所以我按照LearnOpenGL的教程来做相机。我试着渲染一个立方体（用顶点矢量定义），然后绕着立方体转一圈，确保它渲染的正确。我可以很好地渲染立方体的正面，但是一旦我切换着色器使用MVP，什么也渲染不了

void GraphicsProgram::run_program() 
{
    glClearColor(0.0, 0.0, 0.0, 1.0);
    glClear(GL_COLOR_BUFFER_BIT);

    state = RUNNING;

    // TODO: Move these into their respective classes
    // Hardcoded for some testing
    // ----------------------------------------------
    const char *vertexShaderPath = "vertex_shader.vs";
    const char *fragmentShaderPath = "fragment_shader.fs";
    Shader firstShader = Shader(vertexShaderPath, fragmentShaderPath);

    std::vector<Vertex> verts;
    Vertex v1, v2, v3, v4, v5, v6, v7, v8;
    v1.position = { -0.5, -0.5, +0.5 };
    v2.position = { +0.5, -0.5, +0.5 };
    v3.position = { +0.5, +0.5, +0.5 };
    v4.position = { -0.5, +0.5, +0.5 };
    v5.position = { +0.5, -0.5, -0.5 };
    v6.position = { +0.5, +0.5, -0.5 };
    v7.position = { -0.5, +0.5, -0.5 };
    v8.position = { -0.5, -0.5, -0.5 };

    verts.push_back(v1);
    verts.push_back(v2);
    verts.push_back(v3);
    verts.push_back(v4);
    verts.push_back(v5);
    verts.push_back(v6);
    verts.push_back(v7);
    verts.push_back(v8);

    std::vector<unsigned int> indicies = { 
        0, 1, 2, 0, 2, 3, // front
        1, 4, 5, 1, 5, 2, // right
        4, 7, 6, 4, 6, 7, // back
        7, 0, 3, 7, 3, 6, // left
        3, 2, 5, 3, 5, 6, // top
        7, 4, 1, 7, 1, 0  // bottom
    };

    unsigned int VBO, VAO, EBO;
    glGenVertexArrays(1, &VAO);
    glGenBuffers(1, &VBO);
    glGenBuffers(1, &EBO);

    glBindVertexArray(VAO);

    glBindBuffer(GL_ARRAY_BUFFER, VBO);
    glBufferData(GL_ARRAY_BUFFER, verts.size() * sizeof(Vertex), &verts[0], GL_STATIC_DRAW);

    glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, EBO);
    glBufferData(GL_ELEMENT_ARRAY_BUFFER, indicies.size() * sizeof(unsigned int), &indicies[0], GL_STATIC_DRAW);

    glEnableVertexAttribArray(0);
    glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, sizeof(Vertex), (void*)0);

    glBindBuffer(GL_ARRAY_BUFFER, 0);

    glBindVertexArray(0);

    glUseProgram(firstShader.shaderID);

    glm::mat4 projection = glm::perspective(glm::radians(45.0f), (float)SCR_WIDTH / (float)SCR_HEIGHT, 0.1f, 100.0f);
    firstShader.set_mat4("projection", projection);

    while (state == RUNNING) {
        currentFrame = (float)SDL_GetTicks() / 1000;
        deltaTime = lastFrame - currentFrame;
        lastFrame = currentFrame;

        process_input();

        glUseProgram(firstShader.shaderID);

        glm::mat4 view;
        float radius = 10.0f;
        float camX = sin((float)SDL_GetTicks() / 1000) * radius;
        float camZ = cos((float)SDL_GetTicks() / 1000) * radius;
        view = glm::lookAt(glm::vec3(camX, 0.0f, camZ), glm::vec3(0.0f, 0.0f, 0.0f), glm::vec3(0.0f, 1.0f, 0.0f));
        firstShader.set_mat4("view", view);

        glBindVertexArray(VAO);

        glm::mat4 model;
        model = glm::translate(model, glm::vec3(0.0, 0.0, 0.0));
        float angle = 0.0;
        model = glm::rotate(model, glm::radians(angle), glm::vec3(0,0,0));
        firstShader.set_mat4("model", model);

        glDrawElements(GL_TRIANGLES, 24, GL_UNSIGNED_INT, 0);
        SDL_GL_SwapWindow(window);
    }

    shutdown_program();
}

顶点结构：

struct Vertex {
    glm::vec3 position;
    glm::vec3 normal;
    glm::vec2 texCoord;
};

顶点着色器代码：

# version 330 core

layout (location = 0) in vec3 aPos;

out vec4 vertexColor;

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

void main() {
    gl_Position = projection * view * model * vec4(aPos, 1.0f);
    vertexColor = vec4(abs(aPos.x), abs(aPos.y), abs(aPos.z), 1.0);
}

片段着色器：

# version 330 core

in vec4 vertexColor;
out vec4 fragColor;

void main() {
    fragColor = vertexColor;
}

我最初使用的顶点着色器只是接受了顶点位置。