I'm trying to show a 3D model of a box that should rotate according to some accelerometer values that are read in real time (down is where gravity is at).
I have the box, I can use rotate, but when new values come in I can only rotate relative to the current position of the box with rotate. Is there a way to either reset rotation to default values (0, 0, 0) or to set new absolute rotation values in Matlab?
Here's what I've got right now:
I tried to use the delta between old and new values, but the error gets too big too quickly.
rotate changes the actual data of your object, not just a view on it. Therefore, the only way to 'reset' would be to save the original data used to generate the object, and then re-set those data using calls like
set(oh, 'Xdata', origXData)
set(oh, 'Ydata', origYData)
set(oh, 'Zdata', origZData)
where oh is the handle of the object.
An alternative would be not to use rotate but view, which does not modify the object but only the viewpoint. However, a call to view does not change the viewpoint relative to the current one, but only absolutely. Therefore you'd need to keep track of the current viewpoint in a variable, modify it based on your accelerometer readings, and set the new value.
Related
I have a player object that controls like the ship in Asteroids, using speed and direction. This object is fixed in the middle of the screen, but can rotate. Movement of this object is a visual illusion as other objects move past it.
I need to get x and y coordinates of this player object, from an origin of (0, 0) at room start. x and y do not provide this info as the object does not move. Does anyone know how I can get 'fake coordinates', based on the speed and direction?
One thing to make sure is that you're not just getting x and y on their own, as that will get the current object's x and y position. Instead, make sure to reference the object you're trying to get. For example:
var objectX = myShip.x;
var objectY = myShip.y;
show_debug_message("x: " + string(objectX));
show_debug_message("y: " + string(objectY));
I think you are thinking about it wrong. You do not need "fake coordinates". Real coordinates are fine. Give the ship and asteroids/enemies whatever coordinates and velocity vectors you want; randomly generate them if the game is like Asteroids.
The coordinates do not have to be fake; it is just that when you render in your game loop, you render a particular frame of reference. If the origin is the center of the screen, when you paint an object at (x,y) paint it as though it were at (x - ship_x, y - ship_y) -- including the ship, which will be at (0,0). If you wanted to make rotation relative to the ship too, you could do the same thing with rotation.
Now, you have your question tagged as game-maker. I have no idea if game-maker lets you control how sprites are painted like this. If not then you need to maintain the real coordinates as separate properties of objects and let the official (x,y) coordinates be relative to the ship. The trouble with this is that you will have to update all of the objects everytime the ship moves. But like I said I don't know how GameMaker works -- if it is a problem maybe ask a question more specific to GameMaker.
You'll need to think what you'll use to move the ship around, but then use that code on different variables.
Normally, you'll update the x or y if you want to move the ship, but since you're not going to do that, simply use a custom variable that replaces the x and y value (like posx or posy), and use them on the code that would otherwise be used to move the ship around.
I have a 3d model in Xcode using SceneKit, that can rotate around itself, and i would like for it to move forwards based on rotation, for example if it is rotated 236 degrees in the z axis, it wouldn't go straight in x or y, but a bit of both so it would move forwards. Is it possible? Do i have to get any plugins?
No plugins required.
You can do this two main ways:
Move the object's position relative to its rotation by changing its "transform" over time.
Applying force (and/or impulses) over time (or instantly) in the direction you'd like your entity to travel.
Within these two approaches are a LOT of other considerations regarding scene size, resistance, speed, immediacy, etc.
Suppose I plot a surface and at runtime I use the mouse to rotate the surface. Once the right rotation of the surface is achieved, how I can get its state?
Each driver creates a clone of the global scene which is constantly synched and updated with changes in its source. The rotation is done on the clone. I have not tested it, but I think, you can query objects (e.g. the plot cube) in the clone by
panel.GetCurrentScene().First<ILPlotCube>(/*your filter if needed*/)
This instance will reflect all changes done by the user.
The method pointed out in user492238s answer does work. However, GetCurrentScene() assembles a new scene as composition of the global and the local (to the current driver) scene. This can get costly if called frequently. If only individual objects / properties are needed, panel.SceneSyncRoot can be used instead.
Also, the rotation of a plot cube is exposed by the plotcube.Rotation property. So, in order to get the current rotation of a plot cube (including the rotation due to user input):
panel.SceneSyncRoot.First<ILPlotCube>().Rotation
I'm playing with OpenGL ES on iPhone and I'm trying to rotate a model by panning with the finger. I discovered the open source app Molecules that let's you do that and I'm looking at that code, but when it comes to rotate a model of mine I'm able to rotate it only around a point distant in the space (like it was in orbit as a satellite and I am the fixed planet).
Any suggestion on what can be wrong?
I can post the code later , maybe on demand (many lines)
For the most part refer to Molecules you can find it here MOLECULES
If my memory serves me correctly, I think you need to translate the model to the origin, rotate, and then translate back to starting position to get the effect you are after.
I think there is a glTranslate() function, Say the object is at 1,0,0. You should then translate by -1,0,0 to go to origin. That is translate by a vector going from the center of the object to the origin.
The draw code probably looks roughly like this:
glLoadIdentity();
glTranslate(0, 0, -10);
glRotate(...);
drawMolecule();
Now it's important to realize that these transformations are applied in reverse order. If, in drawMolecule, we specify a vertex, then this vertex will first be rotated about the axis given to glRotate (which by definition passes through the local origin of the molecule), and then be translated 10 units in the −z direction.
This makes sense, because glTranslate essentially means: "translate everything that comes after this". This includes the glRotate call itself, so the result of the rotation also gets translated. Had the calls been reversed, then the result of the translation would have been rotated, which results in a rotation about an axis that does not pass through the origin anymore.
Bottom line: to rotate an object about its local origin, put the glRotate call last.
I am trying to figure out how can you drag an image while constraining its movement along a certain path.
I tried several tricks including animation along a path, but couldn't get the animation to play and pause and play backwards - so that seems out of the question.
Any ideas ? anyone ?
What you're basically trying to do is match finger movement to a 'translation' transition.
As the user touches down and starts to move their finger you want to use the current touch point value to create a translation transform which you apply to your UIImageView. Here's how you would do it:
On touch down, save the imageview's starting x,y position.
On move, calculate the delta from old point to new one. This is where you can clamp the values. So you can ignore, say, the y change and only use the x deltas. This means that the image will only move left to right. If you ignore the x and use y, then it only moves up and down.
Once you have the 'new' calculated/clamped x,y values, use it to create a new transform using CGAffineTransformMakeTranslation(x, y). Assign this transform to the UIImageView. The image moves to that place.
Once the finger lifts, figure out the delta from the original starting x,y, point and the lift-off point, then adjust the ImageView's bounds and reset the transform to CGAffineTransformIdentity. This doesn't move the object, but it sets it so subsequent accesses to the ImageView use the actual position and don't have to keep adjusting for transforms.
Moving along on a grid is easy too. Just round out the x,y values in step 2 so they're a multiple of the grid size (i.e. round out to every 10 pixel) before you pass it on to make the translation transform.
If you want to make it extra smooth, surround the code where you assign the transition with UIView animation blocks. Mess around with the easing and timing settings. The image should drag behind a bit but smoothly 'rubber-band' from one touch point to the next.
See this Sample Code : Move Me