Sort out scopes in Simulation::UpdateParticles

src/simulation/Simulation.cpp

@@ -2229,27 +2229,16 @@ void Simulation::delete_part(int x, int y)//calls kill_part with the particle lo
 
 void Simulation::UpdateParticles(int start, int end)
 {
-	int i, j, x, y, t, r, surround_space, s, rt, nt;
-	float mv, dx, dy, nrx, nry, dp, ctemph, ctempl, gravtot;
-	int fin_x, fin_y, clear_x, clear_y, stagnant;
-	float fin_xf, fin_yf, clear_xf, clear_yf;
-	float nn, ct1, ct2, swappage;
-	float pt = R_TEMP;
-	float c_heat = 0.0f;
-	int h_count = 0;
-	int surround[8];
-	int surround_hconduct[8];
-	bool transitionOccurred;
-
 	//the main particle loop function, goes over all particles.
-	for (i = start; i < end && i <= parts_lastActiveIndex; i++)
+	for (auto i = start; i < end && i <= parts_lastActiveIndex; i++)
+	{
 		if (parts[i].type)
 		{
 			debug_mostRecentlyUpdated = i;
-			t = parts[i].type;
+			auto t = parts[i].type;
 
-			x = (int)(parts[i].x+0.5f);
+			auto x = (int)(parts[i].x+0.5f);
-			y = (int)(parts[i].y+0.5f);
+			auto y = (int)(parts[i].y+0.5f);
 
 			// Kill a particle off screen
 			if (x<CELL || y<CELL || x>=XRES-CELL || y>=YRES-CELL)
@@ -2345,18 +2334,28 @@ void Simulation::UpdateParticles(int start, int end)
 #endif
 			}
 
-			transitionOccurred = false;
+			auto transitionOccurred = false;
 
-			j = surround_space = nt = 0;//if nt is greater than 1 after this, then there is a particle around the current particle, that is NOT the current particle's type, for water movement.
+			int surround[8];
-			for (auto nx=-1; nx<2; nx++)
+			auto surround_space = 0;
-				for (auto ny=-1; ny<2; ny++) {
+			auto nt = 0; //if nt is greater than 1 after this, then there is a particle around the current particle, that is NOT the current particle's type, for water movement.
-					if (nx||ny) {
+			{
-						surround[j] = r = pmap[y+ny][x+nx];
+				auto j = 0;
-						j++;
+				for (auto nx=-1; nx<2; nx++)
-						surround_space += (!TYP(r)); // count empty space
+				{
-						nt += (TYP(r)!=t); // count empty space and particles of different type
+					for (auto ny=-1; ny<2; ny++)
+					{
+						if (nx||ny)
+						{
+							auto r = pmap[y+ny][x+nx];
+							surround[j] = r;
+							j++;
+							surround_space += (!TYP(r)); // count empty space
+							nt += (TYP(r)!=t); // count empty space and particles of different type
+						}
 					}
 				}
+			}
 
 			float gel_scale = 1.0f;
 			if (t==PT_GEL)
@@ -2371,10 +2370,10 @@ void Simulation::UpdateParticles(int start, int end)
 					auto offsetX = int(std::round(convGravX + x));
 					auto offsetY = int(std::round(convGravY + y));
 					if ((offsetX != x || offsetY != y) && offsetX >= 0 && offsetX < XRES && offsetY >= 0 && offsetY < YRES) {//some heat convection for liquids
-						r = pmap[offsetY][offsetX];
+						auto r = pmap[offsetY][offsetX];
 						if (!(!r || parts[i].type != TYP(r))) {
 							if (parts[i].temp>parts[ID(r)].temp) {
-								swappage = parts[i].temp;
+								auto swappage = parts[i].temp;
 								parts[i].temp = parts[ID(r)].temp;
 								parts[ID(r)].temp = swappage;
 							}
@@ -2383,42 +2382,43 @@ void Simulation::UpdateParticles(int start, int end)
 				}
 
 				//heat transfer code
-				h_count = 0;
 #ifdef REALISTIC
 				if (t&&(t!=PT_HSWC||parts[i].life==10)&&(elements[t].HeatConduct*gel_scale))
 #else
+				auto h_count = 0;
 				if (t && (t!=PT_HSWC||parts[i].life==10) && rng.chance(int(elements[t].HeatConduct*gel_scale), 250))
 #endif
 				{
 					if (aheat_enable && !(elements[t].Properties&PROP_NOAMBHEAT))
 					{
 #ifdef REALISTIC
-						c_heat = parts[i].temp*96.645/elements[t].HeatConduct*gel_scale*fabs(elements[t].Weight) + hv[y/CELL][x/CELL]*100*(pv[y/CELL][x/CELL]-MIN_PRESSURE)/(MAX_PRESSURE-MIN_PRESSURE)*2;
+						auto c_heat = parts[i].temp*96.645/elements[t].HeatConduct*gel_scale*fabs(elements[t].Weight) + hv[y/CELL][x/CELL]*100*(pv[y/CELL][x/CELL]-MIN_PRESSURE)/(MAX_PRESSURE-MIN_PRESSURE)*2;
 						float c_Cm = 96.645/elements[t].HeatConduct*gel_scale*fabs(elements[t].Weight) + 100*(pv[y/CELL][x/CELL]-MIN_PRESSURE)/(MAX_PRESSURE-MIN_PRESSURE)*2;
-						pt = c_heat/c_Cm;
+						auto pt = c_heat/c_Cm;
 						pt = restrict_flt(pt, -MAX_TEMP+MIN_TEMP, MAX_TEMP-MIN_TEMP);
 						parts[i].temp = pt;
 						//Pressure increase from heat (temporary)
 						pv[y/CELL][x/CELL] += (pt-hv[y/CELL][x/CELL])*0.004;
 						hv[y/CELL][x/CELL] = pt;
 #else
-						c_heat = (hv[y/CELL][x/CELL]-parts[i].temp)*0.04;
+						auto c_heat = (hv[y/CELL][x/CELL]-parts[i].temp)*0.04;
 						c_heat = restrict_flt(c_heat, -MAX_TEMP+MIN_TEMP, MAX_TEMP-MIN_TEMP);
 						parts[i].temp += c_heat;
 						hv[y/CELL][x/CELL] -= c_heat;
 #endif
 					}
-					c_heat = 0.0f;
+					auto c_heat = 0.0f;
 #ifdef REALISTIC
 					float c_Cm = 0.0f;
 #endif
-					for (j=0; j<8; j++)
+					int surround_hconduct[8];
+					for (auto j=0; j<8; j++)
 					{
 						surround_hconduct[j] = i;
-						r = surround[j];
+						auto r = surround[j];
 						if (!r)
 							continue;
-						rt = TYP(r);
+						auto rt = TYP(r);
 						if (rt && elements[rt].HeatConduct && (rt!=PT_HSWC||parts[ID(r)].life==10)
 						        && (t!=PT_FILT||(rt!=PT_BRAY&&rt!=PT_BIZR&&rt!=PT_BIZRG))
 						        && (rt!=PT_FILT||(t!=PT_BRAY&&t!=PT_PHOT&&t!=PT_BIZR&&t!=PT_BIZRG))
@@ -2441,6 +2441,7 @@ void Simulation::UpdateParticles(int start, int end)
 							h_count++;
 						}
 					}
+					float pt = R_TEMP;
 #ifdef REALISTIC
 					if (t==PT_GEL)
 						gel_scale = parts[i].tmp*2.55f;
@@ -2457,13 +2458,14 @@ void Simulation::UpdateParticles(int start, int end)
 #else
 					pt = (c_heat+parts[i].temp)/(h_count+1);
 					pt = parts[i].temp = restrict_flt(pt, MIN_TEMP, MAX_TEMP);
-					for (j=0; j<8; j++)
+					for (auto j=0; j<8; j++)
 					{
 						parts[surround_hconduct[j]].temp = pt;
 					}
 #endif
 
-					ctemph = ctempl = pt;
+					auto ctemph = pt;
+					auto ctempl = pt;
 					// change boiling point with pressure
 					if (((elements[t].Properties&TYPE_LIQUID) && IsElementOrNone(elements[t].HighTemperatureTransition) && (elements[elements[t].HighTemperatureTransition].Properties&TYPE_GAS))
 					        || t==PT_LNTG || t==PT_SLTW)
@@ -2471,7 +2473,7 @@ void Simulation::UpdateParticles(int start, int end)
 					else if (((elements[t].Properties&TYPE_GAS) && IsElementOrNone(elements[t].LowTemperatureTransition) && (elements[elements[t].LowTemperatureTransition].Properties&TYPE_LIQUID))
 					         || t==PT_WTRV)
 						ctempl -= 2.0f*pv[y/CELL][x/CELL];
-					s = 1;
+					auto s = 1;
 
 					//A fix for ice with ctype = 0
 					if ((t==PT_ICEI || t==PT_SNOW) && (!IsElement(parts[i].ctype) || parts[i].ctype==PT_ICEI || parts[i].ctype==PT_SNOW))
@@ -2665,7 +2667,7 @@ void Simulation::UpdateParticles(int start, int end)
 						s = 0;
 #ifdef REALISTIC
 					pt = restrict_flt(pt, MIN_TEMP, MAX_TEMP);
-					for (j=0; j<8; j++)
+					for (auto j=0; j<8; j++)
 					{
 						parts[surround_hconduct[j]].temp = pt;
 					}
@@ -2787,57 +2789,58 @@ void Simulation::UpdateParticles(int start, int end)
 				pv[y/CELL][x/CELL] += 0.25f * CFDS;
 			}
 
-
-			s = 1;
-			gravtot = fabs(gravy[(y/CELL)*XCELLS+(x/CELL)])+fabs(gravx[(y/CELL)*XCELLS+(x/CELL)]);
-			if (elements[t].HighPressureTransition>-1 && pv[y/CELL][x/CELL]>elements[t].HighPressure) {
-				// particle type change due to high pressure
-				if (elements[t].HighPressureTransition!=PT_NUM)
-					t = elements[t].HighPressureTransition;
-				else if (t==PT_BMTL) {
-					if (pv[y/CELL][x/CELL]>2.5f)
-						t = PT_BRMT;
-					else if (pv[y/CELL][x/CELL]>1.0f && parts[i].tmp==1)
-						t = PT_BRMT;
-					else s = 0;
-				}
-				else s = 0;
-			} else if (elements[t].LowPressureTransition>-1 && pv[y/CELL][x/CELL]<elements[t].LowPressure && gravtot<=(elements[t].LowPressure/4.0f)) {
-				// particle type change due to low pressure
-				if (elements[t].LowPressureTransition!=PT_NUM)
-					t = elements[t].LowPressureTransition;
-				else s = 0;
-			} else if (elements[t].HighPressureTransition>-1 && gravtot>(elements[t].HighPressure/4.0f)) {
-				// particle type change due to high gravity
-				if (elements[t].HighPressureTransition!=PT_NUM)
-					t = elements[t].HighPressureTransition;
-				else if (t==PT_BMTL) {
-					if (gravtot>0.625f)
-						t = PT_BRMT;
-					else if (gravtot>0.25f && parts[i].tmp==1)
-						t = PT_BRMT;
-					else s = 0;
-				}
-				else s = 0;
-			} else s = 0;
-
-			// particle type change occurred
-			if (s)
 			{
-				if (t == PT_NONE)
+				auto s = 1;
+				auto gravtot = fabs(gravy[(y/CELL)*XCELLS+(x/CELL)])+fabs(gravx[(y/CELL)*XCELLS+(x/CELL)]);
+				if (elements[t].HighPressureTransition>-1 && pv[y/CELL][x/CELL]>elements[t].HighPressure) {
+					// particle type change due to high pressure
+					if (elements[t].HighPressureTransition!=PT_NUM)
+						t = elements[t].HighPressureTransition;
+					else if (t==PT_BMTL) {
+						if (pv[y/CELL][x/CELL]>2.5f)
+							t = PT_BRMT;
+						else if (pv[y/CELL][x/CELL]>1.0f && parts[i].tmp==1)
+							t = PT_BRMT;
+						else s = 0;
+					}
+					else s = 0;
+				} else if (elements[t].LowPressureTransition>-1 && pv[y/CELL][x/CELL]<elements[t].LowPressure && gravtot<=(elements[t].LowPressure/4.0f)) {
+					// particle type change due to low pressure
+					if (elements[t].LowPressureTransition!=PT_NUM)
+						t = elements[t].LowPressureTransition;
+					else s = 0;
+				} else if (elements[t].HighPressureTransition>-1 && gravtot>(elements[t].HighPressure/4.0f)) {
+					// particle type change due to high gravity
+					if (elements[t].HighPressureTransition!=PT_NUM)
+						t = elements[t].HighPressureTransition;
+					else if (t==PT_BMTL) {
+						if (gravtot>0.625f)
+							t = PT_BRMT;
+						else if (gravtot>0.25f && parts[i].tmp==1)
+							t = PT_BRMT;
+						else s = 0;
+					}
+					else s = 0;
+				} else s = 0;
+
+				// particle type change occurred
+				if (s)
 				{
-					kill_part(i);
+					if (t == PT_NONE)
-					goto killed;
+					{
+						kill_part(i);
+						goto killed;
+					}
+					parts[i].life = 0;
+					// part_change_type could refuse to change the type and kill the particle
+					// for example, changing type to STKM but one already exists
+					// we need to account for that to not cause simulation corruption issues
+					if (part_change_type(i,x,y,t))
+						goto killed;
+					if (t == PT_FIRE)
+						parts[i].life = rng.between(120, 169);
+					transitionOccurred = true;
 				}
-				parts[i].life = 0;
-				// part_change_type could refuse to change the type and kill the particle
-				// for example, changing type to STKM but one already exists
-				// we need to account for that to not cause simulation corruption issues
-				if (part_change_type(i,x,y,t))
-					goto killed;
-				if (t == PT_FIRE)
-					parts[i].life = rng.between(120, 169);
-				transitionOccurred = true;
 			}
 
