Gravity modes and Newtonian gravity for fireworks

Resolves issue #59

2 files changed, 47 insertions, 17 deletions

diff --git a/src/elements/firw.c b/src/elements/firw.c
index 3f392b6..d0e863e 100644
--- a/src/elements/firw.c
+++ b/src/elements/firw.c
@@ -29,8 +29,19 @@ int update_FIRW(UPDATE_FUNC_ARGS) {
 					rt = parts[r>>8].type;
 					if (rt==PT_FIRE||rt==PT_PLSM||rt==PT_THDR)
 					{
+						float gx, gy, multiplier;
+						get_gravity_field(x, y, ptypes[PT_FIRW].gravity, 1.0f, &gx, &gy);
+						if (gx*gx+gy*gy < 0.001f)
+						{
+							float angle = (rand()%6284)*0.001f;//(in radians, between 0 and 2*pi)
+							gx += sinf(angle)*ptypes[PT_FIRW].gravity*0.5f;
+							gy += cosf(angle)*ptypes[PT_FIRW].gravity*0.5f;
+						}
 						parts[i].tmp = 1;
-						parts[i].life = rand()%40+60;
+						parts[i].life = rand()%10+20;
+						multiplier = (parts[i].life+20)*0.2f/sqrtf(gx*gx+gy*gy);
+						parts[i].vx -= gx*multiplier;
+						parts[i].vy -= gy*multiplier;
 					}
 				}
 	}
@@ -38,8 +49,7 @@ int update_FIRW(UPDATE_FUNC_ARGS) {
 		if (parts[i].life<=0) {
 			parts[i].tmp=2;
 		} else {
-			// TODO: different gravity modes + Newtonian gravity
-			parts[i].vy = -parts[i].life*0.04f - 0.1f;
+			parts[i].flags &= ~FLAG_STAGNANT;
 		}
 	}
 	else if (parts[i].tmp>=2) {
@@ -54,8 +64,8 @@ int update_FIRW(UPDATE_FUNC_ARGS) {
 			{
 				magnitude = ((rand()%60)+40)*0.05f;
 				angle = (rand()%6284)*0.001f;//(in radians, between 0 and 2*pi)
-				parts[np].vx = parts[i].vx + cosf(angle)*magnitude;
-				parts[np].vy = parts[i].vy + sinf(angle)*magnitude - 2.5f;
+				parts[np].vx = parts[i].vx*0.5f + cosf(angle)*magnitude;
+				parts[np].vy = parts[i].vy*0.5f + sinf(angle)*magnitude;
 				parts[np].ctype = col;
 				parts[np].tmp = 1;
 				parts[np].life = rand()%40+70;
diff --git a/src/elements/fwrk.c b/src/elements/fwrk.c
index f54877b..d6dc59c 100644
--- a/src/elements/fwrk.c
+++ b/src/elements/fwrk.c
@@ -17,22 +17,42 @@
 
 int update_FWRK(UPDATE_FUNC_ARGS) {
 	int r, rx, ry, np;
-	if ((parts[i].temp>400&&(9+parts[i].temp/40)>rand()%100000&&parts[i].life==0&&!pmap[y-1][x])||parts[i].ctype==PT_DUST)
+	if (parts[i].life==0 && ((parts[i].temp>400&&(9+parts[i].temp/40)>rand()%100000&&surround_space)||parts[i].ctype==PT_DUST))
 	{
-		np = create_part(-1, x , y-1 , PT_FWRK);
-		if (np!=-1)
+		float gx, gy, multiplier, gmax;
+		int randTmp;
+		get_gravity_field(x, y, ptypes[PT_FWRK].gravity, 1.0f, &gx, &gy);
+		if (gx*gx+gy*gy < 0.001f)
 		{
-			parts[np].vy = rand()%8-22;
-			parts[np].vx = rand()%20-rand()%20;
-			parts[np].life=rand()%15+25;
-			parts[np].dcolour = parts[i].dcolour;
-			kill_part(i);
-			return 1;
+			float angle = (rand()%6284)*0.001f;//(in radians, between 0 and 2*pi)
+			gx += sinf(angle)*ptypes[PT_FWRK].gravity*0.5f;
+			gy += cosf(angle)*ptypes[PT_FWRK].gravity*0.5f;
+		}
+		gmax = fmaxf(fabsf(gx), fabsf(gy));
+		if (eval_move(PT_FWRK, (int)(x-(gx/gmax)+0.5f), (int)(y-(gy/gmax)+0.5f), NULL))
+		{
+			multiplier = 15.0f/sqrtf(gx*gx+gy*gy);
+
+			//Some variation in speed parallel to gravity direction
+			randTmp = (rand()%200)-100;
+			gx += gx*randTmp*0.002f;
+			gy += gy*randTmp*0.002f;
+			//and a bit more variation in speed perpendicular to gravity direction
+			randTmp = (rand()%200)-100;
+			gx += -gy*randTmp*0.005f;
+			gy += gx*randTmp*0.005f;
+
+			parts[i].life=rand()%10+18;
+			parts[i].ctype=0;
+			parts[i].vx -= gx*multiplier;
+			parts[i].vy -= gy*multiplier;
+			parts[i].dcolour = parts[i].dcolour;
+			return 0;
 		}
 	}
 	if (parts[i].life>=45)
 		parts[i].life=0;
-	if ((parts[i].life<3&&parts[i].life>0)||(parts[i].vy>6&&parts[i].life>0))
+	if (parts[i].life<3&&parts[i].life>0)
 	{
 		int r = (rand()%245+11);
 		int g = (rand()%245+11);
@@ -47,8 +67,8 @@ int update_FWRK(UPDATE_FUNC_ARGS) {
 			{
 				magnitude = ((rand()%60)+40)*0.05f;
 				angle = (rand()%6284)*0.001f;//(in radians, between 0 and 2*pi)
-				parts[np].vx = parts[i].vx + cosf(angle)*magnitude;
-				parts[np].vy = parts[i].vy + sinf(angle)*magnitude - 2.5f;
+				parts[np].vx = parts[i].vx*0.5f + cosf(angle)*magnitude;
+				parts[np].vy = parts[i].vy*0.5f + sinf(angle)*magnitude;
 				parts[np].ctype = col;
 				parts[np].tmp = 1;
 				parts[np].life = rand()%40+70;