examples/opengl3_example/imgui_impl_glfw_gl3.cpp - external/github.com/ocornut/imgui - Git at Google

 // ImGui GLFW binding with OpenGL3 + shaders
 // https://github.com/ocornut/imgui

 #include <imgui.h>
 #include "imgui_impl_glfw_gl3.h"

 // GL3W/GLFW
 #include <GL/gl3w.h>
 #include <GLFW/glfw3.h>
 #ifdef _MSC_VER
 #undef APIENTRY
 #define GLFW_EXPOSE_NATIVE_WIN32
 #define GLFW_EXPOSE_NATIVE_WGL
 #include <GLFW/glfw3native.h>
 #endif

 // Data
 static GLFWwindow*  g_Window = NULL;
 static double       g_Time = 0.0f;
 static bool         g_MousePressed[3] = { false, false, false };
 static float        g_MouseWheel = 0.0f;
 static GLuint       g_FontTexture = 0;
 static int          g_ShaderHandle = 0, g_VertHandle = 0, g_FragHandle = 0;
 static int          g_AttribLocationTex = 0, g_AttribLocationProjMtx = 0;
 static int          g_AttribLocationPosition = 0, g_AttribLocationUV = 0, g_AttribLocationColor = 0;
 static size_t       g_VboMaxSize = 20000;
 static unsigned int g_VboHandle = 0, g_VaoHandle = 0;

 // This is the main rendering function that you have to implement and provide to ImGui (via setting up 'RenderDrawListsFn' in the ImGuiIO structure)
 // If text or lines are blurry when integrating ImGui in your engine:
 // - in your Render function, try translating your projection matrix by (0.5f,0.5f) or (0.375f,0.375f)
 static void ImGui_ImplGlfwGL3_RenderDrawLists(ImDrawList** const cmd_lists, int cmd_lists_count)
 {
     if (cmd_lists_count == 0)
         return;

     // Setup render state: alpha-blending enabled, no face culling, no depth testing, scissor enabled
     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);
     glActiveTexture(GL_TEXTURE0);

     // Setup orthographic projection matrix
     const float width = ImGui::GetIO().DisplaySize.x;
     const float height = ImGui::GetIO().DisplaySize.y;
     const float ortho_projection[4][4] =
     {
         { 2.0f/width,	0.0f,			0.0f,		0.0f },
         { 0.0f,			2.0f/-height,	0.0f,		0.0f },
         { 0.0f,			0.0f,			-1.0f,		0.0f },
         { -1.0f,		1.0f,			0.0f,		1.0f },
     };
     glUseProgram(g_ShaderHandle);
     glUniform1i(g_AttribLocationTex, 0);
     glUniformMatrix4fv(g_AttribLocationProjMtx, 1, GL_FALSE, &ortho_projection[0][0]);

     // Grow our buffer according to what we need
     size_t total_vtx_count = 0;
     for (int n = 0; n < cmd_lists_count; n++)
         total_vtx_count += cmd_lists[n]->vtx_buffer.size();
     glBindBuffer(GL_ARRAY_BUFFER, g_VboHandle);
     size_t neededBufferSize = total_vtx_count * sizeof(ImDrawVert);
     if (neededBufferSize > g_VboMaxSize)
     {
         g_VboMaxSize = neededBufferSize + 5000;  // Grow buffer
         glBufferData(GL_ARRAY_BUFFER, g_VboMaxSize, NULL, GL_STREAM_DRAW);
     }

     // Copy and convert all vertices into a single contiguous buffer
     unsigned char* buffer_data = (unsigned char*)glMapBuffer(GL_ARRAY_BUFFER, GL_WRITE_ONLY);
     if (!buffer_data)
         return;
     for (int n = 0; n < cmd_lists_count; n++)
     {
         const ImDrawList* cmd_list = cmd_lists[n];
         memcpy(buffer_data, &cmd_list->vtx_buffer[0], cmd_list->vtx_buffer.size() * sizeof(ImDrawVert));
         buffer_data += cmd_list->vtx_buffer.size() * sizeof(ImDrawVert);
     }
     glUnmapBuffer(GL_ARRAY_BUFFER);
     glBindBuffer(GL_ARRAY_BUFFER, 0);
     glBindVertexArray(g_VaoHandle);

