Gravity modes and Newtonian gravity for fireworks

Resolves issue #59

1 files changed, 15 insertions, 5 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;