OpenGL 显示白框，而不是立方体

Question

所以我才刚刚开始使用 OpenGL/GLEW，我正在尝试创建一个多维数据集，但是，在尝试运行这段代码时，我只得到一个白框。

我已经尝试在多台计算机上运行，但结果都一样。

#include <iostream>
#include <GL/glew.h>
#include <GL/freeglut.h>

//GLM OpenMath Header
#include <GL/glm/glm.hpp>
#include <GL/glm/gtc/matrix_transform.hpp>
#include <GL/glm/gtc/type_ptr.hpp>

using namespace std; //standard namespace

#define WINDOW_TITLE "JShinaberry Activity 5" //window title

//Shader program
#ifndef GLSL
#define GLSL(Version, Source) "#version " #Version "\n" #Source
#endif

//Variable declarations for shader, window size init buffer and array objs

GLint shaderProgram, WindowWidth = 800, WindowHeight = 600;
GLuint VBO, VAO, EBO, texture;

//Function Prototypes
void UResizeWindow(int,int);
void URenderGraphics(void);
void UCreateShader(void);
void UCreateBuffers(void);


//vertex shader source code
const GLchar * vertexShaderSource = GLSL(330,
        layout (location = 0) in vec3 position;
        layout (location = 1) in vec3 color;

        out vec3 mobileColor;

        uniform mat4 model;
        uniform mat4 view;
        uniform mat4 projection;

void main(){
        gl_Postion = projection * view * model * vec4(postion, 1.0f);
        mobileColor = color;
    }
);


//fragment shader source code
const GLchar * fragmentShaderSource = GLSL(330,
        in vec3 mobileColor;

        out vec4 gpuColor;

    void main(){

        gpuColor = vec4(mobileColor, 1.0);

    }
);

int main(int argc, char* argv[])
{
    glutInit(&argc, argv);
    glutInitDisplayMode(GLUT_DEPTH | GLUT_DOUBLE | GLUT_RGBA);
    glutInitWindowSize(WindowWidth, WindowHeight);
    glutCreateWindow(WINDOW_TITLE);

    glutReshapeFunc(UResizeWindow);

    glewExperimental = GL_TRUE;
        if (glewInit() != GLEW_OK)
        {
            std::cout << "Failed to initialize GLEW" << std::endl;
            return -1;
        }

    UCreateShader();

    UCreateBuffers();

    //use the shader program
    glUseProgram(shaderProgram);

    glClearColor(0.0f, 0.0f, 0.0f, 1.0f);

    glutDisplayFunc(URenderGraphics);

    glutMainLoop();

    //destroys buffer objects once used
    glDeleteVertexArrays(1, &VAO);
    glDeleteBuffers(1, &VBO);
    glDeleteBuffers(1, &EBO);

    return 0;

}

//Resize the Window

void UResizeWindow(int w, int h)
{
    WindowWidth = w;
    WindowHeight = h;
    glViewport(0, 0, WindowWidth, WindowHeight);

}

void URenderGraphics(void)
{
    glEnable(GL_DEPTH_TEST);

    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

    glBindVertexArray(VAO); //Activate the vertex array object before rendering

    //declares a 4x4 identity martix
    glm::mat4 model;
    model = glm::translate(model, glm::vec3(0.0, 0.0f, 0.0f));
    model = glm::rotate(model, 45.0f, glm::vec3(1.0, 1.0f, 1.0f));
    model = glm::scale(model, glm::vec3(2.0f, 2.0f, 2.0f));


    glm::mat4 view;
    view = glm::translate(view, glm::vec3(0.5f, 0.0f, -5.0f));

    glm::mat4 projection;
    projection = glm::ortho(-5.0f, 5.0f, -5.0f, 5.0f, 0.1f, 100.0f);

    GLint modelLoc = glGetUniformLocation(shaderProgram, "model");
    GLint viewLoc = glGetUniformLocation(shaderProgram, "view");
    GLint projLoc = glGetUniformLocation(shaderProgram, "projection");

    glUniformMatrix4fv(modelLoc, 1, GL_FALSE, glm::value_ptr(model));
    glUniformMatrix4fv(viewLoc, 1, GL_FALSE, glm::value_ptr(view));
    glUniformMatrix4fv(projLoc, 1, GL_FALSE, glm::value_ptr(projection));

    glutPostRedisplay();

