diff --git a/example/Vulkan/VulkanAppFramework.h b/example/Vulkan/VulkanAppFramework.h
index e3a95b01..82afec6c 100644
--- a/example/Vulkan/VulkanAppFramework.h
+++ b/example/Vulkan/VulkanAppFramework.h
@@ -277,8 +277,6 @@ public:
         camera.height=h;
         camera.center.Set(0,0,0,1);
         camera.eye.Set(100,100,0,1);      //xyz三个值不要一样，以方便调试
-        camera.znear=0.01f;
-        camera.zfar=1024;
 
         camera.Refresh();      //更新矩阵计算
     }
diff --git a/inc/hgl/math/Matrix.h b/inc/hgl/math/Matrix.h
index 40072335..098ffac4 100644
--- a/inc/hgl/math/Matrix.h
+++ b/inc/hgl/math/Matrix.h
@@ -94,6 +94,10 @@ namespace hgl
             f / aspect_ratio,   0.0f,   0.0f,                   0.0f,
             0.0f,               -f,     0.0f,                   0.0f,
             0.0f,               0.0f,   zfar / (znear - zfar),  (znear * zfar) / (znear - zfar),
+                                    //  ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+                                    //  某些引擎这两项会乘0.5，那是因为他们是 -1 to 1 的Z值设定，而我们是0 to 1，所以这里不用乘
+                                    //  同理，camera的znear必须为无限接近0的正数，zfar为一个较大的正数，默认使用0.01/1024
+
             0.0f,               0.0f,   -1.0f,                  0.0f);
     }
 
diff --git a/src/SceneGraph/Camera.cpp b/src/SceneGraph/Camera.cpp
index 22356b16..2c27769f 100644
--- a/src/SceneGraph/Camera.cpp
+++ b/src/SceneGraph/Camera.cpp
@@ -20,6 +20,8 @@ namespace hgl
                              nup.x,          nup.y,          nup.z,             0.0f,
                             -forward.x,     -forward.y,     -forward.z/2.0f,    0.0f,
                              0.0f,           0.0f,           0.0f,              1.0f);
+                                                        //  ^^^^^^
+                                                        //      某些引擎此项为0.5，这个会影响最终输出的z值，但我们这里必须为0
 
             return result*translate(-eye.xyz());
         }