从 YouTube 复制的 OpenGl 着色器中的语法错误

Question

我正在尝试学习 OpenGl，现在我想在黑色背景上制作一个带有顶点和着色器的简单红色三角形。我复制了代码 from that YouTube video. 我已经更改了视图内容。那是我的代码：

#include "prec.h"
struct Vector2
{
    float x, y;
};

struct TrianglePos
{
    Vector2 a, b, c;
};

static unsigned int CompileShader(unsigned int type, const std::string& source)
{
    unsigned int id = glCreateShader(type);
    const char* src = source.c_str();
    glShaderSource(id, 1, &src, nullptr);
    glCompileShader(id);

    int result;
    glGetShaderiv(id, GL_COMPILE_STATUS, &result);
    if (!result)
    {
        int length;
        glGetShaderiv(id, GL_INFO_LOG_LENGTH, &length);
        char* message = (char*)alloca(length * sizeof(char));
        glGetShaderInfoLog(id, length, &length, message);
        std::cout << "Failed to compile shader, message: " << message << std::endl;
        glDeleteShader(id);
        return 0;
    }

    return id;
}

static unsigned int createShader(const std::string& vertexShader, const std::string& fragmentShader)
{
    unsigned int program = glCreateProgram();
    unsigned int vs = CompileShader(GL_VERTEX_SHADER, vertexShader);
    unsigned int fs = CompileShader(GL_FRAGMENT_SHADER, fragmentShader);

    glAttachShader(program, vs);
    glAttachShader(program, fs);
    glLinkProgram(program);
    glValidateProgram(program);

    glDeleteShader(vs);
    glDeleteShader(fs);

    return program;
}

int main() {

    if (!glfwInit())
        return -1;


    GLFWwindow *window = glfwCreateWindow(640, 480, "Sand Box GL", NULL, NULL);

    if (!window) {
        std::cout << "problems with window" << std::endl;
        glfwTerminate();
        return -1;
    }

    glfwMakeContextCurrent(window);

    glewExperimental = GL_TRUE;
    if (GLEW_OK != glewInit()) {
        std::cout << "something with glew went wrong" << std::endl;
        return -1;
    }


    TrianglePos trianglePos = {
            -0.5f, -0.5f,
            0.0f, 0.5f,
            0.5f, -0.5f
    };

    unsigned int buffer;
    glGenBuffers(1, &buffer);
    glBindBuffer(GL_ARRAY_BUFFER, buffer);
    glBufferData(GL_ARRAY_BUFFER, sizeof(trianglePos), &trianglePos, GL_STATIC_DRAW);

    glEnableVertexAttribArray(0);
    glVertexAttribPointer(0, 2, GL_FLOAT, GL_FALSE, sizeof(Vector2), 0);

    std::string vertexShader =
            "#version 400 core\n"
            "\n"
            "layout(location = 0) in vec4 position;\n"
            "\n"
            "void main() \n"
            "{\n"
            "   gl_Position = position;\n"
            "}\n";

    std::string fragmentShader =
            "#version 400 core\n"
            "\n"
            "layout(location = 0) out vec4 color;\n"
            "\n"
            "void main()\n"
            "{\n"
            "   color = vec4(1.0, 0.0, 0.0, 1.0);\n"
            "}\n";

    const char *versionGL;
    versionGL = (char *) (glGetString(GL_VERSION));
    std::cout << "openGl version: " << versionGL << std::endl;

    if(GL_VERSION_4_0)
        std::cout << "opengl 4.0 supported" << std::endl;

    unsigned int shader = createShader(vertexShader, fragmentShader);
    glUseProgram(shader);

    while (!glfwWindowShouldClose(window)) {
        glClear(GL_COLOR_BUFFER_BIT);

        glDrawArrays(GL_TRIANGLES, 0, 3);

        glfwSwapBuffers(window);

        glfwPollEvents();
    }
    glfwTerminate();
    return 0;
}

这是预编译头文件 (prec.h): #pragma once

#ifndef GLEWINIT_PREC_H
#define GLEWINIT_PREC_H
#endif //GLEWINIT_PREC_H

#include "GL/glew.h"
#include <GLFW/glfw3.h>

#include <iostream>

程序将其打印到控制台（"OpenGL 4.0 supported" 表示 GL_VERSION_4_0 == true）：

openGl version: 2.1 INTEL-14.5.22 
opengl 4.0 supported

当我尝试运行时，我从顶点和片段着色器的着色器编译器收到此错误消息：

ERROR: 0:1: '' :  version '400' is not supported
ERROR: 0:1: '' : syntax error: #version
ERROR: 0:3: 'layout' : syntax error: syntax error

当我将 #version 400 core 更改为 #version 120 时，我只收到 layout 的语法错误。因此，我认为我搞砸了一些东西。我可以尝试什么？

Answer 1

您的系统不支持 OpenGL 4.0。它只支持 OpenGL 2.1。查看输出

openGl version: 2.1 INTEL-14.5.22

GLSL 1.20 对应 OpenGL 2.1。降级着色器：

顶点着色器

#version 120

attribute vec4 position;

void main()
{
    gl_Position = position;
}

片段着色器

#version 120

void main()
{
    gl_FragColor = vec4(1.0, 0.0, 0.0, 1.0);
}

分别使用Raw string literals (C++11):

std::string vertexShader =
R"(#version 120

attribute vec4 position;

void main()
{
    gl_Position = position;
}
)";

std::string fragmentShader =
R"(#version 120

void main()
{
    gl_FragColor = vec4(1.0, 0.0, 0.0, 1.0);
}
)";

从 YouTube 复制的 OpenGl 着色器中的语法错误

Syntax error in OpenGl shader that is copied from YouTube

c++

opengl

glsl

shader

glew