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imgui/examples/opengl_example/main.cpp

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// ImGui - standalone example application for OpenGL 2, using fixed pipeline
#ifdef _MSC_VER
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#pragma warning (disable: 4996) // 'This function or variable may be unsafe': strcpy, strdup, sprintf, vsnprintf, sscanf, fopen
#endif
#ifdef __clang__
#pragma clang diagnostic ignored "-Wunused-function" // warning: unused function
#endif
#include "../../imgui.h"
#include <stdio.h>
// Glfw/Glew
#define GLEW_STATIC
#include <GL/glew.h>
#include <GLFW/glfw3.h>
#define OFFSETOF(TYPE, ELEMENT) ((size_t)&(((TYPE *)0)->ELEMENT))
static GLFWwindow* window;
static bool mousePressed[2] = { false, false };
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// 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)
static void ImImpl_RenderDrawLists(ImDrawList** const cmd_lists, int cmd_lists_count)
{
if (cmd_lists_count == 0)
return;
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// 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.
glPushAttrib(GL_ENABLE_BIT | GL_COLOR_BUFFER_BIT | GL_TRANSFORM_BIT);
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);
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);
glPushMatrix();
glLoadIdentity();
glOrtho(0.0f, width, height, 0.0f, -1.0f, +1.0f);
glMatrixMode(GL_MODELVIEW);
glPushMatrix();
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.front();
glVertexPointer(2, GL_FLOAT, sizeof(ImDrawVert), (void*)(vtx_buffer + OFFSETOF(ImDrawVert, pos)));
glTexCoordPointer(2, GL_FLOAT, sizeof(ImDrawVert), (void*)(vtx_buffer + OFFSETOF(ImDrawVert, uv)));
glColorPointer(4, GL_UNSIGNED_BYTE, sizeof(ImDrawVert), (void*)(vtx_buffer + OFFSETOF(ImDrawVert, col)));
int vtx_offset = 0;
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for (size_t cmd_i = 0; cmd_i < cmd_list->commands.size(); cmd_i++)
{
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const ImDrawCmd* pcmd = &cmd_list->commands[cmd_i];
glBindTexture(GL_TEXTURE_2D, (GLuint)(intptr_t)pcmd->texture_id);
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;
}
}
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// Restore modified state
glDisableClientState(GL_COLOR_ARRAY);
glDisableClientState(GL_TEXTURE_COORD_ARRAY);
glDisableClientState(GL_VERTEX_ARRAY);
glMatrixMode(GL_MODELVIEW);
glPopMatrix();
glMatrixMode(GL_PROJECTION);
glPopMatrix();
glPopAttrib();
}
// NB: ImGui already provide OS clipboard support for Windows so this isn't needed if you are using Windows only.
static const char* ImImpl_GetClipboardTextFn()
{
return glfwGetClipboardString(window);
}
static void ImImpl_SetClipboardTextFn(const char* text)
{
glfwSetClipboardString(window, text);
}
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// GLFW callbacks to get events
static void glfw_error_callback(int error, const char* description)
{
fputs(description, stderr);
}
static void glfw_mouse_button_callback(GLFWwindow* window, int button, int action, int mods)
{
if (action == GLFW_PRESS && button >= 0 && button < 2)
mousePressed[button] = true;
}
static void glfw_scroll_callback(GLFWwindow* window, double xoffset, double yoffset)
{
ImGuiIO& io = ImGui::GetIO();
io.MouseWheel += (float)yoffset; // Use fractional mouse wheel, 1.0 unit 5 lines.
}
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((unsigned short)c);
}
void InitGL()
{
glfwSetErrorCallback(glfw_error_callback);
if (!glfwInit())
exit(1);
window = glfwCreateWindow(1280, 720, "ImGui OpenGL2 example", NULL, NULL);
glfwMakeContextCurrent(window);
glfwSetKeyCallback(window, glfw_key_callback);
glfwSetMouseButtonCallback(window, glfw_mouse_button_callback);
glfwSetScrollCallback(window, glfw_scroll_callback);
glfwSetCharCallback(window, glfw_char_callback);
glewInit();
}
void LoadFontsTexture()
{
ImGuiIO& io = ImGui::GetIO();
//ImFont* my_font1 = io.Fonts->AddFontDefault();
//ImFont* my_font2 = io.Fonts->AddFontFromFileTTF("extra_fonts/Karla-Regular.ttf", 15.0f);
//ImFont* my_font3 = io.Fonts->AddFontFromFileTTF("extra_fonts/ProggyClean.ttf", 13.0f); my_font3->DisplayOffset.y += 1;
//ImFont* my_font4 = io.Fonts->AddFontFromFileTTF("extra_fonts/ProggyTiny.ttf", 10.0f); my_font4->DisplayOffset.y += 1;
//ImFont* my_font5 = io.Fonts->AddFontFromFileTTF("c:\\Windows\\Fonts\\ArialUni.ttf", 20.0f, io.Fonts->GetGlyphRangesJapanese());
unsigned char* pixels;
int width, height;
io.Fonts->GetTexDataAsAlpha8(&pixels, &width, &height);
GLuint tex_id;
glGenTextures(1, &tex_id);
glBindTexture(GL_TEXTURE_2D, tex_id);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
glTexImage2D(GL_TEXTURE_2D, 0, GL_ALPHA, width, height, 0, GL_ALPHA, GL_UNSIGNED_BYTE, pixels);
// Store our identifier
io.Fonts->TexID = (void *)(intptr_t)tex_id;
}
void InitImGui()
{
ImGuiIO& io = ImGui::GetIO();
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 time step is variable)
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;
LoadFontsTexture();
}
void UpdateImGui()
{
ImGuiIO& io = ImGui::GetIO();
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// Setup resolution (every frame to accommodate for window resizing)
int w, h;
int display_w, display_h;
glfwGetWindowSize(window, &w, &h);
glfwGetFramebufferSize(window, &display_w, &display_h);
io.DisplaySize = ImVec2((float)display_w, (float)display_h); // Display size, in pixels. For clamping windows positions.
// Setup time step
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);
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mouse_x *= (float)display_w / w; // Convert mouse coordinates to pixels
mouse_y *= (float)display_h / h;
io.MousePos = ImVec2((float)mouse_x, (float)mouse_y); // Mouse position, in pixels (set to -1,-1 if no mouse / on another screen, etc.)
io.MouseDown[0] = mousePressed[0] || glfwGetMouseButton(window, GLFW_MOUSE_BUTTON_LEFT) != 0; // If a mouse press event came, always pass it as "mouse held this frame", so we don't miss click-release events that are shorter than 1 frame.
io.MouseDown[1] = mousePressed[1] || glfwGetMouseButton(window, GLFW_MOUSE_BUTTON_RIGHT) != 0;
// Start the frame
ImGui::NewFrame();
}
// Application code
int main(int argc, char** argv)
{
InitGL();
InitImGui();
bool show_test_window = true;
bool show_another_window = false;
ImVec4 clear_col = ImColor(114, 144, 154);
while (!glfwWindowShouldClose(window))
{
ImGuiIO& io = ImGui::GetIO();
mousePressed[0] = mousePressed[1] = false;
glfwPollEvents();
UpdateImGui();
// 1. Show a simple window
// Tip: if we don't call ImGui::Begin()/ImGui::End() the widgets appears in a window automatically called "Debug"
{
static float f;
ImGui::Text("Hello, world!");
ImGui::SliderFloat("float", &f, 0.0f, 1.0f);
ImGui::ColorEdit3("clear color", (float*)&clear_col);
if (ImGui::Button("Test Window")) show_test_window ^= 1;
if (ImGui::Button("Another Window")) show_another_window ^= 1;
ImGui::Text("Application average %.3f ms/frame (%.1f FPS)", 1000.0f / ImGui::GetIO().Framerate, ImGui::GetIO().Framerate);
}
// 2. Show another simple window, this time using an explicit Begin/End pair
if (show_another_window)
{
ImGui::Begin("Another Window", &show_another_window, ImVec2(200,100));
ImGui::Text("Hello");
ImGui::End();
}
// 3. Show the ImGui test window. Most of the sample code is in ImGui::ShowTestWindow()
if (show_test_window)
{
ImGui::SetNextWindowPos(ImVec2(650, 20), ImGuiSetCondition_FirstUseEver);
ImGui::ShowTestWindow(&show_test_window);
}
// Rendering
glViewport(0, 0, (int)io.DisplaySize.x, (int)io.DisplaySize.y);
glClearColor(clear_col.x, clear_col.y, clear_col.z, clear_col.w);
glClear(GL_COLOR_BUFFER_BIT);
ImGui::Render();
glfwSwapBuffers(window);
}
// Cleanup
ImGui::Shutdown();
glfwTerminate();
return 0;
}