OpenGL Cropping Area

/**
* 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;
}
}

 

/**
* Cropping Area
*/
Public class myscissorrenderer extends actmyrenderer {

Private int width;
Private int height;
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 );
}
 
Public void onsurfacechanged (gl10 GL, int width, int height ){
This. width = width;
This. Height = height;

Gl. glviewport (0, 0, width, height );
Ratio = (float) width/(float) height;
Gl. glmatrixmode (gl10.gl _ projection );
Gl. glloadidentity ();
Gl. glfrustumf (-ratio, ratio,-1, 1, 3f, 7f );
}
 
Public void ondrawframe (gl10 GL ){
Gl. glclear (gl10.gl _ color_buffer_bit );
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 );

// Enable Cropping
Gl. glable (gl10.gl _ scissor_test );

// Rotation Angle
Gl. glrotatef (xrotate, 1, 0, 0 );
Gl. glrotatef (yrotate, 0, 1, 0 );

Float [] coords = {
-Ratio, 1f, 2f,
-Ratio,-1f, 2f,
Ratio, 1f, 2f,
Ratio,-1f, 2f
};

// Color array
Float [] [] colors = {
{1f, 0f, 0f, 1f },
{0f, 1f, 0f, 1f },
{0f, 0f, 1f, 1f },
{1f, 1f, 0f, 1f },
{0f, 1f, 1f, 1f },
{1f, 0f, 1f, 1f },
};

Int step = 20;
For (INT I = 0; I <6; I ++ ){
// Set the Cropping Area
Gl. glscissor (I * 20, I * 20, width-(I * 20*2), height-(I * 20*2 ));
// Set the color
Gl. glcolor4f (colors [I] [0], colors [I] [1], colors [I] [2], colors [I] [3]);
Gl. glvertexpointer (3, gl10.gl _ float, 0, bufferutil. arr2bytebuffer (coords ));
Gl. gldrawarrays (gl10.gl _ triangle_strip, 0, 4 );
}
}
}

 

// Main Interface

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 );

}

}