    //Draw the triangles
    glDrawElements(GL_TRIANGLES, 36, GL_UNSIGNED_INT, 0);

    glBindVertexArray(0); //Deactivate the vertex array object

    glutSwapBuffers();

}

//creates the shader program

void UCreateShader()
{
    //vertex shader
    GLint vertexShader = glCreateShader(GL_VERTEX_SHADER);
    glShaderSource(vertexShader, 1, &vertexShaderSource, NULL);
    glCompileShader(vertexShader);

    //fragment shader
    GLint fragmentShader = glCreateShader(GL_FRAGMENT_SHADER);
    glShaderSource(fragmentShader, 1, &fragmentShaderSource, NULL);
    glCompileShader(fragmentShader);

    //shader program
    shaderProgram = glCreateProgram();
    glAttachShader(shaderProgram, vertexShader);
    glAttachShader(shaderProgram, fragmentShader);
    glLinkProgram(shaderProgram);

    //delete the vertex and fragment shaders once linked
    glDeleteShader(vertexShader);
    glDeleteShader(fragmentShader);

}

//creates the buffer and array
void UCreateBuffers()
{

    //position and color data
    GLfloat vertices[] = {
            0.0f,  0.5f,  0.0f,  1.0f, 0.0f, 0.0f,
            0.5f, -0.5f,  0.0f,  0.0f, 1.0f, 0.0f,
           -0.5f, -0.5f,  0.0f,  0.0f, 0.0f, 1.0f,
           -0.5f,  0.5f,  0.0f,  1.0f, 0.0f, 1.0f,

           0.5f, -0.5f, -1.0f,   0.5f, 0.5f, 1.0f,
           0.5f,  0.5f, -1.0f,   1.0f, 1.0f, 0.5f,
          -0.5f,  0.5f, -1.0f,   0.2f, 0.2f, 0.5f,
          -0.5f, -0.5f, -1.0f,   1.0f, 0.0f, 1.0f

                        };
    //index data to share position
    GLuint indices[] = {
                            0, 1, 3,
                            1, 2, 3,
                            0, 1, 4,
                            0, 4, 5,
                            0, 5, 6,
                            0, 3, 6,
                            4, 5, 6,
                            4, 6, 7,
                            2, 3, 6,
                            2, 6, 7,
                            1, 4, 7,
                            1, 2, 7
                        };

    //Generate buffer ids
    glGenVertexArrays(1, &VAO);
    glGenBuffers(1, &VBO);
    glGenBuffers(1, &EBO);

    glBindVertexArray(VAO);

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

    glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, EBO);
    glBufferData(GL_ELEMENT_ARRAY_BUFFER, sizeof(indices), indices, GL_STATIC_DRAW);

    glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 6 * sizeof(GLfloat), (GLvoid*)0);
    glEnableVertexAttribArray(0);

    glVertexAttribPointer (1, 3, GL_FLOAT, GL_FALSE, 6 * sizeof(GLfloat), (GLvoid*)(3 * sizeof(GLfloat)));
    glEnableVertexAttribArray(1);

    glBindVertexArray(0);

}

我已经运行一行一行地看完了，但我不知道为什么它不是运行ning。我虽然我的顶点关闭了，但应该没问题。

Answer 1

几件事：

顶点着色器中的拼写错误：
- gl_Postion（错误）!=gl_Position（正确）
- position != postion（不一致）
确保下次通过glGetShaderiv(..., GL_COMPILE_STATUS, ...) & glGetProgramiv(..., GL_LINK_STATUS, ...) 检查着色器和程序编译 & link 状态；如果他们 return GL_FALSE 这意味着他们未能 compile/link 并且 shader/program 信息日志中有（通常）诊断信息（glGetShaderInfoLog()/glGetProgramInfoLog()).
GLM 不再默认将向量初始化为 (0, 0, 0, 1) 或将矩阵初始化为单位矩阵。

