c++ - 使用 openGL 未按预期显示立方体

Question

我的立方体不是立方体，而是如下所示:

我似乎无法弄清楚为什么它没有呈现为立方体我想知道这里是否有人有任何指示。

我的代码如下:

#define GLEW_STATIC

#include <GL/glew.h>
#include <GLFW/glfw3.h> // glfw manages the window
#include <glm/glm.hpp>
#include <glm/gtc/matrix_transform.hpp>
#include <glm/gtc/type_ptr.hpp>
#include <stdio.h>
#include <chrono>
#include <math.h>

#define GLSL(version , shader) "#version " #version " core \n" #shader

int main() 
{
        glfwInit();

        // setup glfw
        glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3);
        glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 2);
        glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);
        glfwWindowHint(GLFW_OPENGL_FORWARD_COMPAT, GL_TRUE);

        glfwWindowHint(GLFW_RESIZABLE, GL_FALSE);

        // create window
        GLFWwindow* window = glfwCreateWindow(800, 600, "OpenGL", nullptr, nullptr);
        glfwMakeContextCurrent(window);

        // window complete OpenGL code below ---------------------------------------

        // initialise glew
        glewExperimental = GL_TRUE;
        glewInit();

        glEnable(GL_DEPTH_TEST);

        GLuint elements[] = {
                0, 1, 2
        };

        // create the shape of triangle 

        GLfloat vertices[] = {
    -0.5f, -0.5f, -0.5f, 1.0f, 1.0f, 1.0f, 0.0f, 0.0f,
     0.5f, -0.5f, -0.5f, 1.0f, 1.0f, 1.0f, 1.0f, 0.0f,
     0.5f,  0.5f, -0.5f, 1.0f, 1.0f, 1.0f, 1.0f, 1.0f,
     0.5f,  0.5f, -0.5f, 1.0f, 1.0f, 1.0f, 1.0f, 1.0f,
    -0.5f,  0.5f, -0.5f, 1.0f, 1.0f, 1.0f, 0.0f, 1.0f,
    -0.5f, -0.5f, -0.5f, 1.0f, 1.0f, 1.0f, 0.0f, 0.0f,

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

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

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

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

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

        const GLchar* vertexSource = GLSL(150,
                in vec3 position;
                in vec3 color;
                in vec2 texcoord;
                out vec3 Color;
                out vec2 Texcoord;
                uniform mat4 model;
                uniform mat4 view;
                uniform mat4 proj;
                void main()
                {
                        Color = color;
                        Texcoord = texcoord;
                        gl_Position =  proj * view * model * vec4(position, 1.0);
                }
        );

        const GLchar* fragmentSource = GLSL(150,
                in vec3 Color;
                out vec4 outColor;
                void main()
                {
                        outColor = vec4(Color, 1.0);
                }
        );

        GLuint vao;
        glGenVertexArrays(1 ,&vao);
        glBindVertexArray(vao);

        GLuint vbo;
        glGenBuffers(1, &vbo);
        glBindBuffer(GL_ARRAY_BUFFER, vbo);
        glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW);

        GLuint ebo;
        glGenBuffers(1, &ebo);
        glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, ebo);
        glBufferData(GL_ELEMENT_ARRAY_BUFFER, sizeof(elements), elements, GL_STATIC_DRAW);

        // create our shaders
        GLuint vertexShader = glCreateShader(GL_VERTEX_SHADER);
        glShaderSource(vertexShader, 1, &vertexSource, NULL);
        glCompileShader(vertexShader);

        GLuint fragmentShader = glCreateShader(GL_FRAGMENT_SHADER);
        glShaderSource(fragmentShader, 1, &fragmentSource, NULL);
        glCompileShader(fragmentShader);

        GLuint shaderProgram = glCreateProgram();
        glAttachShader(shaderProgram, vertexShader);
        glAttachShader(shaderProgram, fragmentShader);
        glBindFragDataLocation(shaderProgram, 0, "outColor");
        glLinkProgram(shaderProgram);
        glUseProgram(shaderProgram);


