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Big example binding refactor (manually imported from Viewport branch, stripped out of Viewport code). (#1870)
Read examples/README.txt for some details. ImDrawData: Added DisplayPos, DisplaySize fields honored by all backends (not strictly necessary to honor just now, but doing it to be ahead)
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omar
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examples/imgui_impl_opengl2.cpp
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examples/imgui_impl_opengl2.cpp
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// ImGui Renderer for: OpenGL2 (legacy OpenGL, fixed pipeline)
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// This needs to be used along with a Platform Binding (e.g. GLFW, SDL, Win32, custom..)
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// Implemented features:
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// [X] User texture binding. Use 'GLUint' OpenGL texture identifier as void*/ImTextureID. Read the FAQ about ImTextureID in imgui.cpp.
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// **DO NOT USE THIS CODE IF YOUR CODE/ENGINE IS USING MODERN OPENGL (SHADERS, VBO, VAO, etc.)**
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// **Prefer using the code in imgui_impl_opengl3.cpp**
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// This code is mostly provided as a reference to learn how ImGui integration works, because it is shorter to read.
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// If your code is using GL3+ context or any semi modern OpenGL calls, using this is likely to make everything more
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// complicated, will require your code to reset every single OpenGL attributes to their initial state, and might
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// confuse your GPU driver.
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// The GL2 code is unable to reset attributes or even call e.g. "glUseProgram(0)" because they don't exist in that API.
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// CHANGELOG
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// (minor and older changes stripped away, please see git history for details)
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// 2018-06-08: Misc: Extracted imgui_impl_opengl2.cpp/.h away from the old combined GLFW/SDL+OpenGL2 examples.
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// 2018-06-08: OpenGL: Use draw_data->DisplayPos and draw_data->DisplaySize to setup projection matrix and clipping rectangle.
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// 2018-02-16: Misc: Obsoleted the io.RenderDrawListsFn callback and exposed ImGui_ImplGlfwGL2_RenderDrawData() in the .h file so you can call it yourself.
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// 2017-09-01: OpenGL: Save and restore current polygon mode.
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// 2016-09-10: OpenGL: Uploading font texture as RGBA32 to increase compatibility with users shaders (not ideal).
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// 2016-09-05: OpenGL: Fixed save and restore of current scissor rectangle.
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#include "imgui.h"
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#include "imgui_impl_opengl2.h"
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// Include OpenGL header (without an OpenGL loader) requires a bit of fiddling
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#if defined(_WIN32) && !defined(APIENTRY)
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#define APIENTRY __stdcall // It is customary to use APIENTRY for OpenGL function pointer declarations on all platforms. Additionally, the Windows OpenGL header needs APIENTRY.
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#endif
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#if defined(_WIN32) && !defined(WINGDIAPI)
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#define WINGDIAPI __declspec(dllimport) // Some Windows OpenGL headers need this
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#endif
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#if defined(__APPLE__)
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#include <OpenGL/gl.h>
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#else
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#include <GL/gl.h>
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#endif
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// OpenGL Data
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static GLuint g_FontTexture = 0;
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// Functions
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bool ImGui_ImplOpenGL2_Init()
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{
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return true;
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}
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void ImGui_ImplOpenGL2_Shutdown()
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{
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ImGui_ImplOpenGL2_DestroyDeviceObjects();
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}
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void ImGui_ImplOpenGL2_NewFrame()
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{
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if (!g_FontTexture)
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ImGui_ImplOpenGL2_CreateDeviceObjects();
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}
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// OpenGL2 Render function.
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// (this used to be set in io.RenderDrawListsFn and called by ImGui::Render(), but you can now call this directly from your main loop)
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// 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.
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void ImGui_ImplOpenGL2_RenderDrawData(ImDrawData* draw_data)
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{
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// Avoid rendering when minimized, scale coordinates for retina displays (screen coordinates != framebuffer coordinates)
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ImGuiIO& io = ImGui::GetIO();
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int fb_width = (int)(draw_data->DisplaySize.x * io.DisplayFramebufferScale.x);
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int fb_height = (int)(draw_data->DisplaySize.y * io.DisplayFramebufferScale.y);
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if (fb_width == 0 || fb_height == 0)
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return;
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draw_data->ScaleClipRects(io.DisplayFramebufferScale);
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// We are using the OpenGL fixed pipeline to make the example code simpler to read!
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// Setup render state: alpha-blending enabled, no face culling, no depth testing, scissor enabled, vertex/texcoord/color pointers, polygon fill.
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GLint last_texture; glGetIntegerv(GL_TEXTURE_BINDING_2D, &last_texture);
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GLint last_polygon_mode[2]; glGetIntegerv(GL_POLYGON_MODE, last_polygon_mode);
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GLint last_viewport[4]; glGetIntegerv(GL_VIEWPORT, last_viewport);
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GLint last_scissor_box[4]; glGetIntegerv(GL_SCISSOR_BOX, last_scissor_box);
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glPushAttrib(GL_ENABLE_BIT | GL_COLOR_BUFFER_BIT | GL_TRANSFORM_BIT);
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glEnable(GL_BLEND);
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glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
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glDisable(GL_CULL_FACE);
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glDisable(GL_DEPTH_TEST);
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glEnable(GL_SCISSOR_TEST);
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glEnableClientState(GL_VERTEX_ARRAY);
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glEnableClientState(GL_TEXTURE_COORD_ARRAY);
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glEnableClientState(GL_COLOR_ARRAY);
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glEnable(GL_TEXTURE_2D);
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glPolygonMode(GL_FRONT_AND_BACK, GL_FILL);
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//glUseProgram(0); // You may want this if using this code in an OpenGL 3+ context where shaders may be bound
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// Setup viewport, orthographic projection matrix
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// Our visible imgui space lies from draw_data->DisplayPps (top left) to draw_data->DisplayPos+data_data->DisplaySize (bottom right). DisplayMin is typically (0,0) for single viewport apps.