 			//call the particle update function, if there is one
@@ -2862,57 +2865,44 @@ killed:
 			if (!parts[i].vx&&!parts[i].vy)//if its not moving, skip to next particle, movement code it next
 				continue;
 
-			mv = fmaxf(fabsf(parts[i].vx), fabsf(parts[i].vy));
+			int fin_x, fin_y, clear_x, clear_y;
-			if (mv < ISTP)
+			float fin_xf, fin_yf, clear_xf, clear_yf;
 			{
-				clear_x = x;
+				auto mv = fmaxf(fabsf(parts[i].vx), fabsf(parts[i].vy));
-				clear_y = y;
+				if (mv < ISTP)
-				clear_xf = parts[i].x;
-				clear_yf = parts[i].y;
-				fin_xf = clear_xf + parts[i].vx;
-				fin_yf = clear_yf + parts[i].vy;
-				fin_x = (int)(fin_xf+0.5f);
-				fin_y = (int)(fin_yf+0.5f);
-			}
-			else
-			{
-				if (mv > MAX_VELOCITY)
 				{
-					parts[i].vx *= MAX_VELOCITY/mv;
+					clear_x = x;
-					parts[i].vy *= MAX_VELOCITY/mv;
+					clear_y = y;
-					mv = MAX_VELOCITY;
+					clear_xf = parts[i].x;
-				}
+					clear_yf = parts[i].y;
-				// interpolate to see if there is anything in the way
+					fin_xf = clear_xf + parts[i].vx;
-				dx = parts[i].vx*ISTP/mv;
+					fin_yf = clear_yf + parts[i].vy;
-				dy = parts[i].vy*ISTP/mv;
-				fin_xf = parts[i].x;
-				fin_yf = parts[i].y;
-				fin_x = (int)(fin_xf+0.5f);
-				fin_y = (int)(fin_yf+0.5f);
-				bool closedEholeStart = InBounds(fin_x, fin_y) && (bmap[fin_y/CELL][fin_x/CELL] == WL_EHOLE && !emap[fin_y/CELL][fin_x/CELL]);
-				while (1)
-				{
-					mv -= ISTP;
-					fin_xf += dx;
-					fin_yf += dy;
 					fin_x = (int)(fin_xf+0.5f);
 					fin_y = (int)(fin_yf+0.5f);
-					if (edgeMode == EDGE_LOOP)
+				}
+				else
+				{
+					if (mv > MAX_VELOCITY)
 					{
-						bool x_ok = (fin_xf >= CELL-.5f && fin_xf < XRES-CELL-.5f);
+						parts[i].vx *= MAX_VELOCITY/mv;
-						bool y_ok = (fin_yf >= CELL-.5f && fin_yf < YRES-CELL-.5f);
+						parts[i].vy *= MAX_VELOCITY/mv;
-						if (!x_ok)
+						mv = MAX_VELOCITY;
-							fin_xf = remainder_p(fin_xf-CELL+.5f, XRES-CELL*2.0f)+CELL-.5f;
+					}
-						if (!y_ok)
+					// interpolate to see if there is anything in the way
-							fin_yf = remainder_p(fin_yf-CELL+.5f, YRES-CELL*2.0f)+CELL-.5f;
+					auto dx = parts[i].vx*ISTP/mv;
+					auto dy = parts[i].vy*ISTP/mv;
+					fin_xf = parts[i].x;
+					fin_yf = parts[i].y;
+					fin_x = (int)(fin_xf+0.5f);
+					fin_y = (int)(fin_yf+0.5f);
+					bool closedEholeStart = InBounds(fin_x, fin_y) && (bmap[fin_y/CELL][fin_x/CELL] == WL_EHOLE && !emap[fin_y/CELL][fin_x/CELL]);
+					while (1)
+					{
+						mv -= ISTP;
+						fin_xf += dx;
+						fin_yf += dy;
 						fin_x = (int)(fin_xf+0.5f);
 						fin_y = (int)(fin_yf+0.5f);
-					}
-					if (mv <= 0.0f)
-					{
-						// nothing found
-						fin_xf = parts[i].x + parts[i].vx;
-						fin_yf = parts[i].y + parts[i].vy;
 						if (edgeMode == EDGE_LOOP)
 						{
 							bool x_ok = (fin_xf >= CELL-.5f && fin_xf < XRES-CELL-.5f);
@@ -2921,33 +2911,50 @@ killed:
 								fin_xf = remainder_p(fin_xf-CELL+.5f, XRES-CELL*2.0f)+CELL-.5f;
 							if (!y_ok)
