text: // dear imgui: Renderer for modern OpenGL with shaders / programmatic pipeline
  // - Desktop GL: 2.x 3.x 4.x
  // - Embedded GL: ES 2.0 (WebGL 1.0), ES 3.0 (WebGL 2.0)
  // 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!
  //  [X] Renderer: Multi-viewport support. Enable with 'io.ConfigFlags |= ImGuiConfigFlags_ViewportsEnable'.
  //  [x] Renderer: Desktop GL only: Support for large meshes (64k+ vertices) with 16-bit indices.
  
  // 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
  
  // CHANGELOG
  // (minor and older changes stripped away, please see git history for details)
  //  2020-XX-XX: Platform: Added support for multiple windows via the ImGuiPlatformIO interface.
  //  2020-07-10: OpenGL: Added support for glad2 OpenGL loader.
  //  2020-05-08: OpenGL: Made default GLSL version 150 (instead of 130) on OSX.
  //  2020-04-21: OpenGL: Fixed handling of glClipControl(GL_UPPER_LEFT) by inverting projection matrix.
  //  2020-04-12: OpenGL: Fixed context version check mistakenly testing for 4.0+ instead of 3.2+ to enable ImGuiBackendFlags_RendererHasVtxOffset.
  //  2020-03-24: OpenGL: Added support for glbinding 2.x OpenGL loader.
  //  2020-01-07: OpenGL: Added support for glbinding 3.x OpenGL loader.
  //  2019-10-25: OpenGL: Using a combination of GL define and runtime GL version to decide whether to use glDrawElementsBaseVertex(). Fix building with pre-3.2 GL loaders.
  //  2019-09-22: OpenGL: Detect default GL loader using __has_include compiler facility.
  //  2019-09-16: OpenGL: Tweak initialization code to allow application calling ImGui_ImplOpenGL3_CreateFontsTexture() before the first NewFrame() call.
  //  2019-05-29: OpenGL: Desktop GL only: Added support for large mesh (64K+ vertices), enable ImGuiBackendFlags_RendererHasVtxOffset flag.
  //  2019-04-30: OpenGL: Added support for special ImDrawCallback_ResetRenderState callback to reset render state.
  //  2019-03-29: OpenGL: Not calling glBindBuffer more than necessary in the render loop.
  //  2019-03-15: OpenGL: Added a GL call + comments in ImGui_ImplOpenGL3_Init() to detect uninitialized GL function loaders early.
  //  2019-03-03: OpenGL: Fix support for ES 2.0 (WebGL 1.0).
  //  2019-02-20: OpenGL: Fix for OSX not supporting OpenGL 4.5, we don't try to read GL_CLIP_ORIGIN even if defined by the headers/loader.
  //  2019-02-11: OpenGL: Projecting clipping rectangles correctly using draw_data->FramebufferScale to allow multi-viewports for retina display.
  //  2019-02-01: OpenGL: Using GLSL 410 shaders for any version over 410 (e.g. 430, 450).
  //  2018-11-30: Misc: Setting up io.BackendRendererName so it can be displayed in the About Window.
  //  2018-11-13: OpenGL: Support for GL 4.5's glClipControl(GL_UPPER_LEFT) / GL_CLIP_ORIGIN.
  //  2018-08-29: OpenGL: Added support for more OpenGL loaders: glew and glad, with comments indicative that any loader can be used.
  //  2018-08-09: OpenGL: Default to OpenGL ES 3 on iOS and Android. GLSL version default to "#version 300 ES".
  //  2018-07-30: OpenGL: Support for GLSL 300 ES and 410 core. Fixes for Emscripten compilation.
  //  2018-07-10: OpenGL: Support for more GLSL versions (based on the GLSL version string). Added error output when shaders fail to compile/link.
  //  2018-06-08: Misc: Extracted imgui_impl_opengl3.cpp/.h away from the old combined GLFW/SDL+OpenGL3 examples.
  //  2018-06-08: OpenGL: Use draw_data->DisplayPos and draw_data->DisplaySize to setup projection matrix and clipping rectangle.
  //  2018-05-25: OpenGL: Removed unnecessary backup/restore of GL_ELEMENT_ARRAY_BUFFER_BINDING since this is part of the VAO state.
  //  2018-05-14: OpenGL: Making the call to glBindSampler() optional so 3.2 context won't fail if the function is a NULL pointer.
  //  2018-03-06: OpenGL: Added const char* glsl_version parameter to ImGui_ImplOpenGL3_Init() so user can override the GLSL version e.g. "#version 150".
  //  2018-02-23: OpenGL: Create the VAO in the render function so the setup can more easily be used with multiple shared GL context.
  //  2018-02-16: Misc: Obsoleted the io.RenderDrawListsFn callback and exposed ImGui_ImplSdlGL3_RenderDrawData() in the .h file so you can call it yourself.
  //  2018-01-07: OpenGL: Changed GLSL shader version from 330 to 150.
  //  2017-09-01: OpenGL: Save and restore current bound sampler. Save and restore current polygon mode.
  //  2017-05-01: OpenGL: Fixed save and restore of current blend func state.
  //  2017-05-01: OpenGL: Fixed save and restore of current GL_ACTIVE_TEXTURE.
  //  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)
  
