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imgui/examples/sdl_opengl2_example/imgui_impl_sdl_gl2.cpp

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// ImGui SDL2 binding with OpenGL (legacy, fixed pipeline)
// (SDL is a cross-platform general purpose library for handling windows, inputs, OpenGL/Vulkan graphics context creation, etc.)
// Implemented features:
// [X] User texture binding. Cast 'GLuint' OpenGL texture identifier as void*/ImTextureID. Read the FAQ about ImTextureID in imgui.cpp.
// **DO NOT USE THIS CODE IF YOUR CODE/ENGINE IS USING MODERN OPENGL (SHADERS, VBO, VAO, etc.)**
// **Prefer using the code in the sdl_opengl3_example/ folder**
// This code is mostly provided as a reference to learn how ImGui integration works, because it is shorter to read.
// If your code is using GL3+ context or any semi modern OpenGL calls, using this is likely to make everything more
// complicated, will require your code to reset every single OpenGL attributes to their initial state, and might
// confuse your GPU driver.
// The GL2 code is unable to reset attributes or even call e.g. "glUseProgram(0)" because they don't exist in that API.
// You can copy and use unmodified imgui_impl_* files in your project. See main.cpp for an example of using this.
// If you use this binding you'll need to call 4 functions: ImGui_ImplXXXX_Init(), ImGui_ImplXXXX_NewFrame(), ImGui::Render() and ImGui_ImplXXXX_Shutdown().
// If you are new to ImGui, see examples/README.txt and documentation at the top of imgui.cpp.
// https://github.com/ocornut/imgui
// CHANGELOG
// (minor and older changes stripped away, please see git history for details)
// 2018-02-16: Inputs: Added support for mouse cursors, honoring ImGui::GetMouseCursor() value.
// 2018-02-16: Misc: Obsoleted the io.RenderDrawListsFn callback and exposed ImGui_ImplSdlGL2_RenderDrawData() in the .h file so you can call it yourself.
// 2018-02-06: Misc: Removed call to ImGui::Shutdown() which is not available from 1.60 WIP, user needs to call CreateContext/DestroyContext themselves.
// 2018-02-06: Inputs: Added mapping for ImGuiKey_Space.
// 2018-02-05: Misc: Using SDL_GetPerformanceCounter() instead of SDL_GetTicks() to be able to handle very high framerate (1000+ FPS).
// 2018-02-05: Inputs: Keyboard mapping is using scancodes everywhere instead of a confusing mixture of keycodes and scancodes.
// 2018-01-20: Inputs: Added Horizontal Mouse Wheel support.
// 2018-01-19: Inputs: When available (SDL 2.0.4+) using SDL_CaptureMouse() to retrieve coordinates outside of client area when dragging. Otherwise (SDL 2.0.3 and before) testing for SDL_WINDOW_INPUT_FOCUS instead of SDL_WINDOW_MOUSE_FOCUS.
// 2018-01-18: Inputs: Added mapping for ImGuiKey_Insert.
// 2017-09-01: OpenGL: Save and restore current polygon mode.
// 2017-08-25: Inputs: MousePos set to -FLT_MAX,-FLT_MAX when mouse is unavailable/missing (instead of -1,-1).
// 2016-10-15: Misc: Added a void* user_data parameter to Clipboard function handlers.
// 2016-09-05: OpenGL: Fixed save and restore of current scissor rectangle.
// 2016-07-29: OpenGL: Explicitly setting GL_UNPACK_ROW_LENGTH to reduce issues because SDL changes it. (#752)
#include <SDL.h>
#include <SDL_syswm.h>
#include <SDL_opengl.h>
#include "imgui.h"
#include "imgui_impl_sdl_gl2.h"
// Data
static Uint64 g_Time = 0;
static bool g_MousePressed[3] = { false, false, false };
static GLuint g_FontTexture = 0;
static SDL_Cursor* g_SdlCursors[ImGuiMouseCursor_Count_] = { 0 };
// OpenGL2 Render function.
// (this used to be set in io.RenderDrawListsFn and called by ImGui::Render(), but you can now call this directly from your main loop)
// Note that this implementation is little overcomplicated because we are saving/setting up/restoring every OpenGL state explicitly, in order to be able to run within any OpenGL engine that doesn't do so.
void ImGui_ImplSdlGL2_RenderDrawData(ImDrawData* draw_data)
{
// Avoid rendering when minimized, scale coordinates for retina displays (screen coordinates != framebuffer coordinates)
ImGuiIO& io = ImGui::GetIO();
int fb_width = (int)(io.DisplaySize.x * io.DisplayFramebufferScale.x);
int fb_height = (int)(io.DisplaySize.y * io.DisplayFramebufferScale.y);
if (fb_width == 0 || fb_height == 0)
return;
draw_data->ScaleClipRects(io.DisplayFramebufferScale);
// We are using the OpenGL fixed pipeline to make the example code simpler to read!
// Setup render state: alpha-blending enabled, no face culling, no depth testing, scissor enabled, vertex/texcoord/color pointers, polygon fill.
GLint last_texture; glGetIntegerv(GL_TEXTURE_BINDING_2D, &last_texture);
GLint last_polygon_mode[2]; glGetIntegerv(GL_POLYGON_MODE, last_polygon_mode);
GLint last_viewport[4]; glGetIntegerv(GL_VIEWPORT, last_viewport);
GLint last_scissor_box[4]; glGetIntegerv(GL_SCISSOR_BOX, last_scissor_box);
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);
glPolygonMode(GL_FRONT_AND_BACK, GL_FILL);
//glUseProgram(0); // You may want this if using this code in an OpenGL 3+ context where shaders may be bound
// Setup viewport, orthographic projection matrix
glViewport(0, 0, (GLsizei)fb_width, (GLsizei)fb_height);
glMatrixMode(GL_PROJECTION);
glPushMatrix();
glLoadIdentity();
glOrtho(0.0f, io.DisplaySize.x, io.DisplaySize.y, 0.0f, -1.0f, +1.0f);
glMatrixMode(GL_MODELVIEW);
glPushMatrix();
glLoadIdentity();
// Render command lists
for (int n = 0; n < draw_data->CmdListsCount; n++)
{
const ImDrawList* cmd_list = draw_data->CmdLists[n];
const ImDrawVert* vtx_buffer = cmd_list->VtxBuffer.Data;
const ImDrawIdx* idx_buffer = cmd_list->IdxBuffer.Data;
glVertexPointer(2, GL_FLOAT, sizeof(ImDrawVert), (const GLvoid*)((const char*)vtx_buffer + IM_OFFSETOF(ImDrawVert, pos)));
glTexCoordPointer(2, GL_FLOAT, sizeof(ImDrawVert), (const GLvoid*)((const char*)vtx_buffer + IM_OFFSETOF(ImDrawVert, uv)));
glColorPointer(4, GL_UNSIGNED_BYTE, sizeof(ImDrawVert), (const GLvoid*)((const char*)vtx_buffer + IM_OFFSETOF(ImDrawVert, col)));
for (int cmd_i = 0; cmd_i < cmd_list->CmdBuffer.Size; cmd_i++)
{
const ImDrawCmd* pcmd = &cmd_list->CmdBuffer[cmd_i];
if (pcmd->UserCallback)
{
pcmd->UserCallback(cmd_list, pcmd);
}
else
{
glBindTexture(GL_TEXTURE_2D, (GLuint)(intptr_t)pcmd->TextureId);
glScissor((int)pcmd->ClipRect.x, (int)(fb_height - pcmd->ClipRect.w), (int)(pcmd->ClipRect.z - pcmd->ClipRect.x), (int)(pcmd->ClipRect.w - pcmd->ClipRect.y));
glDrawElements(GL_TRIANGLES, (GLsizei)pcmd->ElemCount, sizeof(ImDrawIdx) == 2 ? GL_UNSIGNED_SHORT : GL_UNSIGNED_INT, idx_buffer);
}
idx_buffer += pcmd->ElemCount;
}
}
// Restore modified state
glDisableClientState(GL_COLOR_ARRAY);
glDisableClientState(GL_TEXTURE_COORD_ARRAY);
glDisableClientState(GL_VERTEX_ARRAY);
glBindTexture(GL_TEXTURE_2D, (GLuint)last_texture);
glMatrixMode(GL_MODELVIEW);
glPopMatrix();
glMatrixMode(GL_PROJECTION);
glPopMatrix();
glPopAttrib();
glPolygonMode(GL_FRONT, last_polygon_mode[0]); glPolygonMode(GL_BACK, last_polygon_mode[1]);
glViewport(last_viewport[0], last_viewport[1], (GLsizei)last_viewport[2], (GLsizei)last_viewport[3]);
glScissor(last_scissor_box[0], last_scissor_box[1], (GLsizei)last_scissor_box[2], (GLsizei)last_scissor_box[3]);
}
static const char* ImGui_ImplSdlGL2_GetClipboardText(void*)
{
return SDL_GetClipboardText();
}
static void ImGui_ImplSdlGL2_SetClipboardText(void*, const char* text)
{
SDL_SetClipboardText(text);
}
// You can read the io.WantCaptureMouse, io.WantCaptureKeyboard flags to tell if dear imgui wants to use your inputs.
// - When io.WantCaptureMouse is true, do not dispatch mouse input data to your main application.
// - When io.WantCaptureKeyboard is true, do not dispatch keyboard input data to your main application.
// Generally you may always pass all inputs to dear imgui, and hide them from your application based on those two flags.
bool ImGui_ImplSdlGL2_ProcessEvent(SDL_Event* event)
{
ImGuiIO& io = ImGui::GetIO();
switch (event->type)
{
case SDL_MOUSEWHEEL:
{
if (event->wheel.x > 0) io.MouseWheelH += 1;
if (event->wheel.x < 0) io.MouseWheelH -= 1;
if (event->wheel.y > 0) io.MouseWheel += 1;
if (event->wheel.y < 0) io.MouseWheel -= 1;
return true;
}
case SDL_MOUSEBUTTONDOWN:
{
if (event->button.button == SDL_BUTTON_LEFT) g_MousePressed[0] = true;
if (event->button.button == SDL_BUTTON_RIGHT) g_MousePressed[1] = true;
if (event->button.button == SDL_BUTTON_MIDDLE) g_MousePressed[2] = true;
return true;
}
case SDL_TEXTINPUT:
{
io.AddInputCharactersUTF8(event->text.text);
return true;
}
case SDL_KEYDOWN:
case SDL_KEYUP:
{
int key = event->key.keysym.scancode;
IM_ASSERT(key >= 0 && key < IM_ARRAYSIZE(io.KeysDown));
io.KeysDown[key] = (event->type == SDL_KEYDOWN);
io.KeyShift = ((SDL_GetModState() & KMOD_SHIFT) != 0);
io.KeyCtrl = ((SDL_GetModState() & KMOD_CTRL) != 0);
io.KeyAlt = ((SDL_GetModState() & KMOD_ALT) != 0);
io.KeySuper = ((SDL_GetModState() & KMOD_GUI) != 0);
return true;
}
}
return false;
}
bool ImGui_ImplSdlGL2_CreateDeviceObjects()
{
// Build texture atlas
ImGuiIO& io = ImGui::GetIO();
unsigned char* pixels;
int width, height;
io.Fonts->GetTexDataAsAlpha8(&pixels, &width, &height);
// Upload texture to graphics system
GLint last_texture;
glGetIntegerv(GL_TEXTURE_BINDING_2D, &last_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);
glPixelStorei(GL_UNPACK_ROW_LENGTH, 0);
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;
// Restore state
glBindTexture(GL_TEXTURE_2D, last_texture);
return true;
}
void ImGui_ImplSdlGL2_InvalidateDeviceObjects()
{
if (g_FontTexture)
{
glDeleteTextures(1, &g_FontTexture);
ImGui::GetIO().Fonts->TexID = 0;
g_FontTexture = 0;
}
}
bool ImGui_ImplSdlGL2_Init(SDL_Window* window)
{
// Keyboard mapping. ImGui will use those indices to peek into the io.KeyDown[] array.
ImGuiIO& io = ImGui::GetIO();
io.KeyMap[ImGuiKey_Tab] = SDL_SCANCODE_TAB;
io.KeyMap[ImGuiKey_LeftArrow] = SDL_SCANCODE_LEFT;
io.KeyMap[ImGuiKey_RightArrow] = SDL_SCANCODE_RIGHT;
io.KeyMap[ImGuiKey_UpArrow] = SDL_SCANCODE_UP;
io.KeyMap[ImGuiKey_DownArrow] = SDL_SCANCODE_DOWN;
io.KeyMap[ImGuiKey_PageUp] = SDL_SCANCODE_PAGEUP;
io.KeyMap[ImGuiKey_PageDown] = SDL_SCANCODE_PAGEDOWN;
io.KeyMap[ImGuiKey_Home] = SDL_SCANCODE_HOME;
io.KeyMap[ImGuiKey_End] = SDL_SCANCODE_END;
io.KeyMap[ImGuiKey_Insert] = SDL_SCANCODE_INSERT;
io.KeyMap[ImGuiKey_Delete] = SDL_SCANCODE_DELETE;
io.KeyMap[ImGuiKey_Backspace] = SDL_SCANCODE_BACKSPACE;
io.KeyMap[ImGuiKey_Space] = SDL_SCANCODE_SPACE;
io.KeyMap[ImGuiKey_Enter] = SDL_SCANCODE_RETURN;
io.KeyMap[ImGuiKey_Escape] = SDL_SCANCODE_ESCAPE;
io.KeyMap[ImGuiKey_A] = SDL_SCANCODE_A;
io.KeyMap[ImGuiKey_C] = SDL_SCANCODE_C;
io.KeyMap[ImGuiKey_V] = SDL_SCANCODE_V;
io.KeyMap[ImGuiKey_X] = SDL_SCANCODE_X;
io.KeyMap[ImGuiKey_Y] = SDL_SCANCODE_Y;
io.KeyMap[ImGuiKey_Z] = SDL_SCANCODE_Z;
io.SetClipboardTextFn = ImGui_ImplSdlGL2_SetClipboardText;
io.GetClipboardTextFn = ImGui_ImplSdlGL2_GetClipboardText;
io.ClipboardUserData = NULL;
g_SdlCursors[ImGuiMouseCursor_Arrow] = SDL_CreateSystemCursor(SDL_SYSTEM_CURSOR_ARROW);
g_SdlCursors[ImGuiMouseCursor_TextInput] = SDL_CreateSystemCursor(SDL_SYSTEM_CURSOR_IBEAM);
g_SdlCursors[ImGuiMouseCursor_ResizeAll] = SDL_CreateSystemCursor(SDL_SYSTEM_CURSOR_SIZEALL);
g_SdlCursors[ImGuiMouseCursor_ResizeNS] = SDL_CreateSystemCursor(SDL_SYSTEM_CURSOR_SIZENS);
g_SdlCursors[ImGuiMouseCursor_ResizeEW] = SDL_CreateSystemCursor(SDL_SYSTEM_CURSOR_SIZEWE);
g_SdlCursors[ImGuiMouseCursor_ResizeNESW] = SDL_CreateSystemCursor(SDL_SYSTEM_CURSOR_SIZENESW);
g_SdlCursors[ImGuiMouseCursor_ResizeNWSE] = SDL_CreateSystemCursor(SDL_SYSTEM_CURSOR_SIZENWSE);
#ifdef _WIN32
SDL_SysWMinfo wmInfo;
SDL_VERSION(&wmInfo.version);
SDL_GetWindowWMInfo(window, &wmInfo);
io.ImeWindowHandle = wmInfo.info.win.window;
#else
(void)window;
#endif
return true;
}
void ImGui_ImplSdlGL2_Shutdown()
{
ImGui_ImplSdlGL2_InvalidateDeviceObjects();
for (ImGuiMouseCursor cursor_n = 0; cursor_n < ImGuiMouseCursor_Count_; cursor_n++)
SDL_FreeCursor(g_SdlCursors[cursor_n]);
}
void ImGui_ImplSdlGL2_NewFrame(SDL_Window *window)
{
if (!g_FontTexture)
ImGui_ImplSdlGL2_CreateDeviceObjects();
ImGuiIO& io = ImGui::GetIO();
// Setup display size (every frame to accommodate for window resizing)
int w, h;
int display_w, display_h;
SDL_GetWindowSize(window, &w, &h);
