when I scale my shape [Rectangle] with g2d.scale(2,2) or with AffineTransform , I can't detect correct hit on shape because my shape scale still same as previous and only view of shape is change.
I need solution for solving this problem [change size of shape after Transform].
thanks
You can either use an inverse transform, as shown here, or do the scaling explicitly, as shown here.
Related
I have a java.awt.canvas object and I draw stuff with the Graphics2D (which I get from the bufferStrategy) and I'd like to "zoom" in and out.
So if I zoom in (scaling it up by a factor of 1) such that a line I draw from (0,0) to (10,10) Would be in reality drawn from (0,0) to (20,20)
Is this possible, or do I have to implement this myself?
Take a look at Graphics2D: http://docs.oracle.com/javase/7/docs/api/java/awt/Graphics2D.html
You apply a suitable transformation to the graphics to achieve many transformations, rotate, scale (aka zoom) and translation. Simplest way to zoom would probably be
graphics2d.scale(2.0, 2.0); // draw everything twice the original size
From the above image if I want a portion behind the RED Rectangle I can easily get it,
but the issue I cannot get the portion behind the Yellow Rectangle because it is rotated.
So how can I get a portion of an image from a rotated shape on it?
For example my goal is to get a portion of an Image where the rectangle is located on the image. if someone rotates this rectangle by an x degree [in whatever direction] then it is getting difficult to extract the exact portion of an image after applying rotation.
Any suggestions?
Here a more lengthy description of a possible approach. I do not know the Java2D drawing API very well but if I remember correctly it has the capabilities to do what is required.
First you have to figure out the translation and rotation of the subregion you want compared to an equally size rectangle located straight in the upper left corner in the image. Then invert this transformation.
Make a graphics context which is backed by a bitmap in memory. This one should have the size of the subimage you want. Setup the inverse transformation you calculated earlier on the context and draw your image at position 0,0. As Java2D will take the transformation into account you should now get the sub image you want in the memory bitmap.
Mihir, I think you might be getting distracted by the rotation/AffineTransform aspects of this challenge and it is leading you down the wrong road. Also keep in mind that I don't totally know what you mean by "get" here -- do you want to save out the highlighted region to an image? Do you want to render it as a watermark on another image? etc... I'll just try and answer in the general case to get you down the right track.
What you want is the content from the image defined by the polygon in yellow in your image above; ignoring the fact that it looks like a rotated rectangle.
It is late and I am missing a step in here, but I think this will get you 90% of the way there and clarify the last piece (Graphics2D.setClip) that you need.
Create a java.awt.Polygon that defines the region around the area you want.
Use getBounds() or getBounds2D() to get the width/height of the bounding box required to hold this Polygon when rendered out into a rectangle. (e.g. boundingBox)
Create a new BufferedImage with these width/height values.
Get the Graphics2D from the new BufferedImage (e.g. newG2)
newG2.drawImage(originalImage, boundingBox.x, boundingBox.y, boundingBox.width, boundingBox.height)
NOTE This is where my memory is failing me; at some point you need to set the clip on newG2 (newG2.setClip(someShape)) so when the bounding box is rendered into it, you don't get the full bounding box of graphics rendered in, but instead some subset as defined by the yellow outline.
One easy way to do this is to create two Polygon's:
poly1 = a java.awt.Polygon that defines the yellow selection in the ORIGINAL image.
poly2 = a java.awt.Polygon that defines the exact same shape of Polygon, but shifted to a 0,0 origin point.
poly1 is used to get the bounding box to copy out the full bounding box that encompasses the content selected in yellow (and extra content around it)
poly2 is used to set the clip on the target Graphics2D (newG2) so when the bounding box is rendered into it, we clip back out everything outside of that Yellow shape so we just get the content in Yellow. You'll likely want to use an ARGB image type and set the background of the target image as transparent otherwise you'll get a black fill color.
