Static function can not be accessed or used C++

Question

I am trying to use a static class, but for some reason I am getting a really not helpful error.

This is the static class I am trying to access:

static class Camera
{

public:
    Camera();
    ~Camera();

    static glm::mat4 viewMatrix;

    static void move(float x, float y, float z) {// add 3 more values for the cube
        viewMatrix = glm::lookAt(glm::vec3(x, y, z),glm::vec3(0.0f, 0.0f, 0.0f),glm::vec3(0.0f, 1.0f, 0.0f));
    } 


    static glm::mat4 getViewMatrix() {
        return viewMatrix;
    }
};

This is the way I am trying to access a function:

 Camera::move(xdist, ydist, zdist);

The error:

Severity    Code    Description Project File    Line    Suppression State
Error   LNK2001 unresolved external symbol "public: static struct glm::detail::tmat4x4<float> Camera::viewMatrix" (?viewMatrix@Camera@@2U?$tmat4x4@M@detail@glm@@A) sample

Since static members needs to be initialized once at program startup, you need to create a `.cpp` file with the following definition: `glm::mat4 Camera::viewMatrix(parameters_here);` — Gilles-Philippe Paillé, Oct 24 '19 at 19:10
@Gilles-PhilippePaillé viewMatrix does not take any parameters. Also, this is part of the class what do you mean by creating another .cpp — T.ChD, Oct 24 '19 at 19:12
The linked duplcated question is very broad and does not give any clue on how OP should fix his problem. A better linked question/answer should be provided. — Gilles-Philippe Paillé, Oct 24 '19 at 19:14
Just wondering can you try to initialize the static variable to something like this in this example https://www.tutorialspoint.com/cplusplus/cpp_static_members.htm — BhanuKiran, Oct 24 '19 at 19:14
@Gilles-PhilippePaillé, the problem of `static` class members described in the second answer. https://stackoverflow.com/a/12574407/434551. — R Sahu, Oct 24 '19 at 19:18
@LightnessRacesinOrbit maybe C# or even Java. Definitely means that the question identified as duplicate is irrelevant. — Mark Ransom, Oct 24 '19 at 22:29
In C++, a "static class" has no meaning. You have to define [static members](https://learn.microsoft.com/en-us/cpp/cpp/static-members-cpp?view=vs-2019) in your cpp file . — Jeaninez - MSFT, Oct 25 '19 at 07:26

score 0 · Accepted Answer · answered Oct 25 '19 at 11:57

0

Solved, added this to the cpp file:

 glm::mat4 Camera::viewMatrix = glm::mat4(1.0);

Needed to initialize the viewMatrix in the .cpp not in the .h file

answered Oct 25 '19 at 11:57

T.ChD

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Static function can not be accessed or used C++

1 Answers1