point

I need to get the distance from a lat/lng point to a line. Of course needs to follow the Great Circle. I found a great article on this at http://www.movable-type.co.uk/scripts/latlong.html but the code is not working right. Either I am doing something wrong or there is something missing. Here is the function in question. See the link for the other functions if needed. var R = 3961.3 LatLon.crossTrack = function(lat1, lon1, lat2, lon2, lat3, lon3) { var d13 = LatLon.distHaversine(lat1, lon1, lat3, lon3); var brng12 = LatLon.bearing(lat1, lon1, lat2, lon2); var brng13 = LatLon.bearing(lat1, lon1

The question is: how do you determine if a point is within a polygon? This question has been asked and answered many times. There are multiple methods for determining whether a point is within a polygon. I've grokked the Winding Number algorithm, ported a solid answer from another SO thread into C# and written xUnit tests around it to ensure that I could refactor ruthlessly. The goal was to take an answer, all of which seem to use a procedural programming approach and variable names that are similar to those you'd find in a mathematical formula, and refactor it into a reasonably sound set of

I have a function to draw Bezier Curve through three points. I have already 2 points (start and end) - A and B. How do I calculate middle point between those two points as middle point would be always a little higher or lower than linear function of those two points. Example : Any formulas, ideas would be great! B.K. I think this is what you're looking for: http://blog.sklambert.com/finding-the-control-points-of-a-bezier-curve/ It goes into detail on calculating the various points on a Bezier curve. You may also be interested in this more specific example for your application: http://www

I have a table with a POINT geometry field. I enter latitude/longitude points into it like this: INSERT INTO table( point ) VALUES( POINT( lon_value, lat_value ); Sometimes I do not have lat/lon values to enter. I am unable to enter a blank, a NULL, or an empty POINT() ... since POINT(0,0) is actually a location on the globe, that won't work either. What is the solution here? I would use coordinates of North Pole INSERT INTO table( point ) VALUES( POINT(0.0000,90.0000); If the actual coordinates of the pole may be an issue i would change the lon value from 0.0000. 来源： https://stackoverflow.com

Everything seemed so plain and simple until I had to actually program it. What I've got I uploaded an image to explain it better. I have a circle and I know it's radius center point coordinates each button's initial coordinates (the red circles). I want to be able, when I rotate the gray circle image, with 10 degrees, to calculate red buttons new coordinates (x1y1, x2y2). This shouldn't be hard to achieve for someone who knows math, but I didn't manage to find a suitable solution. I've also searched around here and couldn't find a working solution. Any help is greatly appreciated. Thank you

If I have e.g. 20 points, how can i check to see if those points make up for a circle? It doesnt have to be a perfect circle. For example if I store the coordinates of my mouse every 200ms (as the user moves the mouse), I want to see if the user makes a circle gesture. And I cant expect the user to make a perfect circle. I'd do the following; Compute a best fit circle through the points Calculate a residual for each point (the join distance from the centre to the point minus the best fit circle radius) Accept the result if a large enough percentage of the residuals were below a certain value

I'm trying to implement textured points (e.g. point sprites) in OpenGL ES 2.0 for a particle system. Problem I'm having is the points all render as solid black squares, rather than having the texture properly mapped. I have verified that gl_PointCoord is in fact returning x/y values from 0.0 to 1.0, which would map across the entire texture. The texture2D call always seems to return black though. My vertex shader : attribute vec4 aPosition; attribute float aAlpha; attribute float aSize; varying float vAlpha; uniform mat4 uMVPMatrix; void main() { gl_PointSize = aSize; vAlpha = aAlpha; gl

We had previously implemented tapping to zoom and now we've decided to use icons instead that will zoom in on the center of whats currently being displayed, and we'd like to reuse the code we had for our tap to zoom since we want the same effect, but now we don't know what to pass as the centerpoint. We're using the (CGRect)zoomRectForScale:(float)scale withCenter:(CGPoint)center method which used to accept a center cgpoint from the gesture recognizer that we used for tap zooming; however, since we're no longer using the gesture recognizer we're going to have to figure out what cgpoint to pass