Lightning direction affected by Newtonian gravity

src/elements/ligh.c

@@ -127,7 +127,7 @@ int update_LIGH(UPDATE_FUNC_ARGS)
 	 *
 	 * life - "thickness" of lighting (but anyway one pixel)
 	 *
-	 * tmp - angle of lighting
+	 * tmp - angle of lighting, measured in degrees anticlockwise from the positive x direction
 	 *
 	*/
 	int r,rx,ry, multipler, powderful;

src/powder.c

@@ -947,24 +947,6 @@ inline int create_part(int p, int x, int y, int tv)//the function for creating a
 	}*/
 	switch (t)
 	{
-		case PT_LIGH:
-			if (p==-2)
-			{
-				switch (gravityMode)
-				{
-					default:
-					case 0:
-						parts[i].tmp= 270+rand()%40-20;
-						break;
-					case 1:
-						parts[i].tmp = rand()%360;
-						break;
-					case 2:
-						parts[i].tmp = atan2(x-XCNTR, y-YCNTR)*(180.0f/M_PI)+90;
-				}
-				parts[i].tmp2 = 4;
-			}
-			break;
 		case PT_SOAP:
 			parts[i].tmp = -1;
 			parts[i].tmp2 = -1;
@@ -1175,6 +1157,27 @@ inline int create_part(int p, int x, int y, int tv)//the function for creating a
 				parts[i].tmp2 = 4;//tail
 				parts[i].life = 5;
 			}
+			if (t==PT_LIGH)
+			{
+				float gx, gy, gsize;
+				if (p!=-2)
+				{
+					parts[i].life=30;
+					parts[i].temp=parts[i].life*150.0f; // temperature of the lighting shows the power of the lighting
+				}
+				get_gravity_field(x, y, 1.0f, 1.0f, &gx, &gy);
+				gsize = gx*gx+gy*gy;
+				if (gsize<0.0016f)
+				{
+					float angle = (rand()%6284)*0.001f;//(in radians, between 0 and 2*pi)
+					gsize = sqrtf(gsize);
+					// randomness in weak gravity fields (more randomness with weaker fields)
+					gx += cosf(angle)*(0.04f-gsize);
+					gy += sinf(angle)*(0.04f-gsize);
+				}
+				parts[i].tmp = (((int)(atan2f(-gy, gx)*(180.0f/M_PI)))+rand()%40-20+360)%360;
+				parts[i].tmp2 = 4;
+			}
 	}
 	//and finally set the pmap/photon maps to the newly created particle
 	if (ptypes[t].properties & TYPE_ENERGY)