Question

我一直在尝试在太阳系的openGL（使用JOGL）中实现3D动画到目前为止我有5个不同大小的行星，但我似乎有的问题是我无法添加地球纹理的地图球体可以帮助我完成它的工作吗？

这是我目前在我的Display方法中的代码：

@Override
public void display(GLAutoDrawable drawable) {
    GL2 gl = drawable.getGL().getGL2(); 
    GLU glu = new GLU();
    gl.glClear(GL.GL_COLOR_BUFFER_BIT);

    //make sure we are in model_view mode
    gl.glMatrixMode(GL2.GL_MODELVIEW);
    gl.glLoadIdentity();
    glu.gluLookAt(10,20,20,0,3,0,0, 20, 0);
    //gl.glMatrixMode(GL2.GL_PROJECTION);
    //glu.gluPerspective(45,1,1,25);

    //render ground plane
    gl.glPushMatrix();
    gl.glTranslatef(-10.75f, 3.0f, -1.0f);
    gl.glColor3f(0.3f, 0.5f, 1f);
    GLUquadric earth = glu.gluNewQuadric();
    glu.gluQuadricDrawStyle(earth, GLU.GLU_FILL);
    glu.gluQuadricNormals(earth, GLU.GLU_FLAT);
    glu.gluQuadricOrientation(earth, GLU.GLU_OUTSIDE);
    final float radius = 3.378f;
    final int slices = 89;
    final int stacks = 16;
    glu.gluSphere(earth, radius, slices, stacks);
    glu.gluDeleteQuadric(earth);

    Texture earths;
    try {
      earths = TextureIO.newTexture(new File("earth.png"), true);
    }
    catch (IOException e) {    
      javax.swing.JOptionPane.showMessageDialog(null, e);
    }        
    gl.glPopMatrix();
    //gl.glEnd();

    gl.glPushMatrix();
    gl.glTranslatef(2.75f, 3.0f, -0.0f);
    gl.glColor3f(0.3f, 0.5f, 1f);
    GLUquadric earth1 = glu.gluNewQuadric();
    glu.gluQuadricDrawStyle(earth1, GLU.GLU_FILL);
    glu.gluQuadricNormals(earth1, GLU.GLU_FLAT);
    glu.gluQuadricOrientation(earth1, GLU.GLU_OUTSIDE);
    final float radius1 = 3.378f;
    final int slices1 = 90;
    final int stacks1 = 63;
    glu.gluSphere(earth1, radius1, slices1, stacks1);
    glu.gluDeleteQuadric(earth1);
    gl.glPopMatrix();

    gl.glPushMatrix();
    gl.glTranslatef(3.75f, 6.0f, -7.20f);
    gl.glColor3f(0.3f, 0.5f, 1f);
    GLUquadric earth3 = glu.gluNewQuadric();
    glu.gluQuadricDrawStyle(earth3, GLU.GLU_FILL);
    glu.gluQuadricNormals(earth3, GLU.GLU_FLAT);
    glu.gluQuadricOrientation(earth1, GLU.GLU_OUTSIDE);
    final float radius3 = 1.878f;
    final int slices3 = 89;
    final int stacks3 = 16;
    glu.gluSphere(earth3, radius3, slices3, stacks3);
    glu.gluDeleteQuadric(earth3);
    gl.glPopMatrix();   

    gl.glPushMatrix();
    gl.glTranslatef(12.75f, 2.0f, -7.20f);
    gl.glColor3f(0.3f, 0.5f, 1f);
    GLUquadric earth4 = glu.gluNewQuadric();
    glu.gluQuadricDrawStyle(earth4, GLU.GLU_FILL);
    glu.gluQuadricNormals(earth4, GLU.GLU_FLAT);
    glu.gluQuadricOrientation(earth4, GLU.GLU_OUTSIDE);
    final float radius4 = 1.078f;
    final int slices4 = 89;
    final int stacks4 = 16;
    glu.gluSphere(earth4, radius4, slices4, stacks4);
    glu.gluDeleteQuadric(earth4);

    gl.glPopMatrix(); 

    gl.glPushMatrix();
    gl.glTranslatef(2.75f, -6.0f, -0.0f);
    gl.glColor3f(0.3f, 0.5f, 1f);
    GLUquadric earth5 = glu.gluNewQuadric();
    glu.gluQuadricDrawStyle(earth5, GLU.GLU_FILL);
    glu.gluQuadricNormals(earth5, GLU.GLU_FLAT);
    glu.gluQuadricOrientation(earth5, GLU.GLU_OUTSIDE);
    final float radius5 = 3.778f;
    final int slices5 = 90;
    final int stacks5 = 63;
    glu.gluSphere(earth5, radius5, slices5, stacks5);
    glu.gluDeleteQuadric(earth5);
    gl.glPopMatrix();        