 								fin_yf = remainder_p(fin_yf-CELL+.5f, YRES-CELL*2.0f)+CELL-.5f;
+							fin_x = (int)(fin_xf+0.5f);
+							fin_y = (int)(fin_yf+0.5f);
 						}
-						fin_x = (int)(fin_xf+0.5f);
+						if (mv <= 0.0f)
-						fin_y = (int)(fin_yf+0.5f);
+						{
-						clear_xf = fin_xf-dx;
+							// nothing found
-						clear_yf = fin_yf-dy;
+							fin_xf = parts[i].x + parts[i].vx;
-						clear_x = (int)(clear_xf+0.5f);
+							fin_yf = parts[i].y + parts[i].vy;
-						clear_y = (int)(clear_yf+0.5f);
+							if (edgeMode == EDGE_LOOP)
-						break;
+							{
+								bool x_ok = (fin_xf >= CELL-.5f && fin_xf < XRES-CELL-.5f);
+								bool y_ok = (fin_yf >= CELL-.5f && fin_yf < YRES-CELL-.5f);
+								if (!x_ok)
+									fin_xf = remainder_p(fin_xf-CELL+.5f, XRES-CELL*2.0f)+CELL-.5f;
+								if (!y_ok)
+									fin_yf = remainder_p(fin_yf-CELL+.5f, YRES-CELL*2.0f)+CELL-.5f;
+							}
+							fin_x = (int)(fin_xf+0.5f);
+							fin_y = (int)(fin_yf+0.5f);
+							clear_xf = fin_xf-dx;
+							clear_yf = fin_yf-dy;
+							clear_x = (int)(clear_xf+0.5f);
+							clear_y = (int)(clear_yf+0.5f);
+							break;
+						}
+						//block if particle can't move (0), or some special cases where it returns 1 (can_move = 3 but returns 1 meaning particle will be eaten)
+						//also photons are still blocked (slowed down) by any particle (even ones it can move through), and absorb wall also blocks particles
+						int eval = eval_move(t, fin_x, fin_y, NULL);
+						if (!eval || (can_move[t][TYP(pmap[fin_y][fin_x])] == 3 && eval == 1) || (t == PT_PHOT && pmap[fin_y][fin_x]) || bmap[fin_y/CELL][fin_x/CELL]==WL_DESTROYALL || closedEholeStart!=(bmap[fin_y/CELL][fin_x/CELL] == WL_EHOLE && !emap[fin_y/CELL][fin_x/CELL]))
+						{
+							// found an obstacle
+							clear_xf = fin_xf-dx;
+							clear_yf = fin_yf-dy;
+							clear_x = (int)(clear_xf+0.5f);
+							clear_y = (int)(clear_yf+0.5f);
+							break;
+						}
+						if (bmap[fin_y/CELL][fin_x/CELL]==WL_DETECT && emap[fin_y/CELL][fin_x/CELL]<8)
+							set_emap(fin_x/CELL, fin_y/CELL);
 					}
-					//block if particle can't move (0), or some special cases where it returns 1 (can_move = 3 but returns 1 meaning particle will be eaten)
-					//also photons are still blocked (slowed down) by any particle (even ones it can move through), and absorb wall also blocks particles
-					int eval = eval_move(t, fin_x, fin_y, NULL);
-					if (!eval || (can_move[t][TYP(pmap[fin_y][fin_x])] == 3 && eval == 1) || (t == PT_PHOT && pmap[fin_y][fin_x]) || bmap[fin_y/CELL][fin_x/CELL]==WL_DESTROYALL || closedEholeStart!=(bmap[fin_y/CELL][fin_x/CELL] == WL_EHOLE && !emap[fin_y/CELL][fin_x/CELL]))
-					{
-						// found an obstacle
-						clear_xf = fin_xf-dx;
-						clear_yf = fin_yf-dy;
-						clear_x = (int)(clear_xf+0.5f);
-						clear_y = (int)(clear_yf+0.5f);
-						break;
-					}
-					if (bmap[fin_y/CELL][fin_x/CELL]==WL_DETECT && emap[fin_y/CELL][fin_x/CELL]<8)
-						set_emap(fin_x/CELL, fin_y/CELL);
 				}
 			}
 
