I'm drawing a graph with achartengine. I'm still working on the display, but one thing that's caught my eye already is that the graph lines don't go through the points, they take some path that roughly traces their shape:
How can I make my lines always go through my points?
I was looking in the wrong places (Renderers) for a solution, in the end I noticed I was using a ChartFactory.getCubeLineChartView, changed to ChartFactory.getLineChartView and all is good.
Related
I'm trying to crop rectangles out of an image using OpenCV/Java. I've been somewhat successful finding the lines that make up the rectangular sections I want to crop, but I'm having a hard time finding the best way to do the following:
Connect the segmented lines I've found (see screenshot below) into separate rectangles (lines can be shared by multiple adjacent rectangles)
Determine that a nearly complete rectangle is a rectangle (see broken bottom edge of full rectangle in screenshot, to the left of line #6)
Any guidance is appreciated!
I had been using OpenCV's Impgproc.HoughLinesP, which produced the line segments seen in the question's screenshot. I ended up scrapping that path, opting for a combination of Imgproc.findContours, Imgproc.contourArea and Imgproc.boundingRect instead. This approach worked for me, and allowed me to avoid writing a bunch of recursive line-combining code.
So I'm doing the project of an introduction to Java course and it seems that I chose something that goes way beyond what I'm able to do. :P
Any help would be greatly appreciated. This is what I'm having problems with:
You have a cursor that is controlled by a player (goes forward or
turns 90°) which leaves a colored line as it goes. If you manage to go
over your own line and close a polygon of any shape (only right angles
though), its surface changes color into the color of your line.
I can detect when this situation arises but I am kind of lost as how to actually fill the correct polygon just closed. I can't seem to imagine an algorithm that would cover any case possible.
I looked at the Scanline fill algorithm but I think it would start having problems by the time there are already some polygons already filled in the map.
The Floodfill algorithm would be perfect if I had a way of finding a point inside the polygon, but, as there are many different possibilities, I can't think of a general rule for this.
I'm using an array 2x2 of integers where each color is represented by a number.
Does anyone have an idea on how to approach this problem?
If you can detect the situation then this can be solved in very simple manner. The question is which point to choose as start point for floodfill. The simple answer is: try all of them. Of course it makes a sense to start only with points adjacent to the one where your cursor is located. In this case you will have at most 8 points to check. Even better - at least 2 of them are definitely painted already if current point forms a polygon.
So you have 8 points to check. Launch floodfill 8 times starting from each of those points.
Two things which you probably should keep in mind:
You should try filling the area in cloned version of your field in order to be able to get back if floodfill will not find a polygon.
Launching floodfill second time and later you should reuse this cloned version of your field to see whether it was filled there. This will allow you to check every point at most once and this will make your 8 floodfills almost as fast as 1 floodfill.
Check this question, using Graphics2 and Polygon to fill an arbitrary polygon: java swing : Polygon fill color problem
Finding out whether a point is inside or outside a polygon: http://en.wikipedia.org/wiki/Point_in_polygon
Make sure you use double buffering. If you set individual pixels and don't use double buffering the component may redraw after every pixel was set.
I'm applying the scan-line algorithm to fill in a randomly generated continent-like shape. The main problem I'm having is when the line intersects a point that is a tip. I created some images to help visualize this.
http://i.stack.imgur.com/OlbI5.png
http://i.stack.imgur.com/RACF1.png
I basically need help figuring out how to differentiate if an intersection point is a "tip" or not. Like in the first image, since both are tips, I end up with a line in between them, even though the line is outside of the continent-shape.
try checking to the immediate left and the right of the intersection. If they're both below the red line, than it's a tip.
That's the best i can do without knowing more about how the lines are defined.
Yesterday I tried to solve a Problem I had the entire Day and it is still unsolved. I searched for every combinations of words I could imagine to find solutions on Google etc. But without success. :(
The Problem consists of following idea:
I started programming GLES20 (Not GLES10!) on Android. There are many other ways how to compute matrixes and objects. So there aren't any methods like "Pop" or "push" Matrix.
I want to rotate a globe/sphere only by touching and moving my fingers. Touching functions etc works fine but the rotation itself never does. Everytime I first rotate by x-axis and then rotating by y-axis the rotation is still computed by local space axis of the object and Not two global axis. This happens whatever I do... :/
There are some people searching the solution for the Same Problem, but mostly GLES10 or completly different programming languages, never GLES20 and Java.
I will also post some Code parts later, when I get access to a Computer.
perhaps someone already understands what my Problem is.
Thank you so much! :)
Chrise
In OpenGL ES 2.0 there aren't any of the matrix functions and you're supposed to take care of your own matrices. So, for pushing and popping matrices what you need to do is when you're drawing you copy your matrix to a temporary one, do whatever transformation on it and pass the temporary matrix to the vertex shader.
I am making my own class diagram app in Swing/AWT but i stopped at this functionality:
I want to draw a line between the Class rectangle that already selected and to the target Class rectangle, but line has a feature which is whenever i move one of the rectangles the line that join them get bend in a straight fashion following the moving rectangle , i hope the following picture demonstrate what i want to achieve:
A general guideline or a sample code is highly appreciated
I don't know Java, but the steps you could follow are these:
Find the middle of each line of the rectangles (should be easy, just avarage x1+x2 and y1+y2)
Determine the edges that are closest to each other using Pythagoras formula on the points you got in the previous step.
Start drawing a line starting at xa,ya (first point you got in the step above), and draw it in the direction away from the rectangle. You should know this direction, because you can know the line segment this point is on.
Do the same for xb,yb (point on the second rectangle). If the lines are in opposite directions, you should draw them to halfway xa-xb or ya-yb (depending on if you're drawing horizontally or vertically). If they are perpendicular (is that the right word?) you should draw them to the point where they cross, so you draw the line from xa,ya to xa,yb or xa,ya to xb, ya, depending if you draw the horizontal or vertical line.
There should be some additional check to see if the rectangles overlap. You should not draw lines in the same direction for example. Maybe it would suffice for you to draw just a diagonal line between the two points in those cases where you cannot determine how to draw these straight lines.
For the implementation you could build a line class that uses the observer pattern to listen to the two rectangles it follows, so it can update itself whenever one of them moves or resizes.
http://java-sl.com/connector.html
Hope this helps.
Try with observer pattern. All lines that are connected with a moving object should be notified with new position of the object and 'bent' properly. Of course, first implement some logic that will connect 2 objects.
try creating a class named "ConnectingLine" or similar. this class will then have several segments (that's the name of these line parts in dia, which is currently my favorite uml modeling tool) which will be calculated one by one. you'll have a sepaparate class for this of course ;) called maybe "LineSegment". i think this should make it easier for you to perform the mathematical calculations required to perform this task.
this could also enable making segments "auto routed or not" easy d(^_^)b