}

Answer 1

创建自己的球体网格

简单的 2D 循环通过2个角度（球面坐标系2笛卡尔坐标）。如果想要更高的精度，可以轻松添加椭球属性（地球不是球体）。如果没有，那么你可以对所有行星使用单球面网格，并在使用之前进行缩放......

让a为经度b纬度，从a到0 [rad]和2*PI从b循环-0.5*PI {1}}到+0.5*PI [rad]其中PI=3.1415...是Pi（在C ++ math.h中称为M_PI）。如果您的数学api使用度数，则转换为度PI [rad] = 180.0 [deg]

为每个顶点添加必要的信息

照明法线

    // just unit sphere
    nx=cos(b)*cos(a);
    ny=cos(b)*sin(a);
    nz=sin(b);

纹理坐标（假设矩形非扭曲图像）

    // just convert a,b to <0,1> range
    tx=a/(2.0*PI)
    ty=(b/PI)+0.5;

顶点位置

    // just sphere(rx=ry=rz=r) or ellipsoid (rx=ry=equatorial and rz=polar radius)
    // can also use rx*nx,ry*ny,rz*nz instead ...
    x=rx*cos(b)*cos(a);
    y=ry*cos(b)*sin(a);
    z=rz*sin(b);

将所有这些内容发送到OpenGL

以上所有内容存储在一些内存空间（ CPU 或 GPU ）中，然后发送到渲染。您可以使用旧版glBegin(QUAD_STRIP); ... glEnd();或displaylist / VBO / VAO。在每个行星/身体之前绑定正确的纹理，并且不要忘记更新ModelView矩阵。这就是矿井坐标系的样子：

另外看看这些相关的Q / As：

[edit1] C ++示例

//---------------------------------------------------------------------------
const int nb=15;        // slices
const int na=nb<<1;     // points per equator
class planet
    {
public:
    bool _init;             // has been initiated ?
    GLfloat x0,y0,z0;       // center of planet [GCS]
    GLfloat pos[na][nb][3]; // vertex
    GLfloat nor[na][nb][3]; // normal
    GLfloat txr[na][nb][2]; // texcoord
    GLuint  txrid;          // texture id
    GLfloat t;              // dayly rotation angle [deg]
    planet() { _init=false; txrid=0; x0=0.0; y0=0.0; z0=0.0; t=0.0; }
    ~planet() { if (_init) glDeleteTextures(1,&txrid); }
    void init(GLfloat r,AnsiString texture);        // call after OpenGL is already working !!!
    void draw();
    };
void planet::init(GLfloat r,AnsiString texture)
    {
    if (!_init) { _init=true; glGenTextures(1,&txrid); }

    GLfloat x,y,z,a,b,da,db;
    GLfloat tx0,tdx,ty0,tdy;// just correction if CLAMP_TO_EDGE is not available
    int ia,ib;

    // a,b to texture coordinate system
    tx0=0.0;
    ty0=0.5;
    tdx=0.5/M_PI;
    tdy=1.0/M_PI;