-			stagnant = parts[i].flags & FLAG_STAGNANT;
+			auto stagnant = parts[i].flags & FLAG_STAGNANT;
 			parts[i].flags &= ~FLAG_STAGNANT;
 
 			if (t==PT_STKM || t==PT_STKM2 || t==PT_FIGH)
@@ -3031,25 +3038,26 @@ killed:
 						int lt_glas = (lt == PT_GLAS) || (lt == PT_BGLA);
 						if ((rt_glas && !lt_glas) || (lt_glas && !rt_glas))
 						{
+							float nrx, nry;
 							if (!get_normal_interp(REFRACT|t, parts[i].x, parts[i].y, parts[i].vx, parts[i].vy, &nrx, &nry)) {
 								kill_part(i);
 								continue;
 							}
 
-							r = get_wavelength_bin(&parts[i].ctype);
+							auto r = get_wavelength_bin(&parts[i].ctype);
 							if (r == -1 || !(parts[i].ctype&0x3FFFFFFF))
 							{
 								kill_part(i);
 								continue;
 							}
-							nn = GLASS_IOR - GLASS_DISP*(r-30)/30.0f;
+							auto nn = GLASS_IOR - GLASS_DISP*(r-30)/30.0f;
 							nn *= nn;
 							auto enter = rt_glas && !lt_glas;
 							nrx = enter ? -nrx : nrx;
 							nry = enter ? -nry : nry;
 							nn = enter ? 1.0f/nn : nn;
-							ct1 = parts[i].vx*nrx + parts[i].vy*nry;
+							auto ct1 = parts[i].vx*nrx + parts[i].vy*nry;
-							ct2 = 1.0f - (nn*nn)*(1.0f-(ct1*ct1));
+							auto ct2 = 1.0f - (nn*nn)*(1.0f-(ct1*ct1));
 							if (ct2 < 0.0f) {
 								// total internal reflection
 								parts[i].vx -= 2.0f*ct1*nrx;
@@ -3087,7 +3095,7 @@ killed:
 						kill_part(i);
 						continue;
 					}
-					r = pmap[fin_y][fin_x];
+					auto r = pmap[fin_y][fin_x];
 
 					if ((TYP(r)==PT_PIPE || TYP(r) == PT_PPIP) && !TYP(parts[ID(r)].ctype))
 					{
@@ -3113,6 +3121,7 @@ killed:
 						parts[i].ctype &= mask;
 					}
 
+					float nrx, nry;
 					if (get_normal_interp(t, parts[i].x, parts[i].y, parts[i].vx, parts[i].vy, &nrx, &nry))
 					{
 						if (TYP(r) == PT_CRMC)
@@ -3122,13 +3131,13 @@ killed:
 							rx = cosf(r); ry = sinf(r);
 							anrx = rx * nrx + ry * nry;
 							anry = rx * nry - ry * nrx;
-							dp = anrx*parts[i].vx + anry*parts[i].vy;
+							auto dp = anrx*parts[i].vx + anry*parts[i].vy;
 							parts[i].vx -= 2.0f*dp*anrx;
 							parts[i].vy -= 2.0f*dp*anry;
 						}
 						else
 						{
-							dp = nrx*parts[i].vx + nry*parts[i].vy;
+							auto dp = nrx*parts[i].vx + nry*parts[i].vy;
 							parts[i].vx -= 2.0f*dp*nrx;
 							parts[i].vy -= 2.0f*dp*nry;
 						}
@@ -3201,17 +3210,16 @@ killed:
 					}
 					else
 					{
-						s = 1;
+						auto r = rng.between(0, 1) * 2 - 1;// position search direction (left/right first)
-						r = rng.between(0, 1) * 2 - 1;// position search direction (left/right first)
 						if ((clear_x!=x || clear_y!=y || nt || surround_space) &&
 							(fabsf(parts[i].vx)>0.01f || fabsf(parts[i].vy)>0.01f))
 						{
 							// allow diagonal movement if target position is blocked
 							// but no point trying this if particle is stuck in a block of identical particles
-							dx = parts[i].vx - parts[i].vy*r;
+							auto dx = parts[i].vx - parts[i].vy*r;
-							dy = parts[i].vy + parts[i].vx*r;
+							auto dy = parts[i].vy + parts[i].vx*r;
 
-							mv = std::max(fabsf(dx), fabsf(dy));
+							auto mv = std::max(fabsf(dx), fabsf(dy));
 							dx /= mv;
 							dy /= mv;
 							if (do_move(i, x, y, clear_xf+dx, clear_yf+dy))
@@ -3220,9 +3228,11 @@ killed:
 								parts[i].vy *= elements[t].Collision;
 								goto movedone;
 							}
-							swappage = dx;
+							{
-							dx = dy*r;
+								auto swappage = dx;
-							dy = -swappage*r;
+								dx = dy*r;
+								dy = -swappage*r;
+							}
 							if (do_move(i, x, y, clear_xf+dx, clear_yf+dy))
 							{
 								parts[i].vx *= elements[t].Collision;
@@ -3232,8 +3242,9 @@ killed:
 						}
 						if (elements[t].Falldown>1 && !grav->IsEnabled() && gravityMode==GRAV_VERTICAL && parts[i].vy>fabsf(parts[i].vx))
 						{
-							s = 0;
+							auto s = 0;
 							// stagnant is true if FLAG_STAGNANT was set for this particle in previous frame
+							int rt;
 							if (!stagnant || nt) //nt is if there is an something else besides the current particle type, around the particle
 								rt = 30;//slight less water lag, although it changes how it moves a lot
 							else
@@ -3243,7 +3254,7 @@ killed:
 								rt = int(parts[i].tmp*0.20f+5.0f);
 
