Question

我正在使用本教程学习纹理映射。我试图修改一些代码以查看其是否仍在工作。

我想删除EBO部分，而将VBO与VAO一起使用。为了仅测试纹理映射，我还删除了颜色索引。

所以代码现在看起来像这样：

const unsigned int SCR_WIDTH = 800;
const unsigned int SCR_HEIGHT = 600;

int main()
{
    glfwInit();
    glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3);
    glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 3);
    glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);
    GLFWwindow* window = glfwCreateWindow(SCR_WIDTH, SCR_HEIGHT, "LearnOpenGL", NULL, NULL);
    if (window == NULL)
    {
        std::cout << "Failed to create GLFW window" << std::endl;
        glfwTerminate();
        return -1;
    }
    glfwMakeContextCurrent(window);

    glewInit();

    // build and compile our shader zprogram
    // ------------------------------------
    int vertexShader = glCreateShader(GL_VERTEX_SHADER);
    glShaderSource(vertexShader, 1, &vertexShaderSource, NULL);
    glCompileShader(vertexShader);
    // check for shader compile errors
    int success;
    char infoLog[512];
    glGetShaderiv(vertexShader, GL_COMPILE_STATUS, &success);
    if (!success)
    {
        glGetShaderInfoLog(vertexShader, 512, NULL, infoLog);
        std::cout << "ERROR::SHADER::VERTEX::COMPILATION_FAILED\n" << infoLog << std::endl;
    }
    // fragment shader
    int fragmentShader = glCreateShader(GL_FRAGMENT_SHADER);
    glShaderSource(fragmentShader, 1, &fragmentShaderSource, NULL);
    glCompileShader(fragmentShader);
    // check for shader compile errors
    glGetShaderiv(fragmentShader, GL_COMPILE_STATUS, &success);
    if (!success)
    {
        glGetShaderInfoLog(fragmentShader, 512, NULL, infoLog);
        std::cout << "ERROR::SHADER::FRAGMENT::COMPILATION_FAILED\n" << infoLog << std::endl;
    }
    // link shaders
    int shaderProgram = glCreateProgram();
    glAttachShader(shaderProgram, vertexShader);
    glAttachShader(shaderProgram, fragmentShader);
    glLinkProgram(shaderProgram);
    glGetProgramiv(shaderProgram, GL_LINK_STATUS, &success);
    if (!success) {
        glGetProgramInfoLog(shaderProgram, 512, NULL, infoLog);
        std::cout << "ERROR::SHADER::PROGRAM::LINKING_FAILED\n" << infoLog << std::endl;
    }
    glDeleteShader(vertexShader);
    glDeleteShader(fragmentShader);

    // set up vertex data (and buffer(s)) and configure vertex attributes
    // ------------------------------------------------------------------
    float vertices[] = {
        // positions        // texture coords
        0.5f, -0.5f, 0.0f, 1.0f, 0.0f, // bottom right
        0.5f,  0.5f, 0.0f, 1.0f, 1.0f, // top right
        -0.5f,  0.5f, 0.0f, 0.0f, 1.0f  // top left 
    };

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

    glBindVertexArray(VAO);

    glBindBuffer(GL_ARRAY_BUFFER, VBO);
    glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW);

    // position attribute
    glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 5 * sizeof(float), (void*)0);
    glEnableVertexAttribArray(0);
    // texture coord attribute
    glVertexAttribPointer(1, 2, GL_FLOAT, GL_FALSE, 5 * sizeof(float), (void*)(3 * sizeof(float)));
    glEnableVertexAttribArray(1);

    // load and create a texture 
    // -------------------------
    unsigned int texture1;
    // texture 1
    // ---------
    glGenTextures(1, &texture1);
    glBindTexture(GL_TEXTURE_2D, texture1);
    // set the texture wrapping parameters
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);   // set texture wrapping to GL_REPEAT (default wrapping method)
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);
    // set texture filtering parameters
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
    // load image, create texture and generate mipmaps
    CImage img_handler;
    img_handler.Load(_T("texture.tif"));
    texture_w = img_handler.GetWidth();
    texture_h = img_handler.GetHeight();
    texture = new byte[texture_w * texture_h * 3];
    int cnt = 0;
    for (int y = 0; y < texture_h; y++) {
        for (int x = 0; x < texture_w; x++) {
            COLORREF c = img_handler.GetPixel(x, y);
            texture[cnt++] = GetRValue(c);
            texture[cnt++] = GetGValue(c);
            texture[cnt++] = GetBValue(c);
        }
    }
    glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, texture_w, texture_h, 0, GL_RGB, GL_UNSIGNED_BYTE, texture);
    glGenerateMipmap(GL_TEXTURE_2D);

    // tell opengl for each sampler to which texture unit it belongs to (only has to be done once)
    // -------------------------------------------------------------------------------------------
    glUseProgram(shaderProgram);
    // either set it manually like so:
    glUniform1i(glGetUniformLocation(shaderProgram, "texture1"), 0);

    // render loop
    // -----------
    while (!glfwWindowShouldClose(window))
    {
        glClearColor(0.2f, 0.3f, 0.3f, 1.0f);
        glClear(GL_COLOR_BUFFER_BIT);

        // bind textures on corresponding texture units
        glActiveTexture(GL_TEXTURE0);
        glBindTexture(GL_TEXTURE_2D, texture1);

        // render container
        glUseProgram(shaderProgram);
        glBindVertexArray(VAO);
        glDrawArrays(GL_TRIANGLES, 0, 3);
        //glDrawElements(GL_TRIANGLES, 6, GL_UNSIGNED_INT, 0);

        // glfw: swap buffers and poll IO events (keys pressed/released, mouse moved etc.)
        // -------------------------------------------------------------------------------
        glfwSwapBuffers(window);
        glfwPollEvents();
    }

    // optional: de-allocate all resources once they've outlived their purpose:
    // ------------------------------------------------------------------------
    glDeleteVertexArrays(1, &VAO);
    glDeleteBuffers(1, &VBO);

    // glfw: terminate, clearing all previously allocated GLFW resources.
    // ------------------------------------------------------------------
    glfwTerminate();
    return 0;
}

着色器：

const char *vertexShaderSource = "#version 330 core\n"
"layout (location = 0) in vec3 aPos;\n"
"layout (location = 1) in vec2 aTexCoord;\n"
"out vec2 TexCoord;\n"
"uniform mat4 u_mvp;\n"
"void main()\n"
"{\n"
"   TexCoord = aTexCoord;\n"
"   gl_Position = u_mvp * vec4(aPos.x, aPos.y, aPos.z, 1.0);\n"
"}\0";

const char *fragmentShaderSource = "#version 330 core\n"
"in vec2 TexCoord;\n"
"out vec4 FragColor;\n"
"uniform sampler2D tex_sampler;\n"
"void main()\n"
"{\n"
"   FragColor = texture(tex_sampler, TexCoord);\n"
"}\n\0";

但是，纹理不起作用，仅显示一种颜色。（我使用了Microsoft CImage库，因此上面的代码只能在Windows上运行，但是可以用其他代码替换以在其他平台上工作）

我该如何解决？

RenderDoc输出：

opengl-显示单色的纹理

0 个答案: