OpenGL example: added commented code to load custom font from filesystem

examples/opengl_example/main - Copy.cpp

@@ -0,0 +1,312 @@
+#define GLEW_STATIC
+#include <GL/glew.h>
+#include <GLFW/glfw3.h>
+#define STB_IMAGE_IMPLEMENTATION
+#include "stb_image.h"                  // for .png loading
+#include "../../imgui.h"
+#ifdef _MSC_VER
+#pragma warning (disable: 4996)         // 'This function or variable may be unsafe': strcpy, strdup, sprintf, vsnprintf, sscanf, fopen
+#endif
+
+static GLFWwindow* window;
+static GLuint fontTex;
+static ImVec2 mousePosScale(1.0f, 1.0f);
+
+// This is the main rendering function that you have to implement and provide to ImGui (via setting up 'RenderDrawListsFn' in the ImGuiIO structure)
+// If text or lines are blurry when integrating ImGui in your engine:
+// - in your Render function, try translating your projection matrix by (0.5f,0.5f) or (0.375f,0.375f)
+// - try adjusting ImGui::GetIO().PixelCenterOffset to 0.5f or 0.375f
+static void ImImpl_RenderDrawLists(ImDrawList** const cmd_lists, int cmd_lists_count)
+{
+    if (cmd_lists_count == 0)
+        return;
+
+    // We are using the OpenGL fixed pipeline to make the example code simpler to read!
+    // A probable faster way to render would be to collate all vertices from all cmd_lists into a single vertex buffer.
+    // Setup render state: alpha-blending enabled, no face culling, no depth testing, scissor enabled, vertex/texcoord/color pointers.
+    glEnable(GL_BLEND);
+    glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
+    glDisable(GL_CULL_FACE);
+    glDisable(GL_DEPTH_TEST);
+    glEnable(GL_SCISSOR_TEST);
+    glEnableClientState(GL_VERTEX_ARRAY);
+    glEnableClientState(GL_TEXTURE_COORD_ARRAY);
+    glEnableClientState(GL_COLOR_ARRAY);
+
+    // Setup texture
+    glBindTexture(GL_TEXTURE_2D, fontTex);
+    glEnable(GL_TEXTURE_2D);
+
+    // Setup orthographic projection matrix
+    const float width = ImGui::GetIO().DisplaySize.x;
+    const float height = ImGui::GetIO().DisplaySize.y;
+    glMatrixMode(GL_PROJECTION);
+    glLoadIdentity();
+    glOrtho(0.0f, width, height, 0.0f, -1.0f, +1.0f);
+    glMatrixMode(GL_MODELVIEW);
+    glLoadIdentity();
+
+    // Render command lists
+    for (int n = 0; n < cmd_lists_count; n++)
+    {
+        const ImDrawList* cmd_list = cmd_lists[n];
+        const unsigned char* vtx_buffer = (const unsigned char*)cmd_list->vtx_buffer.begin();
+        glVertexPointer(2, GL_FLOAT, sizeof(ImDrawVert), (void*)(vtx_buffer));
+        glTexCoordPointer(2, GL_FLOAT, sizeof(ImDrawVert), (void*)(vtx_buffer+8));
+        glColorPointer(4, GL_UNSIGNED_BYTE, sizeof(ImDrawVert), (void*)(vtx_buffer+16));
+
+        int vtx_offset = 0;
+        const ImDrawCmd* pcmd_end = cmd_list->commands.end();
+        for (const ImDrawCmd* pcmd = cmd_list->commands.begin(); pcmd != pcmd_end; pcmd++)
+        {
+            glScissor((int)pcmd->clip_rect.x, (int)(height - pcmd->clip_rect.w), (int)(pcmd->clip_rect.z - pcmd->clip_rect.x), (int)(pcmd->clip_rect.w - pcmd->clip_rect.y));
+            glDrawArrays(GL_TRIANGLES, vtx_offset, pcmd->vtx_count);
+            vtx_offset += pcmd->vtx_count;
+        }
+    }
+    glDisable(GL_SCISSOR_TEST);
