ImGui入门教程03.03：空白界面

系列索引：ImGui入门教程教程

使用ImGui创建一个空白窗口。

#include "imgui.h"
#include "imgui_impl_glfw.h"
#include "imgui_impl_opengl2.h"
#include <stdio.h>
#include <GLFW/glfw3.h>

static void glfw_error_callback(int error, const char* description)
{
    fprintf(stderr, "Glfw Error %d: %s\n", error, description);
}

int main(int, char**)
{
    // Setup window
    glfwSetErrorCallback(glfw_error_callback);
    if (!glfwInit())
        return 1;
    GLFWwindow* window = glfwCreateWindow(1280, 720, "Dear ImGui GLFW+OpenGL2 example", NULL, NULL);
    if (window == NULL)
        return 1;
    glfwMakeContextCurrent(window);
    glfwSwapInterval(1); // Enable vsync

    // Setup Dear ImGui context
    IMGUI_CHECKVERSION();
    ImGui::CreateContext();
    ImGuiIO& io = ImGui::GetIO(); (void)io;

    // Setup Dear ImGui style
    ImGui::StyleColorsDark();

    // Setup Platform/Renderer backends
    ImGui_ImplGlfw_InitForOpenGL(window, true);
    ImGui_ImplOpenGL2_Init();

    // Our state
    ImVec4 clear_color = ImVec4(0.45f, 0.55f, 0.60f, 1.00f);

    // Main loop
    while (!glfwWindowShouldClose(window))
    {
        glfwPollEvents();

        // Start the Dear ImGui frame
        ImGui_ImplOpenGL2_NewFrame();
        ImGui_ImplGlfw_NewFrame();
        ImGui::NewFrame();

        // Rendering
        ImGui::Render();
        int display_w, display_h;
        glfwGetFramebufferSize(window, &display_w, &display_h);
        glViewport(0, 0, display_w, display_h);
        glClearColor(clear_color.x * clear_color.w, clear_color.y * clear_color.w, clear_color.z * clear_color.w, clear_color.w);
        glClear(GL_COLOR_BUFFER_BIT);

        ImGui_ImplOpenGL2_RenderDrawData(ImGui::GetDrawData());

        glfwMakeContextCurrent(window);
        glfwSwapBuffers(window);
    }

    // Cleanup
    ImGui_ImplOpenGL2_Shutdown();
    ImGui_ImplGlfw_Shutdown();
    ImGui::DestroyContext();

    glfwDestroyWindow(window);
    glfwTerminate();

    return 0;
}

运行效果为

由此我们可以看出ImGui窗口创建流程。

flowchart LR

A[glfw] --> B[imgui init]
B --> C[imgui backend init]
C --> D[imgui new frame]
D --> E[imgui render data]
E --> F[imgui shutdown]

当然，窗口会涉及模态和非模态问题。