I am trying to achieve an effect like Google Maps and many other (all?) navigation apps: in navigation mode, the current location is displayed at the bottom of the screen, so that the user can see more of the road in front of them.
I already have the code to update the location and also change the map's orientation based on the bearing. Everything works perfectly if I keep the map centered on the location, so I am moving on to the offset part. Here is what I have:
if (followMe) {
float bearing = [...]; // OK until here
mapView.getController().setCenter(currentLocation); // quickly center on location
mapView.getController().scrollBy(0, -(int)(mapView.getHeight() / 2 * 0.8)); // shift
GeoPoint newCenter = mapView.getProjection().getCurrentCenter(); // get the coordinates of the new center
mapView.getController().animateTo(newCenter, null, (long) 1000, bearing); // center again, this time with a nice animation
}
It does not work as intended and produces weird behaviors: the map is centered elsewhere entirely, updates all of a sudden, etc. I suspect it's because of things like sudden changes in the bearing, or maybe I am just getting it wrong.
Any suggestions?
Related
i have an application in qt that loads an image. The user can set a cross by moving the slider with setPixel(). If he decrements the slider, the cross should become smaller and the original pixel should be displayed.
But unfortunately nothing happens when I decrement the slider. The cross keeps its maximum size.
The function, that sets the Pixel
void ImageViewer::applyExampleAlgorithm(int kreuzBreite)
{
if(image!=NULL)
{
for(int i=0;i<((kreuzBreite*std::min(image->width(), image->height())/ 100) / 2);i++)
{
image->setPixelColor(image->width()/2+i,image->height()/2,QColor(255,0,0,0));
image->setPixelColor(image->width()/2-i,image->height()/2,QColor(255,0,0,0));
image->setPixelColor(image->width()/2,image->height()/2+i,QColor(255,0,0,0));
image->setPixelColor(image->width()/2,image->height()/2-i,QColor(255,0,0,0));
}
}
updateImageDisplay();
renewLogging();
}
My Slider
QSlider *slider1 = new QSlider(Qt::Horizontal,0);
slider1->setRange(0,100);
connect(slider1, SIGNAL(valueChanged(int)),this, SLOT(applyExampleAlgorithm(int)));
As you can see, the value changes, but my cross does not.
I think I have to save the original pixel and rewrite it, as soon as the red cross disappears at this point. But I dont really know how.
When the slider value decreases, your function only "draw" a smaller red cross in the bigger one that was drawn before. You can store the original image in a different variable. Then, before drawing the red cross, restore to the original image.
I'm doing a platformer game using cocos2d-x v3 in c++, where the maps are usually very large, the visible screen follows the object through the map.
Let's say I want to show a sprite in the top right corner of the screen and it would be in this position even when the screen is following the object.
Using the object position doesn't do it.
Is there a way to show a sprite or whatever in the screen and it would be in the screen even when the screen is moving?
Ps. I'm super noob in game development
As it's written here, you whould use convertToWorldSpace
convertToWorldSpace converts on-node coords to SCREEN coordinates.convertToWorldSpace will always return SCREEN position of our sprite, might be very useful if you want to capture taps on your sprite but need to move/scale your layer.
Generally, the parent node call this method with the child node position, return the world’s postion of child’s as a result. It seems make no sense calling this method if the caller isn’t the parent…
So, as you can read,
Point point = node1->convertToWorldSpace(node2->getPosition());
the above code will convert the node2‘s coordinates to the coordinates on the screen.
For example if the anchor position of node1 is which will be the bottom left corner of the node1, but not necessarily on the screen. This will convert the position of the node2 which is to the screen coordinate of the point relative to node1 ).
Or if you wish, you can get position relative to scenes' anchor points with function convertToWorldSpaceAR.
So there are some assumptions that will have to be made to answer this question. I am assuming that you are using a Follow action on your layer that contains your map. Check here for example. Something like:
// If your playerNode is the node you want to follow, pass it to the create function.
auto cameraFollowAction = Follow:create(playerNode);
// running the action on the layer that has the game/map on it
mapLayer->runAction(cameraFollowAction);
The code above will cause the viewport to "move" to where the player is in world position. So following the player on your map that's bigger than the current viewport. What I did for my in-game menu/hud is add the Hud onto a different layer and add it to the root of the main game scene. The scene that does not have the follow action running on it. Something like below.
// Hud inherits from layer and has all the elements you need on it.
auto inGameHud = HudLayer::create();
// Add the map/game layer to the root of main game scene
this->addChild(mapLayer, 0);
// Add the hud to the root layer
this->addChild(inGameHud, 1);
The code above assumes 'this' to be your MainGameScene. This restricts the Follow action from scrolling the element off the screen. Your element will be on the screen no matter where in World space your scene currently is.
Let me know if this is clear enough. I can help you out more if you get stuck.
I've managed to do it using a Parallax Node, and using the velocity which the sprite goes to Vec2(0,0), this way it stays always on the same spot in the screen.
You can always just put that sprite into different node / layer that everything else is. That way moving this layer / node won't move the sprite
I'm creating a iOS video camera app using Qt5.4.
For this I need to determine the current orientation of the device to rotate the video in the VideoOutput element.
As we can see there's a autoOrientation property but it doesn't work as I expect: if I keep switching the orientation it starts to have a weird behaviour i.e. setting the wrong orientation.
Then I tried to apply the rotation based on the Screen.primaryOrientation property:
Copying the function defined in this example, I've a created a similar version, which you can find here.
I call it every time width or height changes, like this:
onWidthChanged: { video.orientation = changeOrientation(); }
onHeightChanged: { video.orientation = changeOrientation(); }
However, it seems that the Inverted orientations are completely ignored, which is strange since they are listed in the documentation.
Anyone has any idea about why it's happening?
UPDATE:
I could isolate the problem when using autoOrientation, basically there's a menu on top of the VideoOutput, the menu is a RowLayout, it's visible only if the user clicks on the menu icon, and only if the user clicks on the menu icon the orientation gets messy.
However, in any situation the InvertedPortrait is not recognized.
First of all don't think I'm making a "SFML and/or C++ performance Issue" type question. I'm not satisfied with the performance of this map editor I've been working on and I'm 99% percent sure I'm at fault for it.
Currently how I place tiles on the map is basically I have a function that loops through every single tile on the map and checks if the mouse is hovering over it. I call this function inside another function simply titled handleMouseClick()
This is plenty functional if you were just clicking each time you wanted to place a tile, however I have it sort of like a paintbrush. Even if there's only 500 tiles on the map, it will skip tiles if you drag it across the screen quickly. I need to be able to create maps that have 5000+ tiles and I can't afford so-so performance.
I've looked over my code and made sure I'm not making unnecessary copies. I'm pretty sure that the best way to increase performance would be to change how I check which tile the mouse is changing.
The only idea I have is to have the map in "chunks" so that it will check the tiles of the "chunk" the mouse is in.
Use math. Lets say you have tiles with pixel dimensions {tile.width, tile.height}. And your application's window is a view of the map, and the top left corner of the window is on pixel {view.x, view.y}. And the mouse position, relative to the top left corner of the window is {mouse.x, mouse.y}. You can calculate which tile the mouse is pointing to with the following:
transformed_mouse.x = mouse.x + view.x;
transformed_mouse.y = mouse.y + view.y;
mouse_tile.x = transformed_mouse.x / tile.width;
mouse_tile.y = transformed_mouse.y / tile.height;
For handling a dragging effect where the event system doesn't update fast enough, keep track of where the mouse was for the previous iteration, and use Bresenham's line algorithm to fill in all the tiles between the tile which the mouse is currently pointing to, and the tile which the mouse was pointing to previously.
I have created my own class by extending QGraphicsItem and I want to make it so that when someone does a wheel even while over this item, it scales.
This way, i can have multiple items in a scene, and scale each of them in and out as I please.
The problem is, I want the item to scale under the mouse cursor, much like google maps does. That is, a move forward will keep panning the image and scaling it, so taht the area in the vicinity around my mouse pointer is always in view.
void ImagePixmapItem::wheelEvent ( QGraphicsSceneWheelEvent * event ){
update();
qreal factor = 1.2;
if (event->delta() < 0)
factor = 1.0 / factor;
scale(factor, factor);
scaleFactor *=factor;
this->scene()->setSceneRect(0,0,this->boundingRect().width(), this->boundingRect().height());
}
This is the code I am using to do the scale. The problem is, it always seems to be scaling from the top left corner. Well, this is undesirable, beacuse if I scale in or out too much, eventually my area of interest around the mouse pointer has moved off the screen, and I have to either scroll manually or pan to the location, zoom, pan, etc, until i get to the desired level.
I tried to use the QGraphicsItem::setTransformOriginPoint, but no matter what values I put in there, it still seems to scale and such from the top left.
What can I add to that code I posted to get the desired effect?
I have achieved similar functionality in my Image-Manipulation application (scaling the view and having the area under my mouse stay in place and visible) but I scale the whole graphics-view not a specific item, so I don't know if this code can solve your problem.
Anyway, this is what I do in the constructor of my subclassed QGraphicsView (after I set the scene):
setTransformationAnchor(AnchorUnderMouse);
setResizeAnchor(AnchorViewCenter);
I also use the above functions, after each call to:
MyGraphicsView->setTransform(transform);
I'm not sure if this can help you, but I hope so.