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glViewport(0, 0, (GLsizei)fb_width, (GLsizei)fb_height);
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glMatrixMode(GL_PROJECTION);
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glPushMatrix();
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glLoadIdentity();
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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);
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glMatrixMode(GL_MODELVIEW);
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glPushMatrix();
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glLoadIdentity();
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// Render command lists
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ImVec2 pos = draw_data->DisplayPos;
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for (int n = 0; n < draw_data->CmdListsCount; n++)
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{
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const ImDrawList* cmd_list = draw_data->CmdLists[n];
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const ImDrawVert* vtx_buffer = cmd_list->VtxBuffer.Data;
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const ImDrawIdx* idx_buffer = cmd_list->IdxBuffer.Data;
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glVertexPointer(2, GL_FLOAT, sizeof(ImDrawVert), (const GLvoid*)((const char*)vtx_buffer + IM_OFFSETOF(ImDrawVert, pos)));
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glTexCoordPointer(2, GL_FLOAT, sizeof(ImDrawVert), (const GLvoid*)((const char*)vtx_buffer + IM_OFFSETOF(ImDrawVert, uv)));
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glColorPointer(4, GL_UNSIGNED_BYTE, sizeof(ImDrawVert), (const GLvoid*)((const char*)vtx_buffer + IM_OFFSETOF(ImDrawVert, col)));
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for (int cmd_i = 0; cmd_i < cmd_list->CmdBuffer.Size; cmd_i++)
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{
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const ImDrawCmd* pcmd = &cmd_list->CmdBuffer[cmd_i];
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if (pcmd->UserCallback)
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{
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// User callback (registered via ImDrawList::AddCallback)
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pcmd->UserCallback(cmd_list, pcmd);
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}
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else
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{
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ImVec4 clip_rect = ImVec4(pcmd->ClipRect.x - pos.x, pcmd->ClipRect.y - pos.y, pcmd->ClipRect.z - pos.x, pcmd->ClipRect.w - pos.y);
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if (clip_rect.x < fb_width && clip_rect.y < fb_height && clip_rect.z >= 0.0f && clip_rect.w >= 0.0f)
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{
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// Apply scissor/clipping rectangle
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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));
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// Bind texture, Draw
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glBindTexture(GL_TEXTURE_2D, (GLuint)(intptr_t)pcmd->TextureId);
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glDrawElements(GL_TRIANGLES, (GLsizei)pcmd->ElemCount, sizeof(ImDrawIdx) == 2 ? GL_UNSIGNED_SHORT : GL_UNSIGNED_INT, idx_buffer);
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}
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}
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idx_buffer += pcmd->ElemCount;
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}
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}
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// Restore modified state
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glDisableClientState(GL_COLOR_ARRAY);
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glDisableClientState(GL_TEXTURE_COORD_ARRAY);
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glDisableClientState(GL_VERTEX_ARRAY);
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glBindTexture(GL_TEXTURE_2D, (GLuint)last_texture);
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glMatrixMode(GL_MODELVIEW);
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glPopMatrix();
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glMatrixMode(GL_PROJECTION);
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glPopMatrix();
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glPopAttrib();
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glPolygonMode(GL_FRONT, (GLenum)last_polygon_mode[0]); glPolygonMode(GL_BACK, (GLenum)last_polygon_mode[1]);
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glViewport(last_viewport[0], last_viewport[1], (GLsizei)last_viewport[2], (GLsizei)last_viewport[3]);
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glScissor(last_scissor_box[0], last_scissor_box[1], (GLsizei)last_scissor_box[2], (GLsizei)last_scissor_box[3]);
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}
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bool ImGui_ImplOpenGL2_CreateFontsTexture()
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{
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// Build texture atlas
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ImGuiIO& io = ImGui::GetIO();
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unsigned char* pixels;
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int width, height;
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io.Fonts->GetTexDataAsRGBA32(&pixels, &width, &height); // Load as RGBA 32-bits (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.
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// Upload texture to graphics system
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GLint last_texture;
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glGetIntegerv(GL_TEXTURE_BINDING_2D, &last_texture);
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glGenTextures(1, &g_FontTexture);
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glBindTexture(GL_TEXTURE_2D, g_FontTexture);
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glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
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glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
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glPixelStorei(GL_UNPACK_ROW_LENGTH, 0);
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glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, width, height, 0, GL_RGBA, GL_UNSIGNED_BYTE, pixels);
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// Store our identifier
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io.Fonts->TexID = (void *)(intptr_t)g_FontTexture;
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// Restore state
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glBindTexture(GL_TEXTURE_2D, last_texture);
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return true;
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}
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void ImGui_ImplOpenGL2_DestroyFontsTexture()
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{
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if (g_FontTexture)
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{
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ImGuiIO& io = ImGui::GetIO();
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glDeleteTextures(1, &g_FontTexture);
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io.Fonts->TexID = 0;
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g_FontTexture = 0;
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}
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}
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bool ImGui_ImplOpenGL2_CreateDeviceObjects()
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{
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return ImGui_ImplOpenGL2_CreateFontsTexture();
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}
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void ImGui_ImplOpenGL2_DestroyDeviceObjects()
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{
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ImGui_ImplOpenGL2_DestroyFontsTexture();
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}
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