     int cmd_offset = 0;
     for (int n = 0; n < cmd_lists_count; n++)
     {
         const ImDrawList* cmd_list = cmd_lists[n];
         int vtx_offset = cmd_offset;
         const ImDrawCmd* pcmd_end = cmd_list->commands.end();
         for (const ImDrawCmd* pcmd = cmd_list->commands.begin(); pcmd != pcmd_end; pcmd++)
         {
             glBindTexture(GL_TEXTURE_2D, (GLuint)(intptr_t)pcmd->texture_id);
             glScissor((int)pcmd->clip_rect.x, (int)(height - pcmd->clip_rect.w), (int)(pcmd->clip_rect.z - pcmd->clip_rect.x), (int)(pcmd->clip_rect.w - pcmd->clip_rect.y));
             glDrawArrays(GL_TRIANGLES, vtx_offset, pcmd->vtx_count);
             vtx_offset += pcmd->vtx_count;
         }
         cmd_offset = vtx_offset;
     }

     // Restore modified state
     glBindVertexArray(0);
     glUseProgram(0);
     glDisable(GL_SCISSOR_TEST);
     glBindTexture(GL_TEXTURE_2D, 0);
 }

 static const char* ImGui_ImplGlfwGL3_GetClipboardText()
 {
     return glfwGetClipboardString(g_Window);
 }

 static void ImGui_ImplGlfwGL3_SetClipboardText(const char* text)
 {
     glfwSetClipboardString(g_Window, text);
 }

 void ImGui_ImplGlfwGL3_MouseButtonCallback(GLFWwindow* window, int button, int action, int mods)
 {
     if (action == GLFW_PRESS && button >= 0 && button < 3)
         g_MousePressed[button] = true;
 }

 void ImGui_ImplGlfwGL3_ScrollCallback(GLFWwindow* window, double xoffset, double yoffset)
 {
     g_MouseWheel += (float)yoffset; // Use fractional mouse wheel, 1.0 unit 5 lines.
 }

 void ImGui_ImplGlfwGL3_KeyCallback(GLFWwindow* window, int key, int scancode, int action, int mods)
 {
     ImGuiIO& io = ImGui::GetIO();
     if (action == GLFW_PRESS)
         io.KeysDown[key] = true;
     if (action == GLFW_RELEASE)
         io.KeysDown[key] = false;
     io.KeyCtrl = (mods & GLFW_MOD_CONTROL) != 0;
     io.KeyShift = (mods & GLFW_MOD_SHIFT) != 0;
 }

 void ImGui_ImplGlfwGL3_CharCallback(GLFWwindow* window, unsigned int c)
 {
     ImGuiIO& io = ImGui::GetIO();
     if (c > 0 && c < 0x10000)
         io.AddInputCharacter((unsigned short)c);
 }

 void ImGui_ImplGlfwGL3_CreateFontsTexture()
 {
     ImGuiIO& io = ImGui::GetIO();

     unsigned char* pixels;
     int width, height;
     io.Fonts->GetTexDataAsRGBA32(&pixels, &width, &height);   // Load as RGBA 32-bits for OpenGL3 demo because it is more likely to be compatible with user's existing shader.

     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);
     glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, width, height, 0, GL_RGBA, GL_UNSIGNED_BYTE, pixels);

