OpenGL纹理无法渲染求助：执行代码仅显示紫色屏幕

问题描述 #

刚开始学习OpenGL，尝试渲染纹理时始终失败。运行代码后屏幕仅显示紫色（清屏颜色），纹理未被渲染。已用glGetError()检查无报错，Shader和Voa类的错误检查无异常，纹理加载也未提示错误。

相关代码 #

C++ 主程序代码 #

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);
}

问题分析与修复 #

核心问题：EBO与VAO的绑定顺序错误 #

OpenGL中，EBO的绑定状态是被VAO记录的，必须在绑定VAO之后再绑定EBO，否则VAO不会关联这个EBO。你的代码是先创建并绑定EBO，再绑定VAO，导致后续调用glDrawElements时，VAO没有对应的EBO数据，无法绘制三角形，最终只显示清屏的紫色。

修复后的VAO/EBO初始化代码 #

调整顺序，先绑定VAO，再处理EBO：

//Initialize VOA & VBO
Voa lv_voa(lv_vertices);
lv_voa.BindVertexArrayObject(); // 先激活VAO，让后续的EBO/VBO操作被VAO记录

GLuint lv_EBO;
glGenBuffers(1, &lv_EBO);
glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, lv_EBO); // 此时绑定EBO，VAO会保存这个绑定关系
glBufferData(GL_ELEMENT_ARRAY_BUFFER, lv_indices.size() * sizeof(unsigned int), lv_indices.data(), GL_STATIC_DRAW);

lv_voa.BindVertexBufferObject(GL_ARRAY_BUFFER);
lv_voa.BufferDataSTATIC_DRAW(GL_ARRAY_BUFFER);

// 后续设置顶点属性、uniform的代码不变...

其他需要确认的点 #

1. Voa类的BufferData实现：确保BufferDataSTATIC_DRAW确实将顶点数据正确上传到了VBO中，没有内部逻辑错误。
2. 纹理通道匹配：对于PNG图片，输出lv_nColorChannels确认是否为4（RGBA），当前代码中glTexImage2D的格式设置是正确的，但可以加日志验证。
3. Shader程序激活：确保在渲染循环中，当前使用的Shader程序处于激活状态（你的代码在初始化时调用了lv_shaderProgram.Use()，如果没有切换其他Shader，这部分没问题）。

内容的提问来源于stack exchange，提问作者mathInferno