchEventInSpace:atPoint:isNewEvent to track the user's touches on the graph.
from there you can use the plotPoint:forPlotAreaViewPoint method on the plot space to get the coordinates of the touch.
something like this is a good starting point. it's a bit of a journey to get it all working, but its not too bad once you get the puzzle started.
-(void)handlePlotTouchEventInSpace:(CPTPlotSpace *)space atPoint:(CGPoint)point isNewEvent:(BOOL)newEvent {
NSDecimal plotPoint[2];
CPTXYPlotSpace *xySpace = (CPTXYPlotSpace *)space;
[xySpace plotPoint:plotPoint forPlotAreaViewPoint:point];
after that plotPoint will contain the x and y location of the touch inside the plot space.

Coreplot: Axis Labels Fixed Location

I'm trying to customize a Coreplot graph in many ways I can and the next thing I would like to do is place the X Axis Labels (one that is custom as well) at the bottom of the graph, independent of the X axis' position (whether it's scrolled up or down).
To make it clear, it is similar to giving the labels an offset value of something like 50.0. But offset is not the property I'm looking for since it fixes the labels location relative to the X axis.
Any way this can be done? Or do I have to skip the axisLabels property and place and layer or something manually at the bottom of the graph?
EDIT: Alright, I managed to place an axis on the bottom with CPTConstraints. But it's not on the bottommost. If a plot point is on those levels, the plot line overlaps the labels. I tired padding of the graph but of course, it moves the whole graph, hence the issue persists.
Thanks in advance
Make a second x-axis. Have the first one draw the axis line, tick marks, etc., as normal but no labels. Label the second one and set all of the line style properties to nil so it doesn't draw any of the lines.
Turns out that aside from the graph, the plotAreaFrame property of the CPTGrpah also has paddings. If you give more paddings to plotAreaFrame than that of the graph, the plot will be drawn in a smaller frame and the rest of the graph area will be for you to add what you want (i.e., a second Axis).
Big thanks to #Eric, for trying to answer Every single CorePlot question as soon as possible.
CorePlot does have a lot of customisation than I thought.

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