main.cpp

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// MIT License

// Copyright (c) 2019 Erin Catto

// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:

// The above copyright notice and this permission notice shall be included in all
// copies or substantial portions of the Software.

// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
// SOFTWARE.

#define _CRT_SECURE_NO_WARNINGS
#define IMGUI_DISABLE_OBSOLETE_FUNCTIONS 1

#include "imgui/imgui.h"
#include "imgui_impl_glfw.h"
#include "imgui_impl_opengl3.h"
#include "draw.h"
#include "settings.h"
#include "test.h"

#include <algorithm>
#include <stdio.h>
#include <thread>
#include <chrono>

#if defined(_WIN32)
#include <crtdbg.h>
#endif

GLFWwindow* g_mainWindow = nullptr;
static int32 s_testSelection = 0;
static Test* s_test = nullptr;
static Settings s_settings;
static bool s_rightMouseDown = false;
static b2Vec2 s_clickPointWS = b2Vec2_zero;

void glfwErrorCallback(int error, const char* description)
{
        fprintf(stderr, "GLFW error occured. Code: %d. Description: %s\n", error, description);
}

static inline bool CompareTests(const TestEntry& a, const TestEntry& b)
{
        int result = strcmp(a.category, b.category);
        if (result == 0)
        {
                result = strcmp(a.name, b.name);
        }

        return result < 0;
}

static void SortTests()
{
        std::sort(g_testEntries, g_testEntries + g_testCount, CompareTests);
}

static void CreateUI(GLFWwindow* window, const char* glslVersion = NULL)
{
        IMGUI_CHECKVERSION();
        ImGui::CreateContext();

        bool success;
        success = ImGui_ImplGlfw_InitForOpenGL(window, false);
        if (success == false)
        {
                printf("ImGui_ImplGlfw_InitForOpenGL failed\n");
                assert(false);
        }

        success = ImGui_ImplOpenGL3_Init(glslVersion);
        if (success == false)
        {
                printf("ImGui_ImplOpenGL3_Init failed\n");
                assert(false);
        }

        // Search for font file
        const char* fontPath1 = "data/droid_sans.ttf";
        const char* fontPath2 = "../data/droid_sans.ttf";
        const char* fontPath = nullptr;
        FILE* file1 = fopen(fontPath1, "rb");
        FILE* file2 = fopen(fontPath2, "rb");
        if (file1)
        {
                fontPath = fontPath1;
                fclose(file1);
        }
        
        if (file2)
        {
                fontPath = fontPath2;
                fclose(file2);
        }

        if (fontPath)
        {
                ImGui::GetIO().Fonts->AddFontFromFileTTF(fontPath, 13.0f);
        }
}

static void ResizeWindowCallback(GLFWwindow*, int width, int height)
{
        g_camera.m_width = width;
        g_camera.m_height = height;
        s_settings.m_windowWidth = width;
        s_settings.m_windowHeight = height;
}

static void KeyCallback(GLFWwindow* window, int key, int scancode, int action, int mods)
{
        ImGui_ImplGlfw_KeyCallback(window, key, scancode, action, mods);
        if (ImGui::GetIO().WantCaptureKeyboard)
        {
                return;
        }

        if (action == GLFW_PRESS)
        {
                switch (key)
                {
                case GLFW_KEY_ESCAPE:
                        // Quit
                        glfwSetWindowShouldClose(g_mainWindow, GL_TRUE);
                        break;

                case GLFW_KEY_LEFT:
                        // Pan left
                        if (mods == GLFW_MOD_CONTROL)
                        {
                                b2Vec2 newOrigin(2.0f, 0.0f);
                                s_test->ShiftOrigin(newOrigin);
                        }
                        else
                        {
                                g_camera.m_center.x -= 0.5f;
                        }
                        break;

                case GLFW_KEY_RIGHT:
                        // Pan right
                        if (mods == GLFW_MOD_CONTROL)
                        {
                                b2Vec2 newOrigin(-2.0f, 0.0f);
                                s_test->ShiftOrigin(newOrigin);
                        }
                        else
                        {
                                g_camera.m_center.x += 0.5f;
                        }
                        break;