+    glDisableClientState(GL_COLOR_ARRAY);
+    glDisableClientState(GL_TEXTURE_COORD_ARRAY);
+    glDisableClientState(GL_VERTEX_ARRAY);
+}
+
+static const char* ImImpl_GetClipboardTextFn()
+{
+    return glfwGetClipboardString(window);
+}
+
+static void ImImpl_SetClipboardTextFn(const char* text, const char* text_end)
+{
+    if (!text_end)
+        text_end = text + strlen(text);
+
+    if (*text_end == 0)
+    {
+        // Already got a zero-terminator at 'text_end', we don't need to add one
+        glfwSetClipboardString(window, text);
+    }
+    else
+    {
+        // Add a zero-terminator because glfw function doesn't take a size
+        char* buf = (char*)malloc(text_end - text + 1);
+        memcpy(buf, text, text_end-text);
+        buf[text_end-text] = '\0';
+        glfwSetClipboardString(window, buf);
+        free(buf);
+    }
+}
+
+
+// GLFW callbacks to get events
+static void glfw_error_callback(int error, const char* description)
+{
+    fputs(description, stderr);
+}
+
+static void glfw_scroll_callback(GLFWwindow* window, double xoffset, double yoffset)
+{
+    ImGuiIO& io = ImGui::GetIO();
+    io.MouseWheel = (yoffset != 0.0f) ? yoffset > 0.0f ? 1 : - 1 : 0;           // Mouse wheel: -1,0,+1
+}
+
+static void glfw_key_callback(GLFWwindow* window, int key, int scancode, int action, int mods)
+{
+    ImGuiIO& io = ImGui::GetIO();
+    if (action == GLFW_PRESS)
+        io.KeysDown[key] = true;
+    if (action == GLFW_RELEASE)
+        io.KeysDown[key] = false;
+    io.KeyCtrl = (mods & GLFW_MOD_CONTROL) != 0;
+    io.KeyShift = (mods & GLFW_MOD_SHIFT) != 0;
+}
+
+static void glfw_char_callback(GLFWwindow* window, unsigned int c)
+{
+    if (c > 0 && c < 0x10000)
+        ImGui::GetIO().AddInputCharacter((ImWchar)c);
+}
+
+// OpenGL code based on http://open.gl tutorials
+void InitGL()
+{
+    glfwSetErrorCallback(glfw_error_callback);
+
+    if (!glfwInit())
+        exit(1);
+
+    glfwWindowHint(GLFW_RESIZABLE, GL_FALSE);
+    window = glfwCreateWindow(1280, 720, "ImGui OpenGL example", NULL, NULL);
+    glfwMakeContextCurrent(window);
+    glfwSetKeyCallback(window, glfw_key_callback);
+    glfwSetScrollCallback(window, glfw_scroll_callback);
+    glfwSetCharCallback(window, glfw_char_callback);
+
+    glewInit();
+}
+
+void InitImGui()
+{
+    int w, h;
+    int fb_w, fb_h;
+    glfwGetWindowSize(window, &w, &h);
+    glfwGetFramebufferSize(window, &fb_w, &fb_h);
+    mousePosScale.x = (float)fb_w / w;                  // Some screens e.g. Retina display have framebuffer size != from window size, and mouse inputs are given in window/screen coordinates.
+    mousePosScale.y = (float)fb_h / h;
+
+    ImGuiIO& io = ImGui::GetIO();
+    io.DisplaySize = ImVec2((float)fb_w, (float)fb_h);  // Display size, in pixels. For clamping windows positions.
+    io.DeltaTime = 1.0f/60.0f;                          // Time elapsed since last frame, in seconds (in this sample app we'll override this every frame because our timestep is variable)
+    io.PixelCenterOffset = 0.0f;                        // Align OpenGL texels
+    io.KeyMap[ImGuiKey_Tab] = GLFW_KEY_TAB;             // Keyboard mapping. ImGui will use those indices to peek into the io.KeyDown[] array.
