imgui/examples/opengl3_example/imgui_impl_glfw_gl3.cpp

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// 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
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static GLFWwindow* g_Window = NULL;
static double g_Time = 0.0f;
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static bool g_MousePressed[3] = { false, false, false };
static float g_MouseWheel = 0.0f;
static GLuint g_FontTexture = 0;
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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_VboSize = 0;
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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
GLint last_program, last_texture;
glGetIntegerv(GL_CURRENT_PROGRAM, &last_program);
glGetIntegerv(GL_TEXTURE_BINDING_2D, &last_texture);
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 },
};
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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();
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glBindBuffer(GL_ARRAY_BUFFER, g_VboHandle);
size_t needed_vtx_size = total_vtx_count * sizeof(ImDrawVert);
if (g_VboSize < needed_vtx_size)
{
g_VboSize = needed_vtx_size + 5000 * sizeof(ImDrawVert); // Grow buffer
glBufferData(GL_ARRAY_BUFFER, (GLsizeiptr)g_VboSize, NULL, GL_STREAM_DRAW);
}
// Copy and convert all vertices into a single contiguous buffer
unsigned char* vtx_data = (unsigned char*)glMapBuffer(GL_ARRAY_BUFFER, GL_WRITE_ONLY);
if (!vtx_data)
return;
for (int n = 0; n < cmd_lists_count; n++)
{
const ImDrawList* cmd_list = cmd_lists[n];
memcpy(vtx_data, &cmd_list->vtx_buffer[0], cmd_list->vtx_buffer.size() * sizeof(ImDrawVert));
vtx_data += cmd_list->vtx_buffer.size() * sizeof(ImDrawVert);
}
glUnmapBuffer(GL_ARRAY_BUFFER);
glBindBuffer(GL_ARRAY_BUFFER, 0);
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glBindVertexArray(g_VaoHandle);
int vtx_offset = 0;
for (int n = 0; n < cmd_lists_count; n++)
{
const ImDrawList* cmd_list = cmd_lists[n];
const ImDrawIdx* idx_buffer = (const unsigned short*)&cmd_list->idx_buffer.front();
const ImDrawCmd* pcmd_end = cmd_list->commands.end();
for (const ImDrawCmd* pcmd = cmd_list->commands.begin(); pcmd != pcmd_end; pcmd++)
{
if (pcmd->user_callback)
{
pcmd->user_callback(cmd_list, pcmd);
}
else
{
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));
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glDrawElementsBaseVertex(GL_TRIANGLES, (GLsizei)pcmd->idx_count, GL_UNSIGNED_SHORT, idx_buffer, vtx_offset);
}
idx_buffer += pcmd->idx_count;
}
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vtx_offset += (int)cmd_list->vtx_buffer.size();
}
// Restore modified state
glBindVertexArray(0);
glUseProgram(last_program);
glDisable(GL_SCISSOR_TEST);
glBindTexture(GL_TEXTURE_2D, last_texture);
}
static const char* ImGui_ImplGlfwGL3_GetClipboardText()
{
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return glfwGetClipboardString(g_Window);
}
static void ImGui_ImplGlfwGL3_SetClipboardText(const char* text)
{
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glfwSetClipboardString(g_Window, text);
}
void ImGui_ImplGlfwGL3_MouseButtonCallback(GLFWwindow*, int button, int action, int /*mods*/)
{
if (action == GLFW_PRESS && button >= 0 && button < 3)
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g_MousePressed[button] = true;
}
void ImGui_ImplGlfwGL3_ScrollCallback(GLFWwindow*, double /*xoffset*/, double yoffset)
{
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g_MouseWheel += (float)yoffset; // Use fractional mouse wheel, 1.0 unit 5 lines.
}
void ImGui_ImplGlfwGL3_KeyCallback(GLFWwindow*, int key, int, int action, int mods)
{
ImGuiIO& io = ImGui::GetIO();
if (action == GLFW_PRESS)
io.KeysDown[key] = true;
if (action == GLFW_RELEASE)
io.KeysDown[key] = false;
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(void)mods; // Modifiers are not reliable across systems
io.KeyCtrl = io.KeysDown[GLFW_KEY_LEFT_CONTROL] || io.KeysDown[GLFW_KEY_RIGHT_CONTROL];
io.KeyShift = io.KeysDown[GLFW_KEY_LEFT_SHIFT] || io.KeysDown[GLFW_KEY_RIGHT_SHIFT];
io.KeyAlt = io.KeysDown[GLFW_KEY_LEFT_ALT] || io.KeysDown[GLFW_KEY_RIGHT_ALT];
}
void ImGui_ImplGlfwGL3_CharCallback(GLFWwindow*, 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;
// Cleanup (don't clear the input data if you want to append new fonts later)
io.Fonts->ClearInputData();
io.Fonts->ClearTexData();
}
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";
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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);
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))
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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)
{
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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_PageUp] = GLFW_KEY_PAGE_UP;
io.KeyMap[ImGuiKey_PageDown] = GLFW_KEY_PAGE_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
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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()
{
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if (g_VaoHandle) glDeleteVertexArrays(1, &g_VaoHandle);
if (g_VboHandle) glDeleteBuffers(1, &g_VboHandle);
g_VaoHandle = 0;
g_VboHandle = 0;
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glDetachShader(g_ShaderHandle, g_VertHandle);
glDeleteShader(g_VertHandle);
g_VertHandle = 0;
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glDetachShader(g_ShaderHandle, g_FragHandle);
glDeleteShader(g_FragHandle);
g_FragHandle = 0;
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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;
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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();
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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())
if (glfwGetWindowAttrib(g_Window, GLFW_FOCUSED))
{
double mouse_x, mouse_y;
glfwGetCursorPos(g_Window, &mouse_x, &mouse_y);
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mouse_x *= (float)display_w / w; // Convert mouse coordinates to pixels
mouse_y *= (float)display_h / h;
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io.MousePos = ImVec2((float)mouse_x, (float)mouse_y); // Mouse position, in pixels (set to -1,-1 if no mouse / on another screen, etc.)
}
else
{
io.MousePos = ImVec2(-1,-1);
}
for (int i = 0; i < 3; i++)
{
io.MouseDown[i] = g_MousePressed[i] || glfwGetMouseButton(g_Window, i) != 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.
g_MousePressed[i] = false;
}
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io.MouseWheel = g_MouseWheel;
g_MouseWheel = 0.0f;
// Hide OS mouse cursor if ImGui is drawing it
glfwSetInputMode(g_Window, GLFW_CURSOR, io.MouseDrawCursor ? GLFW_CURSOR_HIDDEN : GLFW_CURSOR_NORMAL);
// Start the frame
ImGui::NewFrame();
}