所以在这样的结构中：
```
glm::mat4 view;
view = glm::translate(view, glm::vec3(0.5f, 0.0f, -5.0f));
```
view 将默认为...某物。很可能是垃圾，尤其是在 Release 模式下。

向 glm::translate() 传递垃圾信息通常不会很好地利用您的时间 :)

在你的 #include GLM 之前 #define GLM_FORCE_CTOR_INIT 或将你的 GLM 对象初始化为正常的东西：
```
glm::mat4 view( 1.0f );
```
您正在使用足够多的类似核心的功能，因此您最好请求一个实际版本化的核心上下文：
```
glutInitContextVersion( 3, 3 );
glutInitContextProfile( GLUT_CORE_PROFILE );
```

总计：

#include <iostream>
#include <GL/glew.h>
#include <GL/freeglut.h>

//GLM OpenMath Header
#include <glm/glm.hpp>
#include <glm/gtc/matrix_transform.hpp>
#include <glm/gtc/type_ptr.hpp>

using namespace std; //standard namespace

#define WINDOW_TITLE "JShinaberry Activity 5" //window title

GLint shaderProgram, WindowWidth = 800, WindowHeight = 600;
GLuint VBO, VAO, EBO, texture;

//Function Prototypes
void UResizeWindow(int,int);
void URenderGraphics(void);
void UCreateBuffers(void);

void CheckStatus( GLuint obj, bool isShader )
{
    GLint status = GL_FALSE, log[ 1 << 11 ] = { 0 };
    ( isShader ? glGetShaderiv : glGetProgramiv )( obj, isShader ? GL_COMPILE_STATUS : GL_LINK_STATUS, &status );
    ( isShader ? glGetShaderInfoLog : glGetProgramInfoLog )( obj, sizeof( log ), NULL, (GLchar*)log );
    if( status == GL_TRUE ) return;
    std::cerr << (GLchar*)log << "\n";
    std::exit( EXIT_FAILURE );
}

void AttachShader( GLuint program, GLenum type, const char* src )
{
    GLuint shader = glCreateShader( type );
    glShaderSource( shader, 1, &src, NULL );
    glCompileShader( shader );
    CheckStatus( shader, true );
    glAttachShader( program, shader );
    glDeleteShader( shader );
}

//vertex shader source code
const char* vert = 1 + R"GLSL(
#version 330 core
layout (location = 0) in vec3 position;
layout (location = 1) in vec3 color;
out vec3 mobileColor;
uniform mat4 model;
uniform mat4 view;
uniform mat4 projection;
void main()
{
    gl_Position = projection * view * model * vec4(position, 1.0f);
    mobileColor = color;
}
)GLSL";

//fragment shader source code
const char* frag = 1 + R"GLSL(
#version 330 core
in vec3 mobileColor;
out vec4 gpuColor;
void main()
{
    gpuColor = vec4(mobileColor, 1.0);
}
)GLSL";

int main(int argc, char* argv[])
{
    glutInit(&argc, argv);
    glutInitContextVersion( 3, 3 );
    glutInitContextProfile( GLUT_CORE_PROFILE );
    glutInitDisplayMode(GLUT_DEPTH | GLUT_DOUBLE | GLUT_RGBA);
    glutInitWindowSize(WindowWidth, WindowHeight);
    glutCreateWindow(WINDOW_TITLE);

    glutReshapeFunc(UResizeWindow);

    glewExperimental = GL_TRUE;
    if (glewInit() != GLEW_OK)
    {
        std::cout << "Failed to initialize GLEW" << std::endl;
        return -1;
    }

    //use the shader program
    shaderProgram = glCreateProgram();
    AttachShader( shaderProgram, GL_VERTEX_SHADER, vert );
    AttachShader( shaderProgram, GL_FRAGMENT_SHADER, frag );
    glLinkProgram( shaderProgram );
    CheckStatus( shaderProgram, false );
    glUseProgram( shaderProgram );

    UCreateBuffers();

    glClearColor(0.0f, 0.0f, 0.0f, 1.0f);

    glutDisplayFunc(URenderGraphics);

    glutMainLoop();

