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| -rw-r--r-- | src/imgui/backends/imgui_impl_opengl2.cpp | 302 |
1 files changed, 302 insertions, 0 deletions
diff --git a/src/imgui/backends/imgui_impl_opengl2.cpp b/src/imgui/backends/imgui_impl_opengl2.cpp new file mode 100644 index 0000000..0d70376 --- /dev/null +++ b/src/imgui/backends/imgui_impl_opengl2.cpp @@ -0,0 +1,302 @@ +// dear imgui: Renderer Backend for OpenGL2 (legacy OpenGL, fixed pipeline) +// This needs to be used along with a Platform Backend (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 use unmodified imgui_impl_* files in your project. See examples/ folder for examples of using this. +// Prefer including the entire imgui/ repository into your project (either as a copy or as a submodule), and only build the backends you need. +// Learn about Dear ImGui: +// - FAQ https://dearimgui.com/faq +// - Getting Started https://dearimgui.com/getting-started +// - Documentation https://dearimgui.com/docs (same as your local docs/ folder). +// - Introduction, links and more at the top of imgui.cpp + +// **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) +// 2022-10-11: Using 'nullptr' instead of 'NULL' as per our switch to C++11. +// 2021-12-08: OpenGL: Fixed mishandling of the the ImDrawCmd::IdxOffset field! This is an old bug but it never had an effect until some internal rendering changes in 1.86. +// 2021-06-29: Reorganized backend to pull data from a single structure to facilitate usage with multiple-contexts (all g_XXXX access changed to bd->XXXX). +// 2021-05-19: OpenGL: Replaced direct access to ImDrawCmd::TextureId with a call to ImDrawCmd::GetTexID(). (will become a requirement) +// 2021-01-03: OpenGL: Backup, setup and restore GL_SHADE_MODEL state, disable GL_STENCIL_TEST and disable GL_NORMAL_ARRAY client state to increase compatibility with legacy OpenGL applications. +// 2020-01-23: OpenGL: 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" +#ifndef IMGUI_DISABLE +#include "imgui_impl_opengl2.h" +#include <stdint.h> // intptr_t + +// Clang/GCC warnings with -Weverything +#if defined(__clang__) +#pragma clang diagnostic push +#pragma clang diagnostic ignored "-Wunused-macros" // warning: macro is not used +#pragma clang diagnostic ignored "-Wnonportable-system-include-path" +#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 + +struct ImGui_ImplOpenGL2_Data +{ + GLuint FontTexture; + + ImGui_ImplOpenGL2_Data() { memset((void*)this, 0, sizeof(*this)); } +}; + +// Backend data stored in io.BackendRendererUserData to allow support for multiple Dear ImGui contexts +// It is STRONGLY preferred that you use docking branch with multi-viewports (== single Dear ImGui context + multiple windows) instead of multiple Dear ImGui contexts. +static ImGui_ImplOpenGL2_Data* ImGui_ImplOpenGL2_GetBackendData() +{ + return ImGui::GetCurrentContext() ? (ImGui_ImplOpenGL2_Data*)ImGui::GetIO().BackendRendererUserData : nullptr; +} + +// Functions +bool ImGui_ImplOpenGL2_Init() +{ + ImGuiIO& io = ImGui::GetIO(); + IM_ASSERT(io.BackendRendererUserData == nullptr && "Already initialized a renderer backend!"); + + // Setup backend capabilities flags + ImGui_ImplOpenGL2_Data* bd = IM_NEW(ImGui_ImplOpenGL2_Data)(); + io.BackendRendererUserData = (void*)bd; + io.BackendRendererName = "imgui_impl_opengl2"; + + return true; +} + +void ImGui_ImplOpenGL2_Shutdown() +{ + ImGui_ImplOpenGL2_Data* bd = ImGui_ImplOpenGL2_GetBackendData(); + IM_ASSERT(bd != nullptr && "No renderer backend to shutdown, or already shutdown?"); + ImGuiIO& io = ImGui::GetIO(); + + ImGui_ImplOpenGL2_DestroyDeviceObjects(); + io.BackendRendererName = nullptr; + io.BackendRendererUserData = nullptr; + IM_DELETE(bd); +} + +void ImGui_ImplOpenGL2_NewFrame() +{ + ImGui_ImplOpenGL2_Data* bd = ImGui_ImplOpenGL2_GetBackendData(); + IM_ASSERT(bd != nullptr && "Did you call ImGui_ImplOpenGL2_Init()?"); + + if (!bd->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); + //glBlendFuncSeparate(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA, GL_ONE, GL_ONE_MINUS_SRC_ALPHA); // In order to composite our output buffer we need to preserve alpha + glDisable(GL_CULL_FACE); + glDisable(GL_DEPTH_TEST); + glDisable(GL_STENCIL_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); + glDisableClientState(GL_NORMAL_ARRAY); + glEnable(GL_TEXTURE_2D); + glPolygonMode(GL_FRONT_AND_BACK, GL_FILL); + glShadeModel(GL_SMOOTH); + 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 other state, e.g. for current shader using the commented 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) + // There are potentially many more states you could need to clear/setup that we can't access from default headers. + // e.g. glBindBuffer(GL_ARRAY_BUFFER, 0), glDisable(GL_TEXTURE_CUBE_MAP). + + // 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. +// Note that this implementation is little overcomplicated because we are saving/setting up/restoring every OpenGL state explicitly. +// This is in order to be able to run within an 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_shade_model; glGetIntegerv(GL_SHADE_MODEL, &last_shade_model); + 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 + offsetof(ImDrawVert, pos))); + glTexCoordPointer(2, GL_FLOAT, sizeof(ImDrawVert), (const GLvoid*)((const char*)vtx_buffer + offsetof(ImDrawVert, uv))); + glColorPointer(4, GL_UNSIGNED_BYTE, sizeof(ImDrawVert), (const GLvoid*)((const char*)vtx_buffer + 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 + ImVec2 clip_min((pcmd->ClipRect.x - clip_off.x) * clip_scale.x, (pcmd->ClipRect.y - clip_off.y) * clip_scale.y); + ImVec2 clip_max((pcmd->ClipRect.z - clip_off.x) * clip_scale.x, (pcmd->ClipRect.w - clip_off.y) * clip_scale.y); + if (clip_max.x <= clip_min.x || clip_max.y <= clip_min.y) + continue; + + // Apply scissor/clipping rectangle (Y is inverted in OpenGL) + glScissor((int)clip_min.x, (int)((float)fb_height - clip_max.y), (int)(clip_max.x - clip_min.x), (int)(clip_max.y - clip_min.y)); + + // Bind texture, Draw + glBindTexture(GL_TEXTURE_2D, (GLuint)(intptr_t)pcmd->GetTexID()); + glDrawElements(GL_TRIANGLES, (GLsizei)pcmd->ElemCount, sizeof(ImDrawIdx) == 2 ? GL_UNSIGNED_SHORT : GL_UNSIGNED_INT, idx_buffer + pcmd->IdxOffset); + } + } + } + + // 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]); + glShadeModel(last_shade_model); + glTexEnvi(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, last_tex_env_mode); +} + +bool ImGui_ImplOpenGL2_CreateFontsTexture() +{ + // Build texture atlas + ImGuiIO& io = ImGui::GetIO(); + ImGui_ImplOpenGL2_Data* bd = ImGui_ImplOpenGL2_GetBackendData(); + 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 + // (Bilinear sampling is required by default. Set 'io.Fonts->Flags |= ImFontAtlasFlags_NoBakedLines' or 'style.AntiAliasedLinesUseTex = false' to allow point/nearest sampling) + GLint last_texture; + glGetIntegerv(GL_TEXTURE_BINDING_2D, &last_texture); + glGenTextures(1, &bd->FontTexture); + glBindTexture(GL_TEXTURE_2D, bd->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->SetTexID((ImTextureID)(intptr_t)bd->FontTexture); + + // Restore state + glBindTexture(GL_TEXTURE_2D, last_texture); + + return true; +} + +void ImGui_ImplOpenGL2_DestroyFontsTexture() +{ + ImGuiIO& io = ImGui::GetIO(); + ImGui_ImplOpenGL2_Data* bd = ImGui_ImplOpenGL2_GetBackendData(); + if (bd->FontTexture) + { + glDeleteTextures(1, &bd->FontTexture); + io.Fonts->SetTexID(0); + bd->FontTexture = 0; + } +} + +bool ImGui_ImplOpenGL2_CreateDeviceObjects() +{ + return ImGui_ImplOpenGL2_CreateFontsTexture(); +} + +void ImGui_ImplOpenGL2_DestroyDeviceObjects() +{ + ImGui_ImplOpenGL2_DestroyFontsTexture(); +} + +//----------------------------------------------------------------------------- + +#if defined(__clang__) +#pragma clang diagnostic pop +#endif + +#endif // #ifndef IMGUI_DISABLE |