  //----------------------------------------
  // OpenGL    GLSL      GLSL
  // version   version   string
  //----------------------------------------
  //  2.0       110       "#version 110"
  //  2.1       120       "#version 120"
  //  3.0       130       "#version 130"
  //  3.1       140       "#version 140"
  //  3.2       150       "#version 150"
  //  3.3       330       "#version 330 core"
  //  4.0       400       "#version 400 core"
  //  4.1       410       "#version 410 core"
  //  4.2       420       "#version 410 core"
  //  4.3       430       "#version 430 core"
  //  ES 2.0    100       "#version 100"      = WebGL 1.0
  //  ES 3.0    300       "#version 300 es"   = WebGL 2.0
  //----------------------------------------
  
  #if defined(_MSC_VER) && !defined(_CRT_SECURE_NO_WARNINGS)
  #define _CRT_SECURE_NO_WARNINGS
  #endif
  
  #include "stpch.h"
  #include "imgui.h"
  #include <glad/glad.h>
  #include "ImGuiOpenGLRenderer.h"
  #include <stdio.h>
  #if defined(_MSC_VER) && _MSC_VER <= 1500 // MSVC 2008 or earlier
  #include <stddef.h>     // intptr_t
  #else
  #include <stdint.h>     // intptr_t
  #endif
  
  // Desktop GL 3.2+ has glDrawElementsBaseVertex() which GL ES and WebGL don't have.
  #if defined(IMGUI_IMPL_OPENGL_ES2) || defined(IMGUI_IMPL_OPENGL_ES3) || !defined(GL_VERSION_3_2)
  #define IMGUI_IMPL_OPENGL_MAY_HAVE_VTX_OFFSET   0
  #else
  #define IMGUI_IMPL_OPENGL_MAY_HAVE_VTX_OFFSET   1
  #endif
  
  // OpenGL Data
  static GLuint       g_GlVersion = 0;                // Extracted at runtime using GL_MAJOR_VERSION, GL_MINOR_VERSION queries (e.g. 320 for GL 3.2)
  static char         g_GlslVersionString[32] = "";   // Specified by user or detected based on compile time GL settings.
  static GLuint       g_FontTexture = 0;
  static GLuint       g_ShaderHandle = 0, g_VertHandle = 0, g_FragHandle = 0;
  static GLint        g_AttribLocationTex = 0, g_AttribLocationProjMtx = 0;                                // Uniforms location
  static GLuint       g_AttribLocationVtxPos = 0, g_AttribLocationVtxUV = 0, g_AttribLocationVtxColor = 0; // Vertex attributes location
  static unsigned int g_VboHandle = 0, g_ElementsHandle = 0;
  
  // Forward Declarations
  static void ImGui_ImplOpenGL3_InitPlatformInterface();
  static void ImGui_ImplOpenGL3_ShutdownPlatformInterface();
  
  // Functions
  bool    ImGui_ImplOpenGL3_Init(const char* glsl_version)
  {
  	// Query for GL version (e.g. 320 for GL 3.2)
  #if !defined(IMGUI_IMPL_OPENGL_ES2)
  	GLint major, minor;
  	glGetIntegerv(GL_MAJOR_VERSION, &major);
  	glGetIntegerv(GL_MINOR_VERSION, &minor);
  	g_GlVersion = (GLuint)(major * 100 + minor * 10);
  #else
  	g_GlVersion = 200; // GLES 2
  #endif
  
  	// Setup back-end capabilities flags
  	ImGuiIO& io = ImGui::GetIO();
  	io.BackendRendererName = "imgui_impl_opengl3";
  #if IMGUI_IMPL_OPENGL_MAY_HAVE_VTX_OFFSET
  	if (g_GlVersion >= 320)
  		io.BackendFlags |= ImGuiBackendFlags_RendererHasVtxOffset;  // We can honor the ImDrawCmd::VtxOffset field, allowing for large meshes.
  #endif
  	io.BackendFlags |= ImGuiBackendFlags_RendererHasViewports;  // We can create multi-viewports on the Renderer side (optional)
  