    // load texture to GPU memory
    if (texture!="")
        {
        Byte q;
        unsigned int *pp;
        int xs,ys,x,y,adr,*txr;
        union { unsigned int c32; Byte db[4]; } c;
        Graphics::TBitmap *bmp=new Graphics::TBitmap;   // new bmp
        bmp->LoadFromFile(texture); // load from file
        bmp->HandleType=bmDIB;      // allow direct access to pixels
        bmp->PixelFormat=pf32bit;   // set pixel to 32bit so int is the same size as pixel
        xs=bmp->Width;              // resolution should be power of 2
        ys=bmp->Height;
        txr=new int[xs*ys];
        for(adr=0,y=0;y<ys;y++)
            {
            pp=(unsigned int*)bmp->ScanLine[y];
            for(x=0;x<xs;x++,adr++)
                {
                // rgb2bgr and copy bmp -> txr[]
                c.c32=pp[x];
                q      =c.db[2];
                c.db[2]=c.db[0];
                c.db[0]=q;
                txr[adr]=c.c32;
                }
            }
        glEnable(GL_TEXTURE_2D);
        glBindTexture(GL_TEXTURE_2D,txrid);
        glPixelStorei(GL_UNPACK_ALIGNMENT, 4);
        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S,GL_CLAMP);
        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T,GL_CLAMP);
        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER,GL_LINEAR);
        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER,GL_LINEAR);
        glTexEnvf(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE,GL_MODULATE);
        glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, xs, ys, 0, GL_RGBA, GL_UNSIGNED_BYTE, txr);
        glDisable(GL_TEXTURE_2D);
        delete bmp;
        delete[] txr;

        // texture coordinates by 1 pixel from each edge (GL_CLAMP_TO_EDGE)
        tx0+=1.0/GLfloat(xs);
        ty0+=1.0/GLfloat(ys);
        tdx*=GLfloat(xs-2)/GLfloat(xs);
        tdy*=GLfloat(ys-2)/GLfloat(ys);
        }
    // correct texture coordinate system (invert x)
    tx0=1.0-tx0; tdx=-tdx;

    da=(2.0*M_PI)/GLfloat(na-1);
    db=     M_PI /GLfloat(nb-1);
    for (ib=0,b=-0.5*M_PI;ib<nb;ib++,b+=db)
    for (ia=0,a= 0.0     ;ia<na;ia++,a+=da)
        {
        x=cos(b)*cos(a);
        y=cos(b)*sin(a);
        z=sin(b);
        nor[ia][ib][0]=x;
        nor[ia][ib][1]=y;
        nor[ia][ib][2]=z;
        pos[ia][ib][0]=r*x;
        pos[ia][ib][1]=r*y;
        pos[ia][ib][2]=r*z;
        txr[ia][ib][0]=tx0+(a*tdx);
        txr[ia][ib][1]=ty0+(b*tdy);
        }
    }
void planet::draw()
    {
    if (!_init) return;
    int ia,ib0,ib1;
    glMatrixMode(GL_MODELVIEW);
    glPushMatrix();
    glLoadIdentity();
    glTranslatef(x0,y0,z0);
    glRotatef(90.0,1.0,0.0,0.0); // rotate planets z axis (North) to OpenGL y axis (Up)
    glRotatef(-t,0.0,0.0,1.0); // rotate planets z axis (North) to OpenGL y axis (Up)

    glEnable(GL_TEXTURE_2D);
    glBindTexture(GL_TEXTURE_2D,txrid);
    glColor3f(1.0,1.0,1.0);
    for (ib0=0,ib1=1;ib1<nb;ib0=ib1,ib1++)
        {
        glBegin(GL_QUAD_STRIP);
        for (ia=0;ia<na;ia++)
            {
            glNormal3fv  (nor[ia][ib0]);
            glTexCoord2fv(txr[ia][ib0]);
            glVertex3fv  (pos[ia][ib0]);
            glNormal3fv  (nor[ia][ib1]);
            glTexCoord2fv(txr[ia][ib1]);
            glVertex3fv  (pos[ia][ib1]);
            }
        glEnd();
        }
    glDisable(GL_TEXTURE_2D);
    glMatrixMode(GL_MODELVIEW);
    glPopMatrix();
    }
//---------------------------------------------------------------------------

<强>用法：

// variable to store planet (global)
planet earth;

// init after OpenGL initialisation
earth.init(1.0,"earth.bmp");

// position update
earth.x0=  0.0;
earth.y0=  0.0;
earth.z0=-20.0;

// add this to render loop
earth.draw(); // draws the planet
earth.t+=2.5; // just rotate planet by 2.5 deg each frame...

我知道它的丑陋但它没有使用任何有趣的东西，只有遗留的 OpenGL 和Math.h（cos(),sin(),M_PI）和 VCL 来进行位图加载。所以重写你的环境，你会没事的。不要忘记每个行星都有自己的纹理，所以你需要每个行星有一个txrid，所以要么将每个行星作为单独的planet变量或重写......

应用地球纹理地图的球体

1 个答案: