Drawing OpenGL line s

/**

* Buffer tool class

*/

Public class bufferutil {

/**

* Convert a floating point group to a byte Buffer

*/

Public static bytebuffer arr2bytebuffer (float [] ARR ){

Bytebuffer Ibb = bytebuffer. allocatedirect (ARR. length * 4 );

Ibb. Order (byteorder. nativeorder ());

Floatbuffer fbb = Ibb. asfloatbuffer ();

Fbb. Put (ARR );

Ibb. Position (0 );

Return Ibb;

}

/**

* Convert list to byte Buffer

*/

Public static bytebuffer list2bytebuffer (list <float> List ){

Bytebuffer Ibb = bytebuffer. allocatedirect (list. Size () * 4 );

Ibb. Order (byteorder. nativeorder ());

Floatbuffer fbb = Ibb. asfloatbuffer ();

For (float F: List ){

Fbb. Put (f );

}

Ibb. Position (0 );

Return Ibb;

}

}

 

/**

* Renderer

*/

Public abstract class abstractmyrenderer implements Android. OpenGL. glsurfaceview. Renderer

{

Private float ratio;

Public float xrotate = 0f; // rotation angle around the X axis

Public float yrotate = 0f; // rotate the angle around the X axis

/**

* 1.

*/

Public void onsurfacecreated (gl10 GL, eglconfig config)

{

// Clear color

Gl. glclearcolor (0f, 0f, 0f, 1f );

// Enable the vertex buffer Array

Gl. glableclientstate (gl10.gl _ vertex_array );

}

/**

* 2.

*/

Public void onsurfacechanged (gl10 GL, int width, int height ){

// Set the viewport

Gl. glviewport (0, 0, width, height );

Ratio = (float) width/(float) height;

// Projection Matrix

Gl. glmatrixmode (gl10.gl _ projection );

// Load the Unit Matrix

Gl. glloadidentity ();

// Set the intercept

Gl. glfrustumf (-ratio, ratio,-1, 1, 3f, 7f );}

/**

* 3.

*/

Public abstract void ondrawframe (gl10 GL );

}

 

Public class mylinesrenderer extends actmyrenderer {

Public void ondrawframe (gl10 GL ){

// Clear the color Buffer

Gl. glclear (gl10.gl _ color_buffer_bit );

// Set the drawing color

Gl. glcolor4f (1f, 0f, 0f, 1f );

// Operation Model View Matrix

Gl. glmatrixmode (gl10.gl _ modelview );

Gl. glloadidentity ();

// Set eye Parameters

Glu. glulookat (GL, 0f, 0f, 5f, 0f, 0f, 0f, 0f, 1f, 0f );

// Rotation Angle

Gl. glrotatef (xrotate, 1, 0, 0 );

Gl. glrotatef (yrotate, 0, 1, 0 );

// Calculate the coordinate of a vertex

Float r = 0.5f;

// Radius

Float x = 0f, y = 0f, Z = 0f;

List <float> coordslist = new arraylist <float> ();

// Draw points cyclically

For (float alpha = 0f; Alpha <math. Pi * 6; alpha = (float) (alpha + math. PI/16 )){

X = (float) (R * Math. Cos (alpha ));

Y = (float) (R * Math. Sin (alpha ));

Coordslist. Add (0f );

Coordslist. Add (0f );

Coordslist. Add (0f );

Coordslist. Add (X );

Coordslist. Add (y );

Coordslist. Add (z );

}

Gl. glvertexpointer (3, gl10.gl _ float, 0, bufferutil. list2bytebuffer (coordslist ));

Gl. gldrawarrays (gl10.gl _ lines, 0, coordslist. Size ()/3 );

}

}

 

/**

* Main Entry of the program

*/

Public class mainactivity extends activity {

Private abstractmyrenderer render;

Private myglsurfaceview view;

Public void oncreate (bundle savedinstancestate ){

Super. oncreate (savedinstancestate );

View = new glsurfaceview (this );

Render = new mytrianglerenderer ();

View. setrenderer (render );

// Glsurfaceview. rendermode_continuously: continuous rendering (default)

// Glsurfaceview. rendermode_when_dirty: Dirty rendering, command rendering

View. setrendermode (glsurfaceview. rendermode_when_dirty );

Setcontentview (View );

}

Public Boolean onkeydown (INT keycode, keyevent event ){

Float step = 5f;

// Up

If (keycode = keyevent. keycode_dpad_up ){

Render. xrotate = render. xrotate-step;

} Else if (keycode = keyevent. keycode_dpad_down ){

Render. xrotate = render. xrotate + step;

} Else if (keycode = keyevent. keycode_dpad_left ){

Render. yrotate = render. yrotate + step;

} Else if (keycode = keyevent. keycode_dpad_right ){

Render. yrotate = render. yrotate-step;

}

// Request rendering, used with dirty Rendering

View. requestrender ();

Return super. onkeydown (keycode, event );

}

}