  	// Store GLSL version string so we can refer to it later in case we recreate shaders.
  	// Note: GLSL version is NOT the same as GL version. Leave this to NULL if unsure.
  #if defined(IMGUI_IMPL_OPENGL_ES2)
  	if (glsl_version == NULL)
  		glsl_version = "#version 100";
  #elif defined(IMGUI_IMPL_OPENGL_ES3)
  	if (glsl_version == NULL)
  		glsl_version = "#version 300 es";
  #elif defined(__APPLE__)
  	if (glsl_version == NULL)
  		glsl_version = "#version 150";
  #else
  	if (glsl_version == NULL)
  		glsl_version = "#version 130";
  #endif
  	IM_ASSERT((int)strlen(glsl_version) + 2 < IM_ARRAYSIZE(g_GlslVersionString));
  	strcpy(g_GlslVersionString, glsl_version);
  	strcat(g_GlslVersionString, "\n");
  
  	// Debugging construct to make it easily visible in the IDE and debugger which GL loader has been selected.
  	// The code actually never uses the 'gl_loader' variable! It is only here so you can read it!
  	// If auto-detection fails or doesn't select the same GL loader file as used by your application,
  	// you are likely to get a crash below.
  	// You can explicitly select a loader by using '#define IMGUI_IMPL_OPENGL_LOADER_XXX' in imconfig.h or compiler command-line.
  	const char* gl_loader = "Unknown";
  	IM_UNUSED(gl_loader);
  #if defined(IMGUI_IMPL_OPENGL_LOADER_GL3W)
  	gl_loader = "GL3W";
  #elif defined(IMGUI_IMPL_OPENGL_LOADER_GLEW)
  	gl_loader = "GLEW";
  #elif defined(IMGUI_IMPL_OPENGL_LOADER_GLAD)
  	gl_loader = "GLAD";
  #elif defined(IMGUI_IMPL_OPENGL_LOADER_GLAD2)
  	gl_loader = "GLAD2";
  #elif defined(IMGUI_IMPL_OPENGL_LOADER_GLBINDING2)
  	gl_loader = "glbinding2";
  #elif defined(IMGUI_IMPL_OPENGL_LOADER_GLBINDING3)
  	gl_loader = "glbinding3";
  #elif defined(IMGUI_IMPL_OPENGL_LOADER_CUSTOM)
  	gl_loader = "custom";
  #else
  	gl_loader = "none";
  #endif
  
  	// Make an arbitrary GL call (we don't actually need the result)
  	// IF YOU GET A CRASH HERE: it probably means that you haven't initialized the OpenGL function loader used by this code.
  	// Desktop OpenGL 3/4 need a function loader. See the IMGUI_IMPL_OPENGL_LOADER_xxx explanation above.
  	GLint current_texture;
  	glGetIntegerv(GL_TEXTURE_BINDING_2D, &current_texture);
  
  	if (io.ConfigFlags & ImGuiConfigFlags_ViewportsEnable)
  		ImGui_ImplOpenGL3_InitPlatformInterface();
  
  	return true;
  }
  
  void    ImGui_ImplOpenGL3_Shutdown()
  {
  	ImGui_ImplOpenGL3_ShutdownPlatformInterface();
  	ImGui_ImplOpenGL3_DestroyDeviceObjects();
  }
  
  void    ImGui_ImplOpenGL3_NewFrame()
  {
  	if (!g_ShaderHandle)
  		ImGui_ImplOpenGL3_CreateDeviceObjects();
  }
  
  static void ImGui_ImplOpenGL3_SetupRenderState(ImDrawData* draw_data, int fb_width, int fb_height, GLuint vertex_array_object)
  {
  	// Setup render state: alpha-blending enabled, no face culling, no depth testing, scissor enabled, polygon fill
  	glEnable(GL_BLEND);
  	glBlendEquation(GL_FUNC_ADD);
  	glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
  	glDisable(GL_CULL_FACE);
  	glDisable(GL_DEPTH_TEST);
  	glEnable(GL_SCISSOR_TEST);
  #ifdef GL_POLYGON_MODE
  	glPolygonMode(GL_FRONT_AND_BACK, GL_FILL);
  #endif
  