     // Store our identifier
     io.Fonts->TexID = (void *)(intptr_t)g_FontTexture;
 }

 bool ImGui_ImplGlfwGL3_CreateDeviceObjects()
 {
     const GLchar *vertex_shader =
         "#version 330\n"
         "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* fragment_shader =
         "#version 330\n"
         "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";

     g_ShaderHandle = glCreateProgram();
     g_VertHandle = glCreateShader(GL_VERTEX_SHADER);
     g_FragHandle = glCreateShader(GL_FRAGMENT_SHADER);
     glShaderSource(g_VertHandle, 1, &vertex_shader, 0);
     glShaderSource(g_FragHandle, 1, &fragment_shader, 0);
     glCompileShader(g_VertHandle);
     glCompileShader(g_FragHandle);
     glAttachShader(g_ShaderHandle, g_VertHandle);
     glAttachShader(g_ShaderHandle, g_FragHandle);
     glLinkProgram(g_ShaderHandle);

     g_AttribLocationTex = glGetUniformLocation(g_ShaderHandle, "Texture");
     g_AttribLocationProjMtx = glGetUniformLocation(g_ShaderHandle, "ProjMtx");
     g_AttribLocationPosition = glGetAttribLocation(g_ShaderHandle, "Position");
     g_AttribLocationUV = glGetAttribLocation(g_ShaderHandle, "UV");
     g_AttribLocationColor = glGetAttribLocation(g_ShaderHandle, "Color");

     glGenBuffers(1, &g_VboHandle);
     glBindBuffer(GL_ARRAY_BUFFER, g_VboHandle);
     glBufferData(GL_ARRAY_BUFFER, g_VboMaxSize, NULL, GL_DYNAMIC_DRAW);

     glGenVertexArrays(1, &g_VaoHandle);
     glBindVertexArray(g_VaoHandle);
     glBindBuffer(GL_ARRAY_BUFFER, g_VboHandle);
     glEnableVertexAttribArray(g_AttribLocationPosition);
     glEnableVertexAttribArray(g_AttribLocationUV);
     glEnableVertexAttribArray(g_AttribLocationColor);

 #define OFFSETOF(TYPE, ELEMENT) ((size_t)&(((TYPE *)0)->ELEMENT))
     glVertexAttribPointer(g_AttribLocationPosition, 2, GL_FLOAT, GL_FALSE, sizeof(ImDrawVert), (GLvoid*)OFFSETOF(ImDrawVert, pos));
     glVertexAttribPointer(g_AttribLocationUV, 2, GL_FLOAT, GL_FALSE, sizeof(ImDrawVert), (GLvoid*)OFFSETOF(ImDrawVert, uv));
     glVertexAttribPointer(g_AttribLocationColor, 4, GL_UNSIGNED_BYTE, GL_TRUE, sizeof(ImDrawVert), (GLvoid*)OFFSETOF(ImDrawVert, col));
 #undef OFFSETOF
     glBindVertexArray(0);
     glBindBuffer(GL_ARRAY_BUFFER, 0);

     ImGui_ImplGlfwGL3_CreateFontsTexture();

     return true;
 }

 bool    ImGui_ImplGlfwGL3_Init(GLFWwindow* window, bool install_callbacks)
 {
     g_Window = window;

     ImGuiIO& io = ImGui::GetIO();
     io.KeyMap[ImGuiKey_Tab] = GLFW_KEY_TAB;                 // Keyboard mapping. ImGui will use those indices to peek into the io.KeyDown[] array.
     io.KeyMap[ImGuiKey_LeftArrow] = GLFW_KEY_LEFT;
     io.KeyMap[ImGuiKey_RightArrow] = GLFW_KEY_RIGHT;
     io.KeyMap[ImGuiKey_UpArrow] = GLFW_KEY_UP;
     io.KeyMap[ImGuiKey_DownArrow] = GLFW_KEY_DOWN;
     io.KeyMap[ImGuiKey_Home] = GLFW_KEY_HOME;
     io.KeyMap[ImGuiKey_End] = GLFW_KEY_END;
     io.KeyMap[ImGuiKey_Delete] = GLFW_KEY_DELETE;
     io.KeyMap[ImGuiKey_Backspace] = GLFW_KEY_BACKSPACE;
     io.KeyMap[ImGuiKey_Enter] = GLFW_KEY_ENTER;
     io.KeyMap[ImGuiKey_Escape] = GLFW_KEY_ESCAPE;
     io.KeyMap[ImGuiKey_A] = GLFW_KEY_A;
     io.KeyMap[ImGuiKey_C] = GLFW_KEY_C;
     io.KeyMap[ImGuiKey_V] = GLFW_KEY_V;
     io.KeyMap[ImGuiKey_X] = GLFW_KEY_X;
     io.KeyMap[ImGuiKey_Y] = GLFW_KEY_Y;
     io.KeyMap[ImGuiKey_Z] = GLFW_KEY_Z;

