Use vector math in cyclone.

src/simulation/simtools/Cyclone.cpp

@@ -16,19 +16,23 @@ int Tool_Cycl::Perform(Simulation * sim, Particle * cpart, int x, int y, int bru
 {
 	/*
 		Air velocity calculation.
-		Air velocity X = cosine of cell angle
-		Angle of cell is calculated via cells X/Y relation to the brush center and arctangent
-		Angle has 1.57 radians added to it (90 degrees) in order to make the velocity be at 90 degrees to the centerpoint.
-		Ditto for Y, except Y uses sine
+		(x, y) -- turn 90 deg -> (-y, x)
 	*/
 	// only trigger once per cell (less laggy)
 	if ((x%CELL) == 0 && (y%CELL) == 0)
 	{
+		if(brushX == x && brushY == y)
+			return 1;
+
 		float *vx = &sim->air->vx[y / CELL][x / CELL];
 		float *vy = &sim->air->vy[y / CELL][x / CELL];
 
-		*vx -= (strength / 16) * (tpt::cos(1.57f + (tpt::atan2(brushY - y, brushX - x))));
-		*vy -= (strength / 16) * (tpt::sin(1.57f + (tpt::atan2(brushY - y, brushX - x))));
+		float dvx = brushX - x;
+		float dvy = brushY - y;
+		float invsqr = 1/sqrtf(dvx*dvx + dvy*dvy);
+
+		*vx -= (strength / 16) * (-dvy)*invsqr;
+		*vy -= (strength / 16) * dvx*invsqr;
 
 		// Clamp velocities
 		if (*vx > 256.0f)