  	// Support for GL 4.5 rarely used glClipControl(GL_UPPER_LEFT)
  	bool clip_origin_lower_left = true;
  #if defined(GL_CLIP_ORIGIN) && !defined(__APPLE__)
  	GLenum current_clip_origin = 0; glGetIntegerv(GL_CLIP_ORIGIN, (GLint*)&current_clip_origin);
  	if (current_clip_origin == GL_UPPER_LEFT)
  		clip_origin_lower_left = false;
  #endif
  
  	// 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);
  	float L = draw_data->DisplayPos.x;
  	float R = draw_data->DisplayPos.x + draw_data->DisplaySize.x;
  	float T = draw_data->DisplayPos.y;
  	float B = draw_data->DisplayPos.y + draw_data->DisplaySize.y;
  	if (!clip_origin_lower_left) { float tmp = T; T = B; B = tmp; } // Swap top and bottom if origin is upper left
  	const float ortho_projection[4][4] =
  	{
  		{ 2.0f / (R - L),   0.0f,         0.0f,   0.0f },
  		{ 0.0f,         2.0f / (T - B),   0.0f,   0.0f },
  		{ 0.0f,         0.0f,        -1.0f,   0.0f },
  		{ (R + L) / (L - R),  (T + B) / (B - T),  0.0f,   1.0f },
  	};
  	glUseProgram(g_ShaderHandle);
  	glUniform1i(g_AttribLocationTex, 0);
  	glUniformMatrix4fv(g_AttribLocationProjMtx, 1, GL_FALSE, &ortho_projection[0][0]);
  #ifdef GL_SAMPLER_BINDING
  	glBindSampler(0, 0); // We use combined texture/sampler state. Applications using GL 3.3 may set that otherwise.
  #endif
  
  	(void)vertex_array_object;
  #ifndef IMGUI_IMPL_OPENGL_ES2
  	glBindVertexArray(vertex_array_object);
  #endif
  
  	// Bind vertex/index buffers and setup attributes for ImDrawVert
  	glBindBuffer(GL_ARRAY_BUFFER, g_VboHandle);
  	glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, g_ElementsHandle);
  	glEnableVertexAttribArray(g_AttribLocationVtxPos);
  	glEnableVertexAttribArray(g_AttribLocationVtxUV);
  	glEnableVertexAttribArray(g_AttribLocationVtxColor);
  	glVertexAttribPointer(g_AttribLocationVtxPos, 2, GL_FLOAT, GL_FALSE, sizeof(ImDrawVert), (GLvoid*)IM_OFFSETOF(ImDrawVert, pos));
  	glVertexAttribPointer(g_AttribLocationVtxUV, 2, GL_FLOAT, GL_FALSE, sizeof(ImDrawVert), (GLvoid*)IM_OFFSETOF(ImDrawVert, uv));
  	glVertexAttribPointer(g_AttribLocationVtxColor, 4, GL_UNSIGNED_BYTE, GL_TRUE, sizeof(ImDrawVert), (GLvoid*)IM_OFFSETOF(ImDrawVert, col));
  }
  
  // OpenGL3 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_ImplOpenGL3_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
  	GLenum last_active_texture; glGetIntegerv(GL_ACTIVE_TEXTURE, (GLint*)&last_active_texture);
  	glActiveTexture(GL_TEXTURE0);
  	GLuint last_program; glGetIntegerv(GL_CURRENT_PROGRAM, (GLint*)&last_program);
  	GLuint last_texture; glGetIntegerv(GL_TEXTURE_BINDING_2D, (GLint*)&last_texture);
  #ifdef GL_SAMPLER_BINDING
  	GLuint last_sampler; glGetIntegerv(GL_SAMPLER_BINDING, (GLint*)&last_sampler);
  #endif
  	GLuint last_array_buffer; glGetIntegerv(GL_ARRAY_BUFFER_BINDING, (GLint*)&last_array_buffer);
  #ifndef IMGUI_IMPL_OPENGL_ES2
  	GLuint last_vertex_array_object; glGetIntegerv(GL_VERTEX_ARRAY_BINDING, (GLint*)&last_vertex_array_object);
  #endif
  #ifdef GL_POLYGON_MODE
  	GLint last_polygon_mode[2]; glGetIntegerv(GL_POLYGON_MODE, last_polygon_mode);
  #endif
  	GLint last_viewport[4]; glGetIntegerv(GL_VIEWPORT, last_viewport);
  	GLint last_scissor_box[4]; glGetIntegerv(GL_SCISSOR_BOX, last_scissor_box);
  	GLenum last_blend_src_rgb; glGetIntegerv(GL_BLEND_SRC_RGB, (GLint*)&last_blend_src_rgb);
  	GLenum last_blend_dst_rgb; glGetIntegerv(GL_BLEND_DST_RGB, (GLint*)&last_blend_dst_rgb);
  	GLenum last_blend_src_alpha; glGetIntegerv(GL_BLEND_SRC_ALPHA, (GLint*)&last_blend_src_alpha);
  	GLenum last_blend_dst_alpha; glGetIntegerv(GL_BLEND_DST_ALPHA, (GLint*)&last_blend_dst_alpha);
  	GLenum last_blend_equation_rgb; glGetIntegerv(GL_BLEND_EQUATION_RGB, (GLint*)&last_blend_equation_rgb);
  	GLenum last_blend_equation_alpha; glGetIntegerv(GL_BLEND_EQUATION_ALPHA, (GLint*)&last_blend_equation_alpha);
  	GLboolean last_enable_blend = glIsEnabled(GL_BLEND);
  	GLboolean last_enable_cull_face = glIsEnabled(GL_CULL_FACE);
  	GLboolean last_enable_depth_test = glIsEnabled(GL_DEPTH_TEST);
  	GLboolean last_enable_scissor_test = glIsEnabled(GL_SCISSOR_TEST);
  
  	// Setup desired GL state
  	// Recreate the VAO every time (this is to easily allow multiple GL contexts to be rendered to. VAO are not shared among GL contexts)
  	// The renderer would actually work without any VAO bound, but then our VertexAttrib calls would overwrite the default one currently bound.
  	GLuint vertex_array_object = 0;
  #ifndef IMGUI_IMPL_OPENGL_ES2
  	glGenVertexArrays(1, &vertex_array_object);
  #endif
  	ImGui_ImplOpenGL3_SetupRenderState(draw_data, fb_width, fb_height, vertex_array_object);
  
  	// 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];
  
  		// Upload vertex/index buffers
  		glBufferData(GL_ARRAY_BUFFER, (GLsizeiptr)cmd_list->VtxBuffer.Size * (int)sizeof(ImDrawVert), (const GLvoid*)cmd_list->VtxBuffer.Data, GL_STREAM_DRAW);
  		glBufferData(GL_ELEMENT_ARRAY_BUFFER, (GLsizeiptr)cmd_list->IdxBuffer.Size * (int)sizeof(ImDrawIdx), (const GLvoid*)cmd_list->IdxBuffer.Data, GL_STREAM_DRAW);
  
  		for (int cmd_i = 0; cmd_i < cmd_list->CmdBuffer.Size; cmd_i++)
  		{
  			const ImDrawCmd* pcmd = &cmd_list->CmdBuffer[cmd_i];
  			if (pcmd->UserCallback != NULL)
  			{
  				// 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_ImplOpenGL3_SetupRenderState(draw_data, fb_width, fb_height, vertex_array_object);
  				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);
  #if IMGUI_IMPL_OPENGL_MAY_HAVE_VTX_OFFSET
  					if (g_GlVersion >= 320)
  						glDrawElementsBaseVertex(GL_TRIANGLES, (GLsizei)pcmd->ElemCount, sizeof(ImDrawIdx) == 2 ? GL_UNSIGNED_SHORT : GL_UNSIGNED_INT, (void*)(intptr_t)(pcmd->IdxOffset * sizeof(ImDrawIdx)), (GLint)pcmd->VtxOffset);
  					else
  #endif
  						glDrawElements(GL_TRIANGLES, (GLsizei)pcmd->ElemCount, sizeof(ImDrawIdx) == 2 ? GL_UNSIGNED_SHORT : GL_UNSIGNED_INT, (void*)(intptr_t)(pcmd->IdxOffset * sizeof(ImDrawIdx)));
  				}
  			}
  		}
  	}
  
  	// Destroy the temporary VAO
  #ifndef IMGUI_IMPL_OPENGL_ES2
  	glDeleteVertexArrays(1, &vertex_array_object);
  #endif
  
  	// Restore modified GL state
  	glUseProgram(last_program);
  	glBindTexture(GL_TEXTURE_2D, last_texture);
  #ifdef GL_SAMPLER_BINDING
  	glBindSampler(0, last_sampler);
  #endif
  	glActiveTexture(last_active_texture);
  #ifndef IMGUI_IMPL_OPENGL_ES2
  	glBindVertexArray(last_vertex_array_object);
  #endif
  	glBindBuffer(GL_ARRAY_BUFFER, last_array_buffer);
  	glBlendEquationSeparate(last_blend_equation_rgb, last_blend_equation_alpha);
  	glBlendFuncSeparate(last_blend_src_rgb, last_blend_dst_rgb, last_blend_src_alpha, last_blend_dst_alpha);
  	if (last_enable_blend) glEnable(GL_BLEND); else glDisable(GL_BLEND);
  	if (last_enable_cull_face) glEnable(GL_CULL_FACE); else glDisable(GL_CULL_FACE);
  	if (last_enable_depth_test) glEnable(GL_DEPTH_TEST); else glDisable(GL_DEPTH_TEST);
  	if (last_enable_scissor_test) glEnable(GL_SCISSOR_TEST); else glDisable(GL_SCISSOR_TEST);
  #ifdef GL_POLYGON_MODE
  	glPolygonMode(GL_FRONT_AND_BACK, (GLenum)last_polygon_mode[0]);
  #endif
  	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]);
  }
  
