纹理不显示

Question

我想在我的三角形上添加纹理，但它只显示为黑色三角形。这是我调用的起始函数：

GLuint vao;
GLuint shader_programme;
extern "C" void UNITY_INTERFACE_EXPORT UNITY_INTERFACE_API createSimpleWindow()
{



    if (std::this_thread::get_id() == MAIN_THREAD_ID)
    {
        oldContext = glfwGetCurrentContext();

        newContext = glfwCreateWindow(640, 480, "window", NULL, oldContext);
        glfwMakeContextCurrent(newContext);
        // start GLEW extension handler
        glewExperimental = GL_TRUE;
        glewInit();

        glEnable(GL_DEPTH_TEST); // enable depth-testing
        glDepthFunc(GL_LESS); // depth-testing interprets a smaller value as "closer"
//triangle pts
        float points[] = {
            0.0f,  0.5f,  0.0f,     0.5f, 1.0f,
            0.5f, -0.5f,  0.0f,     1.0f, 0.0f,
            -0.5f, -0.5f,  0.0f,    0.0f, 0.0f
        };
        GLuint vbo = 0;
        glGenBuffers(1, &vbo);
        glBindBuffer(GL_ARRAY_BUFFER, vbo);
        glBufferData(GL_ARRAY_BUFFER, 9 * sizeof(float), points, GL_STATIC_DRAW);

         vao = 0;
        glGenVertexArrays(1, &vao);
        glBindVertexArray(vao);
        //glEnableVertexAttribArray(0);
        glBindBuffer(GL_ARRAY_BUFFER, vbo);
        glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 6 * sizeof(float), (void*)0);
        glEnableVertexAttribArray(0);
        glVertexAttribPointer(1, 2, GL_FLOAT, GL_FALSE, 6 * sizeof(float), (void*)(3 * sizeof(float)));
        glEnableVertexAttribArray(1);

        GLuint vs = glCreateShader(GL_VERTEX_SHADER);
        glShaderSource(vs, 1, &vertex_shader, NULL);
        glCompileShader(vs);
        GLuint fs = glCreateShader(GL_FRAGMENT_SHADER);
        glShaderSource(fs, 1, &fragment_shader, NULL);
        glCompileShader(fs);

        shader_programme = glCreateProgram();
        glAttachShader(shader_programme, fs);
        glAttachShader(shader_programme, vs);
        glLinkProgram(shader_programme);

         glUseProgram(shader_programme);
        glGenTextures(1, &texture);
        glBindTexture(GL_TEXTURE_2D, texture);
        int width, height, nrComponents;
        unsigned char *data = stbi_load("/Users/roma/Desktop/Escape Tech/BitBucketRepos/blankpluginGLFW/BlankPlugin/PluginSource/source/container2.png", &width, &height, &nrComponents, 0);

        writeToLog("before data");
        if (data) {
            writeToLog("data contained!!!!!!");
        glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, width, height, 0, GL_RGB, GL_UNSIGNED_BYTE, data);
        }
        glUniform1i(glGetUniformLocation(shader_programme, "texture1"), 0);
        //glfwCreateWindow(640, 480, "My Title", NULL, NULL);
        glfwSetKeyCallback(newContext, key_callback);
    }
    else
    {
        writeToLog("not main thread");
    }
}

这是在 while 循环中调用的函数：

extern "C" void UNITY_INTERFACE_EXPORT UNITY_INTERFACE_API windowMainLoop()
{

    writeToLog("render loop");
    glfwMakeContextCurrent(newContext);
    glClearColor(0.0f, 1.0f, 1.0f, 1.0f);

    // loop until the window closed
    if (!glfwWindowShouldClose(newContext)) {
        glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

        if (std::this_thread::get_id() == MAIN_THREAD_ID)
        {
            // bind Texture
            glBindTexture(GL_TEXTURE_2D, texture);
            glUseProgram(shader_programme);
            glBindVertexArray(vao);
            // draw points 0-3 from the currently bound VAO with current in-use shader
            glDrawArrays(GL_TRIANGLES, 0, 3);
            glfwSwapBuffers(newContext);
            // poll the events
            glfwPollEvents();

        }
        //switch back to old context
        glfwMakeContextCurrent(oldContext);
        writeToLog("finished render loop");
    }

}

我的 "if (data)" 语句导致文本开始写入日志，所以我知道图像正在正确加载，但我无法弄清楚为什么三角形是黑色的。

如有任何帮助，我们将不胜感激！

Answer 1

问题是通用顶点属性数据的设置数组。每个属性元组由 5 个分量（x、y、z、u、v）组成：

float points[] = {
    0.0f,  0.5f,  0.0f,    0.5f, 1.0f,
    0.5f, -0.5f,  0.0f,    1.0f, 0.0f,
   -0.5f, -0.5f,  0.0f,    0.0f, 0.0f
};

所以步幅参数必须是5 * siezof(GLfloat)而不是6 * siezof(GLfloat):

glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 5 * sizeof(float), (void*)0);
glEnableVertexAttribArray(0);
glVertexAttribPointer(1, 2, GL_FLOAT, GL_FALSE, 5 * sizeof(float), (void*)(3 * sizeof(float)));
glEnableVertexAttribArray(1);

glBufferData 的第二个参数是以字节为单位的缓冲区大小。您的缓冲区由 GLfloat 类型的 15 (5 * 3) 个元素组成。所以大小是15 * sizeof(float)而不是9 * sizeof(float)：

glBufferData(GL_ARRAY_BUFFER, 15 * sizeof(float), points, GL_STATIC_DRAW);

由于文件的格式是.png所以stbi_load的最后一个参数应该设置为4，以确保得到一个4通道的贴图：

unsigned char *data = stbi_load("?.png", &width, &height, &nrComponents, 4);

glTexImage2D 的格式和内部格式必须是 GL_RGBA。
默认情况下纹理缩小函数（GL_TEXTURE_MIN_FILTER）是GL_NEAREST_MIPMAP_LINEAR（参见glTexParameteri). Since you don't use mip mapping，参数必须更改为GL_LINEAR：

glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, width, height, 0, GL_RGBA, GL_UNSIGNED_BYTE, data);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);

纹理不显示

Texture Not Showing Up

c++

opengl

textures