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// ImGui - standalone example application for OpenGL 3, using programmable pipeline
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# ifdef _MSC_VER
# pragma warning (disable: 4996) // 'This function or variable may be unsafe': strcpy, strdup, sprintf, vsnprintf, sscanf, fopen
# endif
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# include "../../imgui.h"
# define STB_IMAGE_IMPLEMENTATION
# include "../shared/stb_image.h" // stb_image.h for PNG loading
// Glfw/Glew
# define GLEW_STATIC
# include <GL/glew.h>
# include <GLFW/glfw3.h>
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# define OFFSETOF(TYPE, ELEMENT) ((size_t)&(((TYPE *)0)->ELEMENT))
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static GLFWwindow * window ;
static GLuint fontTex ;
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static bool mousePressed [ 2 ] = { false , false } ;
static ImVec2 mousePosScale ( 1.0f , 1.0f ) ;
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// Shader variables
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static int shader_handle , vert_handle , frag_handle ;
static int texture_location , ortho_location ;
static int position_location , uv_location , colour_location ;
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static size_t vbo_max_size = 20000 ;
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static unsigned int vbo_handle , vao_handle ;
// 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:
// - try adjusting ImGui::GetIO().PixelCenterOffset to 0.0f or 0.5f
// - in your Render function, try translating your projection matrix by (0.5f,0.5f) or (0.375f,0.375f)
static void ImImpl_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 ) ;
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glBlendEquation ( GL_FUNC_ADD ) ;
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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 ) ;
glEnable ( GL_SCISSOR_TEST ) ;
// Setup texture
glActiveTexture ( GL_TEXTURE0 ) ;
glBindTexture ( GL_TEXTURE_2D , fontTex ) ;
// Setup orthographic projection matrix
const float width = ImGui : : GetIO ( ) . DisplaySize . x ;
const float height = ImGui : : GetIO ( ) . DisplaySize . y ;
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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 } ,
} ;
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glUseProgram ( shader_handle ) ;
glUniform1i ( texture_location , 0 ) ;
glUniformMatrix4fv ( ortho_location , 1 , GL_FALSE , & ortho_projection [ 0 ] [ 0 ] ) ;
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// Grow our buffer according to what we need
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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 , vbo_handle ) ;
size_t neededBufferSize = total_vtx_count * sizeof ( ImDrawVert ) ;
if ( neededBufferSize > vbo_max_size )
{
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vbo_max_size = neededBufferSize + 5000 ; // Grow buffer
glBufferData ( GL_ARRAY_BUFFER , neededBufferSize , NULL , GL_STREAM_DRAW ) ;
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}
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// Copy and convert all vertices into a single contiguous buffer
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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 ( vao_handle ) ;
int cmd_offset = 0 ;
for ( int n = 0 ; n < cmd_lists_count ; n + + )
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{
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 + + )
{
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 ;
}
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cmd_offset = vtx_offset ;
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}
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// Restore modified state
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glBindVertexArray ( 0 ) ;
glUseProgram ( 0 ) ;
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glDisable ( GL_SCISSOR_TEST ) ;
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glBindTexture ( GL_TEXTURE_2D , 0 ) ;
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}
static const char * ImImpl_GetClipboardTextFn ( )
{
return glfwGetClipboardString ( window ) ;
}
static void ImImpl_SetClipboardTextFn ( const char * text )
{
glfwSetClipboardString ( window , text ) ;
}
// GLFW callbacks to get events
static void glfw_error_callback ( int error , const char * description )
{
fputs ( description , stderr ) ;
}
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static void glfw_mouse_button_callback ( GLFWwindow * window , int button , int action , int mods )
{
if ( action = = GLFW_PRESS & & button > = 0 & & button < 2 )
mousePressed [ button ] = true ;
}
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static void glfw_scroll_callback ( GLFWwindow * window , double xoffset , double yoffset )
{
ImGuiIO & io = ImGui : : GetIO ( ) ;
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io . MouseWheel + = ( float ) yoffset ; // Use fractional mouse wheel, 1.0 unit 5 lines.
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}
static void glfw_key_callback ( 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 ;
}
static void glfw_char_callback ( GLFWwindow * window , unsigned int c )
{
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if ( c > 0 & & c < 0x10000 )
ImGui : : GetIO ( ) . AddInputCharacter ( ( unsigned short ) c ) ;
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}
// OpenGL code based on http://open.gl tutorials
void InitGL ( )
{
glfwSetErrorCallback ( glfw_error_callback ) ;
if ( ! glfwInit ( ) )
exit ( 1 ) ;
glfwWindowHint ( GLFW_RESIZABLE , GL_FALSE ) ;
glfwWindowHint ( GLFW_CONTEXT_VERSION_MAJOR , 3 ) ;
glfwWindowHint ( GLFW_CONTEXT_VERSION_MINOR , 3 ) ;
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glfwWindowHint ( GLFW_OPENGL_PROFILE , GLFW_OPENGL_CORE_PROFILE ) ;
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window = glfwCreateWindow ( 1280 , 720 , " ImGui OpenGL example " , NULL , NULL ) ;
glfwMakeContextCurrent ( window ) ;
glfwSetKeyCallback ( window , glfw_key_callback ) ;
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glfwSetMouseButtonCallback ( window , glfw_mouse_button_callback ) ;
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glfwSetScrollCallback ( window , glfw_scroll_callback ) ;
glfwSetCharCallback ( window , glfw_char_callback ) ;
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glewExperimental = GL_TRUE ;
GLenum err = glewInit ( ) ;
if ( GLEW_OK ! = err )
fprintf ( stderr , " Error: %s \n " , glewGetErrorString ( err ) ) ;
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const GLchar * vertex_shader =
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" #version 330 \n "
" uniform mat4 ortho; \n "
" in vec2 Position; \n "
" in vec2 UV; \n "
" in vec4 Colour; \n "
" out vec2 Frag_UV; \n "
" out vec4 Frag_Colour; \n "
" void main() \n "
" { \n "
" Frag_UV = UV; \n "
" Frag_Colour = Colour; \n "
" gl_Position = ortho*vec4(Position.xy,0,1); \n "
" } \n " ;
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const GLchar * fragment_shader =
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" #version 330 \n "
" uniform sampler2D Texture; \n "
" in vec2 Frag_UV; \n "
" in vec4 Frag_Colour; \n "
" out vec4 FragColor; \n "
" void main() \n "
" { \n "
" FragColor = Frag_Colour * texture( Texture, Frag_UV.st); \n "
" } \n " ;
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shader_handle = glCreateProgram ( ) ;
vert_handle = glCreateShader ( GL_VERTEX_SHADER ) ;
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frag_handle = glCreateShader ( GL_FRAGMENT_SHADER ) ;
glShaderSource ( vert_handle , 1 , & vertex_shader , 0 ) ;
glShaderSource ( frag_handle , 1 , & fragment_shader , 0 ) ;
glCompileShader ( vert_handle ) ;
glCompileShader ( frag_handle ) ;
glAttachShader ( shader_handle , vert_handle ) ;
glAttachShader ( shader_handle , frag_handle ) ;
glLinkProgram ( shader_handle ) ;
texture_location = glGetUniformLocation ( shader_handle , " Texture " ) ;
ortho_location = glGetUniformLocation ( shader_handle , " ortho " ) ;
position_location = glGetAttribLocation ( shader_handle , " Position " ) ;
uv_location = glGetAttribLocation ( shader_handle , " UV " ) ;
colour_location = glGetAttribLocation ( shader_handle , " Colour " ) ;
glGenBuffers ( 1 , & vbo_handle ) ;
glBindBuffer ( GL_ARRAY_BUFFER , vbo_handle ) ;
glBufferData ( GL_ARRAY_BUFFER , vbo_max_size , NULL , GL_DYNAMIC_DRAW ) ;
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glGenVertexArrays ( 1 , & vao_handle ) ;
glBindVertexArray ( vao_handle ) ;
glBindBuffer ( GL_ARRAY_BUFFER , vbo_handle ) ;
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glEnableVertexAttribArray ( position_location ) ;
glEnableVertexAttribArray ( uv_location ) ;
glEnableVertexAttribArray ( colour_location ) ;
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glVertexAttribPointer ( position_location , 2 , GL_FLOAT , GL_FALSE , sizeof ( ImDrawVert ) , ( GLvoid * ) OFFSETOF ( ImDrawVert , pos ) ) ;
glVertexAttribPointer ( uv_location , 2 , GL_FLOAT , GL_FALSE , sizeof ( ImDrawVert ) , ( GLvoid * ) OFFSETOF ( ImDrawVert , uv ) ) ;
glVertexAttribPointer ( colour_location , 4 , GL_UNSIGNED_BYTE , GL_TRUE , sizeof ( ImDrawVert ) , ( GLvoid * ) OFFSETOF ( ImDrawVert , col ) ) ;
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glBindVertexArray ( 0 ) ;
glBindBuffer ( GL_ARRAY_BUFFER , 0 ) ;
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}
void InitImGui ( )
{
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int w , h ;
int display_w , display_h ;
glfwGetWindowSize ( window , & w , & h ) ;
glfwGetFramebufferSize ( window , & display_w , & display_h ) ;
mousePosScale . x = ( float ) display_w / w ; // Some screens e.g. Retina display have framebuffer size != from window size, and mouse inputs are given in window/screen coordinates.
mousePosScale . y = ( float ) display_h / h ;
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ImGuiIO & io = ImGui : : GetIO ( ) ;
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io . DisplaySize = ImVec2 ( ( float ) display_w , ( float ) display_h ) ; // Display size, in pixels. For clamping windows positions.
io . DeltaTime = 1.0f / 60.0f ; // Time elapsed since last frame, in seconds (in this sample app we'll override this every frame because our timestep is variable)
io . PixelCenterOffset = 0.5f ; // Align OpenGL texels
io . KeyMap [ ImGuiKey_Tab ] = GLFW_KEY_TAB ; // Keyboard mapping. ImGui will use those indices to peek into the io.KeyDown[] array.
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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 = ImImpl_RenderDrawLists ;
io . SetClipboardTextFn = ImImpl_SetClipboardTextFn ;
io . GetClipboardTextFn = ImImpl_GetClipboardTextFn ;
// Load font texture
glGenTextures ( 1 , & fontTex ) ;
glBindTexture ( GL_TEXTURE_2D , fontTex ) ;
glTexParameteri ( GL_TEXTURE_2D , GL_TEXTURE_MIN_FILTER , GL_NEAREST ) ;
glTexParameteri ( GL_TEXTURE_2D , GL_TEXTURE_MAG_FILTER , GL_NEAREST ) ;
const void * png_data ;
unsigned int png_size ;
ImGui : : GetDefaultFontData ( NULL , NULL , & png_data , & png_size ) ;
int tex_x , tex_y , tex_comp ;
void * tex_data = stbi_load_from_memory ( ( const unsigned char * ) png_data , ( int ) png_size , & tex_x , & tex_y , & tex_comp , 0 ) ;
glTexImage2D ( GL_TEXTURE_2D , 0 , GL_RGBA , tex_x , tex_y , 0 , GL_RGBA , GL_UNSIGNED_BYTE , tex_data ) ;
stbi_image_free ( tex_data ) ;
}
void UpdateImGui ( )
{
ImGuiIO & io = ImGui : : GetIO ( ) ;
// Setup timestep
static double time = 0.0f ;
const double current_time = glfwGetTime ( ) ;
io . DeltaTime = ( float ) ( current_time - time ) ;
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 ( window , & mouse_x , & mouse_y ) ;
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io . MousePos = ImVec2 ( ( float ) mouse_x * mousePosScale . x , ( float ) mouse_y * mousePosScale . y ) ; // Mouse position, in pixels (set to -1,-1 if no mouse / on another screen, etc.)
