在 OpenGL 中在 3D 平面上渲染 2D 矩形时遇到问题

Question

我在 OpenGL 的 3D 空间中渲染 2D 对象时遇到问题。 每当我编译我的代码时，我都会得到一个紫色的背景，这是我设置的。 但是，我没有看到我应该能够看到的对象。 我认为顶点着色器有问题，但是，我不完全确定。

这是我的代码：

#pragma once

#include <GL/glew.h>
#include <GLFW/glfw3.h>


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

#ifndef STBI_INCLUDE_STB_IMAGE_H
#define STB_IMAGE_IMPLEMENTATION
#include "stb_image.h"
#endif
#include "Shader.h"

class Render3D {
private:
    GLFWwindow* window;
    const int windowWidth = 1920;
    const int windowHeigth = 1080;

    Render3D(Render3D& render){}
    Render3D operator=(Render3D& render) {}
    
    void processInput(GLFWwindow* window) {

        

    }

    void privateInit() {
        if (!glfwInit()) {
            throw(-1);
            std::cout << "Error: GLFW Init Failed" << std::endl;
        }

        glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3);
        glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 3);
        glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);

        window = glfwCreateWindow(windowWidth, windowHeigth, "HAHAH BRRR", NULL, NULL);
        if (window == NULL) {
            std::cout << "Failed to create GLFW Window \n";
            glfwTerminate();
            throw (-1);
        }

        glfwMakeContextCurrent(window);

        glewExperimental = true;
        if (glewInit() != GLEW_OK) {
            std::cout << "GLEW INIT FAILED\n";
            exit(1);
        }

        //The first two parameters set the position of the lower left corner
        glViewport(0, 0, windowWidth, windowHeigth);
    }
    

    


    void render() {

        float positions[] = {

            // positions          // colors           // texture 
                 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 

        };

        unsigned int indices[] = {
            0, 1, 3,
            1, 2, 3

        };

        const char* vertexShader =
            "#version 330 core\n"
            "\n"
            "layout (location = 0) vec3 aPos;\n"
            "layout (location = 1) vec3 aColors;\n"
            "layout (location = 2) vec2 aTex;\n"
            "\n"
            "uniform mat4 model;\n"
            "uniform mat4 view;\n"
            "uniform mat4 projection;\n"
            "\n"
            "out vec3 Colors;\n"
            "out vec2 TextureCoords;\n"
            "\n"
            "void main(){\n"
            "\n"
            "gl_Position = projection * view * model * vec4(aPos, 1.0f);\n"
            "Colors = aColors;\n"
            "TextureCoords = aTex;\n"
            "\n"
            "}\0";

        const char* fragmentShader =
            "#version 330 core\n"
            "\n"
            "out vec4 ourFrag;\n"
            "\n"
            "in vec3 Colors;\n"
            "in vec2 TextureCoords;\n"
            "\n"
            "uniform sampler2D texture1;\n"
            "uniform sampler2D texture2;\n"
            "\n"
            "void main(){\n"
            "\n"
            "ourFrag = mix(texture(texture1, TextureCoords), texture(texture2, TextureCoords), 0.2) * vec4(Colors, 1.0f);;\n"
            "\n"
            "\n"
            "}\0";

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

        glGenVertexArrays(1, &VAO);
        glBindVertexArray(VAO);

        glBindBuffer(GL_ARRAY_BUFFER, VBO);
        glBufferData(GL_ARRAY_BUFFER, sizeof(positions), positions, 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, 8 * sizeof(float), (void*)(0));
        glEnableVertexAttribArray(0);
        
        glVertexAttribPointer(1, 3, GL_FLOAT, GL_FALSE, 8 * sizeof(float), (void*)(3 * sizeof(float)));
        glEnableVertexAttribArray(1);

        glVertexAttribPointer(2, 2, GL_FLOAT, GL_FALSE, 8 * sizeof(float), (void*)(6 * sizeof(float)));
        glEnableVertexAttribArray(2);

        glBindVertexArray(0);

        unsigned int Texture1, Texture2;
        glGenTextures(1, &Texture1);
        glGenTextures(1, &Texture2);

        glBindTexture(GL_TEXTURE_2D, Texture1);

        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_MAG_FILTER, GL_LINEAR);
        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);

        int width, height, nrChannels;
        unsigned char* data = stbi_load("src/Images/woodblock.jpg", &width, &height, &nrChannels, 4);
        if (data) {
            glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, width, height, 0, GL_RGBA, GL_UNSIGNED_BYTE, data);
            glGenerateMipmap(GL_TEXTURE_2D);
        }
        else {
            std::cout << "TEXTURE FAILED:";
            std::cout << stbi_failure_reason() << std::endl;
        }

        glBindTexture(GL_TEXTURE_2D, Texture2);

        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_MAG_FILTER, GL_LINEAR);
        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);

        stbi_set_flip_vertically_on_load(1);
        data = stbi_load("src/Images/awesomeface.png", &width, &height, &nrChannels, 4);
        if (data) {
            glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, width, height, 0, GL_RGBA, GL_UNSIGNED_BYTE, data);
            glGenerateMipmap(GL_TEXTURE_2D);
        }
        else {
            std::cout << "TEXTURE FAILED:";
            std::cout << stbi_failure_reason() << std::endl;
        }


        Shader render3D_Program(vertexShader, fragmentShader, 1);
        render3D_Program.use();

        glUniform1i(glGetUniformLocation(render3D_Program.ID, "texture1"), 0);
        glUniform1i(glGetUniformLocation(render3D_Program.ID, "texture2"), 1);


        while (!glfwWindowShouldClose(window)) {
            processInput(window);

            glClearColor(0.5f, 0.2f, 0.6f, 1.0f);
            glClear(GL_COLOR_BUFFER_BIT);

            glActiveTexture(GL_TEXTURE0);
            glBindTexture(GL_TEXTURE_2D, Texture1);
            glActiveTexture(GL_TEXTURE1);
            glBindTexture(GL_TEXTURE_2D, Texture2);

            render3D_Program.use();
            glm::mat4 model = glm::mat4(1.0f);
            glm::mat4 view1 = glm::mat4(1.0f);
            glm::mat4 projection = glm::mat4(1.0f);

            model = glm::rotate(model, glm::radians(-55.0f), glm::vec3(1.0f, 0.0f, 0.0f));
            view1 = glm::translate(view1, glm::vec3(0.0f, 0.0f, -3.0f));
            projection = glm::perspective(glm::radians(45.0f), (float)windowWidth / (float)windowHeigth, 0.1f, 100.0f);


            glUniformMatrix4fv(glGetUniformLocation(render3D_Program.ID, "model"), 1, GL_FALSE, value_ptr(model));
            glUniformMatrix4fv(glGetUniformLocation(render3D_Program.ID, "view"), 1, GL_FALSE, value_ptr(view1));
            glUniformMatrix4fv(glGetUniformLocation(render3D_Program.ID, "projection"), 1, GL_FALSE, value_ptr(projection));


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

            glfwSwapBuffers(window);
            glfwPollEvents();
        }

        glDeleteVertexArrays(1, &VAO);
        glDeleteBuffers(1, &VBO);
        glDeleteBuffers(1, &VBO);

        glfwTerminate();
    }

public:

    Render3D(){}

    void Init() {
        privateInit();
    }

    void Run() {
        render();
    }

};

此外，这里是 Shader 类：

#ifndef SHADER_H
#define SHADER_H

#include <GL/glew.h>
#include <GLFW/glfw3.h>

#include <string>
#include <fstream>
#include <sstream>
#include <iostream>

class Shader
{
public:
    unsigned int ID;
    // constructor generates the shader on the fly
    // ------------------------------------------------------------------------
    Shader(const char* vertexPath, const char* fragmentPath)
    {
        // 1. retrieve the vertex/fragment source code from filePath
        std::string vertexCode;
        std::string fragmentCode;
        std::ifstream vShaderFile;
        std::ifstream fShaderFile;
        // ensure ifstream objects can throw exceptions:
        vShaderFile.exceptions(std::ifstream::failbit | std::ifstream::badbit);
        fShaderFile.exceptions(std::ifstream::failbit | std::ifstream::badbit);
        try
        {
            // open files
            vShaderFile.open(vertexPath);
            fShaderFile.open(fragmentPath);
            std::stringstream vShaderStream, fShaderStream;
            // read file's buffer contents into streams
            vShaderStream << vShaderFile.rdbuf();
            fShaderStream << fShaderFile.rdbuf();
            // close file handlers
            vShaderFile.close();
            fShaderFile.close();
            // convert stream into string
            vertexCode = vShaderStream.str();
            fragmentCode = fShaderStream.str();
        }
        catch (std::ifstream::failure& e)
        {
            std::cout << "ERROR::SHADER::FILE_NOT_SUCCESFULLY_READ" << std::endl;
        }
        const char* vShaderCode = vertexCode.c_str();
        const char* fShaderCode = fragmentCode.c_str();
        // 2. compile shaders
        unsigned int vertex, fragment;
        // vertex shader
        vertex = glCreateShader(GL_VERTEX_SHADER);
        glShaderSource(vertex, 1, &vShaderCode, NULL);
        glCompileShader(vertex);
        checkCompileErrors(vertex, "VERTEX");
        // fragment Shader
        fragment = glCreateShader(GL_FRAGMENT_SHADER);
        glShaderSource(fragment, 1, &fShaderCode, NULL);
        glCompileShader(fragment);
        checkCompileErrors(fragment, "FRAGMENT");
        // shader Program
        ID = glCreateProgram();
        glAttachShader(ID, vertex);
        glAttachShader(ID, fragment);
        glLinkProgram(ID);
        checkCompileErrors(ID, "PROGRAM");
        // delete the shaders as they're linked into our program now and no longer necessary
        glDeleteShader(vertex);
        glDeleteShader(fragment);
    }

