我尝试在我的sfml应用程序中实现着色器，但是没有成功，当我在ubuntu上用g++编译时，我得到了以下错误：

Failed to compile vertex shader:
0:1(1): error: duplicate storage qualifier

我正在想办法消除这个错误。
下面是我在main.cpp中尝试编译的代码：

#include <SFML/Graphics.hpp>
int main()
{
    sf::RenderWindow window(sf::VideoMode(800, 600), "SFML works!");
    sf::CircleShape shape(100.f);
    shape.setFillColor(sf::Color::Green);
    sf::Shader shader;
    shader.loadFromFile("vertex_shader.vert", "fragment_shader.frag");

    while (window.isOpen())
    {
        sf::Event event;
        while (window.pollEvent(event))
        {
            if (event.type == sf::Event::Closed)
                window.close();
        }

        window.clear();
        window.draw(shape, &shader);
        window.display();
    }

    return 0;
}

vertex_shader.vert”和“fragment_shader.frag”与main.cpp位于同一文件夹中
另外，这里还有vertex_shader.vert：

varying out vec4 vert_pos;

void main()
{
    // transform the vertex position
    vert_pos = gl_ModelViewProjectionMatrix * gl_Vertex;
    gl_Position = gl_ModelViewProjectionMatrix * gl_Vertex; 

    // transform the texture coordinates
    gl_TexCoord[0] = gl_TextureMatrix[0] * gl_MultiTexCoord0;

    // forward the vertex color
    gl_FrontColor = gl_Color;
}

和fragment_shader.片段：

varying in vec4 vert_pos;

uniform sampler2D texture;
uniform bool hasTexture;
uniform vec2 lightPos;

void main()
{
    //Ambient light
    vec4 ambient = vec4(0.02, 0.02, 0.5, 1.0);
    
    //Convert light to view coords
    lightPos = (gl_ModelViewProjectionMatrix * vec4(lightPos, 0, 1)).xy;
    
    //Calculate the vector from light to pixel (Make circular)
    vec2 lightToFrag = lightPos - vert_pos.xy;
    lightToFrag.y = lightToFrag.y / 1.7;

    //Length of the vector (distance)
    float vecLength = clamp(length(lightToFrag) * 2, 0, 1);

    // lookup the pixel in the texture
    vec4 pixel = texture2D(texture, gl_TexCoord[0].xy);

    // multiply it by the color and lighting
    if(hasTexture == true)
    {
        gl_FragColor = gl_Color * pixel * (clamp(ambient + vec4(1-vecLength, 1-vecLength, 1-vecLength, 1), 0, 1));
    }
    else
    {
        gl_FragColor = gl_Color;
    }
}