iPhone OpenGL : Using gluUnProject (port) and detecting clicking on an object

Question

请帮忙，这是我的第四个问题，我很努力，我尝试了一切!

我想做的就是检测 3D 世界(创建的 3D 世界)中对象(立方体)的点击。
这样就可以了http://blog.nova-box.com/2010/05/iphone-ray-picking-glunproject-sample.html但具有完全不同的应用程序结构，并且在渲染缓冲区等方面做了很多工作。

我正在尝试使用 gluUnProject (有人已经移植了它)。

触摸时

    CGPoint pos = [[touches anyObject] locationInView:self.view];

 glGetIntegerv( GL_VIEWPORT, __viewport );
 glGetFloatv( GL_MODELVIEW_MATRIX, __modelview );
 glGetFloatv( GL_PROJECTION_MATRIX, __projection ); 

 int i = 0;
 for (NSDictionary *item in self.players) {

  IMPoint3D playerPos;

  playerPos.x = [[item objectForKey:@"posX"] floatValue];
  playerPos.z = [[item objectForKey:@"posZ"] floatValue];
  playerPos.y = 1.0f;

  if([self checkCollission:pos object:playerPos])
  {
   NSLog(@"FIRE I LOVE YOU MAN %i", i);
  }

  i ++;
 }

取自其他项目的碰撞函数

    #define RAY_ITERATIONS 1000
     #define COLLISION_RADIUS 0.1f

-(Boolean) checkCollission:(CGPoint)winPos object:(IMPoint3D) _object { 

 winPos.y = (float)__viewport[3] - winPos.y;

 Point3D nearPoint;
 Point3D farPoint;
 Point3D rayVector;

 //Retreiving position projected on near plan
 gluUnProject( winPos.x, winPos.y , 0, __modelview, __projection, __viewport, &nearPoint.x, &nearPoint.y, &nearPoint.z);

 //Retreiving position projected on far plan
 gluUnProject( winPos.x, winPos.y,  1, __modelview, __projection, __viewport, &farPoint.x, &farPoint.y, &farPoint.z);

 //Processing ray vector
 rayVector.x = farPoint.x - nearPoint.x;
 rayVector.y = farPoint.y - nearPoint.y;
 rayVector.z = farPoint.z - nearPoint.z;

 float rayLength = sqrtf(POW2(rayVector.x) + POW2(rayVector.y) + POW2(rayVector.z));

 //normalizing ray vector
 rayVector.x /= rayLength;
 rayVector.y /= rayLength;
 rayVector.z /= rayLength;

 Point3D collisionPoint;
 Point3D objectCenter = {_object.x, _object.y, _object.z};

 //Iterating over ray vector to check collisions
 for(int i = 0; i < RAY_ITERATIONS; i++)
 {
  collisionPoint.x = rayVector.x * rayLength/RAY_ITERATIONS*i;
  collisionPoint.y = rayVector.y * rayLength/RAY_ITERATIONS*i;
  collisionPoint.z = rayVector.z * rayLength/RAY_ITERATIONS*i;

  //Checking collision 
  if([Tools poinSphereCollision:collisionPoint center:objectCenter radius:COLLISION_RADIUS])
  {
   return TRUE;
  }
 }

 return FALSE; 
} 

如果有人能解决这个错误，我什至会支付一些现金(如果允许的话)，这让我头疼了好几天。我认为当我得到投影和模型 View 矩阵时需要做一些事情

Answer 1

我不能确定，但​​坐标系似乎是错误的。我使用(对于 2D)这样的东西:

- (CGPoint) unProject: (CGPoint) point
{
    GLfloat x=0, y=0, z=0;
    GLfloat modelMatrix[16]; 
    GLfloat projMatrix[16];
    GLint viewport[4];
    glGetFloatv(GL_MODELVIEW_MATRIX, modelMatrix);
    glGetFloatv(GL_PROJECTION_MATRIX, projMatrix);
    glGetIntegerv(GL_VIEWPORT, viewport);

    CGPoint result = { 0.0f/0.0f, 0.0f/0.0f };
    if(gluUnProject(point.x, size.height-point.y, 0, modelMatrix, projMatrix, viewport, &x, &y, &z) == GL_TRUE) { 
        result.x = x;
        result.y = y;
        //Since we're using an ortho projection, we can ignore z.
        UNUSED(z);
    }
    return result;
}

请注意:size.height-point.y，其中 size 包含屏幕的尺寸。你必须记住，Core Animation for iOS 中屏幕的默认坐标系与 OpenGL 使用的不同。

如果您应用了翻译，则很难弄清楚发生了什么。

我使用 gluUnProject 的实现: http://www.codng.com/2011/02/gluunproject-for-iphoneios.html(免责声明:这是我的个人博客)。

我知道这并不能完全回答您的问题，但可能会有所帮助。