足の動きを作る方法、OpenGL？

Question

ピボットポイント（脚の上端）の周りを脚の動きをしようとすると、代わりに脚を前後に回転させたいときに、脚が間違ったポイントを中心に回転し始めます。

この問題を解決するにはどうすればよいですか？

これは私のコードです。

glPushMatrix(); 

    glTranslatef(x+0.0f, y+6.0f, z-1.5f); 
    glRotatef(walk, 1.0f,0.0f,0.0f); 
    glBegin(GL_QUADS); 
     glTexCoord2f(0.5f,0.0f); glVertex3f(x-1.0f, y-6.0f, z-3.0f); 
     glTexCoord2f(1.0f,0.0f); glVertex3f(x-1.0f, y-6.0f, z-0.5f); 
     glTexCoord2f(1.0f,0.5f); glVertex3f(x-1.0f, y-18.0f, z-0.5f); 
     glTexCoord2f(0.5f,0.5f); glVertex3f(x-1.0f, y-18.0f, z-3.0f); 

     glTexCoord2f(0.5f,0.0f); glVertex3f(x+1.0f, y-6.0f, z-3.0f); 
     glTexCoord2f(1.0f,0.0f); glVertex3f(x+1.0f, y-6.0f, z-0.5f); 
     glTexCoord2f(1.0f,0.5f); glVertex3f(x+1.0f, y-18.0f, z-0.5f); 
     glTexCoord2f(0.5f,0.5f); glVertex3f(x+1.0f, y-18.0f, z-3.0f); 

     glTexCoord2f(0.5f,0.0f); glVertex3f(x-1.0f, y-6.0f, z-3.0f); 
     glTexCoord2f(1.0f,0.0f); glVertex3f(x+1.0f, y-6.0f, z-3.0f); 
     glTexCoord2f(1.0f,0.5f); glVertex3f(x+1.0f, y-18.0f, z-3.0f); 
     glTexCoord2f(0.5f,0.5f); glVertex3f(x-1.0f, y-18.0f, z-3.0f); 

     glTexCoord2f(0.5f,0.0f); glVertex3f(x-1.0f, y-6.0f, z-0.5f); 
     glTexCoord2f(1.0f,0.0f); glVertex3f(x+1.0f, y-6.0f, z-0.5f); 
     glTexCoord2f(1.0f,0.5f); glVertex3f(x+1.0f, y-18.0f, z-0.5f); 
     glTexCoord2f(0.5f,0.5f); glVertex3f(x-1.0f, y-18.0f, z-0.5f); 
glEnd(); 
glPopMatrix(); 
glPushMatrix(); 
    glTranslatef(x+0.0f, y+6.0f, z+1.5f); 
    glRotatef(-walk, 0.0f,0.0f,1.0f); 
    glBegin(GL_QUADS); 
     glTexCoord2f(0.5f,0.0f); glVertex3f(x-1.0f, y-6.0f, z+3.0f); 
     glTexCoord2f(1.0f,0.0f); glVertex3f(x-1.0f, y-6.0f, z+0.5f); 
     glTexCoord2f(1.0f,0.5f); glVertex3f(x-1.0f, y-18.0f, z+0.5f); 
     glTexCoord2f(0.5f,0.5f); glVertex3f(x-1.0f, y-18.0f, z+3.0f); 

     glTexCoord2f(0.5f,0.0f); glVertex3f(x+1.0f, y-6.0f, z+3.0f); 
     glTexCoord2f(1.0f,0.0f); glVertex3f(x+1.0f, y-6.0f, z+0.5f); 
     glTexCoord2f(1.0f,0.5f); glVertex3f(x+1.0f, y-18.0f, z+0.5f); 
     glTexCoord2f(0.5f,0.5f); glVertex3f(x+1.0f, y-18.0f, z+3.0f); 

     glTexCoord2f(0.5f,0.0f); glVertex3f(x-1.0f, y-6.0f, z+3.0f); 
     glTexCoord2f(1.0f,0.0f); glVertex3f(x+1.0f, y-6.0f, z+3.0f); 
     glTexCoord2f(1.0f,0.5f); glVertex3f(x+1.0f, y-18.0f, z+3.0f); 
     glTexCoord2f(0.5f,0.5f); glVertex3f(x-1.0f, y-18.0f, z+3.0f); 

     glTexCoord2f(0.5f,0.0f); glVertex3f(x-1.0f, y-6.0f, z+0.5f); 
     glTexCoord2f(1.0f,0.0f); glVertex3f(x+1.0f, y-6.0f, z+0.5f); 
     glTexCoord2f(1.0f,0.5f); glVertex3f(x+1.0f, y-18.0f, z+0.5f); 
     glTexCoord2f(0.5f,0.5f); glVertex3f(x-1.0f, y-18.0f, z+0.5f); 
glEnd(); 

glPopMatrix(); 

Answer 1

すべてのOpenGLの回転は、点を中心に行われている（0,0,0）。あなたの周りの頂点の特定のポイント（RX、RY、RZ）を回転させるようにしたいのであれば、あなたは次の変換を実行する必要があります。

Translate(-rx, -ry, -rz); 
Rotate(alpha, beta, gamma); 
Translate(rx, ry, rz);