        //GLuint uniColor = glGetUniformLocation(shaderProgram, "triangleColor");
        GLint posAttrib = glGetAttribLocation(shaderProgram, "position");
        glEnableVertexAttribArray(posAttrib);
        glVertexAttribPointer(posAttrib, 2, GL_FLOAT, GL_FALSE,5 * sizeof(float), 0);

        GLint colAttrib = glGetAttribLocation(shaderProgram, "color");
        glEnableVertexAttribArray(colAttrib);
        glVertexAttribPointer(colAttrib, 3, GL_FLOAT, GL_FALSE, 5 * sizeof(float), (void*)(2 * sizeof(float)));
        auto t_start = std::chrono::high_resolution_clock::now();

        GLint uniTrans = glGetUniformLocation(shaderProgram, "model");
        GLint uniView = glGetUniformLocation(shaderProgram, "view");

        glm::mat4 view = glm::lookAt(
                glm::vec3(1.2f, 1.2f, 1.2f),
                glm::vec3(0.0f, 0.0f, 0.0f),
                glm::vec3(0.0f, 0.0f, 1.0f)
        );

        glUniformMatrix4fv(uniView, 1, GL_FALSE, glm::value_ptr(view));
        GLint uniProj = glGetUniformLocation(shaderProgram, "proj");
        glm::mat4 proj = glm::perspective(glm::radians(45.0f), 800.0f / 600.0f, 1.0f, 10.0f);
        glUniformMatrix4fv(uniProj, 1, GL_FALSE, glm::value_ptr(proj));


        while(!glfwWindowShouldClose(window))
        {

                auto t_now = std::chrono::high_resolution_clock::now();
                float time = std::chrono::duration_cast<std::chrono::duration<float> >(t_now - t_start).count();

                glUniform3f(colAttrib, (sin(time * 4.0f) + 1.0f) / 2.0f, 0.0f, 0.0f);
                glClearColor(0.0f, 0.0f, 0.0f, 1.0f);
                glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

                glm::mat4 model = glm::mat4(1.0f);
                model = glm::rotate(
                                model,
                                time * glm::radians(180.0f),
                                glm::vec3(0.0f, 0.0f, 1.0f)
                                );

                glUniformMatrix4fv(uniTrans, 1, GL_FALSE, glm::value_ptr(model));

                glDrawArrays(GL_TRIANGLES, 0, 36);

                glfwPollEvents();
                glfwSwapBuffers(window);

                if (glfwGetKey(window, GLFW_KEY_ESCAPE) == GLFW_PRESS) {
                        glfwSetWindowShouldClose(window, GL_TRUE);
                }
        }

        glDeleteProgram(shaderProgram);
        glDeleteShader(fragmentShader);
        glDeleteShader(vertexShader);

        glDeleteBuffers(1, &vbo);
        glDeleteBuffers(1, &ebo);
        glDeleteVertexArrays(1, &vao);
        glDeleteVertexArrays(1, &vao);

        glfwTerminate();

        return 0;
}

Answer 1

您的 glVertexAttribPointer() 调用暗示数据布局与 vertices 中的内容不匹配。

指定与您的数据相匹配的布局(四分量顶点 (XYZW) + 四分量颜色 (RGBA)):

glVertexAttribPointer
    (
    posAttrib,
    4, // four-component vertices (XYZW)
    GL_FLOAT,
    GL_FALSE,
    8 * sizeof(float), // a new vertex every 8 floats
    0 // first vertex starts zero floats in
    );

glVertexAttribPointer
    (
    colAttrib,
    4, // four-component colors (RGBA)
    GL_FLOAT,
    GL_FALSE,
    8 * sizeof(float), // a new color every 8 floats
    (void*)(4 * sizeof(float)) // first color starts 4 floats in
    );