改进相机的LookAt矩阵

inc/hgl/graph/Camera.h

@@ -28,7 +28,7 @@ namespace hgl
             Vector4f eye;               ///<眼睛坐标
             Vector4f center;            ///<视点坐标
             Vector4f up_vector      =Vector4f(0,0,1,0); ///<向上量(默认0,0,1)
-            Vector4f forward_vector =Vector4f(0,1,0,0); ///<向前量(默认0,1,0)
+            Vector4f forward_vector =Vector4f(0,-1,0,0); ///<向前量(默认0,1,0)
             Vector4f right_vector   =Vector4f(1,0,0,0); ///<向右量(默认0,0,1)
 
         public:

src/SceneGraph/Camera.cpp

@@ -18,7 +18,7 @@ namespace hgl
             Matrix4f result(side.x,         side.y,         side.z,             0.0f,
                             nup.x,          nup.y,          nup.z,              0.0f,
                             -forward.x,     -forward.y,     -forward.z,         0.0f,
-                            0.0f,       0.0f,       0.0f,       1.0f);
+                            -dot(side,eye), -dot(nup,eye),  dot(forward,eye),   1.0f);
 
             return result*translate(-eye.xyz());
         }