     io.RenderDrawListsFn = ImGui_ImplGlfwGL3_RenderDrawLists;
     io.SetClipboardTextFn = ImGui_ImplGlfwGL3_SetClipboardText;
     io.GetClipboardTextFn = ImGui_ImplGlfwGL3_GetClipboardText;
 #ifdef _MSC_VER
     io.ImeWindowHandle = glfwGetWin32Window(g_Window);
 #endif

     if (install_callbacks)
     {
         glfwSetMouseButtonCallback(window, ImGui_ImplGlfwGL3_MouseButtonCallback);
         glfwSetScrollCallback(window, ImGui_ImplGlfwGL3_ScrollCallback);
         glfwSetKeyCallback(window, ImGui_ImplGlfwGL3_KeyCallback);
         glfwSetCharCallback(window, ImGui_ImplGlfwGL3_CharCallback);
     }

     return true;
 }

 void ImGui_ImplGlfwGL3_Shutdown()
 {
     if (g_VaoHandle) glDeleteVertexArrays(1, &g_VaoHandle);
     if (g_VboHandle) glDeleteBuffers(1, &g_VboHandle);
     g_VaoHandle = 0;
     g_VboHandle = 0;

     glDetachShader(g_ShaderHandle, g_VertHandle);
     glDeleteShader(g_VertHandle);
     g_VertHandle = 0;

     glDetachShader(g_ShaderHandle, g_FragHandle);
     glDeleteShader(g_FragHandle);
     g_FragHandle = 0;

     glDeleteProgram(g_ShaderHandle);
     g_ShaderHandle = 0;

     if (g_FontTexture)
     {
         glDeleteTextures(1, &g_FontTexture);
         ImGui::GetIO().Fonts->TexID = 0;
         g_FontTexture = 0;
     }
     ImGui::Shutdown();
 }

 void ImGui_ImplGlfwGL3_NewFrame()
 {
     if (!g_FontTexture)
         ImGui_ImplGlfwGL3_CreateDeviceObjects();

     ImGuiIO& io = ImGui::GetIO();

     // Setup display size (every frame to accommodate for window resizing)
     int w, h;
     int display_w, display_h;
     glfwGetWindowSize(g_Window, &w, &h);
     glfwGetFramebufferSize(g_Window, &display_w, &display_h);
     io.DisplaySize = ImVec2((float)display_w, (float)display_h);

     // Setup time step
     double current_time =  glfwGetTime();
     io.DeltaTime = g_Time > 0.0 ? (float)(current_time - g_Time) : (float)(1.0f/60.0f);
     g_Time = current_time;

     // Setup inputs
     // (we already got mouse wheel, keyboard keys & characters from glfw callbacks polled in glfwPollEvents())
     double mouse_x, mouse_y;
     glfwGetCursorPos(g_Window, &mouse_x, &mouse_y);
     mouse_x *= (float)display_w / w;                                                                    // Convert mouse coordinates to pixels
     mouse_y *= (float)display_h / h;
     io.MousePos = ImVec2((float)mouse_x, (float)mouse_y);                                               // Mouse position, in pixels (set to -1,-1 if no mouse / on another screen, etc.)

     io.MouseDown[0] = g_MousePressed[0] || glfwGetMouseButton(g_Window, GLFW_MOUSE_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] || glfwGetMouseButton(g_Window, GLFW_MOUSE_BUTTON_RIGHT) != 0;
     io.MouseDown[2] = g_MousePressed[2] || glfwGetMouseButton(g_Window, GLFW_MOUSE_BUTTON_MIDDLE) != 0;
     g_MousePressed[0] = false;
     g_MousePressed[1] = false;
     g_MousePressed[2] = false;

     io.MouseWheel = g_MouseWheel;
     g_MouseWheel = 0.0f;