+    io.KeyMap[ImGuiKey_LeftArrow] = GLFW_KEY_LEFT;
+    io.KeyMap[ImGuiKey_RightArrow] = GLFW_KEY_RIGHT;
+    io.KeyMap[ImGuiKey_UpArrow] = GLFW_KEY_UP;
+    io.KeyMap[ImGuiKey_DownArrow] = GLFW_KEY_DOWN;
+    io.KeyMap[ImGuiKey_Home] = GLFW_KEY_HOME;
+    io.KeyMap[ImGuiKey_End] = GLFW_KEY_END;
+    io.KeyMap[ImGuiKey_Delete] = GLFW_KEY_DELETE;
+    io.KeyMap[ImGuiKey_Backspace] = GLFW_KEY_BACKSPACE;
+    io.KeyMap[ImGuiKey_Enter] = GLFW_KEY_ENTER;
+    io.KeyMap[ImGuiKey_Escape] = GLFW_KEY_ESCAPE;
+    io.KeyMap[ImGuiKey_A] = GLFW_KEY_A;
+    io.KeyMap[ImGuiKey_C] = GLFW_KEY_C;
+    io.KeyMap[ImGuiKey_V] = GLFW_KEY_V;
+    io.KeyMap[ImGuiKey_X] = GLFW_KEY_X;
+    io.KeyMap[ImGuiKey_Y] = GLFW_KEY_Y;
+    io.KeyMap[ImGuiKey_Z] = GLFW_KEY_Z;
+
+    io.RenderDrawListsFn = ImImpl_RenderDrawLists;
+    io.SetClipboardTextFn = ImImpl_SetClipboardTextFn;
+    io.GetClipboardTextFn = ImImpl_GetClipboardTextFn;
+
+    // Load font texture
+    glGenTextures(1, &fontTex);
+    glBindTexture(GL_TEXTURE_2D, fontTex);
+    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
+    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
+
+#if 0
+	// Default font (embedded in code)
+    const void* png_data;
+    unsigned int png_size;
+    ImGui::GetDefaultFontData(NULL, NULL, &png_data, &png_size);
+    int tex_x, tex_y, tex_comp;
+    void* tex_data = stbi_load_from_memory((const unsigned char*)png_data, (int)png_size, &tex_x, &tex_y, &tex_comp, 0);
+#else
+	// Custom font from filesystem
+	io.Font = new ImBitmapFont();
+	io.Font->LoadFromFile("../../extra_fonts/arial_unicode_ms_18_CJK.fnt");
+	io.FontTexUvForWhite = ImVec2(3.f/255.f,55.f/512.f);
+    int tex_x, tex_y, tex_comp;
+    void* tex_data = stbi_load("../../extra_fonts/arial_unicode_ms_18_CJK.png", &tex_x, &tex_y, &tex_comp, 4);
+	
+	// Automatically find pure white pixel from the texture we just loaded
+	for (int tex_data_off = 0; tex_data_off < tex_x*tex_y; tex_data_off++)
+		if (((unsigned int*)tex_data)[tex_data_off] == 0xffffffff)
+		{
+			io.FontTexUvForWhite = ImVec2((float)(tex_data_off % tex_x)/(tex_x-1.0f), (float)(tex_data_off / tex_x)/(tex_y-1.0f));
+			break;
+		}
+#endif
+
+    glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, tex_x, tex_y, 0, GL_RGBA, GL_UNSIGNED_BYTE, tex_data);
+	stbi_image_free(tex_data);
+}
+
+void UpdateImGui()
+{
+    ImGuiIO& io = ImGui::GetIO();
+
+    // Setup timestep
+    static double time = 0.0f;
+    const double current_time =  glfwGetTime();
+    io.DeltaTime = (float)(current_time - time);
+    time = current_time;
+
+    // Setup inputs
+    // (we already got mouse wheel, keyboard keys & characters from glfw callbacks polled in glfwPollEvents())
+    double mouse_x, mouse_y;
+    glfwGetCursorPos(window, &mouse_x, &mouse_y);
+    io.MousePos = ImVec2((float)mouse_x * mousePosScale.x, (float)mouse_y * mousePosScale.y); // Mouse position, in pixels (set to -1,-1 if no mouse / on another screen, etc.)
