Simple pendulum

C++/Simple pendulum/main.cpp

@@ -0,0 +1,101 @@
+#include <iostream>
+#include <sstream>
+#include <math.h>
+
+#include "rect.h"
+
+#define OLC_PGE_APPLICATION
+#include "olcPixelGameEngine.h"
+
+#define PI 3.14159265359
+
+class SimplePendulum : public olc::PixelGameEngine {
+public:
+    SimplePendulum() {
+        sAppName = "Simple Pendulum";
+    }
+
+    bool OnUserCreate() override {
+        return true;
+    }
+
+    bool OnUserUpdate(float fElapsedTime) override {
+        /* START CALCULATONS */
+        if (!m_isStopped) {
+            m_aAccel = ((-1 * m_gravity / m_pLength) * sin(m_theta) * m_pMass) * fElapsedTime;
+
+            m_aVelocity += m_aAccel *= m_pDamping;
+            m_theta += m_aVelocity;
+        }
+
+        m_x = m_pLength * sin(m_theta) + m_pivotX;
+        m_y = m_pLength * cos(m_theta) + m_pivotY;
+        /* END CALCULATIONS */
+        draw();
+
+        std::stringstream angularVel;
+        angularVel << "Angular velocity: " << m_aVelocity;
+        DrawString(0, 0, angularVel.str(), olc::BLACK);
+        std::stringstream angularAccel;
+        angularAccel << "Angular acceleration: " << m_aAccel;
+        DrawString(0, 10, angularAccel.str(), olc::BLACK);
+        std::stringstream coords;
+        coords << "Pendulum bob pos X:" << m_x << " Y: " << m_y;
+        DrawString(0, 20, coords.str(), olc::BLACK);
+
+        Rect p;
+        p.SetRect(m_x - 40, m_y - 40, 80, 80);
+        if (p.Contains(Vec2<int>(GetMouseX(), GetMouseY()))) {
+            DrawRect(p.x, p.y, p.w, p.h, olc::DARK_MAGENTA);
+            if (GetMouse(0).bHeld) {
+                m_isStopped = true;
+                m_theta = atan2(GetMouseX() - m_pivotX, GetMouseY() - m_pivotY);
+                m_aAccel = 0.0f;
+                m_aVelocity = 0.0f;
+            }  else {
+                m_isStopped = false;
+            }
+        } else {
+            DrawRect(p.x, p.y, p.w, p.h, olc::RED);
+            m_isStopped = false;
+        }
+
+        return true;
+    }
+
+    void draw() {
+        Clear(olc::WHITE);
+        FillCircle(m_pivotX, m_pivotY, 8, olc::RED);
+        DrawLine(m_pivotX, m_pivotY, m_x, m_y, olc::BLACK);
+        if (!m_isStopped) {
+            FillCircle(m_x, m_y, 20, olc::BLACK);
+        } else {
+            FillCircle(m_x, m_y, 20, olc::DARK_GREY);
+        }
+    }
+private:
+    bool m_isStopped = false;
+    float m_theta = PI / 4;
+
+    float m_pivotX = 500;
+    float m_pivotY = 20;
+    float m_x = 500;
+    float m_y = 220;
+
+    float m_pLength = 300;
+
+    float m_aVelocity = 0.0f;
+    float m_aAccel = 0.0f;
+
+    float m_gravity = 9.81;
+    float m_pMass = 5;
+
+    float m_pDamping = 0.9;
+};
+
+int main(int argc, char** argv) {
+    SimplePendulum app;
+    if (app.Construct(1000, 600, 1, 1)) 
+        app.Start();
+    return 0;
+}