Trying to understand logic behind the magic of timezones, offsets, etc... Looking at example of finding an offset with moment-timezone library, and can't understand why offset is different in both cases?
moment.tz.zone('America/Los_Angeles').offset(1403465838805); // 420
moment.tz.zone('America/Los_Angeles').offset(1388563200000); // 480
Related
Hello to the community,
I would have one more question on Highcharts. I am working closely with designers and they prefer to have charts given to them with a predefined height, width, and text size, in millimetres (not pixels). That is because ultimately these charts are going to be printed out in reports.
Right now designers enter the value they want for a specific chart in millimetres onto a spreadsheet, and I convert all that to px before making the chart.
To convert pixel to mm I use:
px = mm * DPI / 25.4 since 1in = 25.4 mm.
For point (pt) to pixel I use:
px = pt * DPI/72 since 1pt = 1/72th of 1in.
Where DPI is a variable given to me: usually 300.
However the font size tends to be much bigger than it should be (it looks like it is 20 pt on the chart when I want 12 pt), and the chart dimensions also seem to be wrong.
My first question: do my calculations look right? (I am afraid I am not much of an image expert).
My second question: would there be a way to specify chart dimensions in a different format than pixel when configuring a chart on Highcharts, by any chance?
Thank you so very much!
You can use some of the already existing converters to get those values, like: https://www.unitconverters.net/typography/millimeter-to-pixel-x.htm
You can use CSS to set parameters for the container that the chart is rendered inside, demo: https://jsfiddle.net/BlackLabel/vu41gdt6/
#container {
height: 15rem;
width: 15rem;
}
Consider use regular CSS units for the charts on you web app and change them only for printing needs.
API: https://api.highcharts.com/highcharts/chart.events.beforePrint
Useful article: Using cm/mm on the CSS of a web app that replicates paper interaction is a good practice?
I have some experience with Metal and quite a bit with Unity and am familiar with setting up meshes, buffers, and the backing data for drawing; but not so much the math/shader side. What I'm struggling with is how to get an endless scrolling world. So if I pan far to the right side I can see the left side and keep going.
The application of this would be a seamless terrain that a player could scroll in any direction forever and have it just wrap.
I don't want to duplicate everything on draw and offset it, that seems horrendously inefficient. I am hoping for a way to either use some magic matrix math or some sort of shader to get things wrapping/drawing where they should when panning the map. I've searched all over for some sort of guide or explanation of how to get this working but haven't come up with anything.
I know a lot of old (dos) games did this somehow, is it still possible? Is there a reason why it seems the industry has migrated away from this type of scrolling (bounding to edges vs wrapping)?
I have created a simple example demonstrating what you're looking for (I think).
The basic idea of it is that you draw the map in a repeating grid, using the drawPrimitives(type:vertexStart:vertexCount:instanceCount:) method on MTLRenderCommandEncoder. As the instance count you want to pass in the number of identical maps you want to draw, extending it as far as needed to not see where it ends. In my example I used a simple 5x5 grid.
To not have the user see the edge of the map, we're gonna calculate their position modulo 1 (or whatever size your map is):
func didDrag(dx: CGFloat, dy: CGFloat) {
// Move user position on drag, adding 1 to not get below 0
x += Float(dx) * draggingSpeed + 1
z += Float(dy) * draggingSpeed + 1
x.formTruncatingRemainder(dividingBy: 1)
z.formTruncatingRemainder(dividingBy: 1)
}
This is how it looks:
Just a follow up on what I have actually implemented. First I essentially have an array of x,y points with altitude, terrain type and all that jazz. Using some simple % and additions/subtractions it is trivial to get the nodes around a point to generate triangles
On a draw I calculate the first showing point and the last showing point and calculate the groups of triangles shown between those points. The first/last point take into account wrapping, it is then pretty trivial to have an endless wrapping world. For each group a translation offset is passed via a uniform matrix for that group which will position that section where it should belong.
I set it via renderEncoder.setVertexBytes(&uniform, length:..., offset:...)
So I am using the Charts framework (formerly ios-charts) for a couple of charts.
One of them in a bar chart where the y-axis is duration in seconds - that I then convert into readable minute:second notation with a formatter.
But the selected interval of labels bugs me a little. I would like to control them so they are only shown at intervals that makes sense for this - like say every half or full minute. But I can't seem to find a way to do that for that axis. Only the x-axis seems to have options for that?
So am I missing something here? Or it is not in the framework?
Whoops. Never mind. I found the 'granularity' property on the axis right after asking. And it seems to do what I need.
I'm using the ios-charts library and I have a LineChart View that has x values that are dates from every weekday of this year. On the y-axis I have values between 0 and 25.
I would like to zoom in on different intervals on the LineChart View.
For example only show Data for week X one time and later change to show data for three months, etc etc.
I did not find anything in the documentation on how to do this. I used the "zoom" function with out any success.
(Example : Zoom and show the last 20 days on the x axis or zoom and show the last three months)
Has someone does this before?
It's a tough question and very advanced control. I guess you need to read carefully about the code, focusing on moveViewToX, and the logic and functions in ChartTransformer. Combining some tricks and calculations, you may find a way to fine-grainedly controll what you want to display.
Also, there is a property:
/// the maximum number of entried to which values will be drawn
internal var _maxVisibleValueCount = 100
may also help you.
I want to use my own Unit"system".
Something like 1 Pixel is equals to 0.01 Units.
Now when I want to draw something with my own Unitsystem, I always have to multiply/divide the value by 100.
I've found some answers that mentioned to use matrix in SpriteBatch.Begin, but I dont know how.
Could someone help me^^?
Spritebatch.Begin()´s last parameter can be a transform matrix.
TransformMatrix = Matrix.CreateScale(0.01);
spriteBatch.Begin(SpriteSortMode.Immediate, null, null, null, null, null, TransformMatrix);
Farseer Physics provides a ConvertUnits class for this kind of thing. From memory the methods you're interested in are ToSimUnits and ToDisplayUnits. The Farseer documentation describes it like this:
// 1 meter = 64 pixels
ConvertUnits.SetDisplayUnitToSimUnitRatio(64f);
// If you object is 512 pixels wide and 128 pixels high:
float width = ConvertUnits.ToSimUnits(512f) // 8 meters
float height = ConvertUnits.ToSimUnits(128f) // 2 meters
So the rules are:
Whenever you need to input pixels to the engine, you need to convert the number to meters first.
Whenever you take a value from the engine, and draw it on the screen, you need to convert it to pixels first.
If you follow those simple rules, you will have a stable physics simulation.
On a related topic, you should look into resolution independence.