     // Start the frame
     ImGui::NewFrame();
 }
	// ImGui GLFW binding with OpenGL3 + shaders
	// https://github.com/ocornut/imgui

	#include <imgui.h>
	#include "imgui_impl_glfw_gl3.h"

	// GL3W/GLFW
	#include <GL/gl3w.h>
	#include <GLFW/glfw3.h>
	#ifdef _MSC_VER
	#undef APIENTRY
	#define GLFW_EXPOSE_NATIVE_WIN32
	#define GLFW_EXPOSE_NATIVE_WGL
	#include <GLFW/glfw3native.h>
	#endif

	// Data
	static GLFWwindow* g_Window = NULL;
	static double g_Time = 0.0f;
	static bool g_MousePressed[3] = { false, false, false };
	static float g_MouseWheel = 0.0f;
	static GLuint g_FontTexture = 0;
	static int g_ShaderHandle = 0, g_VertHandle = 0, g_FragHandle = 0;
	static int g_AttribLocationTex = 0, g_AttribLocationProjMtx = 0;
	static int g_AttribLocationPosition = 0, g_AttribLocationUV = 0, g_AttribLocationColor = 0;
	static size_t g_VboMaxSize = 20000;
	static unsigned int g_VboHandle = 0, g_VaoHandle = 0;

	// This is the main rendering function that you have to implement and provide to ImGui (via setting up 'RenderDrawListsFn' in the ImGuiIO structure)
	// If text or lines are blurry when integrating ImGui in your engine:
	// - in your Render function, try translating your projection matrix by (0.5f,0.5f) or (0.375f,0.375f)
	static void ImGui_ImplGlfwGL3_RenderDrawLists(ImDrawList** const cmd_lists, int cmd_lists_count)
	{
	if (cmd_lists_count == 0)
	return;

	// Setup render state: alpha-blending enabled, no face culling, no depth testing, scissor enabled
	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);
	glActiveTexture(GL_TEXTURE0);

	// Setup orthographic projection matrix
	const float width = ImGui::GetIO().DisplaySize.x;
	const float height = ImGui::GetIO().DisplaySize.y;
	const float ortho_projection[4][4] =
	{
	{ 2.0f/width, 0.0f, 0.0f, 0.0f },
	{ 0.0f, 2.0f/-height, 0.0f, 0.0f },
	{ 0.0f, 0.0f, -1.0f, 0.0f },
	{ -1.0f, 1.0f, 0.0f, 1.0f },
	};
	glUseProgram(g_ShaderHandle);
	glUniform1i(g_AttribLocationTex, 0);
	glUniformMatrix4fv(g_AttribLocationProjMtx, 1, GL_FALSE, &ortho_projection[0][0]);

	// Grow our buffer according to what we need
	size_t total_vtx_count = 0;
	for (int n = 0; n < cmd_lists_count; n++)
	total_vtx_count += cmd_lists[n]->vtx_buffer.size();
	glBindBuffer(GL_ARRAY_BUFFER, g_VboHandle);
	size_t neededBufferSize = total_vtx_count * sizeof(ImDrawVert);
	if (neededBufferSize > g_VboMaxSize)
	{
	g_VboMaxSize = neededBufferSize + 5000; // Grow buffer
	glBufferData(GL_ARRAY_BUFFER, g_VboMaxSize, NULL, GL_STREAM_DRAW);
	}

	// Copy and convert all vertices into a single contiguous buffer
	unsigned char* buffer_data = (unsigned char*)glMapBuffer(GL_ARRAY_BUFFER, GL_WRITE_ONLY);
	if (!buffer_data)
	return;
	for (int n = 0; n < cmd_lists_count; n++)
	{
	const ImDrawList* cmd_list = cmd_lists[n];
	memcpy(buffer_data, &cmd_list->vtx_buffer[0], cmd_list->vtx_buffer.size() * sizeof(ImDrawVert));
	buffer_data += cmd_list->vtx_buffer.size() * sizeof(ImDrawVert);
	}
	glUnmapBuffer(GL_ARRAY_BUFFER);
	glBindBuffer(GL_ARRAY_BUFFER, 0);
	glBindVertexArray(g_VaoHandle);