                case GLFW_KEY_DOWN:
                        // Pan down
                        if (mods == GLFW_MOD_CONTROL)
                        {
                                b2Vec2 newOrigin(0.0f, 2.0f);
                                s_test->ShiftOrigin(newOrigin);
                        }
                        else
                        {
                                g_camera.m_center.y -= 0.5f;
                        }
                        break;

                case GLFW_KEY_UP:
                        // Pan up
                        if (mods == GLFW_MOD_CONTROL)
                        {
                                b2Vec2 newOrigin(0.0f, -2.0f);
                                s_test->ShiftOrigin(newOrigin);
                        }
                        else
                        {
                                g_camera.m_center.y += 0.5f;
                        }
                        break;

                case GLFW_KEY_HOME:
                        // Reset view
                        g_camera.m_zoom = 1.0f;
                        g_camera.m_center.Set(0.0f, 20.0f);
                        break;

                case GLFW_KEY_Z:
                        // Zoom out
                        g_camera.m_zoom = b2Min(1.1f * g_camera.m_zoom, 20.0f);
                        break;

                case GLFW_KEY_X:
                        // Zoom in
                        g_camera.m_zoom = b2Max(0.9f * g_camera.m_zoom, 0.02f);
                        break;

                case GLFW_KEY_R:
                        // Reset test
                        delete s_test;
                        s_test = g_testEntries[s_settings.m_testIndex].createFcn();
                        break;

                case GLFW_KEY_SPACE:
                        // Launch a bomb.
                        if (s_test)
                        {
                                s_test->LaunchBomb();
                        }
                        break;

                case GLFW_KEY_O:
                        s_settings.m_singleStep = true;
                        break;

                case GLFW_KEY_P:
                        s_settings.m_pause = !s_settings.m_pause;
                        break;

                case GLFW_KEY_LEFT_BRACKET:
                        // Switch to previous test
                        --s_testSelection;
                        if (s_testSelection < 0)
                        {
                                s_testSelection = g_testCount - 1;
                        }
                        break;

                case GLFW_KEY_RIGHT_BRACKET:
                        // Switch to next test
                        ++s_testSelection;
                        if (s_testSelection == g_testCount)
                        {
                                s_testSelection = 0;
                        }
                        break;

                case GLFW_KEY_TAB:
                        g_debugDraw.m_showUI = !g_debugDraw.m_showUI;

                default:
                        if (s_test)
                        {
                                s_test->Keyboard(key);
                        }
                }
        }
        else if (action == GLFW_RELEASE)
        {
                s_test->KeyboardUp(key);
        }
        // else GLFW_REPEAT
}

static void CharCallback(GLFWwindow* window, unsigned int c)
{
        ImGui_ImplGlfw_CharCallback(window, c);
}

static void MouseButtonCallback(GLFWwindow* window, int32 button, int32 action, int32 mods)
{
        ImGui_ImplGlfw_MouseButtonCallback(window, button, action, mods);

        double xd, yd;
        glfwGetCursorPos(g_mainWindow, &xd, &yd);
        b2Vec2 ps((float)xd, (float)yd);

        // Use the mouse to move things around.
        if (button == GLFW_MOUSE_BUTTON_1)
        {
        //<##>
        //ps.Set(0, 0);
                b2Vec2 pw = g_camera.ConvertScreenToWorld(ps);
                if (action == GLFW_PRESS)
                {
                        if (mods == GLFW_MOD_SHIFT)
                        {
                                s_test->ShiftMouseDown(pw);
                        }
                        else
                        {
                                s_test->MouseDown(pw);
                        }
                }
                
                if (action == GLFW_RELEASE)
                {
                        s_test->MouseUp(pw);
                }
        }
        else if (button == GLFW_MOUSE_BUTTON_2)
        {
                if (action == GLFW_PRESS)
                {       
                        s_clickPointWS = g_camera.ConvertScreenToWorld(ps);
                        s_rightMouseDown = true;
                }

                if (action == GLFW_RELEASE)
                {
                        s_rightMouseDown = false;
                }
        }
}

static void MouseMotionCallback(GLFWwindow*, double xd, double yd)
{
        b2Vec2 ps((float)xd, (float)yd);

        b2Vec2 pw = g_camera.ConvertScreenToWorld(ps);
        s_test->MouseMove(pw);
        
        if (s_rightMouseDown)
        {
                b2Vec2 diff = pw - s_clickPointWS;
                g_camera.m_center.x -= diff.x;
                g_camera.m_center.y -= diff.y;
                s_clickPointWS = g_camera.ConvertScreenToWorld(ps);
        }
}