SDL_GL_GetDrawableSize(window, &display_w, &display_h);
io.DisplaySize = ImVec2((float)w, (float)h);
io.DisplayFramebufferScale = ImVec2(w > 0 ? ((float)display_w / w) : 0, h > 0 ? ((float)display_h / h) : 0);
// Setup time step (we don't use SDL_GetTicks() because it is using millisecond resolution)
static Uint64 frequency = SDL_GetPerformanceFrequency();
Uint64 current_time = SDL_GetPerformanceCounter();
io.DeltaTime = g_Time > 0 ? (float)((double)(current_time - g_Time) / frequency) : (float)(1.0f / 60.0f);
g_Time = current_time;
// Setup mouse inputs (we already got mouse wheel, keyboard keys & characters from our event handler)
int mx, my;
Uint32 mouse_buttons = SDL_GetMouseState(&mx, &my);
io.MousePos = ImVec2(-FLT_MAX, -FLT_MAX);
io.MouseDown[0] = g_MousePressed[0] || (mouse_buttons & SDL_BUTTON(SDL_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] = g_MousePressed[1] || (mouse_buttons & SDL_BUTTON(SDL_BUTTON_RIGHT)) != 0;
io.MouseDown[2] = g_MousePressed[2] || (mouse_buttons & SDL_BUTTON(SDL_BUTTON_MIDDLE)) != 0;
g_MousePressed[0] = g_MousePressed[1] = g_MousePressed[2] = false;
// We need to use SDL_CaptureMouse() to easily retrieve mouse coordinates outside of the client area. This is only supported from SDL 2.0.4 (released Jan 2016)
#if (SDL_MAJOR_VERSION >= 2) && (SDL_MINOR_VERSION >= 0) && (SDL_PATCHLEVEL >= 4)
if ((SDL_GetWindowFlags(window) & (SDL_WINDOW_MOUSE_FOCUS | SDL_WINDOW_MOUSE_CAPTURE)) != 0)
io.MousePos = ImVec2((float)mx, (float)my);
bool any_mouse_button_down = false;
for (int n = 0; n < IM_ARRAYSIZE(io.MouseDown); n++)
any_mouse_button_down |= io.MouseDown[n];
if (any_mouse_button_down && (SDL_GetWindowFlags(window) & SDL_WINDOW_MOUSE_CAPTURE) == 0)
SDL_CaptureMouse(SDL_TRUE);
if (!any_mouse_button_down && (SDL_GetWindowFlags(window) & SDL_WINDOW_MOUSE_CAPTURE) != 0)
SDL_CaptureMouse(SDL_FALSE);
#else
if ((SDL_GetWindowFlags(window) & SDL_WINDOW_INPUT_FOCUS) != 0)
io.MousePos = ImVec2((float)mx, (float)my);
#endif
// Hide OS mouse cursor if ImGui is drawing it
ImGuiMouseCursor cursor = ImGui::GetMouseCursor();
if (io.MouseDrawCursor || cursor == ImGuiMouseCursor_None)
{
SDL_ShowCursor(0);
}
else
{
SDL_SetCursor(g_SdlCursors[cursor]);
SDL_ShowCursor(1);
}
// Start the frame. This call will update the io.WantCaptureMouse, io.WantCaptureKeyboard flag that you can use to dispatch inputs (or not) to your application.
ImGui::NewFrame();
}
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