另一个 OpenGL 纹理未渲染后

Question

我刚刚开始学习 OpenGL，但没能渲染出我想要的纹理。每当我执行下面的代码时，我都会看到一个紫色屏幕，没有渲染纹理。我尝试通过 glGetError() 进行更多错误检查。但这并没有让我有任何进展。另外，我确保在 Shader 和 Voa 类中完成错误检查。由于这些类没有报告任何错误，因此它们工作正常。纹理似乎也在加载，因为我也没有收到任何错误。如果有人能告诉我我做错了什么，我将不胜感激。这是代码：

C++代码：

int main()
{
    GLFWwindow* lv_window = Init(static_cast<int>(GlobalVar::Mouse::lv_screenWidth), static_cast<int>(GlobalVar::Mouse::lv_screenHeight));

    if (lv_window == nullptr) {
        return -1;
    }

    std::vector<float> lv_vertices
    {
    //Position        //Color              //Texture coordinates
    0.5f,  0.5f, 0.0f,    1.0f, 0.0f, 0.0f,    1.0f, 1.0f,                   
    0.5f, -0.5f, 0.0f,    0.0f, 1.0f, 0.0f,    1.0f, 0.0f,  
       -0.5f, -0.5f, 0.0f,    0.0f, 0.0f, 1.0f,    0.0f, 0.0f,
       -0.5f,  0.5f, 0.0f,    1.0f, 1.0f, 0.0f,    0.0f, 1.0f,
    };

    std::vector<unsigned int> lv_indices
        {
        0, 1, 3,
        1, 2, 3
    };

    glClearColor(0.5f, 0.4f, 0.8f, 1.0f);

    int lv_width, lv_height, lv_nColorChannels;


    //First texture
    GLuint lv_texture;
    glGenTextures(1, &lv_texture);
    glActiveTexture(GL_TEXTURE0);
    glBindTexture(GL_TEXTURE_2D, lv_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);

    stbi_uc* lv_textureData = stbi_load("C:/Users/source/repos/firstProjectGL/Images/container.jpg", &lv_width, &lv_height, &lv_nColorChannels, 0);

    if (lv_textureData != nullptr) {
        glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, lv_width, lv_height, 0, GL_RGB, GL_UNSIGNED_BYTE, lv_textureData);
        glGenerateMipmap(GL_TEXTURE_2D);
    }
    else {
        std::cout << "Texture failed to be generated!\n";
    }
    stbi_image_free(lv_textureData);


    //Second Texture
    GLuint lv_texture2;
    glGenTextures(1, &lv_texture2);
    glActiveTexture(GL_TEXTURE1);
    glBindTexture(GL_TEXTURE_2D, lv_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_MIN_FILTER, GL_LINEAR);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
    stbi_set_flip_vertically_on_load(true);
    
    lv_textureData = stbi_load("C:/Users/source/repos/firstProjectGL/Images/Happyface.png", &lv_width, &lv_height, &lv_nColorChannels, 0);
    if (lv_textureData != nullptr) {
        glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, lv_width, lv_height, 0, GL_RGBA, GL_UNSIGNED_BYTE, lv_textureData);
        glGenerateMipmap(GL_TEXTURE_2D);
    }
    else {
        std::cout << "Texture2 failed to be generated!\n";
    }
    stbi_image_free(lv_textureData);

    
        //Compile & Link Shader
        std::string lv_vertexShader = "vTextureTest.txt";
    std::string lv_fragmentShader = "fTextureTest.txt";
    Shader lv_shaderProgram(lv_vertexShader, lv_fragmentShader);
    lv_shaderProgram.Use();


        //Initialize VOA & VBO
    Voa lv_voa(lv_vertices);
    GLuint lv_EBO;
    glGenBuffers(1, &lv_EBO);
    glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, lv_EBO);
    glBufferData(GL_ELEMENT_ARRAY_BUFFER, lv_indices.size() * sizeof(unsigned int), lv_indices.data(), GL_STATIC_DRAW);
    
    lv_voa.BindVertexArrayObject();
    lv_voa.BindVertexBufferObject(GL_ARRAY_BUFFER);
    lv_voa.BufferDataSTATIC_DRAW(GL_ARRAY_BUFFER);
    
    lv_voa.SetUniform1i(lv_shaderProgram.GetShaderID(), "lv_ourTexture", 0);
    lv_voa.SetUniform1i(lv_shaderProgram.GetShaderID(), "lv_ourTexture2", 1);
    glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 8 * sizeof(float), reinterpret_cast<void*>(0));
    glEnableVertexAttribArray(0);
    glVertexAttribPointer(1, 3, GL_FLOAT, GL_FALSE, 8 * sizeof(float), reinterpret_cast<void*>(3 * sizeof(float)));
    glEnableVertexAttribArray(1);
    glVertexAttribPointer(2, 2, GL_FLOAT, GL_FALSE, 8 * sizeof(float), reinterpret_cast<void*>(6 * sizeof(float)));
    glEnableVertexAttribArray(2);


        glEnable(GL_DEPTH_TEST);
    
    //Render loop
    while (!glfwWindowShouldClose(lv_window)) {

        glfwPollEvents();
        glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
        glDrawElements(GL_TRIANGLES, 6, GL_UNSIGNED_INT, 0);
        glfwSwapBuffers(lv_window);
    }


    glfwTerminate();
    return 0;

}

顶点着色器：

#version 330 core

layout (location = 0) in vec3 lv_pos;
layout (location = 1) in vec3 lv_color;
layout (location = 2) in vec2 lv_texCoordInput;

out vec3 lv_ourColor;
out vec2 lv_texCoord;

void main()
{
    gl_Position = vec4(lv_pos, 1.0);
    lv_ourColor = lv_color;
    lv_texCoord = lv_texCoordInput;
}

片段着色器：

#version 330 core

out vec4 lv_fragColor;
in vec3 lv_ourColor;
in vec2 lv_texCoord;

uniform sampler2D lv_ourTexture;
uniform sampler2D lv_ourTexture2;

void main()
{
    lv_fragColor = mix(texture(lv_ourTexture, lv_texCoord), texture(lv_ourTexture2, lv_texCoord), 0.2);
}

Answer 1

索引缓冲区 (

ELEMENT_ARRAY_BUFFER

) 绑定存储在顶点数组对象中。当

glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, ...)

被调用时，元素缓冲区对象 ID 存储在当前绑定的顶点数组对象中。因此，VAO 必须使用

glBindVertexArray(VAO)

绑定在元素缓冲区之前。

Voa lv_voa(lv_vertices);
lv_voa.BindVertexArrayObject();             // <--- bind the VAO here

GLuint lv_EBO;
glGenBuffers(1, &lv_EBO);
glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, lv_EBO);
glBufferData(GL_ELEMENT_ARRAY_BUFFER, lv_indices.size() * sizeof(unsigned int), lv_indices.data(), GL_STATIC_DRAW);