黑屏，没有错误OpenGL，C++

编程问答 2022-06-01

问题描述

所以我一直在尝试编写一个在屏幕上显示四边形的基本程序。 无论我做什么，它都只显示黑屏。 我检查了图书馆，一切都已链接。 我检查了代码，一切似乎都很好（但我知道它不是） 但最荒谬的是：当我将一个看似相同的程序粘贴到同一台计算机上的同一个项目时，它可以工作，而当我再次粘贴该程序时，它又不起作用。

顺便说一句 - 我也尝试通过在线文本差异查找器运行它......它表明它是同一回事。

原始代码（不起作用）：

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

static unsigned int CompileShader(const std::string& source,unsigned int type) {
    unsigned int shader = glCreateShader(type);
    const char* src = source.c_str();
    glShaderSource(shader,1,&src,nullptr);
    glCompileShader(shader);
    int result;
    glGetShaderiv(shader,GL_COMPILE_STATUS,&result);
    // i - int
    // v - vector
    if (result == GL_FALSE) {
        std::cout << "Shader cannot be compiled.\n" << (type == GL_VERTEX_SHADER ? "vertex s." : "fragments.") << "\n";
        int length;
        glGetShaderiv(shader,GL_INFO_LOG_LENGTH,&length);
        char* message = (char*)_malloca(length * sizeof(char));
        glGetShaderInfoLog(shader,length,&length,message);
        std::cout << message << "\n";
        glDeleteShader(shader);
    }
    return shader;
}
static int CreateShader(const std::string& vShader,const std::string& fShader) {
    unsigned int program = glCreateProgram();
    unsigned int vs = CompileShader(vShader,GL_VERTEX_SHADER);
    unsigned int fs = CompileShader(fShader,GL_FRAGMENT_SHADER);
    glAttachShader(program,vs);
    glAttachShader(program,fs);
    glLinkProgram(program);
    glValidateProgram(program);
    glDeleteShader(vs);
    glDeleteShader(fs);
    return program;
}
int main() {
    glfwInit();
    GLFWwindow* window = glfwCreateWindow(1280,720,"CITY ENGINE",0);
    glfwMakeContextCurrent(window);
    glewInit();
    float vertices[8] = { 0.1f,0.1f,-0.1f,-0.1f };
    unsigned int varray;
    glGenVertexArrays(1,&varray);
    glBindVertexArray(varray);
    unsigned int vbuffer;
    glGenBuffers(1,&vbuffer);
    glBindBuffer(vbuffer,GL_ARRAY_BUFFER);
    glBufferData(GL_ARRAY_BUFFER,4 * 2 * sizeof(float),vertices,GL_STATIC_DRAW);
    glVertexAttribPointer(0,2,GL_FLOAT,GL_FALSE,sizeof(float) * 2,0);
    glEnabLevertexAttribArray(0);
    unsigned int indices[6] = { 0,3,0 };
    unsigned int ibuffer;
    glGenBuffers(1,&ibuffer);
    glBindBuffer(ibuffer,GL_ELEMENT_ARRAY_BUFFER);
    glBufferData(GL_ELEMENT_ARRAY_BUFFER,6 * sizeof(unsigned int),indices,GL_STATIC_DRAW);
    unsigned int shader = CreateShader(
        "#version 330 core\n"
        "\n"
        "layout(location = 0) in vec4 position;\n"
        "\n"
        "void main()\n"
        "{\n"
        "gl_Position = position;\n"
        "};\n","#version 330 core\n"
        "\n"
        "layout(location = 0) out vec4 color;\n"
        "uniform vec4 u_Color;\n"
        "\n"
        "void main()\n"
        "{\n"
        "   color = u_Color;\n"
        "};\n"
    );
    gluseProgram(shader);
    int location = glGetUniformlocation(shader,"u_Color");
    gluniform4f(location,0.3f,1.0f,1.0f);
    glBindVertexArray(0);
    gluseProgram(0);
    glBindBuffer(0,GL_ARRAY_BUFFER);
    glBindBuffer(0,GL_ELEMENT_ARRAY_BUFFER);
    while (!glfwWindowShouldClose(window)) {
        glClear(GL_COLOR_BUFFER_BIT);
        glBindVertexArray(varray);
        glBindBuffer(ibuffer,GL_ELEMENT_ARRAY_BUFFER);
        gluseProgram(shader);
        glDrawElements(GL_TRIANGLES,6,GL_UNSIGNED_INT,nullptr);
        glfwSwapBuffers(window);
        glfwPollEvents();
    }
}

工作：

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

static unsigned int CompileShader(const std::string& source,fs);
    glLinkProgram(program);
    glValidateProgram(program);
    glDeleteShader(vs);
    glDeleteShader(fs);
    return program;
}
int main() {
    glfwInit();
    GLFWwindow* window;
    window = glfwCreateWindow(640,480,"Modern OpenGL Test",NULL,NULL);
    glfwMakeContextCurrent(window);
    glewInit();
    float vertices[] = {
        -0.5f,-0.5f,0.5f,};
    unsigned int indices[] = {
        0,0
    };
    unsigned int varray;
    glGenVertexArrays(1,&varray);
    glBindVertexArray(varray);
    unsigned int vb;
    glGenBuffers(1,&vb);
    glBindBuffer(GL_ARRAY_BUFFER,vb);
    glBufferData(GL_ARRAY_BUFFER,0);
    glEnabLevertexAttribArray(0);
    unsigned int ib;
    glGenBuffers(1,&ib);
    glBindBuffer(GL_ELEMENT_ARRAY_BUFFER,ib);
    glBufferData(GL_ELEMENT_ARRAY_BUFFER,GL_STATIC_DRAW);
    unsigned int shaders = CreateShader(
     "#version 330 core\n"
     "\n"
     "layout(location = 0) in vec4 position;\n"
     "\n"
     "void main()\n"
     "{\n"
     "   gl_Position = position;\n"
     "};\n","#version 330 core\n"
     "\n"
     "layout(location = 0) out vec4 color;\n"
     "\n"
     "uniform vec4 u_Color;\n"
     "\n"
     "void main()\n"
     "{\n"
     "  color = u_Color;\n"
     "};\n");
    gluseProgram(shaders);
    int location = glGetUniformlocation(shaders,1.0f);
    glBindVertexArray(0);
    gluseProgram(0);
    glBindBuffer(GL_ARRAY_BUFFER,0);
    glBindBuffer(GL_ELEMENT_ARRAY_BUFFER,0);
    while (!glfwWindowShouldClose(window)) {
        glClear(GL_COLOR_BUFFER_BIT);
        glBindVertexArray(varray);
        gluseProgram(shaders);
        glBindBuffer(ib,GL_ELEMENT_ARRAY_BUFFER);
        glDrawElements(GL_TRIANGLES,nullptr);
        glfwSwapBuffers(window);
        glfwPollEvents();
    }
    glDeleteProgram(shaders);
    glfwTerminate();
}

解决方法

Notepad++ compare 返回文件之间的 2 个显着差异。

  1. glBindBuffer(GL_ARRAY_BUFFER,vb); -> glBindBuffer(vbuffer,GL_ARRAY_BUFFER);
  2. glBindBuffer(GL_ELEMENT_ARRAY_BUFFER,ib); -> glBindBuffer(ibuffer,GL_ELEMENT_ARRAY_BUFFER);

快速查看 docs.gl 告诉我第一个参数应该是 target 而不是 buffer

c++glewglfwopenglopenglopengl