+    io.MouseDown[0] = glfwGetMouseButton(window, GLFW_MOUSE_BUTTON_LEFT) != 0;
+    io.MouseDown[1] = glfwGetMouseButton(window, GLFW_MOUSE_BUTTON_RIGHT) != 0;
+
+    // Start the frame
+    ImGui::NewFrame();
+}
+
+// Application code
+int main(int argc, char** argv)
+{
+    InitGL();
+    InitImGui();
+
+    while (!glfwWindowShouldClose(window))
+    {
+        ImGuiIO& io = ImGui::GetIO();
+        io.MouseWheel = 0;
+        glfwPollEvents();
+        UpdateImGui();
+
+        // Create a simple window
+        // Tip: if we don't call ImGui::Begin()/ImGui::End() the widgets appears in a window automatically called "Debug"
+        static bool show_test_window = true;
+        static bool show_another_window = false;
+        static float f;
+        ImGui::Text("Hello, world!");
+        ImGui::SliderFloat("float", &f, 0.0f, 1.0f);
+        show_test_window ^= ImGui::Button("Test Window");
+        show_another_window ^= ImGui::Button("Another Window");
+
+        // Calculate and show framerate
+        static float ms_per_frame[120] = { 0 };
+        static int ms_per_frame_idx = 0;
+        static float ms_per_frame_accum = 0.0f;
+        ms_per_frame_accum -= ms_per_frame[ms_per_frame_idx];
+        ms_per_frame[ms_per_frame_idx] = ImGui::GetIO().DeltaTime * 1000.0f;
+        ms_per_frame_accum += ms_per_frame[ms_per_frame_idx];
+        ms_per_frame_idx = (ms_per_frame_idx + 1) % 120;
+        const float ms_per_frame_avg = ms_per_frame_accum / 120;
+        ImGui::Text("Application average %.3f ms/frame (%.1f FPS)", ms_per_frame_avg, 1000.0f / ms_per_frame_avg);
+
+        // Show the ImGui test window
+        // Most of user example code is in ImGui::ShowTestWindow()
+        if (show_test_window)
+        {
+            ImGui::SetNewWindowDefaultPos(ImVec2(650, 20));        // Normally user code doesn't need/want to call it because positions are saved in .ini file anyway. Here we just want to make the demo initial state a bit more friendly!
+            ImGui::ShowTestWindow(&show_test_window);
+        }
+
+		ImGui::Begin("Test UTF-8 with Arial Unicode Ms, Size 18");
+		ImGui::Text("Hello, actual world!");
+		ImGui::Text("かきくけこ 日本語");
+		ImGui::Text("いろはにほへと ちりぬるを わかよたれそ つねならむ うゐのおくやま けふこえて あさきゆめみし ゑひもせす（ん）");
+		ImGui::Text("色は匂へど 散りぬるを 我が世誰ぞ 常ならむ 有為の奥山 今日越えて 浅き夢見じ 酔ひもせず（ん）");
+		ImGui::Button("無理");
+		ImGui::SameLine();
+		ImGui::Button("オーケー！");
+		static char test[256] = "hello 日本語";
+		ImGui::InputText("utf8", test, 256);
+		ImGui::End();
+
+        // Show another simple window
+        if (show_another_window)
+        {
+            ImGui::Begin("Another Window", &show_another_window, ImVec2(200,100));
+            ImGui::Text("Hello");
+            ImGui::End();
+        }
+
+        // Rendering
+        glViewport(0, 0, (int)io.DisplaySize.x, (int)io.DisplaySize.y);
+        glClearColor(0.8f, 0.6f, 0.6f, 1.0f);
+        glClear(GL_COLOR_BUFFER_BIT);
+        ImGui::Render();
+        glfwSwapBuffers(window);
+    }
+
+    ImGui::Shutdown();
+    glfwTerminate();
+    return 0;
+}
+