	int cmd_offset = 0;
	for (int n = 0; n < cmd_lists_count; n++)
	{
	const ImDrawList* cmd_list = cmd_lists[n];
	int vtx_offset = cmd_offset;
	const ImDrawCmd* pcmd_end = cmd_list->commands.end();
	for (const ImDrawCmd* pcmd = cmd_list->commands.begin(); pcmd != pcmd_end; pcmd++)
	{
	glBindTexture(GL_TEXTURE_2D, (GLuint)(intptr_t)pcmd->texture_id);
	glScissor((int)pcmd->clip_rect.x, (int)(height - pcmd->clip_rect.w), (int)(pcmd->clip_rect.z - pcmd->clip_rect.x), (int)(pcmd->clip_rect.w - pcmd->clip_rect.y));
	glDrawArrays(GL_TRIANGLES, vtx_offset, pcmd->vtx_count);
	vtx_offset += pcmd->vtx_count;
	}
	cmd_offset = vtx_offset;
	}

	// Restore modified state
	glBindVertexArray(0);
	glUseProgram(0);
	glDisable(GL_SCISSOR_TEST);
	glBindTexture(GL_TEXTURE_2D, 0);
	}

	static const char* ImGui_ImplGlfwGL3_GetClipboardText()
	{
	return glfwGetClipboardString(g_Window);
	}

	static void ImGui_ImplGlfwGL3_SetClipboardText(const char* text)
	{
	glfwSetClipboardString(g_Window, text);
	}

	void ImGui_ImplGlfwGL3_MouseButtonCallback(GLFWwindow* window, int button, int action, int mods)
	{
	if (action == GLFW_PRESS && button >= 0 && button < 3)
	g_MousePressed[button] = true;
	}

	void ImGui_ImplGlfwGL3_ScrollCallback(GLFWwindow* window, double xoffset, double yoffset)
	{
	g_MouseWheel += (float)yoffset; // Use fractional mouse wheel, 1.0 unit 5 lines.
	}

	void ImGui_ImplGlfwGL3_KeyCallback(GLFWwindow* window, int key, int scancode, int action, int mods)
	{
	ImGuiIO& io = ImGui::GetIO();
	if (action == GLFW_PRESS)
	io.KeysDown[key] = true;
	if (action == GLFW_RELEASE)
	io.KeysDown[key] = false;
	io.KeyCtrl = (mods & GLFW_MOD_CONTROL) != 0;
	io.KeyShift = (mods & GLFW_MOD_SHIFT) != 0;
	}

	void ImGui_ImplGlfwGL3_CharCallback(GLFWwindow* window, unsigned int c)
	{
	ImGuiIO& io = ImGui::GetIO();
	if (c > 0 && c < 0x10000)
	io.AddInputCharacter((unsigned short)c);
	}

	void ImGui_ImplGlfwGL3_CreateFontsTexture()
	{
	ImGuiIO& io = ImGui::GetIO();

	unsigned char* pixels;
	int width, height;
	io.Fonts->GetTexDataAsRGBA32(&pixels, &width, &height); // Load as RGBA 32-bits for OpenGL3 demo because it is more likely to be compatible with user's existing shader.

	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);
	glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, width, height, 0, GL_RGBA, GL_UNSIGNED_BYTE, pixels);

	// Store our identifier
	io.Fonts->TexID = (void *)(intptr_t)g_FontTexture;
	}

	bool ImGui_ImplGlfwGL3_CreateDeviceObjects()
	{
	const GLchar *vertex_shader =
	"#version 330\n"
	"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* fragment_shader =
	"#version 330\n"
	"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";

	g_ShaderHandle = glCreateProgram();
	g_VertHandle = glCreateShader(GL_VERTEX_SHADER);
	g_FragHandle = glCreateShader(GL_FRAGMENT_SHADER);
	glShaderSource(g_VertHandle, 1, &vertex_shader, 0);
	glShaderSource(g_FragHandle, 1, &fragment_shader, 0);
	glCompileShader(g_VertHandle);
	glCompileShader(g_FragHandle);
	glAttachShader(g_ShaderHandle, g_VertHandle);
	glAttachShader(g_ShaderHandle, g_FragHandle);
	glLinkProgram(g_ShaderHandle);