    Shader(const char* VertexShader, const char* FragmentShader, bool Specifier) {
       unsigned int vertex = glCreateShader(GL_VERTEX_SHADER);
       unsigned int fragment = glCreateShader(GL_FRAGMENT_SHADER);
       glShaderSource(vertex, 1, &VertexShader, NULL);
       glShaderSource(fragment, 1, &FragmentShader, NULL);
       glCompileShader(vertex);

       int successVertex;
       char infoLogVertex[512];
       glGetShaderiv(vertex, GL_COMPILE_STATUS, &successVertex);
       if (!successVertex) {
           glGetShaderInfoLog(vertex, 512, NULL, infoLogVertex);
           std::cout << "ERROR::SHADER::VERTEX::COMPILATION_FAILED\n" << infoLogVertex << std::endl;
       }

       glCompileShader(fragment);
       int successFragment;
       glGetShaderiv(fragment, GL_COMPILE_STATUS, &successFragment);
       if (!successFragment){
           glGetShaderInfoLog(fragment, 512, NULL, infoLogVertex);
           std::cout << "ERROR::SHADER:FRAGMENT::COMPILATION_FAILED\n" << infoLogVertex << std::endl;
       }

       ID = glCreateProgram();
       glAttachShader(ID, vertex);
       glAttachShader(ID, fragment);
       glLinkProgram(ID);
       checkCompileErrors(ID, "PROGRAM");

       glDeleteShader(vertex);
       glDeleteShader(fragment);

    }

    // activate the shader
    // ------------------------------------------------------------------------
    void use()
    {
        glUseProgram(ID);
    }
    // utility uniform functions
    // ------------------------------------------------------------------------
    void setBool(const std::string& name, bool value) const
    {
        glUniform1i(glGetUniformLocation(ID, name.c_str()), (int)value);
    }
    // ------------------------------------------------------------------------
    void setInt(const std::string& name, int value) const
    {
        glUniform1i(glGetUniformLocation(ID, name.c_str()), value);
    }
    // ------------------------------------------------------------------------
    void setFloat(const std::string& name, float value) const
    {
        glUniform1f(glGetUniformLocation(ID, name.c_str()), value);
    }

private:
    // utility function for checking shader compilation/linking errors.
    // ------------------------------------------------------------------------
    void checkCompileErrors(unsigned int shader, std::string type)
    {
        int success;
        char infoLog[1024];
        if (type != "PROGRAM")
        {
            glGetShaderiv(shader, GL_COMPILE_STATUS, &success);
            if (!success)
            {
                glGetShaderInfoLog(shader, 1024, NULL, infoLog);
                std::cout << "ERROR::SHADER_COMPILATION_ERROR of type: " << type << "\n" << infoLog << "\n -- --------------------------------------------------- -- " << std::endl;
            }
        }
        else
        {
            glGetProgramiv(shader, GL_LINK_STATUS, &success);
            if (!success)
            {
                glGetProgramInfoLog(shader, 1024, NULL, infoLog);
                std::cout << "ERROR::PROGRAM_LINKING_ERROR of type: " << type << "\n" << infoLog << "\n -- --------------------------------------------------- -- " << std::endl;
            }
        }
    }
};
#endif

Answer 1

您的顶点着色器无法编译，因为您错过了顶点着色器输入（属性）的in类型限定符：

 layout (location = 0) vec3 aPos; layout (location = 1) vec3 aColors; layout (location = 2) vec2 aTex;

它一定要是：

layout (location = 0) in vec3 aPos;
layout (location = 1) in vec3 aColors;
layout (location = 2) in vec2 aTex;