[#111] Fixed vanishing particles

projects/sph/shaders/force.comp

@@ -4,7 +4,7 @@
 const float PI = 3.1415926535897932384626433832795;
 
 #define h 0.045
-#define gravity 9.81
+#define gravity -9.81
 #define mass 0.1
 #define viscosity 1500
 

projects/sph/shaders/pressure.comp

@@ -59,7 +59,7 @@ void main() {
             densitySum += mass * poly6(dist);
         }
     }
-    outParticle[id].density = densitySum;
+    outParticle[id].density = max(densitySum, 0.001f);
     outParticle[id].pressure = max((densitySum - offset), 0) * gasConstant;
     outParticle[id].position = inParticle[id].position;
     outParticle[id].velocity = inParticle[id].velocity;