imgui/examples/opengl_example/imgui_impl_glfw.cpp

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// ImGui GLFW binding with OpenGL
// https://github.com/ocornut/imgui
#include <imgui.h>
#include "imgui_impl_glfw.h"
// GLFW
#include <GLFW/glfw3.h>
#ifdef _MSC_VER
#undef APIENTRY
#define GLFW_EXPOSE_NATIVE_WIN32
#define GLFW_EXPOSE_NATIVE_WGL
#include <GLFW/glfw3native.h>
#endif
// Data
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static GLFWwindow* g_Window = NULL;
static double g_Time = 0.0f;
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static bool g_MousePressed[3] = { false, false, false };
static float g_MouseWheel = 0.0f;
static GLuint g_FontTexture = 0;
// 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 ImGui_ImplGlfw_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.
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);
//glUseProgram(0); // You may want this if using this code in an OpenGL 3+ context
// 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
#define OFFSETOF(TYPE, ELEMENT) ((size_t)&(((TYPE *)0)->ELEMENT))
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();
const ImDrawIdx* idx_buffer = (const unsigned short*)&cmd_list->idx_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)));
for (size_t cmd_i = 0; cmd_i < cmd_list->commands.size(); cmd_i++)
{
const ImDrawCmd* pcmd = &cmd_list->commands[cmd_i];
if (pcmd->user_callback)
{
pcmd->user_callback(cmd_list, pcmd);
}
else
{
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));
glDrawElements(GL_TRIANGLES, pcmd->idx_count, GL_UNSIGNED_SHORT, idx_buffer);
}
idx_buffer += pcmd->idx_count;
}
}
#undef OFFSETOF
// Restore modified state
glDisableClientState(GL_COLOR_ARRAY);
glDisableClientState(GL_TEXTURE_COORD_ARRAY);
glDisableClientState(GL_VERTEX_ARRAY);
glBindTexture(GL_TEXTURE_2D, 0);
glMatrixMode(GL_MODELVIEW);
glPopMatrix();
glMatrixMode(GL_PROJECTION);
glPopMatrix();
glPopAttrib();
}
static const char* ImGui_ImplGlfw_GetClipboardText()
{
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return glfwGetClipboardString(g_Window);
}
static void ImGui_ImplGlfw_SetClipboardText(const char* text)
{
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glfwSetClipboardString(g_Window, text);
}
void ImGui_ImplGlfw_MouseButtonCallback(GLFWwindow*, int button, int action, int /*mods*/)
{
if (action == GLFW_PRESS && button >= 0 && button < 3)
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g_MousePressed[button] = true;
}
void ImGui_ImplGlfw_ScrollCallback(GLFWwindow*, double /*xoffset*/, double yoffset)
{
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g_MouseWheel += (float)yoffset; // Use fractional mouse wheel, 1.0 unit 5 lines.