 							auto nx = -1, ny = -1;
-							for (j=clear_x+r; j>=0 && j>=clear_x-rt && j<clear_x+rt && j<XRES; j+=r)
+							for (auto j=clear_x+r; j>=0 && j>=clear_x-rt && j<clear_x+rt && j<XRES; j+=r)
 							{
 								if ((TYP(pmap[fin_y][j])!=t || bmap[fin_y/CELL][j/CELL])
 									&& (s=do_move(i, x, y, (float)j, fin_yf)))
@@ -3266,7 +3277,7 @@ killed:
 							r = (parts[i].vy>0) ? 1 : -1;
 
 							if (s==1)
-								for (j=ny+r; j>=0 && j<YRES && j>=ny-rt && j<ny+rt; j+=r)
+								for (auto j=ny+r; j>=0 && j<YRES && j>=ny-rt && j<ny+rt; j+=r)
 								{
 									if ((TYP(pmap[j][nx])!=t || bmap[j/CELL][nx/CELL]) && do_move(i, nx, ny, (float)nx, (float)j))
 										break;
@@ -3282,11 +3293,11 @@ killed:
 						else if (elements[t].Falldown>1 && fabsf(pGravX*parts[i].vx+pGravY*parts[i].vy)>fabsf(pGravY*parts[i].vx-pGravX*parts[i].vy))
 						{
 							float nxf, nyf, prev_pGravX, prev_pGravY, ptGrav = elements[t].Gravity;
-							s = 0;
+							auto s = 0;
 							// stagnant is true if FLAG_STAGNANT was set for this particle in previous frame
 							// nt is if there is something else besides the current particle type around the particle
 							// 30 gives slightly less water lag, although it changes how it moves a lot
-							rt = (!stagnant || nt) ? 30 : 10;
+							auto rt = (!stagnant || nt) ? 30 : 10;
 
 							// clear_xf, clear_yf is the last known position that the particle should almost certainly be able to move to
 							nxf = clear_xf;
@@ -3294,12 +3305,12 @@ killed:
 							auto nx = clear_x;
 							auto ny = clear_y;
 							// Look for spaces to move horizontally (perpendicular to gravity direction), keep going until a space is found or the number of positions examined = rt
-							for (j=0;j<rt;j++)
+							for (auto j=0;j<rt;j++)
 							{
 								// Calculate overall gravity direction
 								GetGravityField(nx, ny, ptGrav, 1.0f, pGravX, pGravY);
 								// Scale gravity vector so that the largest component is 1 pixel
-								mv = std::max(fabsf(pGravX), fabsf(pGravY));
+								auto mv = std::max(fabsf(pGravX), fabsf(pGravY));
 								if (mv<0.0001f) break;
 								pGravX /= mv;
 								pGravY /= mv;
@@ -3346,12 +3357,12 @@ killed:
 								// Keep going until the particle is blocked (by something that isn't the same element) or the number of positions examined = rt
 								clear_x = nx;
 								clear_y = ny;
-								for (j=0;j<rt;j++)
+								for (auto j=0;j<rt;j++)
 								{
 									// Calculate overall gravity direction
 									GetGravityField(nx, ny, ptGrav, 1.0f, pGravX, pGravY);
 									// Scale gravity vector so that the largest component is 1 pixel
-									mv = std::max(fabsf(pGravX), fabsf(pGravY));
+									auto mv = std::max(fabsf(pGravX), fabsf(pGravY));
 									if (mv<0.0001f) break;
 									pGravX /= mv;
 									pGravY /= mv;
@@ -3391,10 +3402,13 @@ killed:
 movedone:
 			continue;
 		}
+	}
 
 	//'f' was pressed (single frame)
 	if (framerender)
+	{
 		framerender--;
+	}
 }
 
 void Simulation::RecalcFreeParticles(bool do_life_dec)