ref: 79ec91c85156980bb4ec7d652c21ae6d233015c5
dir: /DoConfig/imgui/imgui_impl_opengl2.cpp/
// dear imgui: Renderer for OpenGL2 (legacy OpenGL, fixed pipeline)
// This needs to be used along with a Platform Binding (e.g. GLFW, SDL, Win32, custom..)
// Implemented features:
// [X] Renderer: User texture binding. Use 'GLuint' OpenGL texture identifier as void*/ImTextureID. Read the FAQ about ImTextureID!
// You can copy and use unmodified imgui_impl_* files in your project. See main.cpp for an example of using this.
// If you are new to dear imgui, read examples/README.txt and read the documentation at the top of imgui.cpp.
// https://github.com/ocornut/imgui
// **DO NOT USE THIS CODE IF YOUR CODE/ENGINE IS USING MODERN OPENGL (SHADERS, VBO, VAO, etc.)**
// **Prefer using the code in imgui_impl_opengl3.cpp**
// 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.
// CHANGELOG
// (minor and older changes stripped away, please see git history for details)
// 2020-01-23: OpenGL: Explicitly backup, setup and restore GL_TEXTURE_ENV to increase compatibility with legacy OpenGL applications.
// 2019-04-30: OpenGL: Added support for special ImDrawCallback_ResetRenderState callback to reset render state.
// 2019-02-11: OpenGL: Projecting clipping rectangles correctly using draw_data->FramebufferScale to allow multi-viewports for retina display.
// 2018-11-30: Misc: Setting up io.BackendRendererName so it can be displayed in the About Window.
// 2018-08-03: OpenGL: Disabling/restoring GL_LIGHTING and GL_COLOR_MATERIAL to increase compatibility with legacy OpenGL applications.
// 2018-06-08: Misc: Extracted imgui_impl_opengl2.cpp/.h away from the old combined GLFW/SDL+OpenGL2 examples.
// 2018-06-08: OpenGL: Use draw_data->DisplayPos and draw_data->DisplaySize to setup projection matrix and clipping rectangle.
// 2018-02-16: Misc: Obsoleted the io.RenderDrawListsFn callback and exposed ImGui_ImplOpenGL2_RenderDrawData() in the .h file so you can call it yourself.
// 2017-09-01: OpenGL: Save and restore current polygon mode.
// 2016-09-10: OpenGL: Uploading font texture as RGBA32 to increase compatibility with users shaders (not ideal).
// 2016-09-05: OpenGL: Fixed save and restore of current scissor rectangle.
#include "imgui.h"
#include "imgui_impl_opengl2.h"
#if defined(_MSC_VER) && _MSC_VER <= 1500 // MSVC 2008 or earlier
#include <stddef.h> // intptr_t
#else
#include <stdint.h> // intptr_t
#endif
// Include OpenGL header (without an OpenGL loader) requires a bit of fiddling
#if defined(_WIN32) && !defined(APIENTRY)
#define APIENTRY __stdcall // It is customary to use APIENTRY for OpenGL function pointer declarations on all platforms. Additionally, the Windows OpenGL header needs APIENTRY.
#endif
#if defined(_WIN32) && !defined(WINGDIAPI)
#define WINGDIAPI __declspec(dllimport) // Some Windows OpenGL headers need this
#endif
#if defined(__APPLE__)
#define GL_SILENCE_DEPRECATION
#include <OpenGL/gl.h>
#else
#include <GL/gl.h>
#endif
// OpenGL Data
static GLuint g_FontTexture = 0;
// Functions
bool ImGui_ImplOpenGL2_Init()
{
// Setup back-end capabilities flags
ImGuiIO& io = ImGui::GetIO();
io.BackendRendererName = "imgui_impl_opengl2";
return true;
}
void ImGui_ImplOpenGL2_Shutdown()
{
ImGui_ImplOpenGL2_DestroyDeviceObjects();
}
void ImGui_ImplOpenGL2_NewFrame()
{
if (!g_FontTexture)
ImGui_ImplOpenGL2_CreateDeviceObjects();
}
static void ImGui_ImplOpenGL2_SetupRenderState(ImDrawData* draw_data, int fb_width, int fb_height)
{
// Setup render state: alpha-blending enabled, no face culling, no depth testing, scissor enabled, vertex/texcoord/color pointers, polygon fill.
glEnable(GL_BLEND);
glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
glDisable(GL_CULL_FACE);
glDisable(GL_DEPTH_TEST);
glDisable(GL_LIGHTING);
glDisable(GL_COLOR_MATERIAL);
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);
glTexEnvi(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_MODULATE);
// If you are using this code with non-legacy OpenGL header/contexts (which you should not, prefer using imgui_impl_opengl3.cpp!!),
// you may need to backup/reset/restore current shader using the lines below. DO NOT MODIFY THIS FILE! Add the code in your calling function:
// GLint last_program;
// glGetIntegerv(GL_CURRENT_PROGRAM, &last_program);
// glUseProgram(0);
// ImGui_ImplOpenGL2_RenderDrawData(...);
// glUseProgram(last_program)
// Setup viewport, orthographic projection matrix
// Our visible imgui space lies from draw_data->DisplayPos (top left) to draw_data->DisplayPos+data_data->DisplaySize (bottom right). DisplayPos is (0,0) for single viewport apps.