static void ScrollCallback(GLFWwindow* window, double dx, double dy)
{
        ImGui_ImplGlfw_ScrollCallback(window, dx, dy);
        if (ImGui::GetIO().WantCaptureMouse)
        {
                return;
        }

        if (dy > 0)
        {
                g_camera.m_zoom /= 1.1f;
        }
        else
        {
                g_camera.m_zoom *= 1.1f;
        }
}

static void RestartTest()
{
        delete s_test;
        s_test = g_testEntries[s_settings.m_testIndex].createFcn();
}

static void UpdateUI()
{
        int menuWidth = 180;
        if (g_debugDraw.m_showUI)
        {
                ImGui::SetNextWindowPos(ImVec2((float)g_camera.m_width - menuWidth - 10, 10));
                ImGui::SetNextWindowSize(ImVec2((float)menuWidth, (float)g_camera.m_height - 20));

                ImGui::Begin("Tools", &g_debugDraw.m_showUI, ImGuiWindowFlags_NoMove | ImGuiWindowFlags_NoResize | ImGuiWindowFlags_NoCollapse);

                if (ImGui::BeginTabBar("ControlTabs", ImGuiTabBarFlags_None))
                {
                        if (ImGui::BeginTabItem("Controls"))
                        {
                                ImGui::SliderInt("Vel Iters", &s_settings.m_velocityIterations, 0, 50);
                                ImGui::SliderInt("Pos Iters", &s_settings.m_positionIterations, 0, 50);
                                ImGui::SliderFloat("Hertz", &s_settings.m_hertz, 5.0f, 120.0f, "%.0f hz");
                                
                                ImGui::Separator();

                                ImGui::Checkbox("Sleep", &s_settings.m_enableSleep);
                                ImGui::Checkbox("Warm Starting", &s_settings.m_enableWarmStarting);
                                ImGui::Checkbox("Time of Impact", &s_settings.m_enableContinuous);
                                ImGui::Checkbox("Sub-Stepping", &s_settings.m_enableSubStepping);

                                ImGui::Separator();

                                ImGui::Checkbox("Shapes", &s_settings.m_drawShapes);
                                ImGui::Checkbox("Joints", &s_settings.m_drawJoints);
                                ImGui::Checkbox("AABBs", &s_settings.m_drawAABBs);
                                ImGui::Checkbox("Contact Points", &s_settings.m_drawContactPoints);
                                ImGui::Checkbox("Contact Normals", &s_settings.m_drawContactNormals);
                                ImGui::Checkbox("Contact Impulses", &s_settings.m_drawContactImpulse);
                                ImGui::Checkbox("Friction Impulses", &s_settings.m_drawFrictionImpulse);
                                ImGui::Checkbox("Center of Masses", &s_settings.m_drawCOMs);
                                ImGui::Checkbox("Statistics", &s_settings.m_drawStats);
                                ImGui::Checkbox("Profile", &s_settings.m_drawProfile);

                                ImVec2 button_sz = ImVec2(-1, 0);
                                if (ImGui::Button("Pause (P)", button_sz))
                                {
                                        s_settings.m_pause = !s_settings.m_pause;
                                }

                                if (ImGui::Button("Single Step (O)", button_sz))
                                {
                                        s_settings.m_singleStep = !s_settings.m_singleStep;
                                }

                                if (ImGui::Button("Restart (R)", button_sz))
                                {
                                        RestartTest();
                                }

                                if (ImGui::Button("Quit", button_sz))
                                {
                                        glfwSetWindowShouldClose(g_mainWindow, GL_TRUE);
                                }

                                ImGui::EndTabItem();
                        }

                        ImGuiTreeNodeFlags leafNodeFlags = ImGuiTreeNodeFlags_OpenOnArrow | ImGuiTreeNodeFlags_OpenOnDoubleClick;
                        leafNodeFlags |= ImGuiTreeNodeFlags_Leaf | ImGuiTreeNodeFlags_NoTreePushOnOpen;

                        ImGuiTreeNodeFlags nodeFlags = ImGuiTreeNodeFlags_OpenOnArrow | ImGuiTreeNodeFlags_OpenOnDoubleClick;