  bool ImGui_ImplOpenGL3_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);
  #ifdef GL_UNPACK_ROW_LENGTH
  	glPixelStorei(GL_UNPACK_ROW_LENGTH, 0);
  #endif
  	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_ImplOpenGL3_DestroyFontsTexture()
  {
  	if (g_FontTexture)
  	{
  		ImGuiIO& io = ImGui::GetIO();
  		glDeleteTextures(1, &g_FontTexture);
  		io.Fonts->TexID = 0;
  		g_FontTexture = 0;
  	}
  }
  
  // If you get an error please report on github. You may try different GL context version or GLSL version. See GL<>GLSL version table at the top of this file.
  static bool CheckShader(GLuint handle, const char* desc)
  {
  	GLint status = 0, log_length = 0;
  	glGetShaderiv(handle, GL_COMPILE_STATUS, &status);
  	glGetShaderiv(handle, GL_INFO_LOG_LENGTH, &log_length);
  	if ((GLboolean)status == GL_FALSE)
  		fprintf(stderr, "ERROR: ImGui_ImplOpenGL3_CreateDeviceObjects: failed to compile %s!\n", desc);
  	if (log_length > 1)
  	{
  		ImVector<char> buf;
  		buf.resize((int)(log_length + 1));
  		glGetShaderInfoLog(handle, log_length, NULL, (GLchar*)buf.begin());
  		fprintf(stderr, "%s\n", buf.begin());
  	}
  	return (GLboolean)status == GL_TRUE;
  }
  
  // If you get an error please report on GitHub. You may try different GL context version or GLSL version.
  static bool CheckProgram(GLuint handle, const char* desc)
  {
  	GLint status = 0, log_length = 0;
  	glGetProgramiv(handle, GL_LINK_STATUS, &status);
  	glGetProgramiv(handle, GL_INFO_LOG_LENGTH, &log_length);
  	if ((GLboolean)status == GL_FALSE)
  		fprintf(stderr, "ERROR: ImGui_ImplOpenGL3_CreateDeviceObjects: failed to link %s! (with GLSL '%s')\n", desc, g_GlslVersionString);
  	if (log_length > 1)
  	{
  		ImVector<char> buf;
  		buf.resize((int)(log_length + 1));
  		glGetProgramInfoLog(handle, log_length, NULL, (GLchar*)buf.begin());
  		fprintf(stderr, "%s\n", buf.begin());
  	}
  	return (GLboolean)status == GL_TRUE;
  }
  
  bool    ImGui_ImplOpenGL3_CreateDeviceObjects()
  {
  	// Backup GL state
  	GLint last_texture, last_array_buffer;
  	glGetIntegerv(GL_TEXTURE_BINDING_2D, &last_texture);
  	glGetIntegerv(GL_ARRAY_BUFFER_BINDING, &last_array_buffer);
  #ifndef IMGUI_IMPL_OPENGL_ES2
  	GLint last_vertex_array;
  	glGetIntegerv(GL_VERTEX_ARRAY_BINDING, &last_vertex_array);
  #endif
  
  	// Parse GLSL version string
  	int glsl_version = 130;
  	sscanf(g_GlslVersionString, "#version %d", &glsl_version);
  
  	const GLchar* vertex_shader_glsl_120 =
  		"uniform mat4 ProjMtx;\n"
  		"attribute vec2 Position;\n"
  		"attribute vec2 UV;\n"
  		"attribute vec4 Color;\n"
  		"varying vec2 Frag_UV;\n"
  		"varying vec4 Frag_Color;\n"
  		"void main()\n"
  		"{\n"
  		"    Frag_UV = UV;\n"
  		"    Frag_Color = Color;\n"
  		"    gl_Position = ProjMtx * vec4(Position.xy,0,1);\n"
  		"}\n";
  
