Aha... you mean 'how to rotate using the touchscreen'. You're on the right track :-)
However, i found that gluUnProject in the api did not work for some reason. I wrote my own (do a search on this forum). Handling swipes and translate them into rotations is not trivial. I wrote the app "The Gube", a 3D rubix cube, and handling the user input (touch screen, trackball) is what i spent most my time on. It can not be explained in just a post here (without giving away my code). Some pointers: -On ACTION_DOWN, determine which patch/object your finger is touching. -On a swipe (onFling/onScroll on GestureDetector) and given the earlier found patch/object, determine which direction the swipe is happening in 3D space. -Using the patch/object's normal determine the relation of the swipe relative to the patch and rotate the patch/object accordingly. - To have a smooth interaction with swiping the screen and actually rotating the objects; don't do all the 3D math and such in your main GUI thread. Instead post user-action objects to a queue that is handled by your opengl rendering-thread. The rendering-thread not only renders your cube, but also reads the user-action objects from the queue and does the appropriate 3D handling and instructs the rendering engine how to modify the view/model accordingly. It took me a few months to get this right... On Jul 14, 11:25 pm, quill <quill...@163.com> wrote: > I have read the API Demo code. > I have come up an idea to do it like this: > 1)Map the touch point to 3D coordinates, and we can get a line when > touch point moved, as Line1; > 2)Also we can get another line which is vertical to the screen. Signed > as Line2: gluunproject(x,y,0)-->gluunproject(x,y,1); > 3)Line1 and Line2 can form a plane, and we can get the plane's normal > line, it is just the rotation axis; > 4)With a proper angle according to the touch point's moving distant, > we can rotate the object. > But this idea has come up a problem. how can I know the previous state > of the object? I can't use the total angle to rotate because the axis > is changable. I use gl.glLoadMatrixf(mModelViewMatrix, 0) to reach the > previous state and then do glRotatef, it can work when I slip my > finger quickly, but it works bad when I slip slowly. > > On Jul 14, 11:34 pm, Streets Of Boston <flyingdutc...@gmail.com> > wrote: > > > > > Take a careful look at the API Demo code. > > And then take a look at the OpenGL ES documentation > > (http://www.khronos.org/opengles/) > > Having the code that shows you how to rotate around the X or Y axis, > > it should not be hard to figure out how to rotate along the Z axis > > > On Jul 14, 11:23 am, quill <quill...@163.com> wrote: > > > > In the api demo, there is an example for how to rotate a cube, but it > > > can only rotate about X axis or Y axis, without Z-Axis Rotation. > > > So how to perform 3D Rotation? Any advice is appreciated.- Hide quoted > > > text - > > > - Show quoted text -- Hide quoted text - > > - Show quoted text - --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "Android Developers" group. To post to this group, send email to android-developers@googlegroups.com To unsubscribe from this group, send email to android-developers-unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/android-developers?hl=en -~----------~----~----~----~------~----~------~--~---
