c++ - main.cpp 中的代码可以工作，但是当我把它放在一个类中时它没有

Question

我有一些简单的代码可以在屏幕上绘制一个 30x30 的球。当它全部在 main.cpp 中时它工作得很好，但是当我把它放到它自己单独的类中时，我得到一个非常微弱的灰色框，而不是占据屏幕的右上角。当我将我在 Ball 类中的确切代码粘贴到 main.cpp 中时，它再次完美运行。

当代码在 Ball 类中时：

当我将 Ball 类中的所有代码粘贴到 main 中时（以及 Ball 类之前的情况）：

代码可以在这里找到。

主文件

#include "Includes.hpp"

static unsigned int Width = 800;
static unsigned int Height = 600;


int main()
{   

bool CursorEnabled = true;
bool PolygonMode = false;

//Camera.CameraInit(45.0f , Width , Height , Model);   use ortho instead \/
Camera.CameraInit (Width, Height, glm::mat4 (1.0f));

GLuint vao;
glGenVertexArrays (1 , &vao);
glBindVertexArray(vao);

Ball ball;

float LastTime = glfwGetTime(); // (for deltatime)

while (true)
{
    float DeltaTime = glfwGetTime() - LastTime; // Deltatime init
    LastTime = glfwGetTime(); // update for deltatime

    glClearColor (0.0f , 0.0f , 0.0f , 1.0f);
    glClear (GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

    ball.Draw();

    glfwSwapBuffers();

    if (glfwGetKey (GLFW_KEY_ESC) || !glfwGetWindowParam(GLFW_OPENED))
    {
        std::cout << "\nShutdown command. Exiting...\n" << std::flush;
        return 0;
    }


}

}

球.hpp

#ifndef BALL
#define BALL

class Ball
{
private:
//Vertices and UV coordiantes.
std::vector <glm::vec2> ballVert;
std::vector <glm::vec2> ballUV;

//Buffers
GLuint vertBuf;
GLuint uvBuf;

//Image
GLuint ballTex;

//IDs for the shader.
GLuint shader;
GLuint MVPid;
GLuint sampler;
GLuint coord;
GLuint uv;

public:
//Constructor
Ball();

void Draw();

};

#endif

球.cpp

#include "Includes.hpp"

Ball::Ball()
{
//Create ball vertices and UV coords
ballVert.push_back(glm::vec2(0 , 0));                                       /*left      /\*/
ballVert.push_back(glm::vec2(0 , 30));                                      /*right    /  \*/
ballVert.push_back(glm::vec2(30 , 0));                                      /*top     ------*/

ballVert.push_back(glm::vec2(0 , 30));                                       /*left      /\*/
ballVert.push_back(glm::vec2(30 , 30));                                      /*right    /  \*/
ballVert.push_back(glm::vec2(30 , 0));                                       /*top     ------*/

ballUV.push_back(glm::vec2(0 , 1));
ballUV.push_back(glm::vec2(0 , 0));
ballUV.push_back(glm::vec2(1 , 1));

ballUV.push_back(glm::vec2(0 , 0));
ballUV.push_back(glm::vec2(1 , 0));
ballUV.push_back(glm::vec2(1 , 1));

//Load the image
ballTex = SOIL_load_OGL_texture (
"img/ball.png",
SOIL_LOAD_AUTO,
SOIL_CREATE_NEW_ID, SOIL_FLAG_MIPMAPS | SOIL_FLAG_INVERT_Y | SOIL_FLAG_NTSC_SAFE_RGB | SOIL_FLAG_COMPRESS_TO_DXT);

//Generate buffers
glGenBuffers (1 , &vertBuf);
glBindBuffer (GL_ARRAY_BUFFER , vertBuf);
glBufferData (GL_ARRAY_BUFFER , ballVert.size() * sizeof(glm::vec2) , &ballVert[0] , GL_STATIC_DRAW);

glGenBuffers (1 , &uvBuf);
glBindBuffer (GL_ARRAY_BUFFER , uvBuf);
glBufferData (GL_ARRAY_BUFFER , ballUV.size() * sizeof (glm::vec2) , &ballUV[0] , GL_STATIC_DRAW);

shader = Game.LoadShaders ("src/glsl/ball.vert" , "src/glsl/ball.frag");
MVPid = glGetUniformLocation (shader , "MVP");
sampler = glGetUniformLocation (shader, "sampler");
coord = glGetAttribLocation(shader, "coord");
uv = glGetAttribLocation (shader, "uv");


}

void Ball::Draw()
{
glUseProgram (shader);
    glUniformMatrix4fv(MVPid, 1, GL_FALSE, &Camera.GetMVP()[0][0]); // Send MVP     to shader

    glActiveTexture (GL_TEXTURE0); // bind the ball texture
    glBindTexture (GL_TEXTURE_2D, ballTex);
    glUniform1i (sampler , 0);
        glEnableVertexAttribArray (coord); // sending the vertex data
            glBindBuffer(GL_ARRAY_BUFFER, vertBuf);
                glVertexAttribPointer(
                    coord, // The attribute we want to configure
                    2,                  // size
                    GL_FLOAT,           // type
                    GL_FALSE,           // normalized?
                    0,                  // stride
                    (void*)0            // array buffer offset
                    );

        glEnableVertexAttribArray (uv);
            glBindBuffer (GL_ARRAY_BUFFER , uvBuf);
                glVertexAttribPointer (uv, 2, GL_FLOAT, GL_FALSE, 0,     (void*)0);

    // Draw the triangle !
            glDrawArrays(GL_TRIANGLES, 0, ballVert.size()); 

        glDisableVertexAttribArray(coord);
        glDisableVertexAttribArray(uv);
}