glViewport(0, 0, (GLsizei)fb_width, (GLsizei)fb_height);
glMatrixMode(GL_PROJECTION);
glPushMatrix();
glLoadIdentity();
glOrtho(draw_data->DisplayPos.x, draw_data->DisplayPos.x + draw_data->DisplaySize.x, draw_data->DisplayPos.y + draw_data->DisplaySize.y, draw_data->DisplayPos.y, -1.0f, +1.0f);
glMatrixMode(GL_MODELVIEW);
glPushMatrix();
glLoadIdentity();
}
// 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_ImplOpenGL2_RenderDrawData(ImDrawData* draw_data)
{
// Avoid rendering when minimized, scale coordinates for retina displays (screen coordinates != framebuffer coordinates)
int fb_width = (int)(draw_data->DisplaySize.x * draw_data->FramebufferScale.x);
int fb_height = (int)(draw_data->DisplaySize.y * draw_data->FramebufferScale.y);
if (fb_width == 0 || fb_height == 0)
return;
// Backup GL state
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);
GLint last_tex_env_mode; glGetTexEnviv(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, &last_tex_env_mode);
glPushAttrib(GL_ENABLE_BIT | GL_COLOR_BUFFER_BIT | GL_TRANSFORM_BIT);
// Setup desired GL state
ImGui_ImplOpenGL2_SetupRenderState(draw_data, fb_width, fb_height);
// Will project scissor/clipping rectangles into framebuffer space
ImVec2 clip_off = draw_data->DisplayPos; // (0,0) unless using multi-viewports
ImVec2 clip_scale = draw_data->FramebufferScale; // (1,1) unless using retina display which are often (2,2)
// 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)
{
// User callback, registered via ImDrawList::AddCallback()
// (ImDrawCallback_ResetRenderState is a special callback value used by the user to request the renderer to reset render state.)
if (pcmd->UserCallback == ImDrawCallback_ResetRenderState)
ImGui_ImplOpenGL2_SetupRenderState(draw_data, fb_width, fb_height);
else
pcmd->UserCallback(cmd_list, pcmd);
}
else
{
// Project scissor/clipping rectangles into framebuffer space
ImVec4 clip_rect;
clip_rect.x = (pcmd->ClipRect.x - clip_off.x) * clip_scale.x;
clip_rect.y = (pcmd->ClipRect.y - clip_off.y) * clip_scale.y;
clip_rect.z = (pcmd->ClipRect.z - clip_off.x) * clip_scale.x;
clip_rect.w = (pcmd->ClipRect.w - clip_off.y) * clip_scale.y;
if (clip_rect.x < fb_width && clip_rect.y < fb_height && clip_rect.z >= 0.0f && clip_rect.w >= 0.0f)
{
// Apply scissor/clipping rectangle
glScissor((int)clip_rect.x, (int)(fb_height - clip_rect.w), (int)(clip_rect.z - clip_rect.x), (int)(clip_rect.w - clip_rect.y));
// Bind texture, Draw
glBindTexture(GL_TEXTURE_2D, (GLuint)(intptr_t)pcmd->TextureId);
glDrawElements(GL_TRIANGLES, (GLsizei)pcmd->ElemCount, sizeof(ImDrawIdx) == 2 ? GL_UNSIGNED_SHORT : GL_UNSIGNED_INT, idx_buffer);
}
}
idx_buffer += pcmd->ElemCount;
}
}
// Restore modified GL 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, (GLenum)last_polygon_mode[0]); glPolygonMode(GL_BACK, (GLenum)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]);
glTexEnvi(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, last_tex_env_mode);
}
bool ImGui_ImplOpenGL2_CreateFontsTexture()
{
// Build texture atlas
ImGuiIO& io = ImGui::GetIO();
unsigned char* pixels;
int width, height;
io.Fonts->GetTexDataAsRGBA32(&pixels, &width, &height); // Load as RGBA 32-bit (75% of the memory is wasted, but default font is so small) because it is more likely to be compatible with user's existing shaders. If your ImTextureId represent a higher-level concept than just a GL texture id, consider calling GetTexDataAsAlpha8() instead to save on GPU memory.
// 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_RGBA, width, height, 0, GL_RGBA, GL_UNSIGNED_BYTE, pixels);
// Store our identifier
io.Fonts->TexID = (ImTextureID)(intptr_t)g_FontTexture;
// Restore state
glBindTexture(GL_TEXTURE_2D, last_texture);
return true;
}
void ImGui_ImplOpenGL2_DestroyFontsTexture()
{
if (g_FontTexture)
{
ImGuiIO& io = ImGui::GetIO();
glDeleteTextures(1, &g_FontTexture);
io.Fonts->TexID = 0;
g_FontTexture = 0;
}
}
bool ImGui_ImplOpenGL2_CreateDeviceObjects()
{
return ImGui_ImplOpenGL2_CreateFontsTexture();
}
void ImGui_ImplOpenGL2_DestroyDeviceObjects()
{
ImGui_ImplOpenGL2_DestroyFontsTexture();
}