                        if (ImGui::BeginTabItem("Tests"))
                        {
                                int categoryIndex = 0;
                                const char* category = g_testEntries[categoryIndex].category;
                                int i = 0;
                                while (i < g_testCount)
                                {
                                        bool categorySelected = strcmp(category, g_testEntries[s_settings.m_testIndex].category) == 0;
                                        ImGuiTreeNodeFlags nodeSelectionFlags = categorySelected ? ImGuiTreeNodeFlags_Selected : 0;
                                        bool nodeOpen = ImGui::TreeNodeEx(category, nodeFlags | nodeSelectionFlags);

                                        if (nodeOpen)
                                        {
                                                while (i < g_testCount && strcmp(category, g_testEntries[i].category) == 0)
                                                {
                                                        ImGuiTreeNodeFlags selectionFlags = 0;
                                                        if (s_settings.m_testIndex == i)
                                                        {
                                                                selectionFlags = ImGuiTreeNodeFlags_Selected;
                                                        }
                                                        ImGui::TreeNodeEx((void*)(intptr_t)i, leafNodeFlags | selectionFlags, "%s", g_testEntries[i].name);
                                                        if (ImGui::IsItemClicked())
                                                        {
                                                                delete s_test;
                                                                s_settings.m_testIndex = i;
                                                                s_test = g_testEntries[i].createFcn();
                                                                s_testSelection = i;
                                                        }
                                                        ++i;
                                                }
                                                ImGui::TreePop();
                                        }
                                        else
                                        {
                                                while (i < g_testCount && strcmp(category, g_testEntries[i].category) == 0)
                                                {
                                                        ++i;
                                                }
                                        }

                                        if (i < g_testCount)
                                        {
                                                category = g_testEntries[i].category;
                                                categoryIndex = i;
                                        }
                                }
                                ImGui::EndTabItem();
                        }
                        ImGui::EndTabBar();
                }

                ImGui::End();

                s_test->UpdateUI();
        }
}

//
int main(int, char**)
{
#if defined(_WIN32)
        // Enable memory-leak reports
        _CrtSetDbgFlag(_CRTDBG_LEAK_CHECK_DF | _CrtSetDbgFlag(_CRTDBG_REPORT_FLAG));
#endif

        char buffer[128];

        s_settings.Load();
        SortTests();

        glfwSetErrorCallback(glfwErrorCallback);

        g_camera.m_width = s_settings.m_windowWidth;
        g_camera.m_height = s_settings.m_windowHeight;

        if (glfwInit() == 0)
        {
                fprintf(stderr, "Failed to initialize GLFW\n");
                return -1;
        }

#if __APPLE__
    const char* glslVersion = "#version 150";
#else
    const char* glslVersion = NULL;
#endif

        glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3);
        glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 3);
        glfwWindowHint(GLFW_OPENGL_FORWARD_COMPAT, GL_TRUE);
        glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);

        sprintf(buffer, "Box2D Testbed Version %d.%d.%d", b2_version.major, b2_version.minor, b2_version.revision);

        bool fullscreen = false;
        if (fullscreen)
        {
                g_mainWindow = glfwCreateWindow(1920, 1080, buffer, glfwGetPrimaryMonitor(), NULL);
        }
        else
        {
                g_mainWindow = glfwCreateWindow(g_camera.m_width, g_camera.m_height, buffer, NULL, NULL);
        }

        if (g_mainWindow == NULL)
        {
                fprintf(stderr, "Failed to open GLFW g_mainWindow.\n");
                glfwTerminate();
                return -1;
        }

        glfwMakeContextCurrent(g_mainWindow);

        // Load OpenGL functions using glad
        int version = gladLoadGL(glfwGetProcAddress);
        printf("GL %d.%d\n", GLAD_VERSION_MAJOR(version), GLAD_VERSION_MINOR(version));
        printf("OpenGL %s, GLSL %s\n", glGetString(GL_VERSION), glGetString(GL_SHADING_LANGUAGE_VERSION));

        glfwSetScrollCallback(g_mainWindow, ScrollCallback);
        glfwSetWindowSizeCallback(g_mainWindow, ResizeWindowCallback);
        glfwSetKeyCallback(g_mainWindow, KeyCallback);
        glfwSetCharCallback(g_mainWindow, CharCallback);
        glfwSetMouseButtonCallback(g_mainWindow, MouseButtonCallback);
        glfwSetCursorPosCallback(g_mainWindow, MouseMotionCallback);
        glfwSetScrollCallback(g_mainWindow, ScrollCallback);

        g_debugDraw.Create();

