c++ - 使用 SFML 和 OpenGL 显示白色三角形？

Question

我应该在输出上看到一个白色三角形，但我只看到黑屏。我认为问题出在 glsl 着色器上。我的代码有什么问题？

#define GLEW_STATIC
#include <iostream>
#include <GL/glew.h>
#include <SFML/Window.hpp>
#include <SFML/OpenGL.hpp>
#include <SFML/System.hpp>
#include <SFML/Graphics.hpp>
using namespace std;
// Shader sources
const char* vertexSource = R"glsl(
    #version 330 core

    in vec2 position;

    void main()
    {
        gl_Position = vec4(position, 0.0, 1.0);
    }
)glsl";


       const char* fragmentSource = R"glsl(
    #version 330 core

out vec4 outColor;

void main()
{
    outColor = vec4(1.0, 1.0, 1.0, 1.0);
}
    )glsl";


int main()
{


        sf::ContextSettings settings;
        settings.depthBits = 24;
        settings.stencilBits = 8;
        settings.antialiasingLevel = 2;
        settings.majorVersion = 3;
        settings.minorVersion = 2;
        settings.attributeFlags = sf::ContextSettings::Core;

        sf::RenderWindow window(sf::VideoMode(800, 600), "OpenGL", sf::Style::Titlebar | sf::Style::Close, settings);
         // Initialize GLEW
    glewExperimental = GL_TRUE;
    glewInit();

        //generate a vao
        GLuint vao;
        glGenVertexArrays(1, &vao);
        glBindVertexArray(vao);


          //generate 1 buffer
        GLuint vbo;
        glGenBuffers(1, &vbo);


        float vertices[] = {
     0.0f,  0.5f, // Vertex 1 (X, Y)
     0.5f, -0.5f, // Vertex 2 (X, Y)
    -0.5f, -0.5f  // Vertex 3 (X, Y)
        };


        glBindBuffer(GL_ARRAY_BUFFER, vbo);
        glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW);

        //compiling the vertex shader
        GLuint vertexshader = glCreateShader(GL_VERTEX_SHADER);
        glShaderSource(vertexshader, 1, &vertexSource, NULL);


        glCompileShader(vertexshader);

        GLint shaderstatus;
        glGetShaderiv(vertexshader, GL_COMPILE_STATUS, &shaderstatus);
        char buffer[512];
        glGetShaderInfoLog(vertexshader, 512, NULL, buffer);
       while (shaderstatus = true){

        cout << "vertex" << endl;
        cout << buffer << endl;
        break;

        }
       //compiling the fragment shader
        GLuint fragmentshader = glCreateShader(GL_FRAGMENT_SHADER);
        glShaderSource(fragmentshader, 1, &fragmentSource, NULL);
        glCompileShader(fragmentshader);

        GLint fragmentstatus;
        glGetShaderiv(fragmentshader, GL_COMPILE_STATUS, &fragmentstatus);
        char bufferfrag[512];
        glGetShaderInfoLog(fragmentshader, 512, NULL, bufferfrag);
        while (fragmentstatus = true){
        cout << "fragment" << endl;
        cout << bufferfrag << endl;
       break;

        }
       //connecting vertex and fragment shaders
        GLuint shaderprogram = glCreateProgram();
        glAttachShader(shaderprogram, vertexshader);
        glAttachShader(shaderprogram, fragmentshader);
        glBindFragDataLocation(shaderprogram, 0, "outColor");

        glLinkProgram(shaderprogram);
        glUseProgram(shaderprogram);

        GLint posAttrib = glGetAttribLocation(shaderprogram, "Position");
        glVertexAttribPointer(posAttrib, 2, GL_FLOAT, GL_FALSE, 0, 0);
        glEnableVertexAttribArray(posAttrib);





        while (window.isOpen())
    {
        // Process events
        sf::Event event;
        while (window.pollEvent(event))
        {
            // Close window : exit
            if (event.type == sf::Event::Closed)
                window.close();
        }

        // Clear screen
        window.clear();

        //window.clear();

        glDrawArrays(GL_TRIANGLES, 0, 3);


        // Update the window
        window.display();
    }



        return 0;
}

Answer 1

在线:

GLint posAttrib = glGetAttribLocation(shaderprogram, "Position");

“Position”中的 p 应该是小写的，因为 GLSL 区分大小写。 此外，在:

while (shaderstatus = true){

    cout << "vertex" << endl;
    cout << buffer << endl;
    break;

}

应该有两个等号，因为这是为了测试相等性，而不是将 shaderstatus 设置为 true。