I'm trying to plot a 2D field using imshow. I'd like the colors to rescale after zooming in so I can see more detail.
The only solution I know of is to take the coordinates of the box returned by a RectangleSelector event and replot a submatrix of the original data. Is there a better solution?
You could use interactive plotting with pylab.ion and update the plot using the draw command instead of the show command. Then, in your code, make a while loop that prompts you for keyboard input. At each iteration, if you enter -1 the program exists. Otherwise, maybe you enter something like x1, y1, x2, y2 which depicts a bounding box you want to zoom in on in your coordinate axes, and then your program makes a new figure, re-computes the relevant data onto new grids involving the input x1, y1, x2, y2, and re-plot. If you save all the input coordinates, you could even have a special keyboard input for "undo" (as in, zoom back out to where I just was). This should not be very hard to implement, the only question will be how severe the computation is to re-sample your image onto the zoomed-in grid.
After doing a lot of searching, I couldn't find any alternatives. However, implementing this with the RectangleSelector and just replotting a submatrix of the original data turned out to work well.
Related
I am currently trying to draw an oscillation using Octave. This is what I want to achieve in the end:
In this diagram, the y axis arrow is drawn in the middle of the graph instead of at the top or bottom.
I think this way it makes a lot of sense because the arrow kind of mirrors the graph itself periodically.
Now, what I have so far:
x = [0:.1:10];
plot(x, sin(x);
box off
Which looks like this:
But I can't get the y axis arrow to be in the middle. So far I've read
The axis documentation
The page about two-dimensional plots
But I can't find anything about positioning the axis. Thanks for any help in advance.
Using your example:
x = [0:.1:10];
plot(x, sin(x));
box off
set( gca, 'xaxislocation', 'origin' )
Some more, possibly helpful tips:
In general, if you don't know what parameters are available in a graphical object handle, and you want to "check", you can use get with an empty string, e.g. get( gca, '' ) to check all the parameters that you can 'get' or 'set' on the current axes object.
Similarly, if you want to check what values a particular parameter can be set to, you can do, e.g. set( gca, 'xaxislocation' ), i.e. without providing the value to set it to. If that particular parameter only accepts values from a specific set of values (instead of e.g. a numerical array), then Octave will then show you what these options are (and also which is the default).
Obviously, if you know what you're looking for, you can also just go straight to the relevant page in the octave manual and search the page for it :)
Since the online manual is quite large, and has no 'search' facility of its own (it does within octave, but the online version doesn't), in order to jump straight to the relevant section I often find it useful to do a duckduckgo (or google) site-specific search, e.g. "xaxislocation site:https://octave.org/doc/v6.2.0/"
I'm absolutely new to Pixel Blender (started a couple of hours ago).
My client wants a classic folding effect for his app, I've shown him some example of folding effect via masks and he didn't like them, so I decide to dive in Pixel Blender to try to write him a custom shader.
Thx God I've found this one and I'm modyfing it by playing with values. But how can I trace / print / echo values from Pixel Blender ToolKit? This would speed up a lot all the tests I'm doing.
Here i've found in the comments that it's not possible, is it true?
Thx a lot
Well, you cannot directly trace values in Pixel Bender, but you can, for example, make a certain bitmap, then apply that filter with requested values and trace reultant bitmap's pixel values to find out what point corresponded the one selected.
For example, you make a 256x256 bitmap, with each point (x,y) having "x" red and "y" green component value. Then you apply that filter with selected values, and either display the result, or respond to clicks and trace underlying color's red and green values, which will give you the exact point on the source bitmap.
I want to visualize a scatter plot using Prefuse. The difference from typical scatter plot is here I want to use rectangle instead of circle or point. And the reason is I want to visualize the time and duration at the same time. Does anyone know how to set rectangle's length or width according to data in the table? I haven't got the right answer after searching the web.
I initially wants to draw rectangle using this parameter.
