如何围绕坐标系的中心旋转分子？

Question

我正在使用OpenGL ES 2构建一个Android应用程序来绘制分子。我画了分子，但我不知道如何添加触摸事件来旋转我的原始原子周围的分子位于（0,0,0），就像我想在Oxy周围旋转2原子Hidro与Oxy位于（0,0） ，0）

我已阅读了一些指南touch和Rotate the sphere around another，但我不明白它是如何运作的。这是我渲染分子的代码，希望有人可以帮助我！

public class MoleculeRenderer extends Activity implements Renderer {

private final Context context;
private String t="1";

private final float[] projectionMatrix = new float[16];
private final float[] modelMatrix = new float[16];
private final float[] viewMatrix = new float[16];
private final float[] viewProjectionMatrix = new float[16];
private final float[] modelViewProjectionMatrix = new float[16];

private Atom atom;
public Float height;
public Float radius;
String amount,amount1;
private Cylinder cylinder;
public ArrayList<Point> apl;
public ArrayList<CoCylinder> acl;
public ArrayList<Float> angle;
public MainRenderer id;

InputStream is;
// private TextureShaderProgram textureProgram;
private ColorShaderProgram colorProgram;

// private int texture;


public MoleculeRenderer(Context context) {
    this.context = context;     
    id=(MainRenderer) context;
    apl=id.lp;
    acl=id.lc;
    angle=id.angle;
    amount=id.amount;
    amount1=id.amount1;
    height=id.link;
    radius=id.radius;
}

public void setT(String l){
    t = l;
}

public String getT(){
    return t;
}

@Override
public void onSurfaceCreated(GL10 glUnused, EGLConfig config) {
    glClearColor(0.0f, 0.0f, 0.0f, 0.0f);

    atom = new Atom(radius, 200);
    cylinder = new Cylinder(0.01f, height-2*radius, 64);

    // textureProgram = new TextureShaderProgram(context);
    colorProgram = new ColorShaderProgram(context);

    // texture = TextureHelper.loadTexture(context,
    // R.drawable.air_hockey_surface);
}

@Override
public void onSurfaceChanged(GL10 glUnused, int width, int height) {
    // Set the OpenGL viewport to fill the entire surface.
    glViewport(0, 0, width, height);
    MatrixHelper.perspectiveM(projectionMatrix, 45, (float) width
            / (float) height, 1f, 10f);
    setLookAtM(viewMatrix, 0, 0.6f, 0.8f, 1.9f, 0f, 0f, 0f, 0f, 1f, 0f);
}

@Override
public void onDrawFrame(GL10 glUnused) {
    // Clear the rendering surface.
    glClear(GL_COLOR_BUFFER_BIT);

    multiplyMM(viewProjectionMatrix, 0, projectionMatrix, 0, viewMatrix, 0);
    colorProgram.useProgram();
    drawsphere();
    drawCylinder();

}

private void positionObjectInScene1(float x, float y, float z) {
    setIdentityM(modelMatrix, 0);
    translateM(modelMatrix, 0, x, y, z);
    multiplyMM(modelViewProjectionMatrix, 0, viewProjectionMatrix, 0,
            modelMatrix, 0);
}

private void positionObjectInScene2(float angle, float x, float y, float z) {
    setIdentityM(modelViewProjectionMatrix, 0);
    rotateM(modelMatrix, 0, angle, x, y, z);
    multiplyMM(modelViewProjectionMatrix, 0, viewProjectionMatrix, 0,
            modelMatrix, 0);
}



private void drawsphere() {
    for (int i = 0; i < apl.size(); i++) {
        float x = apl.get(i).getx();
        float y = apl.get(i).gety();
        float z = apl.get(i).getz();
        //Log.d("ANDROID", "X = " + x + " Y = " + y + " Z = " + z);
        positionObjectInScene1(x, y, z);
        if(i<Integer.parseInt(amount))
        {
            colorProgram.setUniforms(modelViewProjectionMatrix, 0.5f, 0.5f,0.5f);
        }
        else if (i>=Integer.parseInt(amount) &&i<(Integer.parseInt(amount1)+ Integer.parseInt(amount)))
        {
            colorProgram.setUniforms(modelViewProjectionMatrix, 0.2f, 0.3f, 0.3f);
        }
        else 
            colorProgram.setUniforms(modelViewProjectionMatrix, 0f, 0f, 1f);
        atom.bindData(colorProgram);
        atom.draw();
    }
}

private void drawCylinder() {
    for (int i = 0; i < acl.size(); i++) {
        Point point = acl.get(i).getCylinder();
        Log.d("cylinder", "X = " + point.x + " Y = " + point.y + " Z = " + point.z);
        Point convert = convert(point);
        //Log.d("ANDROID", "X = " + convert.x + " Y = " +convert.y + " Z = " + convert.z);
        //Log.d("cylinder", "x " + convert.x + "y " + convert.y + "z " + convert.z);
        positionObjectInScene1(point.x, point.y , point.z );
        if(convert.x==0 && convert.y==0 && convert.z ==0){
            positionObjectInScene2(90, 0 , 0 , 1f );
        }
        else
            positionObjectInScene2(angle.get(i), convert.x , convert.y , convert.z );
        colorProgram.setUniforms(modelViewProjectionMatrix, 1f, 1f, 1f);
        cylinder.bindData(colorProgram);
        cylinder.draw();
    }
}

public Point convert(Point point) {
    Point orgin = new Point(0, (float) (point.y + 0.1), 0);
    float x, y, z;
    x = (orgin.y * point.z) - (orgin.z * point.y);
    y = (orgin.z * point.x) - (orgin.x * point.z);
    z = (orgin.x * point.y) - (orgin.y * point.x);
    return new Point(x, y, z);
}

}