i am using blender to create my models, and loading them into Libgdx, if i create them with the Origin in the center of the model like below and then use this code to create the rigid body, all works fine
Vector3 hescoWallHalfExtents = new Vector3(hescoWall.calculateBoundingBox(bounds).getDimensions()).scl(0.5f);
however if i place the bottom of the model level with the ground like this
then the btRigidbody is offset like this
is there an obvious way that i can offset the height of the rigidbody?
many thanks.
Spriggsy
The center (origin) of the rigid body is the same as the center of mass and therefor an important property for the physics simulation. You could "move" this center using a btCompoundShape if you like, but this will also influence the physics simulation and therefore probably won't give you satisfying results.
Alternatively, you could compensate for the difference of physics origin and visual origin in your btMotionState. For example by setting ModelInstance#transform to the provided worldTransform multiplied by the a Matrix4 instance which contains the offset (use Matrix4#translate for example).
However, this is probably just making it more complex than it needs to be. You could say that the real question is why you want offset the center of model compared to the body? For example, in you second image the center of the model appears to be same as the in the first image. You only moved the Node, basically indicating that you want to provide an initial value for the ModelInstance#transform member. You can achieve this by instantiating the ModelInstance as follows:
modelInstance = new ModelInstance(model, "coneNode", true);
Replace "coneNode" with the name of the node as created it in your modeling application. The last (true) argument tells the ModelInstance to set its transform member to the transformation you've given it in the modeling application. If needed, you can call modelInstance.transform.translate(x, y, z); or modelInstance.transform.trn(x, y, z); to move the modelInstance relative to this transformation.
A more in-depth explanation of this can be found here: http://blog.xoppa.com/loading-a-scene-with-libgdx/
Note that this only works if you're using .g3db or .g3dj files (e.g. using fbx-conv) created from a file format that supports node transformations (e.g. .fbx, but not .obj)
Related
When you're using the Flash/Animate IDE and you select something on the stage with the Free Transform Tool, then move the transformation point (the white circle), what is it actually doing in frame script? DisplayObjects only have x and y properties, there's no transformX or transformY.
I have a MovieClip place on the stage through the Flash IDE with various transformations applied to it, and I would like to be able to replicate those in Actionscript.
When you're creating a display object in IDE, moving transformation point makes IDE move everything inside that object in reverse direction coordinates wise. It's like if you're moving a zero point of a local coordinates system, leaving everything else intact, the contents will then have their coordinates altered.
In order to simulate this behavior, you can nest your display object being created into a container sprite, then when your user drags transformation center, you move the wrapper sprite to the new coordinates and alter its nested object's ( the one with all the contents) coordinates by negative delta between old and new positions of virtual zero.
I wish to use the "intersects" (from Starling) to create a collision, but i don't know how to convert my Quad "player" and my Quad "block" to Rectangles.
Can someone help?
Quad contains a getBounds public method that returns a new rectangle (or an updated one if passed in on the second param), so:
var playerRect:Rectangle = quadPlayer.getBounds(this);
var blockRect:Rectangle = blockPlayer.getBounds(this);
if (playerRect.intersects(blockRect)) {
trace("Collision!");
}
Now, I am using this as I do not know your display list hierarchy and this do not know which coordinate system your quads are in, so adjust accordingly.
http://doc.starling-framework.org/current/starling/display/DisplayObject.html
Transforming coordinates
Within the display tree, each object has its own local coordinate system. If you rotate a container, you rotate that coordinate system - and thus all the children of the container.
Sometimes you need to know where a certain point lies relative to another coordinate system. That's the purpose of the method getTransformationMatrix. It will create a matrix that represents the transformation of a point in one coordinate system to another.
http://doc.starling-framework.org/current/starling/display/Quad.html
getBounds(targetSpace:DisplayObject, out:Rectangle = null):Rectangle
[override] Returns a rectangle that completely encloses the object as it appears in another coordinate system.
I'm new to Geotools. I am developing a simple application that shows a map and I would like to dynamically place a bitmap or vector symbol on it (for example to show where the current position is, like in navigation systems).
Now, what I've done already is:
showing a map given one or more shapefile.
center the map on the last inserted position.
add shapes to new layers when needed.
What I need to do is to create an overlay with images at given coordinates on the map area (to be clear, I don't want to generate a raster layer on disk, I just want to paint on the screen).
My guess is that I have to somehow directly use the Graphics2D instance inside JMapPane, is that correct? In this case how can I convert from the geographic coordinates to pixel coordinates on the drawing pane? Or are there some geotools functions/classes that I should be looking for?
Thank you.
Answering myself, since I found the solution.