io . MouseDown [ 0 ] = mousePressed [ 0 ] | | glfwGetMouseButton ( 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 ] = mousePressed [ 1 ] | | glfwGetMouseButton ( window , GLFW_MOUSE_BUTTON_RIGHT ) ! = 0 ;
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// Start the frame
ImGui : : NewFrame ( ) ;
}
// Application code
int main ( int argc , char * * argv )
{
InitGL ( ) ;
InitImGui ( ) ;
while ( ! glfwWindowShouldClose ( window ) )
{
ImGuiIO & io = ImGui : : GetIO ( ) ;
io . MouseWheel = 0 ;
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mousePressed [ 0 ] = mousePressed [ 1 ] = false ;
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glfwPollEvents ( ) ;
UpdateImGui ( ) ;
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static bool show_test_window = true ;
static bool show_another_window = false ;
// 1. Show a simple window
// Tip: if we don't call ImGui::Begin()/ImGui::End() the widgets appears in a window automatically called "Debug"
{
static float f ;
ImGui : : Text ( " Hello, world! " ) ;
ImGui : : SliderFloat ( " float " , & f , 0.0f , 1.0f ) ;
show_test_window ^ = ImGui : : Button ( " Test Window " ) ;
show_another_window ^ = ImGui : : Button ( " Another Window " ) ;
// Calculate and show frame rate
static float ms_per_frame [ 120 ] = { 0 } ;
static int ms_per_frame_idx = 0 ;
static float ms_per_frame_accum = 0.0f ;
ms_per_frame_accum - = ms_per_frame [ ms_per_frame_idx ] ;
ms_per_frame [ ms_per_frame_idx ] = ImGui : : GetIO ( ) . DeltaTime * 1000.0f ;
ms_per_frame_accum + = ms_per_frame [ ms_per_frame_idx ] ;
ms_per_frame_idx = ( ms_per_frame_idx + 1 ) % 120 ;
const float ms_per_frame_avg = ms_per_frame_accum / 120 ;
ImGui : : Text ( " Application average %.3f ms/frame (%.1f FPS) " , ms_per_frame_avg , 1000.0f / ms_per_frame_avg ) ;
}
// 2. Show another simple window, this time using an explicit Begin/End pair
if ( show_another_window )
{
ImGui : : Begin ( " Another Window " , & show_another_window , ImVec2 ( 200 , 100 ) ) ;
ImGui : : Text ( " Hello " ) ;
ImGui : : End ( ) ;
}
// 3. Show the ImGui test window. Most of the sample code is in ImGui::ShowTestWindow()
if ( show_test_window )
{
ImGui : : SetNewWindowDefaultPos ( ImVec2 ( 650 , 20 ) ) ; // Normally user code doesn't need/want to call this, because positions are saved in .ini file. Here we just want to make the demo initial state a bit more friendly!
ImGui : : ShowTestWindow ( & show_test_window ) ;
}
// Rendering
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glViewport ( 0 , 0 , ( int ) io . DisplaySize . x , ( int ) io . DisplaySize . y ) ;
glClearColor ( 0.8f , 0.6f , 0.6f , 1.0f ) ;
glClear ( GL_COLOR_BUFFER_BIT ) ;
ImGui : : Render ( ) ;
glfwSwapBuffers ( window ) ;
}
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// Cleanup
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if ( vao_handle ) glDeleteVertexArrays ( 1 , & vao_handle ) ;
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if ( vbo_handle ) glDeleteBuffers ( 1 , & vbo_handle ) ;
glDetachShader ( shader_handle , vert_handle ) ;
glDetachShader ( shader_handle , frag_handle ) ;
glDeleteShader ( vert_handle ) ;
glDeleteShader ( frag_handle ) ;
glDeleteProgram ( shader_handle ) ;
ImGui : : Shutdown ( ) ;
glfwTerminate ( ) ;
return 0 ;
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}