Smoke particles

Co-authored-by: sigonasr2 <sigonasr2@gmail.com>

Smoke.h

@@ -0,0 +1,54 @@
+
+#include "pixelGameEngine.h"
+#include <algorithm>
+
+using namespace olc;
+
+class Smoke{
+    float riseSpd;
+    std::vector<vf2d> points;
+    std::vector<vf2d> uvs;
+    std::vector<Pixel> cols;
+    vf2d size;
+    vf2d pos;
+    float fadeSpd=1; //How much alpha to drop down per second.
+    int freq=rand()%2+1;
+    float alpha=128;
+    public:
+    Smoke(vf2d size, vf2d pos, float riseSpd=5.f, float fadeSpd=100)
+    :size(size),riseSpd(riseSpd),fadeSpd(fadeSpd) {
+        int ind=0;
+        points.push_back({pos.x,pos.y});
+        uvs.push_back({0,0});
+        cols.push_back(Pixel(128,128,128,128));
+        for (float i=0;i<2*M_PI;i+=2*M_PI/64) {
+            points.push_back({sinf(i)*size.x+pos.x,cosf(i)*size.y+pos.y});
+            uvs.push_back({0,0});
+            cols.push_back(Pixel(128,128,128,128));
+        }
+        points.push_back(points[1]);
+        uvs.push_back({0,0});
+        cols.push_back(Pixel(128,128,128,128));
+    };
+
+    void update(float fElapsedTime) {
+        alpha=std::clamp(alpha-fadeSpd*fElapsedTime,0.f,255.f);
+        for (int i=0;i<points.size();i++) {
+            points[i].y-=(riseSpd+rand()%1000/1000.0F*riseSpd*4)*fElapsedTime;
+            cols[i].a=(int)alpha;
+        }
+    }
+
+    void render(PixelGameEngine*engine) {
+        engine->DrawPolygonDecal(nullptr,points,uvs,cols);
+    }
+
+    bool expired() {
+        for (int i=0;i<cols.size();i++) {
+            if (cols[i].a>0) {
+                return false;
+            }
+        }
+        return true;
+    }
+};