The problem is that it is only moving the image one direction along the slope of the line. I've tried making a condition that checks to see if the target area is to the left of the current position, and if so then make the X/Y differences negative, but that works very sporadically, and make the image move in crazy ways sometime.
On Aug 28, 5:33 pm, Jeffrey <[email protected]> wrote: > This almost works, but when I click on a point that has a smaller X > value than it's current position it reverses the Y Direction. > > On Aug 27, 1:01 pm, Robert Green <[email protected]> wrote: > > > > > Direction will be in the range -180 to 180 so don't use abs! Always > > use sin/cos for y/x respectively when in y+ down 2D coordinate > > systems, otherwise x/y respectively. > > > Here is kind of what you want > > > // tickDelta should be something like .016f to .033f - definitely > > should total 1.0f per second :) > > float tickDelta = (currentMs - lastMs) / 1000f; > > // now mMoveSpeed can be expressed in units-per-second and it'll work > > at any framerate if you multiply by tickdelta > > > float touchDelta = (float)(TouchY - V.CurY) / (TouchX - V.CurX); > > float dirRads = (float)Math.atan(touchDelta); > > float amountX = (float)Math.cos(dirRads) * mMoveSpeed * tickDelta; > > float amountY = (float)Math.sin(dirRads) * mMoveSpeed * tickDelta; > > x += amountX; > > y += amountY; > > > // no additional checks needed. This is how you do 2D directional > > movement. > > // this assumes that either TouchX/TouchY or V is set only when the > > touch is touched down initially so that a vector is made when the > > touch moves and that value is not updated. > > > On Aug 26, 8:40 pm, Jeffrey <[email protected]> wrote: > > > > I know this is more of a general programming question, but my Android > > > friends here have always been helpful. I am trying to make an image > > > move from one part of the screen to a position the user touches, as a > > > constant speed. I don't know the best way to go about doing this and > > > the way I have been trying to get to work is taxing my brain too much. > > > > I have been using geometry to calculate slope, then using Sin * > > > movement speed to calculate the difference in X,Y coordinates. > > > > This is the code I'm looking at: > > > > TouchX = V.TX; (This is the touch event > > > coordinates > > > TouchY = > > > V.TY; ) > > > > Slope = (TouchY - V.CurY) / (TouchX - V.CurX); > > > (this figures out > > > the slope of the line to the touch point) > > > DegreeSlopeY = Math.atan(Slope); > > > DegreeSlopeY = Math.abs(DegreeSlopeY); > > > (this is so > > > that I can calculate the direction the image should travel along the > > > slope) > > > DegreeSlopeX = (90.0000000000000 - DegreeSlopeY); > > > NewY = (mMoveSpeed * Math.sin(DegreeSlopeY)); > > > (This calculates the > > > shift in Y axis for the image) > > > NewX = (mMoveSpeed * Math.sin(DegreeSlopeX)); > > > (This calculates the > > > shift in X axis for the image) > > > if(TouchX < V.CenterX) NewX = -NewX; (This is > > > to finish > > > calculating the correct X axis direction to travel) > > > if(TouchY < V.CenterY) NewY = -NewY; (This is > > > to finish > > > calculating the correct X axis direction to travel) > > > > The problem that I'm having is the image is veering way of course when > > > traveling in Y heavy paths. When traveling horizontally it works > > > almost perfect. > > > > I know there is probably an easier way though I don't know how to use > > > a lot of things (like OpenGLES) so if your advice is to use a > > > different method please link a tutorial for that method if you know of > > > one. > > > > Thanks in advance. -- You received this message because you are subscribed to the Google Groups "Android Developers" group. To post to this group, send email to [email protected] To unsubscribe from this group, send email to [email protected] For more options, visit this group at http://groups.google.com/group/android-developers?hl=en
