Android 3D Rotation triangle (1)

Package com. Sunny;

Import Android. App. activity;
Import Android. OS. Bundle;

Public class mainactivity extends activity {
Private Static final string log_tag = mainactivity. Class. getsimplename ();
Private vortexview _ vortexview;
/** Called when the activity is first created .*/
@ Override
Public void oncreate (bundle savedinstancestate ){
Super. oncreate (savedinstancestate );
_ Vortexview = new vortexview (this );
Setcontentview (_ vortexview );
}
}

Vortexview

Package com. Sunny;

Import Android. content. context;
Import Android. OpenGL. glsurfaceview;
Import Android. View. motionevent;

public class vortexview extends glsurfaceview {// inherits glsurfaceview because it will help us draw 3D images
Private Static final string log_tag = vortexview. class. getsimplename ();
private vortexrenderer _ Renderer; // an Renderer contains everything necessary to draw a frame.
Public vortexview (context) {
super (context);
// todo auto-generated constructor stub
_ Renderer = new vortexrenderer ();
setrenderer (_ Renderer );
}< BR >@ override
Public Boolean ontouchevent (final motionevent event) {
// todo auto-generated method stub
queueevent (New runnable () {

@ Override
Public void run () {// call the setcolor method in Renderer
// Todo auto-generated method stub
_ Renderer. setcolor (event. getx ()/getwidth (), event. Gety ()/getheight (), 1.0f );
_ Renderer. setangle (event. getx ()/10 );
}

});
Return true;
}

}

Vortexrenderer

Package com. Sunny;
Import java. NiO. bytebuffer;
Import java. NiO. byteorder;
Import java. NiO. floatbuffer;
Import java. NiO. Protocol buffer;

Import javax. microedition. khronos. EGL. eglconfig;
Import javax. microedition. khronos. opengles. gl10;

Import Android. OpenGL. glsurfaceview;
Public class vortexrenderer implements glsurfaceview. Renderer {
Private Static final string log_tag = vortexrenderer. Class. getsimplename ();
Private float _ Red = 0.9f; // use floating point numbers to define each color in the RGB Color System
Private float _ Green = 0.2f;
Private float _ Blue = 0.2f;

Private writable buffer _ indexbuffer; // Save the index
Private floatbuffer _ vertexbuffer; // coordinates of the triangle
Private short [] _ indicesarray = {0, 1, 2 };
Private int _ nrofvertices = 3; // defines the number of vertices required. For a triangle, three vertices are required.

Private float _ angle;
Public void setangle (float angle ){
_ Angle = angle;
}
Public void setcolor (float R, float g, float B ){
_ Red = R;
_ Green = g;
_ Blue = B;
}
Private void inittriangle (){
// Allocate the required memory for the two buffers.
// Float has 4 bytes
Bytebuffer vBB = bytebuffer. allocatedirect (_ nrofvertices * 3*4 );
VBB. Order (byteorder. nativeorder ());
_ Vertexbuffer = vBB. asfloatbuffer ();
// Short has 2 bytes
Bytebuffer Ibb = bytebuffer. allocatedirect (_ nrofvertices * 2 );
Ibb. Order (byteorder. nativeorder ());
_ Indexbuffer = Ibb. asw.buffer ();

Float [] coords = {
-0.5f,-0.5f, 0f, // (x1, Y1, Z1)
0.5f,-0.5f, 0f, // (X2, Y2, Z2)
0f, 0.5f, 0f // (X3, Y3, Z3)
};
_ Vertexbuffer. Put (coords );
_ Indexbuffer. Put (_ indicesarray );

_ Vertexbuffer. Position (0 );
_ Indexbuffer. Position (0 );
}


@ Override
Public void onsurfacecreated (gl10 GL, eglconfig config) {// called after surface is created
// Todo auto-generated method stub
Gl. glableclientstate (gl10.gl _ vertex_array); // sets OpenGL to use the vertex array to draw
Inittriangle ();
}

@ Override
Public void onsurfacechanged (gl10 GL, int W, int h) {// called after the surface changes, for example, when switching from the portrait screen to the landscape Screen
// Todo auto-generated method stub
Gl. glviewport (0, 0, W, H );
}

@ Override
Public void ondrawframe (gl10 GL) {// when calling a drawing method at any time
// Todo auto-generated method stub
// Set Rotation
Gl. glrotatef (_ angle, 0f, 1f, 0f); // rotate around the Y axis. The value in the parameter represents a vector, marking the coordinate axis in which the triangle rotates.

// Define the color we want to be displayed as the "clipping wall"
Gl. glclearcolor (_ Red, _ Green, _ Blue, 1.0f );
// Clear the color buffer to show the clearcolor we called abve...
Gl. glclear (gl10.gl _ color_buffer_bit );
// Set the color of our element to set the triangle to dark red
Gl. glcolor4f (0.5f, 0f, 0f, 0.5f );
// Define the vertices we want to draw
/* Use glvertexpointer () to initialize vertex pointer.
* The first parameter is the size, which is also the vertex dimension. We use 3D coordinates x, y, and z.
* The second parameter, gl_float, defines the data type used in the buffer.
* The third variable is 0, because our coordinates are compact in the array and no offset is used.
* The last and fourth parameter vertex buffering.
*/
Gl. glvertexpointer (3, gl10.gl _ float, 0, _ vertexbuffer );
// Finally draw the vertices
/* Gldrawelements () draws all these elements.
* The first parameter defines the elements to be drawn.
* The second parameter defines the number of elements,
* The third is the data type used by indices.
* The last one is the index buffer used to draw the vertex.
*/
Gl. gldrawelements (gl10.gl _ triangles, _ nrofvertices, gl10.gl _ unsigned_short, _ indexbuffer );

}

}