ShapeAction shape = new ShapeAction(group, Constants.SHAPE_RECTANGLE);
But I didn't find the way to change only the length of it but to change the whole size. Could anyone give me some instructions? Thanks.
Assuming you want to create a visualization similar to LifeLines or a GANTT chart.
To achive this, prefuse has to be extended prefuse on several points. Here is an outline:
Add a field to the VisualTable to store the x coordinate at the end of the rectangle
Extend AxisLayout to determine the additionally the end of the rectangle.
Extend AbstractShapeRenderer draw a rectangle using the end coordinate
I wonder if you could/would help me.
I have a page (java script/ html5/webgl)
and I am displaying a set of points,
then when the user pressess on a point I would lik to find the x and y coordinates that I set in the first place.(range of 0 to 1)
what I get from the even is the x and y screen coordinates (pixals)
from even.offsetX and so.
what is the right math to get to the acsual points?
please help
In regular OpenGL, the command you need is gluUnProject:
http://www.opengl.org/sdk/docs/man/xhtml/gluUnProject.xml
For WebGL, you will have to roll your own since it doesn't have any fixed function pipeline support. Assuming that you are using standard transformation matrices, you can just modify the formulas in that man page. It would be hard to say anything more specific without the details of you set up your coordinate systems.
To clarify things, what i am trying to do is to get the openGL coordinates and manipulate them in my mfc code. not to get an openGL object. i'm using the mfc to control the position of the objects in the openGL.
Hi, i'm trying to find the naswer on the web and can't find a full solution that i can use and that will work...
I'm developing a MFC project with static picture as the canvas for an openGL class that draw the grphics for my game.
On moush down, i need to retrive a shape coordinate from the openGL class.
I'm looking for a way to convert the openGL coordinates to MFC coordinates but no matter what i try i get junk after using the gluProject or gluUnProject (i've tried to do both ways but non is working)
GLdouble modelMatrix[16];
glGetDoublev(GL_MODELVIEW_MATRIX,modelMatrix);
GLdouble projMatrix[16];
glGetDoublev(GL_PROJECTION_MATRIX,projMatrix);
int viewport[4];
glGetIntegerv(GL_VIEWPORT,viewport);
POINT mouse; // Stores The X And Y Coords For The Current Mouse Position
GetCursorPos(&mouse); // Gets The Current Cursor Coordinates (Mouse Coordinates)
ScreenToClient(hWnd, &mouse);
GLdouble winX, winY, winZ; // Holds Our X, Y and Z Coordinates
winX; = (float)point.x; // Holds The Mouse X Coordinate
winY; = (float)point.y; // Holds The Mouse Y Coordinate
winY = (float)viewport[3] - winY;
glReadPixels(winX, winY, 1, 1, GL_DEPTH_COMPONENT, GL_FLOAT, &winZ);
GLdouble posX=s1->getPosX(), posY=s1->getPosY(), posZ=s1->getPosZ(); // Hold The Final Values
gluUnProject( winX, winY, winZ, modelMatrix, projMatrix, viewport, &posX, &posY, &posZ);
gluProject(posX, posY, posZ, modelMatrix, projMatrix, viewport, &winX, &winY, &winZ);
This is just part of the code i've tried. ofcourse not gluProject and gluUnProject together. just had them both here to show.....and i know there is lots of junk over there, its from some of my tries...
p.s. i've tried many many more combinations and examples from the web and nothing seem to work in my case....
Can any one show me what is the right way to do the transformation?
10x
It looks like you're trying to retrieve the object (or objects) that is/are at a particular point. If this is the case, gluProject and/or gluUnProject isn't really a very suitable tool for the task. OpenGL has a selection mode intended specifically for this kind of task.
In typical use, you specify a small square (e.g., 5x5 pixels) around the mouse click spot with gluPickMatrix, set selection mode with glRenderMode, set a buffer with glSwelectBuffer, and then draw your scene. The drawing doesn't go to the screen, but fills the buffer you specified wiyh records of what was drawn within the specified area.