    //destroys buffer objects once used
    glDeleteVertexArrays(1, &VAO);
    glDeleteBuffers(1, &VBO);
    glDeleteBuffers(1, &EBO);

    return 0;

}

void UResizeWindow(int w, int h)
{
    WindowWidth = w;
    WindowHeight = h;
    glViewport(0, 0, WindowWidth, WindowHeight);
}

void URenderGraphics(void)
{
    glEnable(GL_DEPTH_TEST);

    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

    glBindVertexArray(VAO); //Activate the vertex array object before rendering

    //declares a 4x4 identity martix
    glm::mat4 model( 1.0f );
    model = glm::translate(model, glm::vec3(0.0, 0.0f, 0.0f));
    model = glm::rotate(model, 45.0f, glm::vec3(1.0, 1.0f, 1.0f));
    model = glm::scale(model, glm::vec3(2.0f, 2.0f, 2.0f));


    glm::mat4 view( 1.0f );
    view = glm::translate(view, glm::vec3(0.5f, 0.0f, -5.0f));

    glm::mat4 projection;
    projection = glm::ortho(-5.0f, 5.0f, -5.0f, 5.0f, 0.1f, 100.0f);

    GLint modelLoc = glGetUniformLocation(shaderProgram, "model");
    GLint viewLoc = glGetUniformLocation(shaderProgram, "view");
    GLint projLoc = glGetUniformLocation(shaderProgram, "projection");

    glUniformMatrix4fv(modelLoc, 1, GL_FALSE, glm::value_ptr(model));
    glUniformMatrix4fv(viewLoc, 1, GL_FALSE, glm::value_ptr(view));
    glUniformMatrix4fv(projLoc, 1, GL_FALSE, glm::value_ptr(projection));

    glutPostRedisplay();

    //Draw the triangles
    glDrawElements(GL_TRIANGLES, 36, GL_UNSIGNED_INT, 0);

    glBindVertexArray(0); //Deactivate the vertex array object

    glutSwapBuffers();
}

//creates the buffer and array
void UCreateBuffers()
{
    //position and color data
    GLfloat vertices[] =
    {
        0.0f,  0.5f,  0.0f,  1.0f, 0.0f, 0.0f,
        0.5f, -0.5f,  0.0f,  0.0f, 1.0f, 0.0f,
        -0.5f, -0.5f,  0.0f,  0.0f, 0.0f, 1.0f,
        -0.5f,  0.5f,  0.0f,  1.0f, 0.0f, 1.0f,

        0.5f, -0.5f, -1.0f,   0.5f, 0.5f, 1.0f,
        0.5f,  0.5f, -1.0f,   1.0f, 1.0f, 0.5f,
        -0.5f,  0.5f, -1.0f,   0.2f, 0.2f, 0.5f,
        -0.5f, -0.5f, -1.0f,   1.0f, 0.0f, 1.0f,
    };

    //index data to share position
    GLuint indices[] =
    {
        0, 1, 3,
        1, 2, 3,
        0, 1, 4,
        0, 4, 5,
        0, 5, 6,
        0, 3, 6,
        4, 5, 6,
        4, 6, 7,
        2, 3, 6,
        2, 6, 7,
        1, 4, 7,
        1, 2, 7,
    };

    //Generate buffer ids
    glGenVertexArrays(1, &VAO);
    glGenBuffers(1, &VBO);
    glGenBuffers(1, &EBO);

    glBindVertexArray(VAO);

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

    glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, EBO);
    glBufferData(GL_ELEMENT_ARRAY_BUFFER, sizeof(indices), indices, GL_STATIC_DRAW);

    glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 6 * sizeof(GLfloat), (GLvoid*)0);
    glEnableVertexAttribArray(0);

    glVertexAttribPointer (1, 3, GL_FLOAT, GL_FALSE, 6 * sizeof(GLfloat), (GLvoid*)(3 * sizeof(GLfloat)));
    glEnableVertexAttribArray(1);

    glBindVertexArray(0);
}

OpenGL 显示白框，而不是立方体

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