I think this is the right direction for the clips; I was up to my eyeballs in Java2D for years and years but have been out of it for a while and forget if this will give you exactly what you want or not; you might need to tweak it around, but these are all the tools you need.
I've been looking around and i couldn't find an answer to this but what I have done is create a cube / box and the camera will squash and stretch depending on where I am looking at. This all seems to resolve it self when the screen is perfectly square but when I'm using 16:9 it stretches and squashes the shapes. Is it possible to change this?
16:9
and this is 500px X 500px
As a side question would it be possible to change the color of background "sky"?
OpenGL uses a cube [-1,1]^3 to represent the frustum in normalized device coordinates. The Viewport transform strechtes this in x and y direction to [0,width] and [0,height]. So to get the correct output aspect ratio, you have to take the viewport dimensions into account when transfroming the vertices into clip space. Usually, this is part of the projection matrix. The old fixed-function gluPerspective() function has a parameter to directly create a frustum for a given aspect ratio. As you do not show any code, it is hard to suggest what you actually should change, but it should be quite easy, as it boils down to a simple scale operation along x and y.
To the side question: That color is defined by the values the color buffer is set to when clearing the it. You can set the color via glClearColor().
Does anyone know how can I get a sprite/bitmap to rotate by a certain angle where the point on one the sides will always remain in the same position.
I have a blue line in the image and I need one of the sides to remain in the same position at all times.
It would be great help if somebody could tell me how to do this.
Im trying to do this in Andengine/Java. So a solution in either would be most helpful.
Thanks
Regards,
Yaro
The AndEngine has a good method called setRotationCenter. :) By default rotation center set to center of sprite (half of width, half of height). You can easily change this point.
The AndEngine is quite limited with regard to rotation and positioning, I've faced a similar problem on my own, and the only way to solve it was overriding methods and extending classes.
I'd recommend you to implantation the a new method which will set the rotation axis, and override the setRotation() method, to use this axis, I guess you could figure out how to rotate the sprite on a different axis by changing its position which changing its rotation
I just find out a solution for rotate a sprite at any center point. First you create a virtual entity and attach your sprite into this entity (notice: position of sprite is relative with your entity), then you move rotation center of the sprite (default at center of image) to overlap the rotation center of the entity. Final, you set rotation for the entity instead of the sprite. Hope this helpful ^^
I've got a set of Java2D calls that draw vectors on a graphics context. I'd like for the image to be doubled in size and then rotated 90 degrees.
I'm using the following code to do this:
Graphics2D g2 = // ... get graphics 2d somehow ...
AffineTransform oldTransform = g2.getTransform();
AffineTransform newTransform = (AffineTransform)oldTransform.clone();
newTransform.concatenate(AffineTransform.getTranslateInstance(x1, x2));
newTransform.concatenate(AffineTransform.getScaleInstance((double)newW/(double)iconW, (double)newH/(double)iconH));
newTransform.concatenate(AffineTransform.getRotateInstance(Math.toRadians(rotationAngle), (double)iconW/2.0d, (double)iconH/2.0d));
// ... do my drawing ...
This rotates and scales, however, the scale isn't applied the way I would like. It is as if it is rotated before scaling, thus making the image wider on the wrong axis.
Is there a better way to do this?
I believe those transforms are implemented like a stack - so the last transform is performed first. Try reversing the order of the rotate and scale transformations and you should get what you are looking for.
newTransform.concatenate(AffineTransform.getTranslateInstance(x1, x2));
newTransform.concatenate(AffineTransform.getRotateInstance(Math.toRadians(rotationAngle), (double)iconW/2.0d, (double)iconH/2.0d));
newTransform.concatenate(AffineTransform.getScaleInstance((double)newW/(double)iconW, (double)newH/(double)iconH));
Rotations are always performed about the origin. In order to rotate about a certain point you must translate the points.
This page explains the maths behind what you're trying to do and show why transformations need to be applied in a certain order.
Change the order in which you concatenate the transforms to control the order in which they are applied in the composite.