	g_AttribLocationTex = glGetUniformLocation(g_ShaderHandle, "Texture");
	g_AttribLocationProjMtx = glGetUniformLocation(g_ShaderHandle, "ProjMtx");
	g_AttribLocationPosition = glGetAttribLocation(g_ShaderHandle, "Position");
	g_AttribLocationUV = glGetAttribLocation(g_ShaderHandle, "UV");
	g_AttribLocationColor = glGetAttribLocation(g_ShaderHandle, "Color");

	glGenBuffers(1, &g_VboHandle);
	glBindBuffer(GL_ARRAY_BUFFER, g_VboHandle);
	glBufferData(GL_ARRAY_BUFFER, g_VboMaxSize, NULL, GL_DYNAMIC_DRAW);

	glGenVertexArrays(1, &g_VaoHandle);
	glBindVertexArray(g_VaoHandle);
	glBindBuffer(GL_ARRAY_BUFFER, g_VboHandle);
	glEnableVertexAttribArray(g_AttribLocationPosition);
	glEnableVertexAttribArray(g_AttribLocationUV);
	glEnableVertexAttribArray(g_AttribLocationColor);

	#define OFFSETOF(TYPE, ELEMENT) ((size_t)&(((TYPE *)0)->ELEMENT))
	glVertexAttribPointer(g_AttribLocationPosition, 2, GL_FLOAT, GL_FALSE, sizeof(ImDrawVert), (GLvoid*)OFFSETOF(ImDrawVert, pos));
	glVertexAttribPointer(g_AttribLocationUV, 2, GL_FLOAT, GL_FALSE, sizeof(ImDrawVert), (GLvoid*)OFFSETOF(ImDrawVert, uv));
	glVertexAttribPointer(g_AttribLocationColor, 4, GL_UNSIGNED_BYTE, GL_TRUE, sizeof(ImDrawVert), (GLvoid*)OFFSETOF(ImDrawVert, col));
	#undef OFFSETOF
	glBindVertexArray(0);
	glBindBuffer(GL_ARRAY_BUFFER, 0);

	ImGui_ImplGlfwGL3_CreateFontsTexture();

	return true;
	}

	bool ImGui_ImplGlfwGL3_Init(GLFWwindow* window, bool install_callbacks)
	{
	g_Window = window;

	ImGuiIO& io = ImGui::GetIO();
	io.KeyMap[ImGuiKey_Tab] = GLFW_KEY_TAB; // Keyboard mapping. ImGui will use those indices to peek into the io.KeyDown[] array.
	io.KeyMap[ImGuiKey_LeftArrow] = GLFW_KEY_LEFT;
	io.KeyMap[ImGuiKey_RightArrow] = GLFW_KEY_RIGHT;
	io.KeyMap[ImGuiKey_UpArrow] = GLFW_KEY_UP;
	io.KeyMap[ImGuiKey_DownArrow] = GLFW_KEY_DOWN;
	io.KeyMap[ImGuiKey_Home] = GLFW_KEY_HOME;
	io.KeyMap[ImGuiKey_End] = GLFW_KEY_END;
	io.KeyMap[ImGuiKey_Delete] = GLFW_KEY_DELETE;
	io.KeyMap[ImGuiKey_Backspace] = GLFW_KEY_BACKSPACE;
	io.KeyMap[ImGuiKey_Enter] = GLFW_KEY_ENTER;
	io.KeyMap[ImGuiKey_Escape] = GLFW_KEY_ESCAPE;
	io.KeyMap[ImGuiKey_A] = GLFW_KEY_A;
	io.KeyMap[ImGuiKey_C] = GLFW_KEY_C;
	io.KeyMap[ImGuiKey_V] = GLFW_KEY_V;
	io.KeyMap[ImGuiKey_X] = GLFW_KEY_X;
	io.KeyMap[ImGuiKey_Y] = GLFW_KEY_Y;
	io.KeyMap[ImGuiKey_Z] = GLFW_KEY_Z;