  	const GLchar* vertex_shader_glsl_130 =
  		"uniform mat4 ProjMtx;\n"
  		"in vec2 Position;\n"
  		"in vec2 UV;\n"
  		"in vec4 Color;\n"
  		"out vec2 Frag_UV;\n"
  		"out vec4 Frag_Color;\n"
  		"void main()\n"
  		"{\n"
  		"    Frag_UV = UV;\n"
  		"    Frag_Color = Color;\n"
  		"    gl_Position = ProjMtx * vec4(Position.xy,0,1);\n"
  		"}\n";
  
  	const GLchar* vertex_shader_glsl_300_es =
  		"precision mediump float;\n"
  		"layout (location = 0) in vec2 Position;\n"
  		"layout (location = 1) in vec2 UV;\n"
  		"layout (location = 2) in vec4 Color;\n"
  		"uniform mat4 ProjMtx;\n"
  		"out vec2 Frag_UV;\n"
  		"out vec4 Frag_Color;\n"
  		"void main()\n"
  		"{\n"
  		"    Frag_UV = UV;\n"
  		"    Frag_Color = Color;\n"
  		"    gl_Position = ProjMtx * vec4(Position.xy,0,1);\n"
  		"}\n";
  
  	const GLchar* vertex_shader_glsl_410_core =
  		"layout (location = 0) in vec2 Position;\n"
  		"layout (location = 1) in vec2 UV;\n"
  		"layout (location = 2) in vec4 Color;\n"
  		"uniform mat4 ProjMtx;\n"
  		"out vec2 Frag_UV;\n"
  		"out vec4 Frag_Color;\n"
  		"void main()\n"
  		"{\n"
  		"    Frag_UV = UV;\n"
  		"    Frag_Color = Color;\n"
  		"    gl_Position = ProjMtx * vec4(Position.xy,0,1);\n"
  		"}\n";
  
  	const GLchar* fragment_shader_glsl_120 =
  		"#ifdef GL_ES\n"
  		"    precision mediump float;\n"
  		"#endif\n"
  		"uniform sampler2D Texture;\n"
  		"varying vec2 Frag_UV;\n"
  		"varying vec4 Frag_Color;\n"
  		"void main()\n"
  		"{\n"
  		"    gl_FragColor = Frag_Color * texture2D(Texture, Frag_UV.st);\n"
  		"}\n";
  
  	const GLchar* fragment_shader_glsl_130 =
  		"uniform sampler2D Texture;\n"
  		"in vec2 Frag_UV;\n"
  		"in vec4 Frag_Color;\n"
  		"out vec4 Out_Color;\n"
  		"void main()\n"
  		"{\n"
  		"    Out_Color = Frag_Color * texture(Texture, Frag_UV.st);\n"
  		"}\n";
  
  	const GLchar* fragment_shader_glsl_300_es =
  		"precision mediump float;\n"
  		"uniform sampler2D Texture;\n"
  		"in vec2 Frag_UV;\n"
  		"in vec4 Frag_Color;\n"
  		"layout (location = 0) out vec4 Out_Color;\n"
  		"void main()\n"
  		"{\n"
  		"    Out_Color = Frag_Color * texture(Texture, Frag_UV.st);\n"
  		"}\n";
  
  	const GLchar* fragment_shader_glsl_410_core =
  		"in vec2 Frag_UV;\n"
  		"in vec4 Frag_Color;\n"
  		"uniform sampler2D Texture;\n"
  		"layout (location = 0) out vec4 Out_Color;\n"
  		"void main()\n"
  		"{\n"
  		"    Out_Color = Frag_Color * texture(Texture, Frag_UV.st);\n"
  		"}\n";
  
  	// Select shaders matching our GLSL versions
  	const GLchar* vertex_shader = NULL;
  	const GLchar* fragment_shader = NULL;
  	if (glsl_version < 130)
  	{
  		vertex_shader = vertex_shader_glsl_120;
  		fragment_shader = fragment_shader_glsl_120;
  	}
  	else if (glsl_version >= 410)
  	{
  		vertex_shader = vertex_shader_glsl_410_core;
  		fragment_shader = fragment_shader_glsl_410_core;
  	}
  	else if (glsl_version == 300)
  	{
  		vertex_shader = vertex_shader_glsl_300_es;
  		fragment_shader = fragment_shader_glsl_300_es;
  	}
  	else
  	{
  		vertex_shader = vertex_shader_glsl_130;
  		fragment_shader = fragment_shader_glsl_130;
  	}
  