}
void ImGui_ImplGlFw_KeyCallback(GLFWwindow*, int key, int, int action, int mods)
{
ImGuiIO& io = ImGui::GetIO();
if (action == GLFW_PRESS)
io.KeysDown[key] = true;
if (action == GLFW_RELEASE)
io.KeysDown[key] = false;
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(void)mods; // Modifiers are not reliable across systems
io.KeyCtrl = io.KeysDown[GLFW_KEY_LEFT_CONTROL] || io.KeysDown[GLFW_KEY_RIGHT_CONTROL];
io.KeyShift = io.KeysDown[GLFW_KEY_LEFT_SHIFT] || io.KeysDown[GLFW_KEY_RIGHT_SHIFT];
io.KeyAlt = io.KeysDown[GLFW_KEY_LEFT_ALT] || io.KeysDown[GLFW_KEY_RIGHT_ALT];
}
void ImGui_ImplGlfw_CharCallback(GLFWwindow*, unsigned int c)
{
ImGuiIO& io = ImGui::GetIO();
if (c > 0 && c < 0x10000)
io.AddInputCharacter((unsigned short)c);
}
bool ImGui_ImplGlfw_CreateDeviceObjects()
{
ImGuiIO& io = ImGui::GetIO();
// Build texture
unsigned char* pixels;
int width, height;
io.Fonts->GetTexDataAsAlpha8(&pixels, &width, &height);
// Create texture
glGenTextures(1, &g_FontTexture);
glBindTexture(GL_TEXTURE_2D, g_FontTexture);
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)g_FontTexture;
// Cleanup (don't clear the input data if you want to append new fonts later)
io.Fonts->ClearInputData();
io.Fonts->ClearTexData();
return true;
}
void ImGui_ImplGlfw_InvalidateDeviceObjects()
{
if (g_FontTexture)
{
glDeleteTextures(1, &g_FontTexture);
ImGui::GetIO().Fonts->TexID = 0;
g_FontTexture = 0;
}
}
bool ImGui_ImplGlfw_Init(GLFWwindow* window, bool install_callbacks)
{
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g_Window = window;
ImGuiIO& io = ImGui::GetIO();
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 = ImGui_ImplGlfw_RenderDrawLists;
io.SetClipboardTextFn = ImGui_ImplGlfw_SetClipboardText;
io.GetClipboardTextFn = ImGui_ImplGlfw_GetClipboardText;
#ifdef _MSC_VER
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io.ImeWindowHandle = glfwGetWin32Window(g_Window);
#endif
if (install_callbacks)
{
glfwSetMouseButtonCallback(window, ImGui_ImplGlfw_MouseButtonCallback);
glfwSetScrollCallback(window, ImGui_ImplGlfw_ScrollCallback);
glfwSetKeyCallback(window, ImGui_ImplGlFw_KeyCallback);
glfwSetCharCallback(window, ImGui_ImplGlfw_CharCallback);
}
return true;
}
void ImGui_ImplGlfw_Shutdown()
{
ImGui_ImplGlfw_InvalidateDeviceObjects();
ImGui::Shutdown();
}
void ImGui_ImplGlfw_NewFrame()
{
if (!g_FontTexture)
ImGui_ImplGlfw_CreateDeviceObjects();
ImGuiIO& io = ImGui::GetIO();
// Setup display size (every frame to accommodate for window resizing)
int w, h;
int display_w, display_h;
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glfwGetWindowSize(g_Window, &w, &h);
glfwGetFramebufferSize(g_Window, &display_w, &display_h);
io.DisplaySize = ImVec2((float)display_w, (float)display_h);
// Setup time step
double current_time = glfwGetTime();
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io.DeltaTime = g_Time > 0.0 ? (float)(current_time - g_Time) : (float)(1.0f/60.0f);
g_Time = current_time;
// Setup inputs
// (we already got mouse wheel, keyboard keys & characters from glfw callbacks polled in glfwPollEvents())
if (glfwGetWindowAttrib(g_Window, GLFW_FOCUSED))
{
double mouse_x, mouse_y;
glfwGetCursorPos(g_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;
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io.MousePos = ImVec2((float)mouse_x, (float)mouse_y); // Mouse position, in pixels (set to -1,-1 if no mouse / on another screen, etc.)
}
else
{
io.MousePos = ImVec2(-1,-1);
}
for (int i = 0; i < 3; i++)
{
io.MouseDown[i] = g_MousePressed[i] || glfwGetMouseButton(g_Window, i) != 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.
g_MousePressed[i] = false;
}
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io.MouseWheel = g_MouseWheel;
g_MouseWheel = 0.0f;
// Hide OS mouse cursor if ImGui is drawing it
glfwSetInputMode(g_Window, GLFW_CURSOR, io.MouseDrawCursor ? GLFW_CURSOR_HIDDEN : GLFW_CURSOR_NORMAL);
// Start the frame
ImGui::NewFrame();
}