I need to make a plot with the cut edges, something like this:
The right and bottom edges should be a polygon, like on a design drawing. No ticks or labels are needed there. No clippings is assumed (actually plot will be strictly inside of the polygon area). Is there easy way for this?
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i am quite a beginner in Gmsh and am trying to create a mesh for hydrodynamic simulation from coastlines. I used splines for the complex coastline for simplicity, but the produced mesh crossed over the coastlines. What should i do to make the mesh not cross over the bounding curves?
Image for reference
Your mesh is simply to coarse in the moment. The points of each Triangle in the mesh lie on the real geometry/coastline but the edges are linearly connected and do not care about the geometry.
In order to refine the mesh you might try to press Mesh->Refine by Splitting a couple of times and see split the few current cells. The mesh should get finer and should not violate the geometry boarder by as much as right now.
BUT by this you'll only make the "issue" less obvious to see. On a smaller scale you will always see mesh cells that are partly "outside" the geometry borders. You cannot prevent this with concave meshes like the one you have here. If you have s.th. convex like a circle all elements will strictly lie inside the geometry border.
So as a first step, make a finer mesh until you are satisfied with the match between geometry and mesh.
Hi stackoverflow community,
This is a continuation of a question I asked 6 months regarding calculating the area and position of dynamically formed rectangles. The solution provided for that worked a treat but now I want to take this a step further.
Some background - I'm working on a puzzle game using Cocos2D/Box2D were the player draws lines on the screen. Depending on were the player draws, I want to then work out the area and position of polygons that appear as a result of the drawn lines.
In the following image, the black border represents a playing area, this will always be the same shape. The grey lines are player drawn and will always be straight. The green square is an obstacle. The obstacle objects will be convex shapes. The formed polygons (3 in this case) are the blue areas and are the shapes I'm trying to get the coordinates and area for.
I think I'll be fine with working out the area of a polygon using determinants but before that, I need to work out the coordinates of the blue polygons and I'm not sure how to do this.
I've got the lines (x,y) coordinates for both ends, the coordinates for the obstacle and the corner coordinates for the black border. Using those, is it possible to work out the coordinates of the blue polygons or am I approaching this the wrong way?
UPDATE - response to duffymo
Thanks for your answer. To explain further, each object mentioned is defined and encapsulated in a class i.e. I've got a Line/Obstacle/PlayingArea object. My polygon object is encapsulated in a 'Rectangle' object. Each one of these objects has it's own properties associated with it such as its coordinates/area/ID/state etc...
In order to keep track of all the objects, I've got an over-seeing singleton object which holds all of the Line objects / Obstacle objects etc in their own respective array. This way, I can loop through say all Lines and know were each one has been drawn by the player.
The game is a bit like classic JezzBall so I need to be able to create these polygon shapes when a user draws a line because the polygon shape will be used as my way of detecting if that particular area contains a ball. If not the area needs to be filled.
Since you already have the nodes and edges for your polygons, I'd recommend that you calculate the centroids, perimeters, and areas using contour integration You can express the centroids and areas as contour integrals using Green's theorem.
You can use Gaussian quadrature to do piecewise integration along each edge.
It'll be fast and accurate; it'll work on polygons of arbitrary complexity.
UPDATE: Objective-C is an object-oriented language. I don't know it myself, but I believe it's based on ideas from C and C++. Since that's the case, I'd recommend that you start writing more in terms of objects. Arrays of coordinates? They need to encapsulated together. I'd suggest a Point abstraction that encapsulates a point (id, x, y) together. Make a Grid that has a List of Points.
It sounds like users supply the relationship between Points to form Polygons. That's not clear from your description, so it's not a surprise that you're having trouble implementing it.
I have this plot as part of a PySide program;
And there are two problems I have with it. The first is the ugly grey border. I know I can can get rid of it using the toolbar option, but I can't find a way to it programatically, or make it default to that when it plots...
The second issue, is that it is drawing the grid lines on top of the surface, which I would rather it didn't do... How do I get the grid lines to be drawn underneath the surface?
EDIT:
i'm using version 1.1.1;
this doesn't happen for all plot types - i.e.
that is fine.
If i try and plot multiple objects, then it can be a problem;
but i understand that's a limitation of mplot3d not being a try 3D engine, just a set of 3D images with a Z-Ordering, so the order of objects drawn becomes orientation dependant. (same graph - different angle: enter link description here).
The grid lines should surely always be at the bottom of the drawing though, no? Is there a way to force them to be?
Will.
I'm using Core Plot to graph linear equations.
I would like to be able to supply two different data points and have a line drawn between them, but also extrapolated beyond the points themselves so that the line extends all the way to the edges of the plot area.
For example, given a 20x20 plot area with the origin centered and points at -5,-5 and 5,5, the line (green below) would extend all the way from -10,10 to 10,10 (blue below).
Is this possible? Is the best option just to find the plot range (which will be different each time) and find two points that are outside of it? I'm not sure if this will work; I have user interaction enabled and I want to make sure that the user can't accidentally pan far enough that the line will end.
Your idea of finding two endpoints outside the plot range is what I'd do. If you've limited the scrolling range, just pick points at the limits of that range. If not, you'll need to monitor changes to the plot space ranges with a plot space delegate and update the plot as needed.
I have a Core-Plot Graph within a Mac Application. But the inside table is appearing shifted down and to the left of the containing "frame/border" so that neither of the axis' are showing. I cannot figure out how to change this does anyone know what parameters I need to change to fix this?
Update: Sorry I did not realize I could upload an image, I have done so know and will try your suggestions in the mean-time.
Not sure what you mean by "inside table". It would be easier to offer suggestions if you could post a screenshot.
Without seeing what's wrong, here are some common areas to look at:
If you haven't already done so, look at the example apps included with Core Plot for ideas. The Plot Gallery app has many sample plots and the others are useful, too.
You may need to add padding (paddingLeft, paddingBottom, etc.) on the graph and/or plot area frame. Padding the graph pushes everything in away from the edges of the graph. Padding the plot area frame pushes the plot area in so the axes and titles can hang outside the plot area (the area where the plots are drawn).
If you want to keep an axes pinned to a specific place, e.g., the edge of the graph, set up a floating axis. Otherwise make sure the orthogonal coordinate is set (it defaults to 0). For example, the orthogonal coordinate for the x-axis is the y-value where the x-axis crosses the y-axis.