  	// Create shaders
  	const GLchar* vertex_shader_with_version[2] = { g_GlslVersionString, vertex_shader };
  	g_VertHandle = glCreateShader(GL_VERTEX_SHADER);
  	glShaderSource(g_VertHandle, 2, vertex_shader_with_version, NULL);
  	glCompileShader(g_VertHandle);
  	CheckShader(g_VertHandle, "vertex shader");
  
  	const GLchar* fragment_shader_with_version[2] = { g_GlslVersionString, fragment_shader };
  	g_FragHandle = glCreateShader(GL_FRAGMENT_SHADER);
  	glShaderSource(g_FragHandle, 2, fragment_shader_with_version, NULL);
  	glCompileShader(g_FragHandle);
  	CheckShader(g_FragHandle, "fragment shader");
  
  	g_ShaderHandle = glCreateProgram();
  	glAttachShader(g_ShaderHandle, g_VertHandle);
  	glAttachShader(g_ShaderHandle, g_FragHandle);
  	glLinkProgram(g_ShaderHandle);
  	CheckProgram(g_ShaderHandle, "shader program");
  
  	g_AttribLocationTex = glGetUniformLocation(g_ShaderHandle, "Texture");
  	g_AttribLocationProjMtx = glGetUniformLocation(g_ShaderHandle, "ProjMtx");
  	g_AttribLocationVtxPos = (GLuint)glGetAttribLocation(g_ShaderHandle, "Position");
  	g_AttribLocationVtxUV = (GLuint)glGetAttribLocation(g_ShaderHandle, "UV");
  	g_AttribLocationVtxColor = (GLuint)glGetAttribLocation(g_ShaderHandle, "Color");
  
  	// Create buffers
  	glGenBuffers(1, &g_VboHandle);
  	glGenBuffers(1, &g_ElementsHandle);
  
  	ImGui_ImplOpenGL3_CreateFontsTexture();
  
  	// Restore modified GL state
  	glBindTexture(GL_TEXTURE_2D, last_texture);
  	glBindBuffer(GL_ARRAY_BUFFER, last_array_buffer);
  #ifndef IMGUI_IMPL_OPENGL_ES2
  	glBindVertexArray(last_vertex_array);
  #endif
  
  	return true;
  }
  
  void    ImGui_ImplOpenGL3_DestroyDeviceObjects()
  {
  	if (g_VboHandle) { glDeleteBuffers(1, &g_VboHandle); g_VboHandle = 0; }
  	if (g_ElementsHandle) { glDeleteBuffers(1, &g_ElementsHandle); g_ElementsHandle = 0; }
  	if (g_ShaderHandle && g_VertHandle) { glDetachShader(g_ShaderHandle, g_VertHandle); }
  	if (g_ShaderHandle && g_FragHandle) { glDetachShader(g_ShaderHandle, g_FragHandle); }
  	if (g_VertHandle) { glDeleteShader(g_VertHandle); g_VertHandle = 0; }
  	if (g_FragHandle) { glDeleteShader(g_FragHandle); g_FragHandle = 0; }
  	if (g_ShaderHandle) { glDeleteProgram(g_ShaderHandle); g_ShaderHandle = 0; }
  
  	ImGui_ImplOpenGL3_DestroyFontsTexture();
  }
  
  //--------------------------------------------------------------------------------------------------------
  // MULTI-VIEWPORT / PLATFORM INTERFACE SUPPORT
  // This is an _advanced_ and _optional_ feature, allowing the back-end to create and handle multiple viewports simultaneously.
  // If you are new to dear imgui or creating a new binding for dear imgui, it is recommended that you completely ignore this section first..
  //--------------------------------------------------------------------------------------------------------
  
  static void ImGui_ImplOpenGL3_RenderWindow(ImGuiViewport* viewport, void*)
  {
  	if (!(viewport->Flags & ImGuiViewportFlags_NoRendererClear))
  	{
  		ImVec4 clear_color = ImVec4(0.0f, 0.0f, 0.0f, 1.0f);
  		glClearColor(clear_color.x, clear_color.y, clear_color.z, clear_color.w);
  		glClear(GL_COLOR_BUFFER_BIT);
  	}
  	ImGui_ImplOpenGL3_RenderDrawData(viewport->DrawData);
  }
  
  static void ImGui_ImplOpenGL3_InitPlatformInterface()
  {
  	ImGuiPlatformIO& platform_io = ImGui::GetPlatformIO();
  	platform_io.Renderer_RenderWindow = ImGui_ImplOpenGL3_RenderWindow;
  }
  
  static void ImGui_ImplOpenGL3_ShutdownPlatformInterface()
  {
  	ImGui::DestroyPlatformWindows();
  }