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imgui/examples/opengl_example/main.cpp

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#define GLEW_STATIC
#include <GL/glew.h>
#include <GLFW/glfw3.h>
#define STB_IMAGE_IMPLEMENTATION
#include "stb_image.h" // for .png loading
#include "../../imgui.h"
#ifdef _MSC_VER
#pragma warning (disable: 4996) // 'This function or variable may be unsafe': strcpy, strdup, sprintf, vsnprintf, sscanf, fopen
#endif
static GLFWwindow* window;
static GLuint fontTex;
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// 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)
// - try adjusting ImGui::GetIO().PixelCenterOffset to 0.5f or 0.375f
static void ImImpl_RenderDrawLists(ImDrawList** const cmd_lists, int cmd_lists_count)
{
if (cmd_lists_count == 0)
return;
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// We are using the OpenGL fixed pipeline to make the example code simpler to read!
// A probable faster way to render would be to collate all vertices from all cmd_lists into a single vertex buffer.
// Setup render state: alpha-blending enabled, no face culling, no depth testing, scissor enabled, vertex/texcoord/color pointers.
glEnable(GL_BLEND);
glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
glDisable(GL_CULL_FACE);
glDisable(GL_DEPTH_TEST);
glEnable(GL_SCISSOR_TEST);
glEnableClientState(GL_VERTEX_ARRAY);
glEnableClientState(GL_TEXTURE_COORD_ARRAY);
glEnableClientState(GL_COLOR_ARRAY);
// Setup texture
glBindTexture(GL_TEXTURE_2D, fontTex);
glEnable(GL_TEXTURE_2D);
// Setup orthographic projection matrix
const float width = ImGui::GetIO().DisplaySize.x;
const float height = ImGui::GetIO().DisplaySize.y;
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
glOrtho(0.0f, width, height, 0.0f, -1.0f, +1.0f);
glMatrixMode(GL_MODELVIEW);
glLoadIdentity();
// Render command lists
for (int n = 0; n < cmd_lists_count; n++)
{
const ImDrawList* cmd_list = cmd_lists[n];
const unsigned char* vtx_buffer = (const unsigned char*)cmd_list->vtx_buffer.begin();
glVertexPointer(2, GL_FLOAT, sizeof(ImDrawVert), (void*)(vtx_buffer));
glTexCoordPointer(2, GL_FLOAT, sizeof(ImDrawVert), (void*)(vtx_buffer+8));
glColorPointer(4, GL_UNSIGNED_BYTE, sizeof(ImDrawVert), (void*)(vtx_buffer+16));
int vtx_offset = 0;
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;
}
}
glDisable(GL_SCISSOR_TEST);
glDisableClientState(GL_COLOR_ARRAY);
glDisableClientState(GL_TEXTURE_COORD_ARRAY);
glDisableClientState(GL_VERTEX_ARRAY);
}
static const char* ImImpl_GetClipboardTextFn()
{
return glfwGetClipboardString(window);
}
static void ImImpl_SetClipboardTextFn(const char* text, const char* text_end)
{
if (!text_end)
text_end = text + strlen(text);
if (*text_end == 0)
{
// Already got a zero-terminator at 'text_end', we don't need to add one
glfwSetClipboardString(window, text);
}
else
{
// Add a zero-terminator because glfw function doesn't take a size
char* buf = (char*)malloc(text_end - text + 1);
memcpy(buf, text, text_end-text);
buf[text_end-text] = '\0';
glfwSetClipboardString(window, buf);
free(buf);
}
}
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// GLFW callbacks to get events
static void glfw_error_callback(int error, const char* description)
{
fputs(description, stderr);
}
static void glfw_scroll_callback(GLFWwindow* window, double xoffset, double yoffset)
{
ImGuiIO& io = ImGui::GetIO();
io.MouseWheel = (yoffset != 0.0f) ? yoffset > 0.0f ? 1 : - 1 : 0; // Mouse wheel: -1,0,+1
}
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)
{
if (c > 0 && c <= 255)
ImGui::GetIO().AddInputCharacter((char)c);
}
// OpenGL code based on http://open.gl tutorials
void InitGL()
{
glfwSetErrorCallback(glfw_error_callback);
if (!glfwInit())
exit(1);
glfwWindowHint(GLFW_RESIZABLE, GL_FALSE);
window = glfwCreateWindow(1280, 720, "ImGui OpenGL example", NULL, NULL);
glfwMakeContextCurrent(window);
glfwSetKeyCallback(window, glfw_key_callback);
glfwSetScrollCallback(window, glfw_scroll_callback);
glfwSetCharCallback(window, glfw_char_callback);
glewInit();
}
void InitImGui()
{
int w, h;
glfwGetWindowSize(window, &w, &h);
ImGuiIO& io = ImGui::GetIO();
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io.DisplaySize = ImVec2((float)w, (float)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 = 0.0f; // Align OpenGL texels
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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 = 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);
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] = glfwGetMouseButton(window, GLFW_MOUSE_BUTTON_LEFT) != 0;
io.MouseDown[1] = glfwGetMouseButton(window, GLFW_MOUSE_BUTTON_RIGHT) != 0;
// 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;
glfwPollEvents();
UpdateImGui();
// Create a simple window
// Tip: if we don't call ImGui::Begin()/ImGui::End() the widgets appears in a window automatically called "Debug"
static bool show_test_window = true;
static bool show_another_window = false;
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 framerate
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);
// Show the ImGui test window
// Most of user example code is in ImGui::ShowTestWindow()
if (show_test_window)
{
ImGui::SetNewWindowDefaultPos(ImVec2(650, 20)); // Normally user code doesn't need/want to call it because positions are saved in .ini file anyway. Here we just want to make the demo initial state a bit more friendly!
ImGui::ShowTestWindow(&show_test_window);
}
// Show another simple window
if (show_another_window)
{
ImGui::Begin("Another Window", &show_another_window, ImVec2(200,100));
ImGui::Text("Hello");
ImGui::End();
}
// Rendering
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);
}
ImGui::Shutdown();
glfwTerminate();
return 0;
}