        CreateUI(g_mainWindow, glslVersion);

        s_settings.m_testIndex = b2Clamp(s_settings.m_testIndex, 0, g_testCount - 1);
        s_testSelection = s_settings.m_testIndex;
        s_test = g_testEntries[s_settings.m_testIndex].createFcn();

        // Control the frame rate. One draw per monitor refresh.
        //glfwSwapInterval(1);

        glClearColor(0.2f, 0.2f, 0.2f, 1.0f);

        std::chrono::duration<double> frameTime(0.0);
        std::chrono::duration<double> sleepAdjust(0.0);

        while (!glfwWindowShouldClose(g_mainWindow))
        {
                std::chrono::steady_clock::time_point t1 = std::chrono::steady_clock::now();

                glfwGetWindowSize(g_mainWindow, &g_camera.m_width, &g_camera.m_height);
        
        int bufferWidth, bufferHeight;
        glfwGetFramebufferSize(g_mainWindow, &bufferWidth, &bufferHeight);
        glViewport(0, 0, bufferWidth, bufferHeight);

                glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

                ImGui_ImplOpenGL3_NewFrame();
                ImGui_ImplGlfw_NewFrame();

                ImGui::NewFrame();

                if (g_debugDraw.m_showUI)
                {
                        ImGui::SetNextWindowPos(ImVec2(0.0f, 0.0f));
                        ImGui::SetNextWindowSize(ImVec2(float(g_camera.m_width), float(g_camera.m_height)));
                        ImGui::SetNextWindowBgAlpha(0.0f);
                        ImGui::Begin("Overlay", nullptr, ImGuiWindowFlags_NoTitleBar | ImGuiWindowFlags_NoInputs | ImGuiWindowFlags_AlwaysAutoResize | ImGuiWindowFlags_NoScrollbar);
                        ImGui::End();

                        const TestEntry& entry = g_testEntries[s_settings.m_testIndex];
                        sprintf(buffer, "%s : %s", entry.category, entry.name);
                        s_test->DrawTitle(buffer);
                }

                s_test->Step(s_settings);

                UpdateUI();

                // ImGui::ShowDemoWindow();
                        
                if (g_debugDraw.m_showUI)
                {
                        sprintf(buffer, "%.1f ms", 1000.0 * frameTime.count());
                        g_debugDraw.DrawString(5, g_camera.m_height - 20, buffer);
                }

                ImGui::Render();
                ImGui_ImplOpenGL3_RenderDrawData(ImGui::GetDrawData());

                glfwSwapBuffers(g_mainWindow);

                if (s_testSelection != s_settings.m_testIndex)
                {
                        s_settings.m_testIndex = s_testSelection;
                        delete s_test;
                        s_test = g_testEntries[s_settings.m_testIndex].createFcn();
                        g_camera.m_zoom = 1.0f;
                        g_camera.m_center.Set(0.0f, 20.0f);
                }

                glfwPollEvents();

                // Throttle to cap at 60Hz. This adaptive using a sleep adjustment. This could be improved by
                // using mm_pause or equivalent for the last millisecond.
                std::chrono::steady_clock::time_point t2 = std::chrono::steady_clock::now();
                std::chrono::duration<double> target(1.0 / 60.0);
                std::chrono::duration<double> timeUsed = t2 - t1;
                std::chrono::duration<double> sleepTime = target - timeUsed + sleepAdjust;
                if (sleepTime > std::chrono::duration<double>(0))
                {
                        std::this_thread::sleep_for(sleepTime);
                }

                std::chrono::steady_clock::time_point t3 = std::chrono::steady_clock::now();
                frameTime = t3 - t1;

                // Compute the sleep adjustment using a low pass filter
                sleepAdjust = 0.9 * sleepAdjust + 0.1 * (target - frameTime);
        }

        delete s_test;
        s_test = nullptr;

        g_debugDraw.Destroy();
        ImGui_ImplOpenGL3_Shutdown();
        ImGui_ImplGlfw_Shutdown();
        glfwTerminate();

        s_settings.Save();

        return 0;
}