OpenGL着色器问题（不显示任何内容）

Question

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void myDisplay(void)
{
glClearColor(0.2f, 0.3f, 0.3f, 1.0f);
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

glBindFramebuffer(GL_FRAMEBUFFER, 0);
glDisable(GL_DEPTH_TEST);


glActiveTexture(GL_TEXTURE0);
glBindTexture(GL_TEXTURE_2D, texture);
glEnable(GL_TEXTURE_2D);

glMatrixMode(GL_MODELVIEW);
glLoadIdentity(); 
glTranslatef(0, 0, -10);

glTexEnvf(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_DECAL);

glUseProgram(ourShader);
glBindVertexArray(VAO); 
glDrawElements(GL_TRIANGLES, 6, GL_UNSIGNED_INT, 0);

glutSwapBuffers();
}

int main(){
//glut initialization stuff...left this out



float vertices[] = {
        // positions          // colors           // texture coords
         0.5f,  0.5f, 0.0f,   1.0f, 0.0f, 0.0f,   1.0f, 1.0f,   // top right
         0.5f, -0.5f, 0.0f,   0.0f, 1.0f, 0.0f,   1.0f, 0.0f,   // bottom right
        -0.5f, -0.5f, 0.0f,   0.0f, 0.0f, 1.0f,   0.0f, 0.0f,   // bottom left
        -0.5f,  0.5f, 0.0f,   1.0f, 1.0f, 0.0f,   0.0f, 1.0f    // top left 
    };
    float texCoords[] = {
    0.0f, 0.0f,  // lower-left corner  
    1.0f, 0.0f,  // lower-right corner
    0.5f, 1.0f   // top-center corner
    };

    unsigned int indices[] = {
       0, 1, 3, // first triangle
       1, 2, 3  // second triangle
    };

    //frameBuffer
    glGenBuffers(1, &FBO);
    glBindFramebuffer(GL_FRAMEBUFFER, FBO);

    if (glCheckFramebufferStatus(GL_FRAMEBUFFER) != GL_FRAMEBUFFER_COMPLETE)
        std::cout << "ERROR: Framebuffer not bound" << std::endl;

    glBindFramebuffer(GL_FRAMEBUFFER, 0);
    //glDeleteFramebuffers(1, &fbo);


    //VAO
    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);

    // Vertex Attributes 
    glEnableVertexAttribArray(0); //pozicija
    glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 8 * sizeof(GLfloat), (void*)(0));
    glEnableVertexAttribArray(1); //boja
    glVertexAttribPointer(1, 3, GL_FLOAT, GL_FALSE, 8 * sizeof(GLfloat), (void*)(3 * sizeof(GLfloat)));
    glEnableVertexAttribArray(2); //boja
    glVertexAttribPointer(2, 3, GL_FLOAT, GL_FALSE, 8 * sizeof(GLfloat), (void*)(6 * sizeof(GLfloat)));

    glEnable(GL_TEXTURE_2D);
    glGenTextures(1, &texture);
    glActiveTexture(GL_TEXTURE0); 
    glBindTexture(GL_TEXTURE_2D, texture);

    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);

    std::string path = "C:\\Projects\\Myproj\\container.jpg";
    bool success = loadTexture(path,texture_data,&tex_width, &tex_height, &nchannels);
    if (success) 
    {
        glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, tex_width, tex_height, 0, GL_RGB, GL_UNSIGNED_BYTE, texture_data);
        glGenerateMipmap(GL_TEXTURE_2D);
    }
    else 
    {
        std::cout << "ERROR::STBI::FAILED TO LOAD TEXTURE" << std::endl;
    }

    stbi_image_free(texture_data);

    int success_f;
    char infoLog[512];

    vertexShader = glCreateShader(GL_VERTEX_SHADER);
    glShaderSource(vertexShader, 1, &vertexShaderSource, NULL);
    glCompileShader(vertexShader);
    getShaderStatus(vertexShader, &success_f, infoLog);

    fragmentShader = glCreateShader(GL_FRAGMENT_SHADER);
    glShaderSource(fragmentShader, 1, &fragmentShaderSource, NULL);
    glCompileShader(fragmentShader);
    getShaderStatus(fragmentShader, &success_f, infoLog);


    ourShader = glCreateProgram();
    glAttachShader(ourShader, vertexShader);
    glAttachShader(ourShader, fragmentShader);
    glLinkProgram(ourShader);
    getShaderStatus(ourShader, &success_f, infoLog);

    glUseProgram(ourShader);
    glUniform1i(glGetUniformLocation(ourShader, "ourTexture"), 0);

    glDeleteShader(vertexShader);
    glDeleteShader(fragmentShader);


    glutMainLoop();
}

const char* vertexShaderSource =
"#version 330 core\n"
"layout(location = 0) in vec3 aPos;\n"
"layout(location = 1) in vec3 aColor;\n"
"layout(location = 2) in vec2 aTexCoord;\n"
"out vec3 ourColor;\n"
"out vec2 TexCoord;\n"
"void main()\n"
"{\n"
"gl_Position = vec4(aPos, 1.0);\n"
"ourColor = aColor;\n"
"TexCoord = aTexCoord;\n"
"}\n";

const char* fragmentShaderSource =
"#version 330 core\n"
"out vec4 FragColor;\n"
"in vec3 ourColor;\n"
"in vec2 TexCoord;\n"
"uniform sampler2D ourTexture;\n"
"void main()\n"
"{\n"
"FragColor = texture(ourTexture, TexCoord);\n"
"}\n";

Answer 1

glenable(GL_TEXTURE_2D)在使用着色器时是不必要的，因为是否使用纹理在（片段）着色器中实现。
着色器代码定义是否应用纹理。glenable(GL_TEXTURE_2D)用于不推荐使用的固定函数管道，仅不使用着色器。

同样，使用固定函数矩阵堆栈(GlMatrixMode、GlloadidEntity、GluPerspective、...)也是无用的。必须使用统一变量(mat4)。这些函数改变固定函数矩阵堆栈上的矩阵。这些矩阵应用于由glvertex或glvertexpointer设置的固定函数顶点坐标，但只有在没有着色器代码的情况下才可以。
如果有着色器，您必须自己进行矩阵转换。
在GLSL中存在诸如gl_modelviewmatrix、gl_projectionmatrix或gl_modelviewprojectionmatrix之类的内置制服，它们允许您访问固定函数矩阵堆栈上的矩阵。但是这种制服也是不推荐的，在GLSL#Version330 Core中也没有更多的可访问性。

用两个制服mat4 u_proj和mat4 u_view编写着色器。通过着色器代码转换顶点坐标。

#version 330 core

layout(location = 0) in vec3 aPos;
layout(location = 1) in vec3 aColor;
layout(location = 2) in vec2 aTexCoord;

out vec3 ourColor;
out vec2 TexCoord;

uniform mat4 u_proj;
uniform mat4 u_view;

void main()
{
    gl_Position = u_proj * u_view * vec4(aPos, 1.0);
    ourColor = aColor;
    TexCoord = aTexCoord;
}

GLint proj_loc = glGetUniformLocation(ourShader, "u_proj");
GLint view_loc = glGetUniformLocation(ourShader, "u_view");

#include <glm/glm.hpp>
#include <glm/gtc/matrix_transform.hpp>
#include <glm/gtc/type_ptr.hpp>

glm::mat4 proj = glm::perspective(glm::radians(fov_degrees)), aspect, near, far);
glm::mat4 view = glm::lookAt(eye, target, up);

glUniformMatrix4fv(proj_loc, 1, GL_FALSE, glm::value_ptr(proj));
glUniformMatrix4fv(view_loc, 1, GL_FALSE, glm::value_ptr(view));

glGetShaderiv(shader_ID, GL_COMPILE_STATUS, &status);

glGetProgramiv(program_ID, GL_LINK_STATUS, success_f);

glVertexAttribPointer(2,
    2,                 // <---- 2 instead of 3 
    GL_FLOAT,
    GL_FALSE,
    8 * sizeof(GLfloat),
    (void*)(6 * sizeof(GLfloat))
); 

glDrawArrays(GL_TRIANGLES, 0, 6); // <---- 6 instead of 2

bool loadTexture(
   const std::string &filename,
   unsigned char*& buff,           // < ---- unsigned char*&
   int* w, int* h, int* nc);

void myDisplay(void) 
{

    // ....

    glBindVertexArray(VAO);

    // unecessary:
    //glEnableVertexAttribArray(0);
    //glEnableVertexAttribArray(1); 
    //glEnableVertexAttribArray(2);