	io.RenderDrawListsFn = ImGui_ImplGlfwGL3_RenderDrawLists;
	io.SetClipboardTextFn = ImGui_ImplGlfwGL3_SetClipboardText;
	io.GetClipboardTextFn = ImGui_ImplGlfwGL3_GetClipboardText;
	#ifdef _MSC_VER
	io.ImeWindowHandle = glfwGetWin32Window(g_Window);
	#endif

	if (install_callbacks)
	{
	glfwSetMouseButtonCallback(window, ImGui_ImplGlfwGL3_MouseButtonCallback);
	glfwSetScrollCallback(window, ImGui_ImplGlfwGL3_ScrollCallback);
	glfwSetKeyCallback(window, ImGui_ImplGlfwGL3_KeyCallback);
	glfwSetCharCallback(window, ImGui_ImplGlfwGL3_CharCallback);
	}

	return true;
	}

	void ImGui_ImplGlfwGL3_Shutdown()
	{
	if (g_VaoHandle) glDeleteVertexArrays(1, &g_VaoHandle);
	if (g_VboHandle) glDeleteBuffers(1, &g_VboHandle);
	g_VaoHandle = 0;
	g_VboHandle = 0;

	glDetachShader(g_ShaderHandle, g_VertHandle);
	glDeleteShader(g_VertHandle);
	g_VertHandle = 0;

	glDetachShader(g_ShaderHandle, g_FragHandle);
	glDeleteShader(g_FragHandle);
	g_FragHandle = 0;

	glDeleteProgram(g_ShaderHandle);
	g_ShaderHandle = 0;

	if (g_FontTexture)
	{
	glDeleteTextures(1, &g_FontTexture);
	ImGui::GetIO().Fonts->TexID = 0;
	g_FontTexture = 0;
	}
	ImGui::Shutdown();
	}

	void ImGui_ImplGlfwGL3_NewFrame()
	{
	if (!g_FontTexture)
	ImGui_ImplGlfwGL3_CreateDeviceObjects();

	ImGuiIO& io = ImGui::GetIO();

	// Setup display size (every frame to accommodate for window resizing)
	int w, h;
	int display_w, display_h;
	glfwGetWindowSize(g_Window, &w, &h);
	glfwGetFramebufferSize(g_Window, &display_w, &display_h);
	io.DisplaySize = ImVec2((float)display_w, (float)display_h);

	// Setup time step
	double current_time = glfwGetTime();
	io.DeltaTime = g_Time > 0.0 ? (float)(current_time - g_Time) : (float)(1.0f/60.0f);
	g_Time = current_time;

	// Setup inputs
	// (we already got mouse wheel, keyboard keys & characters from glfw callbacks polled in glfwPollEvents())
	double mouse_x, mouse_y;
	glfwGetCursorPos(g_Window, &mouse_x, &mouse_y);
	mouse_x *= (float)display_w / w; // Convert mouse coordinates to pixels
	mouse_y *= (float)display_h / h;
	io.MousePos = ImVec2((float)mouse_x, (float)mouse_y); // Mouse position, in pixels (set to -1,-1 if no mouse / on another screen, etc.)

	io.MouseDown[0] = g_MousePressed[0] \|\| glfwGetMouseButton(g_Window, GLFW_MOUSE_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] \|\| glfwGetMouseButton(g_Window, GLFW_MOUSE_BUTTON_RIGHT) != 0;
	io.MouseDown[2] = g_MousePressed[2] \|\| glfwGetMouseButton(g_Window, GLFW_MOUSE_BUTTON_MIDDLE) != 0;
	g_MousePressed[0] = false;
	g_MousePressed[1] = false;
	g_MousePressed[2] = false;

	io.MouseWheel = g_MouseWheel;
	g_MouseWheel = 0.0f;

	// Start the frame
	ImGui::NewFrame();
	}