I did it by extending class org.geotools.map.DirectLayer, which provides a way to define a custom layer by extending its draw(Graphics2D, MapContent) method. Graphic elements are placed at the correct coordinates by using the worldToScreen affine transform provided by geotools. For example, to define a Point2D placed at the current position given real-world coordinates:
AffineTransform worldToScreen = viewport.getWorldToScreen();
Point2D worldPoint = new Point2D.Double(currentPosition.x, currentPosition.y);
Point2D screenPoint = worldToScreen.transform(worldPoint, null);
Once the draw() method is defined, just instantiate and add as a layer to your MapContent instance.
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.
I know that there are people out there creating classes for this (ie http://coreyoneil.com/portfolio/index.php?project=5). But I want to learn how to do it myself so I can create everything I need the way I need.
I've read about BitMap and BitMapData. I should be able to .draw the MovieClips onto a BitMap so I could then cycle the pixels looking for the collisions. However, It's weird and confusing dealing with the offsets.. And it seams like the MyBitMap.rect has always x = 0 and y = 0... and I can't seam to find the original position of the things...
I'm thinking of doing a hitTestObject first, then if this was positive, I would investigate the intersection betwen the movieclips rectangles for the pixel collisions.
But then there is also another problem (the rotation of movieclips)...
...I need some enlightment here on how to do it.
Please, any help would be appreciated..
If you're using BitmapData objects with transparency you can use BitmapData.hitTest(firstPoint:Point, firstAlphaThreshold:uint, secondObject:Object, secondBitmapDataPoint:Point = null, secondAlphaThreshold:uint = 1):Boolean.
You'll have to change from global coords to the local BitmapData coords which will require a bit of math if it is rotated. That's easily achieved (look up affine transform for more info on wiki):
var coordTransform:Matrix = new Matrix();
coordTransform.rotate(rotationRadians);
coordTransform.translate(x, y);
coordTransform.transformPoint(/* your point */);
A classic reference for pixel perfect collision detection in flash is this Grant Skinner's article. It's AS2, but the logic is the same for AS3 (there are ports available if you google a bit).
If I recall correctly, this particular implementation worked as long as both tested objects had the same parent, but that can be fixed.
About BitmapData x and y values, I understand it could be confusing; however, the way it works makes sense to me. A BitmapData is just what the name implies: pixel data. It's not a display object, and cannot be in the display list; so having x or y different than 0 doesn't really make sense, if you think about it. The easiest way to deal with this is probably storing the (x,y) offset of the source object (the display object you have drawn from) and translate it to the global coordinate space so you can compare any objects, no matter what's their position in the display list (using something like var globalPoint:Point = source.parent.localToGlobal(new Point(source.x,source.y)).
I've previously used Troy Gilbert's pixel perfect collision detection class (adapted from Andre Michelle, Grant Skinner and Boulevart) which works really well (handles rotation, different parents, etc.):
http://troygilbert.com/2007/06/pixel-perfect-collision-detection-in-actionscript3/
http://troygilbert.com/2009/08/pixel-perfect-collision-detection-revisited/
and from there he has also linked to this project (which I've not used, but looks really impressive):
http://www.coreyoneil.com/portfolio/index.php?project=5
I managed to do it after all, and I already wrote my class for collision detections,/collisions angle and other extras.
The most confusing process is maybe to align the bitmaps correctly for comparing. When whe draw() a movieclip into a a BitmapData, if we addChild() the corresponding Bitmap we can see that part of it is not visible. it appears to be drawn from the center to right and down only, leaving the top and left parts away from beeing drawn. The solution is giving a transform matrix in the second argument of the draw method that aligns the bitmap and makes it all be drawn.
this is an example of a function in my class to create a bitmap for comparing:
static public function createAlignedBitmap(mc: MovieClip, mc_rect: Rectangle): BitmapData{
var mc_offset: Matrix;
var mc_bmd: BitmapData;
mc_offset = mc.transform.matrix;
mc_offset.tx = mc.x - mc_rect.x;
mc_offset.ty = mc.y - mc_rect.y;
mc_bmd = new BitmapData(mc_rect.width, mc_rect.height, true, 0);
mc_bmd.draw(mc, mc_offset);
return mc_bmd;
}
in order to use it, if you are on the timeline, you do:
className.createAlignedBitmap(myMovieClip, myMovieClip.getBounds(this))
Notice the use of getBounds which return the rectangle in which the movie clip is embedded. This allows the calculation of the offset matrix.
This method is quite similar to the on shown here http://www.mikechambers.com/blog/2009/06/24/using-bitmapdata-hittest-for-collision-detection/
By the ways, if this is an interesting matter for you, check my other question which I'll post in a few moments.